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Fundamentals of Water Heating

1. 56 Rheem Water Heaters Ruud Water Heaters 2600 Gunter Park Drive East Montgomery AL 36109 1413 1 800 HEATERS www rheem com PRINTED IN U S A 08 02 WP FORM NO SVC100 REV 1
2. Fundamentals Training Manual Rev 1 After you have calculated the actual peak hour demand load you can use a make and model chart to choose the correct water heater within 2 gallons capacity When selecting the proper size look for the first hour rating on the model chart The first hour rating is a function of the initial storage capacity plus the ability of the water heater to heat while in use In the example above you would select a Rheem residential electric water heater with a 65 gal lon storage capacity Use the table below to calculate the Peak Hour Demand A Avg Gallons Times per Total Hot Household Activity per activity hour Water used Shower or bath 20 Shave 2 Washing hands or face 4 Shampoo hair 4 Washing dishes by hand 4 Automatic dishwasher 14 Food preparation for a meal 5 Automatic clothes washer 32 Total Peak Hour Demand gallons Table 7 Peak Hour Demand Calculation Blank Worksheet Investigate the owners pattern of hot water usage Some sample questions may include Number of people in the family kids teenagers How many bathrooms garden tub or hot tub Automatic dishwasher Clothes washer Frequent visitors or family guests Recent remodeling involving hot water appliances 27 Fundamentals Training Manual Rev 1 ENERGY FACTOR Energy Factor is a relative number that is a standard measure for storage water heating products It is determined through a Department of Energy DOE standard test pr
3. tank All water heaters manufactured by Rheem Ruud have a separate and special connection designed for the T amp P valve When checking the valve also check the rating plate on the valve The BTU rating of the valve must equal or exceed the BTU rating of the water heater Fig 11 T amp P Valve Cutaway View Here are some common T amp P valve errors No T amp P installed or pressure only relief valve installed Non code or insufficient rating T amp P valve installed T amp P installed in the cold water line T amp P installed a distance from the tank such as in the hot outlet line T amp P has been altered repaired plugged or restricted Tips for the Temperature and Pressure Relief drain line Run to a safe place of disposal floor drain or outside Drain piping should be the same size as the valve discharge through its entire length Pitch downward from the valve and terminate 6 inches above the floor drain No longer than 30 feet Do not use more than four elbows Do not install a shut off valve in the drain line and terminate unthreaded Discharge of the T amp P indicates the existence of an unsafe temperature or pressure condition Fig 12 Proper T amp P Valve locations for residential or commercial water heaters 19 Fundamentals Training Manual Rev 1 PLUMBING CROSS OVER A plumbing cross over is a condition whereby cold water is allowed to flow into the hot water system The plumbing system in a home is divided into t
4. with regard to electric heaters the more insulation the more efficient the heater becomes Today s foam material utilizes an HCFC blowing agent which is environmentally friendly R Tech Anode Patented anode design that reduces current draw and results in a longer anode life Works in conjunction with the resistered heating element and is also effective with aggressive water areas which produce hydrogen sulfide smelly water R Value A measure of insulating value Generally the higher the R Value the greater the resistance to heat loss Recovery Gallons of water per hour a water heater can raise the temperature of by 90 Generally the higher the BTU input rate the faster the recovery rate is Recovery rates are also a component of the First Hour Rating Recovery Efficiency The percent of heat value transferred from its fuel source The better the recovery efficiency the more energy efficient a water heater is Electric water heaters are assumed to be 98 effi cient as virtually all the electric energy is transferred to the water Gas water heaters can have recovery efficiency rates of 76 up to over 90 This is only one measure of efficiency the ENERGY FACTOR is the best overall measure of a water heaters efficiency Recovery Rating All certified commercial water heaters are required to be stamped with this information It is the quantity of water obtained by dividing the manufacturer s input rating in BTU per hour by
5. 9 THERMAL EXPANSION TANKS 000060666 cece ccc cece eee eee eee eee 17 FIG 10 TEMPERATURE amp PRESSURE RELIEF VALVE eeeeevereeeeeeeereeeeee 18 FIG 11 T amp P VALVE CUTAWAY VIEW oo ooooooooooocorornororcrcrcrrnorr rro 19 FIG 12 PROPER T amp P VALVE LOCATIONS FOR RESIDENTIAL OR COMMERCIAL WATER HEATERS 19 FIG 13 SERIES INSTALLATION 9 5 Base a aed Geese wb lee ws aio ele Db ww WS ge eik 30 FIG 14 PARALLEL INSTALLATION 6254 that a Be SEE EEA es 31 TABLE 1 TABLE 2 TABLE 3 TABLE 4 TABLE 5 TABLE 6 TABLE 7 TABLE 8 RHEEM Fundamentals Training Manual Rev 1 Index of Tables SCALDING a a 3 PRESSURE BUILD UP IN A CLOSED SYSTEM eeeeeeveeeeeeeveeeeeeeeeee 16 SHOWER TIME AVAILABLE eveveveeneeevereeeeneeenereeeeneeeeee 23 DRAW TEST AND FLOW RATES voices a o 24 WATER HEATER RECOVERY RATES IN GALLONS PER HOUR oooooooooooo coo ooo 25 SAMPLE PEAK HOUR DEMAND CALCULATION 446666 26 PEAK HOUR DEMAND CALCULATION BLANK WORKSHEET o oooooooo ooo occ ro ooooo o 27 PERCENTAGE OF HOT AND COLD WATER MIX ooooocoooooooococccrrrrrcrrcn rs roo 32 Technical Support Line MANUFACTURING Service Department COMPANY 1 800 HEATER3 WATER HEATER DIVISION 1 800 432 8373 Ouestion comments Or
6. If the water stops flowing at your hot faucet the washing machine mixing valve is caus ing the cross over 5 If the flow does not stop then you must check by feel each of the feed lines to each of the single handle faucets If you find one faucet where both feed lines are equally cold that faucet is allowing an internal cross over to occur and should be rebuilt or replaced 6 If none of the above resolve the cross over a direct cross over exists in the plumbing somewhere This means the hot water sub system and the cold water sub system are direct ly tied together after the water heater When performing this test in a home that has only mixing single spigot faucets the test must be done twice Each test must be done using a different faucet The faucet used for the first test may be causing the problem and should be tested in the off position In a house with all double handle faucets you may find a shower head with a built in shut off shut off valve is connected directly to the shower head If the user shuts the shower head valve off but leaves the double handle tub facets open this would allow a direct cross over to occur 20 Fundamentals Training Manual Rev 1 HOT WATER AVAILABILITY AND CONSUMPTION FACTORS Before studying methods of computing recovery capacities of water heaters we should understand the meaning of several common ly used terms Recovery Capacity The maximum amount of water that can be heated by a
7. In residential applications this is usually restricted to a single delivery point such as a shower head Stand by heat loss Natural migration of heat from the inner tank to the atmosphere Insulation technology and insulation thickness significantly reduce stand by heat loss BTU British Thermal Unit The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit Since one gallon of water weighs 8 33 pounds it would require 8 33 BTU to raise one gallon of water one degree Fahrenheit The exact amount of fuel that the water must utilize 21 Fundamentals Training Manual Rev 1 in order to actually transfer the 8 33 BTU into the water is determined by the efficiency of the water heater in question Electric water heaters are considered to be 95 efficient that is 95 of the energy is transferred as heat into the water Therefore we can divide the standard BTU by the efficiency rating of the water heater to determine actual amount of BTU energy The formula would look like this 8 33 95 8 77 BTU Cold Inlet Temperature The temperature of outside water coming into a water heating system Throughout most of the U S this temperature is considered to be 40 F during the coldest months Peak Period Peak period refers to the time during the day when the water heating system experiences its greatest draw demand With the exception of applications that require continuous hot water draw tests hav
8. ambient air pressure and assists in the updraft movement of combustion gases Draft Hood equipped water heaters operate under a non positive type vent pressure The heat of the flue products provides the thermal lift to achieve a draft in the vent with cold air entering the combustion chamber to replace the hotter air rising The draft hood also functions as a relief opening in the event that the flue becomes blocked or experiences a down draft Drain Valve Valve used primarily to drain the hot water when performing periodic cleaning or replacing a part Draw Rate The rate at which water is drawn from a water heating system usually expressed in gallons per 41 Fundamentals Training Manual Rev 1 minute GPM In residential applications this is usually restricted to a single delivery point such as a shower head Dry Firing Refers to the condition of supplying power to an element in a water heater that is not complete ly full of water Power supplied to an element not submerged in water can cause the element to burn out and fail to operate ECO Energy Cut Off A safety cut off switch built into the thermostat of a water heater to shut off the flow of gas or electricity before temperatures reach unsafe levels The ECO will trip off at approximately 170 degrees Fahrenheit electric or 190 degrees Fahrenheit gas Efficiency Efficiency 1s a measure of performance expressing the results obtained as a percentage of effort put i
9. common mistake is incorrectly determining the source of the sulfur Hydrogen sulfide in most areas is usually present in the source water Hydrogen sulfide is pres ent in the incoming cold water supply and normally found only in ground water Hydrogen sul fide gas can produce a favorable condition for the growth of organisms referred to as sulfate reducing bacteria This favorable condition is enhanced with the application of heat such as in a water heater The smell is most noticeable with the first hot water draw in the morning or maybe when you get home from work In this instance the smell can be produced in the hot water system when sulfates are converted to sulfide by bacterial reduction These bacteria are known as Desulfovibrio Desulfuricans It is possible to completely remove the hydrogen sulfide at the point of entry only to have it re formed in the water heater To determine if the water heater is involved run the cold water only inside the house preferably in a shower stall If no 7 Fundamentals Training Manual Rev 1 odor is detected turn off the cold water and run the hot water only The presence of sulfur in the hot water but not the cold indicates that bacterial activity is the cause of the sulfur smell Iron Iron is a common element in nature It is not surprising that most surface or ground water contains some iron Natural iron usually occurs as an insoluble oxide but the ground water recharge process collects
10. demands during peak periods Radio controlled or timed meters are the most common method of off peak metering Orifice Device on the burner assembly that controls the flow of gas to the burner Output The output on a water heater is normally given in gallons per hour at a 100 F temperature rise It is the quantity of water that the heater will deliver at 140 F when the cold start temperature is 40 F All water heaters are stamped with this output rating in gallons per hour PVC Venting 3 PVC or ABS schedule 40 pipe can be used to vent Power Vent water heaters Peak Period Peak period refers to the time during the day when the water heating system experiences it greatest draw demand With the exception of applications that require continuous hot water draw tests have shown that the peak period of hot water usage will occur once or twice a day in residential applications Peak periods for commercial applications are dramatically different A peak period in a school gymnasium shower may occur ever hour Phase For ease of production and distribution AC is distributed in what is known as 3 phase supply using three active wires and one neutral wire On a 240 480 volt supply the voltage between any one active wire and the neutral wire is 240 volts The voltage between any two active wires is 480 volts Pilot Bracket The means by which the pilot is mounted to the burner The bracket also holds the thermocou ple or sensor in fixed re
11. deterioration or water quality by creat ing taste odor and staining problems Fundamentals Training Manual Rev 1 Turbidity Turbidity is the term given to anything that is suspended in a water supply It is found in most surface waters but usually doesn t exist in ground waters except in shallow wells and springs after heavy rains Turbidity gives the water a cloudy appearance or shows up as dirty sediment Undissolved materials such as sand clay silt or suspended iron contribute to turbidi ty Turbidity can cause the staining of sinks and fixtures as well as the discoloring of fabrics Turbidity can be particles in the water consisting of finely divided solids larger than molecules but not visible by the naked eye Odors amp Taste Taste and odor problems of many different types can be encountered in water that is heated Troublesome compounds may result from biological growth or industrial activities The tastes and odors may be produced in the water supply in the water treatment plant from reac tions with treatment chemicals in the distribution system or in the plumbing of consumers Tastes and odors can be caused by mineral contaminants in the water such as the salty taste of water when large quantities of chlorides are present or the rotten egg odor caused by hydrogen sulfide Moderate concentrations of algae in the water can cause it to have a grassy musty or spicy odor Decaying vegetation is probably the most com
12. gal of water 80 degrees F at 100 efficiency 1 Kwhr will raise 4 1 gal of water 100 degrees F at 100 efficiency Formula for mixing hot water M C H C Percent of hot water required to produce desired mixed temperature Where M mixed water temperature C cold water temperature H hot water temperature For example How much of a shower is hot water and how much is cold water My shower temperature is 105 F my water heater thermostat is set on 120 F and the cold water inlet temperature is 50 F 105 50 55 120 50 70 79 of the shower is 120 hot water This formula for mixing hot water is important when explaining a NOT ENOUGH HOT WATER trouble call and the water heater is functioning properly 34 Fundamentals Training Manual Rev 1 Fahrenheit to Centigrade F 32 556 For example Convert my water heater thermostat setting of 120 F to Celsius 120 32 556 88 556 49 C Centigrade to Fahrenheit C 1 8 32 For example Convert the outside temperature of 49 C to Fahrenheit 49 1 8 32 88 2 32 120 F Electric Energy Costs Kwhr x fuel costs energy costs If Tuse 100 kilowatt hours of electricity how much will it cost if each kilowatt hour costs 05 100 x 05 5 00 Electric To obtain gallons per hour GPH recovery WATTS 2 42 x temp rise F I have a 30 gallon electric heater non simulta neous operation 4500 watt elements What is
13. gallons available is initially slightly higher than the 70 rule due to the heating action of the heating elements during usage Eventually demand will consume the hot water faster than the elements can heat The chart above shows the actual amount of hot water available at 40 PSI system pres sure during the first hour of delivery and what that amount means in terms of shower time A higher system pressure will reduce shower time A common problem is the complaint of not enough hot water Earlier in this manual there was some diagnostics for mechanical failures that can cause this problem As you can see the source of the problem may not be mechanical it may be consumption Demand rate may also be another source of problem For example a shower head distributing 9 gallons per minute GPM will have less shower time than a shower head with 3 gallons per minute The lower the GPM the more hot water available DRAW TEST AND FLOW RATES Testing show head flow rate Flow rate is simply the gallons per minute GPM of water a faucet will allow at full force Flow rate of a shower head or other faucet fixture is important in determining the con sumption patterns of a user Using a bucket and a watch with a second hand draw cold shower water at full volume for 15 seconds Using the draw test table and a quart measure determine the number of quarts drawn in the 15 second period For example a homeowner has a 40 gallon water heater set to 12
14. hot water demand is taken equally from each unit For every gallon of hot water drawn from each unit one gallon of cold water is introduced into the water heater Each heater will then perform the same amount of work to heat the cold water TEMPERATURE AND ios PRESSURE GAUGE ot 7 MOT WATER SUPPLY HOT WATER RETURN te FROM FURTHEST FIXTURE sa O A r SR 2 a CS CIRCULATING PUMP 24 D g 7 SWING CHECK VALVE INSTALL ON HORIZONTAL ONLY e COLD WATER SUPPLY Fig 14 Parallel Installation Another important point of parallel installation is the length of the supply piping and delivery piping they must all be the same length Because the water pressure is constant along the cold inlet piping and hot water supply piping the heater with the closest run will do the majority of the work When installing heaters and storage tanks in parallel it is important to accurately plan and measure the distances from the cold water supply pipe to the heaters and from the hot water outlet on the heater to the hot water supply line This will equalize the work between the two water heaters Storage tanks are another option using parallel installation One heater is used to heat the water to thermostat temperature The heated water is stored in two storage tanks piped in parallel As the water is consumed at its point of use it is drawn equally from the two storage tanks and replaced with heated water fr
15. iron in a soluble form that is dissolved in water The water is clear when drawn but turns cloudy when it comes in contact with air The air oxidizes the fer rous iron and converts it to ferric iron Ferric iron or ferric hydroxide is visible in the water when drawn hence the name red water iron Heme iron is organically bound iron complexed with decomposed vegetation The organic materials complexed with the iron are called tannins or lignins These organics cause the water to have a weak tea or coffee color Certain types of bacteria use iron as an energy source They oxidize the iron from its ferrous state to its ferric state and deposit it in the slimy gelatinous material which surround them These bacteria grow in stringy clumps and are found in most iron bearing waters At 0 3 parts per million or greater concentrations iron can produce brown or red stains on plumbing fixtures laundry or masonry surfaces In higher concentrations it can produce an unpleasant metallic taste in the water Iron can also produce favorable conditions for the growth of iron bacteria Left untreated these bacteria results in a jelly like slimy mass This mass can cause clogged pipes and filter screens and produce a foul tasting water Other indica tions of the presence of iron are Black or rust colored particles that settle to the bottom of a container Water appears rusty or has a red or yellow color when drawn from a faucet Slimy brown or red film in p
16. mean If the thermostat is set on 120 degrees the unit should deliver 70 of tank volume at a temperature between 100 degrees and 120 degrees What does 70 of tank capacity mean It means 70 of the gallons capacity listed on the rating plate For example Tank capacity in gallons 70 rule in gallons 30 21 40 28 50 35 65 45 1 2 75 52 1 2 80 56 24 Fundamentals Training Manual Rev 1 Why only 70 of the tank capacity Simple cold water is entering the heater as the hot water is being used This cold water mixes with the hot water in the tank Much the same as cooling off a hot beverage with a little cold water the water heater works on the same principle As a hot water faucet is turned on the dip tube attached on the cold water inlet side of the heater delivers the cold water to the bottom of the tank The pressure of the incoming cold water pushes the hot water out of the tank Once enough cold water has entered the tank and mixed with the hot water this will cause the water to turn warm then tepid then cold This is how we calculate the 70 rule Once you have used the 70 of available hot water the water will quickly become cold As hot water is being used the thermostat s on the heater will demand heat and the unit will start to recover This means it will heat water even while hot water is being used The recovery capabilities of a water heater are standard characteristics and are factored in with the 70 rule to det
17. minutes will cause the bubbles to rise into the atmosphere and the water will turn clear The analogy is to boil a pot of water As the cold water is heated air bubbles form on the side of the pot These air bubbles are the 5 Fundamentals Training Manual Rev 1 gasses formed by the application of heat to the water The same thing happens on a smaller scale inside a water heater Heating water causes existing minerals to settle faster and in larger quantities As the water is heated it becomes lighter and less dense The naturally occurring solids although not visible to the eye will settle at a faster rate The result is sediment collecting at the bottom of the tank Routine draining maintenance will help reduce the collection of sediment If a homeowner does not periodi cally drain and flush the tank the sediment will harden on the bottom the tank The result is a clogged drain valve and reduced efficiency of the heater especially in gas water heaters Hot water is more corrosive than cold water Water is a universal solvent and will naturally corrode or dissolve most materials This corrosion is nothing more than a chemical reaction steel water oxygen rust Chemical reactions are usually accelerated with the appli cation of heat This is also true of corrosion reactions in hot water The rate of corrosion approximately doubles from 140 F to 160 F and doubles again from 160 F to 180 F With these few ideas i
18. returns to the same polarity Generally 60 cycle AC is supplied The cycles do not affect heating elements but may effect auxiliary equipment such as solenoids or coils Synchronous motors as used in clocks and tim ing mechanisms are directly affected by changes in cycle see also Hertz D C Direct Current Electrical supply in which the polarity of the two wires whether wire is positive or negative does not change Batteries produce DC DC supply is also found in railway use on board some ships and in older types of generating equipment While elements will operate equally on DC or AC auxiliary equipment such as thermostats motors etc do not and special arrange ments have to be made to enable an appliance designed for AC to operate on DC D O E Department of Energy Regulates the efficiency standards of all residential gas and electric water heaters with capaci ties from 20 to 120 gallons and inputs up to 75 000 BTU The current NAECA standards are 40 Fundamentals Training Manual Rev 1 administered by the Department of Energy which is required to review and recommend changes to the efficiency standards Dielectric unions Generally a plastic lined nipple used in water systems of dissimilar metals to break the galvanic circuit such as that created by copper and galvanized steel In most modern homes where cop per piping is used throughout the use of dielectric unions is not necessary Dip Tube A non metallic tub
19. seam or rupture Fig 8 Tank with Bulged Bottom The following figures are from an actual test conducted expressly to point out the dan ger of what happens to water pressure when heated a closed system Water Temperature F Tank Pressure P S I 74 80 75 85 76 105 78 125 80 T amp P actuates about here 145 82 175 85 225 88 275 90 At this point the tank bottom will 310 95 start to reverse and eventually 400 100 break a weld and leak 520 Table 2 Pressure build up in a Closed System Rheem water heater tanks are manufactured and tested to withstand a test pressure of 300 PSI and a working pressure of 150 PSI A bulged bottom immediately indicates that the tank has been subjected to a pressure in excess of 300 PSI and is not covered by warranty THERMAL EXPANSION When water is heated it expands Reacting to physical law water expands in volume as its temperature rises In a 40 gallon water heater water being heated to its thermostat setting will end up expanding to about 40 53 gallons when the desired temperature is reached The extra volume created by this expansion must go somewhere Before the advent of cross connection control expanded water that exceeded the capaci ty of the tank flowed back to the city main where it was easily dissipated It was open at the city side of the supply system Today with back flow preventers water meter check valves and 16 Fundamentals Training Manual Rev 1 pressure reducin
20. see ccc cc cee eee ce eee eee eects 26 ENERGY FACTOR 44 052058 baie E DASS sides aha AA GG TE 28 VACATIONS AND LONG TERM IDLE TIME veveeeeeeeereveeeeeeeereeeeee 28 SUBMERGED WATER HEATERS 44 44 68 5 toas os A Ee ORE NAIR ER OSE NARS rev 29 INSTALLATION SERIES AND PARALLEL cece eee cc ccc eee eee eee eee eee eee e 29 SERIES INSTALLATION A a Sree a Bee Sree Gases 30 PARALLEL INSTALLATION aasian titara veais ado dees E jidam Wb SR GAR 8 E E ere lee a 31 PERCENTAGE OF HOT AND COLD 32 FORMULAS AND FACTS vii a E a EEA dieses ele A woes 34 GLOSSARY a A A a At EE 37 FIG SCALDING WARNING 5000 e a led wie WE Wie Oe Be Rare eed whe Word ele a 3 FIG 2 FLAMMABLE VAPORS WARNING cee cece c cece eee cece eee eee eee 4 FIG 3 WATER HARDNESS aeree a a a 6 kata A A E ae ed 6 FIG 4 SEDIMENT BUMD UP o ieena A A Beck See BAW OER lore Bese ee OES 7 FIG 5 2 NEW ANODE ROD 552666 5 1844 30080 alata Bend A ie 9 FIG 6 PARTIALLY SACRIFICED ANODE ROD wo ee ccc cc cet eee eee eect eee eee eee 10 FIG 7 FULLY SACRIFICED ANODE ROD eveeeeueveeeeeeeeeeeeeeeeeeeeeeee 11 FIG 8 TANK WITH BULGED BOTTOM eee eee ect ccc eee eee 16 FIG
21. suggestions for this manual may be directed to the Technical Training Administrator 2600 Gunter Park Drive East Montgomery AL 36109 1413 FAX 334 260 1341 Email Techserv Orheem com Copyright 82000 Rheem Manufacturing Company Water Heater Division Warnings and Cautions Before inspecting diagnosing repairing or operating any water heater be sure to exam ine all of the safety and warning labels on the tank Follow the instruction on these warning labels Read and understand the Use and Care Manual that was shipped with the water heater Failure to do so can result in unsafe operation of the water heater resulting in property damage bodily injury or death Should you have any problems reading or following the instructions in the Use and Care Manual seek the help of a licensed and qualified professional Fundamentals Training Manual Rev 1 INTRODUCTION This is a training manual not a job site service manual nor a parts manual The intent of this manual is to train users of residential or commercial water heaters using gas or electrici ty as a fuel source This manual does not assume any particular user liability skill level expe rience or expertise The terms and component parts used in this manual are current manufac tured items or vendor provided items used in Rheem water heaters Finally we encourage all users to exercise good common sense and check your local plumbing gas and electrical codes WATER HEAT
22. the recover GPH if my cold water is 40 F and my thermostat is set to 120 F 4500 2 42 x 80 23 gallons per hour Gas Energy Costs Cubic feet x fuel costs energy costs If I use 100 cubic feet of gas how much will it cost if each cubic foot costs 075 100 x 075 7 50 Gas To obtain gallons per hour GPH recovery HOURLY INPUT BTUs 11 0 x temp rise F I have a 30 gallon gas heater rated at 40 000 BTUs What is the recover GPH if my cold water is 40 F and my thermostat is 120 F 45 gallons per hour 35 Fundamentals Training Manual Rev 1 Electric Gas Temperature Rise F Temperature Rise F WATTS HOURLY INPUT BTUs 2 42 x GPH 11 0 x GPH I have a 30 gallon electric heater non simulta I have a 30 gallon gas heater rated at 40 000 neous operation 4500 watt elements What is BTUs What is the maximum temperature rise the maximum temperature rise if the heater can if the heater can recover 45 gallons per hour recover 23 gallons per hour 4500 40 000 2 42 x 23 80 degrees temp rise 11 0 x 45 80 degrees temp rise NOTES 36 Fundamentals Training Manual Rev 1 GLOSSARY Aerated Pilot Pilots which inject primary air through an air intake opening and mix the air and gas before burning A G A American Gas Association The association which governs the testing and certification to the ANSI Z21 10 1 standards of residential natur
23. water heater tank is under a certain pressure depending on the supply pressure in the system the cold water supply pressure to the residence As this water is heated its volume increases If there is no check valve pressure reducing valve or other obstruction in the cold water line the system is open and water pressure will back up into the cold water supply line If enough pressure exists inside the water heater the pressure will force water back into the municipal supply system Therefore in an open system the water pressure in the water heater tank will always be equal to the supply pressure Some municipalities are introducing codes that prevent this return to the city main system The presence of a check valve backflow preventer water pressure reducing valve or closing the shut off valve in the cold water line makes the plumbing system a closed system 15 Fundamentals Training Manual Rev 1 In this situation the increased water pressure is trapped inside the heater tank and cannot back up or equalize into the cold water supply line Being trapped the pressure will become increasingly greater Eventually the pressure inside the water heater will exceed the limits of the Temperature amp Pressure relief T amp P valve and the valve will discharge If the T amp P valve is not installed or not operating an even more serious condition could develop If the pressure inside the tank is not released the tank may split a weld
24. 0 50 63 69 75 81 88 94 100 55 60 67 73 80 87 93 100 60 57 64 71 79 86 93 100 65 54 62 69 71 85 92 100 70 50 58 67 75 83 92 100 75 45 55 64 73 82 91 100 Cold Inlet Cold Inlet Table 8 Percentage of Hot and Cold Water Mix 32 Fundamentals Training Manual Rev 1 Thermostat 135 Mixed Temperature 100 105 110 115 120 125 130 133 40 63 68 74 19 84 89 95 100 45 6l 61 72 18 83 89 94 100 50 59 65 71 76 82 88 94 100 55 56 63 69 75 81 88 94 100 60 53 60 67 73 80 87 93 100 65 50 57 64 71 79 86 93 100 70 46 54 62 69 77 85 92 100 75 42 50 58 67 75 83 92 100 Thermostat 140 Mixed Temperature 100 105 110 115 120 125 130 135 140 40 60 65 70 75 80 85 90 95 100 Cold Inlet Cold Inlet 58 63 68 74 79 84 89 95 100 50 56 61 67 72 78 83 89 94 100 55 53 59 65 71 76 82 88 94 100 60 50 56 63 69 75 81 88 94 100 65 47 53 60 67 73 80 87 93 100 70 43 50 57 64 71 79 86 93 100 75 38 46 54 62 69 77 85 92 100 Thermostat 150 Mixed Temperature 100 110 120 130 140 150 Gold Inlet 40 x 55 64 73 82 91 100 Commercial 50 50 60 70 80 90 100 60 44 56 67 78 89 100 Temperatures 70 38 50 63 75 88 100 Thermostat 160 Mixed Temperature 100 110 120 130 140 150 160 Cola me
25. 0 F That will allow approximately 36 gallons of hot shower water at 110 If the homeowner has a conservative flow rate of 3 GPM the shower will last 12 minutes If the homeowner has a wasteful flow 23 Fundamentals Training Manual Rev 1 rate of 9 GPM the shower will last 4 minutes Very often the homeowner will complain of NOT ENOUGH HOT WATER and blame the water heater Actually the water heater is fine the homeowner has a wasteful consumption pattern and possibly an undersized water heater NUMBER OF QUARTS GALLONS PER MINUTE IN 15 SECONDS FLOW GPM 1 1 2 2 3 3 4 4 i 7 7 8 8 9 9 10 10 Table 4 Draw Test and Flow Rates FIRST HOUR DELIVERY First Hour Delivery or sometimes called first hour rating is a term that describes the performance capability of the water heater By definition first hour delivery is the calculated amount of hot water a fully heated water heater can deliver in the first hour period This means you start with a water heater that has recovered to its thermostat setting fully heated and someone starts to use hot water such as in a shower It does not mean the hot water will last for one full hour The Federal Government requires manu facturers to put a yellow ENERGYGUIDE label on a residential water heater This label shows the first hour rating for the product A residential water heater will deliver 70 of tank capacity at the thermostat setting minus 20 degrees What does this
26. 1100 BTU per gallon This is based on a 100 F temperature rise 75 percent thermal efficiency and a nominal specific heat for water of 8 25 BTU per gallon per F Resistored Element Element available from Rheem that has a small resistor built into the element to reduce cathod ic reaction with the water inside the tank ALL electric water heater elements supplied by Rheem are resistered Roof Jack Vent Used with manufactured housing gas water heaters the roof jack is the venting system from the water heater to the outside air It is adjustable to accommodate different roof thickness and pitches A roof jack supplied by Rheem is required on any mobile home direct vent water heater 49 Fundamentals Training Manual Rev 1 SCAQMD South Coast Air Quality Management District Required by the Environment Protection Agency to limit the amount of nitrous oxides Nox emissions from residential natural gas water heaters up to 75 000 BTU The SCAQMD requirements are enforced in various areas of California Safety Shut off Valve A device on a gas appliance which shuts off the gas supply to the appliance to prevent a haz ardous situation A flame failure safety shut off or safety pilot operates when the actuating flame becomes extinguished A 100 shutoff valve cuts off all gas including main and pilot burners Other types may cut off only the supply to main burners Sanitizing Water 180 F Sanitization means the effective bactericida
27. ER SAFETY Here are some important safety issues to consider when servicing or repairing a water heater Scalding ADANGER Water temperature over 125 F can cause severe burns instantly or death from scalds Children disabled and elderly are at highest risk of being scalded See Instruction manual before setting temperature at water heater Feel water before bathing or showering Temperature limiting valves are available see manual Fig 1 Scalding Warning Table courtesy of Shriner s Burn Institute Water temperatures over 125 degrees Fahrenheit can cause severe burns instantly or death from scalds Children disabled and elderly are at the highest risk of being scalded and may require a thermostat setting of 120 degrees or lower to pre vent contact with HOT water Safety and energy conservation are factors to be considered when selecting the water temperature setting of a water heaters thermostat It will take less than five seconds to produce a serious burn if the water temperature is 140 degrees Maximum water temperatures occur just after the water heater has recovered heated all the water in the tank to the ther mostat setting To find the hot water temperature being deliv ered turn on a hot water faucet place a thermometer in the hot water stream and read the temperature on the thermometer You may also consider installing thermostatically controlled shower and tub valves which reduce the water temperatur
28. Fundamentals of Water Heating Fundamentals Training Manual Rev 1 Fundamentals of Water Heating Training Manual Table of Contents INTRODUCTION A e Bb Se A A A E WES t 3 WATER HEATER SAFETY carora terane fu tata re ira ute Wee s one oleva mia aa te v e 3 WATER CHEMISTRY 5 ANODE RODS AND CATHODIC PROTECTION evenueveveeneveeeeeeeeeeeeeeeer reed 9 MILKY WATER AND DISSOLVED GASSES 2 ccc cece ccc cece cee eee eee e eee ents ee 11 SMELLY WATER AND THE ROTTEN EGG ODOR oooooooooooooooccccrrrrrrcrccrrrrnnnoo oso 12 CHLORINATION OF WATER HEATER TANKS eeeveveeeeeeeeeeeeeeeeeeeeeeee 13 DIAGNOSING YOUR WATER PROBLEM cece cece cece reece eee eee eee eee eee 14 OPEN AND CLOSED WATER HEATER SYSTEMS cc ccc cc cece eee cece ee eee eee e eset eeeees 15 THERMAL EXPANSION 35404 sennie e ninio e kroner 6 acs Scale ii siii taa 16 TEMPERATURE AND PRESSURE RELIEF T amp P VALVES ooooooooooooooooooorrrrrcrrcrooo 18 PLUMBING CROSS OVER viii ee at vk telke valele ii 418 viel 20 HOT WATER AVAILABILITY AND CONSUMPTION FACTORS eeeeeneeeeeeeeeerereeee 21 DRAW TEST AND FLOW RATES a EAE acs E Ste Sean ve BES 0 See a8 aj Vise JAMIE ace lid ore 23 FIRST HOUR DELIVERY iste A SSS NSS IA Ee ea Mies ONS PRR OS BAG 24 SIZING OF A RESIDENTIAL WATER HEATER
29. If the water heater is to remain idle for an extended period to time such as a week long vacation the power and the water to the water heater should be turned off to conserve energy Water heaters that have been idle for a long time are a safety hazard Hydrogen gas can be produced in a hot water system that has not been used for a long period of time generally two weeks or more Hydrogen gas is extremely flammable To dis sipate hydrogen gas from a heater it is recommended that the hot water faucet be opened for several minutes at the kitchen sink before using any electrical appliance connected to the hot water system If hydrogen gas is present there will probably be an unusual noise such as air escaping through the pipe as the water begins to flow Do not smoke or use an open flame near the faucet at the time it is open 28 Fundamentals Training Manual Rev 1 SUBMERGED WATER HEATERS If your water heater s gas or electric has been submerged in water DO NOT ATTEMPT to repair install or operate the product Due to the conductivity of water along with its corrosive properties all the operational controls are rendered unsafe As for the insula tion properties of the product it would have become saturated with water which cannot be removed resulting in exterior corrosion and failure of the product The affected water heater s should be removed made unusable and replaced with a new unit As a further note warranties on our pro
30. Sacrificed Anode Rod MILKY WATER AND DISSOLVED GASSES Gasses such as oxygen chlorine carbon dioxide hydrogen sulfide and others are solu ble in water In fact water is made up of two gasses Hydrogen and Oxygen H O The amount of gas that water can hold is decreased as the temperature of the water increases For example a pot of cold water is placed on a stove to boil When the pot is first put on the stove there are no 11 Fundamentals Training Manual Rev 1 bubbles As the water is heated bubbles form on the bottom and sides of the pot This is the perfect example of gasses naturally present in the water being released as the temperature of the water increases Another point that is noteworthy is that hot water from a faucet may also expel these naturally occurring gasses One of the more common occurrences is the phenomenon called milky water The hot water when drawn into a clear glass may appear discolored or chalky Allow the glass to stand for a few minutes and the water becomes clear By allowing the water to stand for several minutes the small gas bubbles that give the appearance of milky water will dissipate and the condition will clear Aerated faucets may help in reducing the likelihood of this happening In the plumbing field we should also be aware of a couple of other effects of this gas release As pressure inside a plumbing system increases the waters ability to retain dissolved gasses increases The hi
31. al and LP gas fired water heaters AGA is funded primarily from the gas utili ties and their mission is to support these utilities and manufacturers in the promotion of gas and gas consuming appliances With the exception of the mobile home direct vent model which 1s U L certified all residential gas water heaters are AGA certified Air Shutter Means by which the size of the primary air opening may be varied to control the amount of pri mary air intake Alternating Current A C Electrical supply in which the polarity of the hot wire whether wire is positive or negative reverses rapidly A C is the normal electrical supply in all parts of the United States Ambient Temperature The ambient temperature is the average temperature of the atmosphere in the vicinity of the appliance Performance of water heaters is generally checked with reference to ambient tem perature rather than a fixed temperature to allow for a statement of performance which will hold true for summer and winter performance AMP or AMPERE amp A measure of flow of electric current An electrical circuit or electrical wiring is designed to take a certain maximum current load and this should not be exceeded The amps flowing through an appliance are calculated by dividing the watts loading by the voltage Anode The positive electrode of an electrical cell is called the cathode An anode may be in the form of an expendable electrode used to reduce or prevent corrosio
32. all a gas water catch fire causing death or 4 ig on all the time and heater where flammable products will be severe burns 2 will ignite flammable stored or used unless the main burner and pilot flames are at least eighteen inches above the floor This will reduce but not eliminate the risk of vapors being ignited by the main burner or pilot flame Do not use or store flammable products such as gasoline solvents or adhesives in the same room or area near the water heater Keep flammable products 1 far away from heater 2 in approved containers vapors Vapors 1 cannot be seen 2 are heavier than air 3 go a long way on the floor and 4 can be carried from other rooms to the pilot 3 tightly closed and flame by air currents Gaseous Fuels 4 out of children s reach Both liquid petroleum and natural gas Installation are at least 18 above the Do not install water heater floor This will reduce but not have an odorant added to help in their detec Where flammable products will eliminate the risk of vapors tion Some people may not be physically able be stored or used unless the being ignited by the main to smell or recognize this odorant If you are main burner and pilot flames burner or pilot flame not sure or unfamiliar about the smell aSSOC1 Read and follow water heater warnings and instructions If owners ated with LP or natural gas ask your local manual is missing contact the retailer or m
33. anufacturer 9 gas supplier Fig 2 Flammable Vapors Warning If you smell gas leave the house immediately and make sure your family and pets leave also Leave the doors open for ventilation Go to a neighbors house and call your gas supplier a gualified service agency or the fire department Keep the area clear until the service call has been made the leak corrected and a gualified agency has determined the areas to be safe See the Use and Care Manual included with each water heater for additional safety information Fundamentals Training Manual Rev 1 WATER CHEMISTRY All of the water that we use in our homes comes from either a ground water source or a surface water source Ground water sources include a well surface water sources include lakes streams or reservoirs According to the U S Geological Survey in 1990 about 44 of domestic water comes from ground sources The remaining 56 comes from a surface water source Each person uses an average of about 100 gallons of water per day This includes baths showers cooking clothes and dish washing grooming and waste disposal The largest user of household water is the toilet followed by the shower Toilets 35 gallons Baths showers 28 gallons Clothes washing 18 gallons Faucets 13 gallons Dishwashing 3 gallons With the exception of the toilet flush all of the these activities either use hot water or have the potential to use hot water That means that 64 of our a
34. ater itself combined with the oxygen content of the water and heat present establish an environment conducive to corrosion Some definitions that may be helpful are Electrolysis An electromagnetic field produced by the movement of water in a confined space As water is heated the hot water rises to the top of the tank Obviously the inner storage tank is a confined space Cathodic protection Minute electrical current produced by the heating of water is known as electrolysis The inner tank of the water heater acts as a magnet or receiver of this electrical circuit As the water is heated metals inside the tank steel tank brass fittings anode rod attract the electrical current By designing an anode rod more conductive of elec tricity than the steel tank the steel tank is protected The process of the sacrificial anode rod is known as cathodic protection Fig 6 Partially Sacrificed Anode Rod Here is a portion of a galvanic series chart showing the reaction of metals in relationship to its negativity or ability to conduct electricity The more negative or anodic the metal is the greater the ability to conduct electricity before the steel water heater tank Corroded end anodic or corroding state Magnesium Zinc Aluminum Steel or Iron tank construction Lead Tin Brasses Copper Bronzes Protected end cathodic or non corroding You can see from the chart that magnesium and aluminum standard metals in anode
35. copper Iron rust tannins humic acid same stains as wet tree leaves have fall en on concrete manganese chlorine excessive air or parti possible sediment in cles in the water Potential Causes salt water intrusion into water source corrosive water caus ing leaching natural ly occurring high mineral content corrosive water caus ing leaching natural ly occurring high mineral content usu ally in private wells industrial activities close by waste dis posal close by 14 water heater Potential Contaminants sodium inorganic salts iron manganese undisclosed minerals semi volatile organic compounds herbi cides pesticides Suggested Treatment Options contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility let water stand and it will go away flush sedi ment from heater Suggested Treatment Options contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility Does your water have a strange odor Does your water have a strange texture Fu
36. d to an appliance The Nominal Thermal Input N T I is the basic or nominal input at which the unit was tested and to which published performance figures apply For gas units the N T I should be measured in BTU per hour Orifice size sup plied and published gas pressure at the orifice give N T I on one particular gas only and adjust ment may be needed on other gas types Electrical appliances are rated in Kilowatts or Watts 1 Kilowatt equals 1000 watts Again this applies only to the voltage for which the element is designed Thermocouple Bi metal device that when heated by the pilot flame carries millivolt current to the magnet assembly inside the gas control valve Typically seen on residential applications Thermopile Serves same function as a thermocouple however it contains a group of thermocouples built in series and has a larger diameter than a thermocouple Typically seen on commercial applica tions 52 Fundamentals Training Manual Rev 1 Thermostat A device which automatically maintains a predetermined temperature in an appliance Thermostats can be of the immersion type where the actuating components are immersed in the fluid whose temperature is to be controlled or of the surface mounted type where the actu ating components sense the fluids temperature through the wall of the tank Thermostats can be snap acting i e operate from full on to full off and vice versa or modulating operating grad ually
37. dely used device to deal with the effects of thermal expansion On being heated all solids and liquids expand the exact amount of expansion varying with different materials The expansion of metals is used to operate solid stem thermostats where two materials of different expansion characteristics are coupled The different expansion rates of the two materials can operate a valve or switching mechanism The expansion of liquids on heating has three effects First there is an increase in volume This increase has to be allowed for by provision of a relief valve which allows the extra volume of water to leave the storage cylinder The second effect is that expansion with heat makes the liquid less dense making heated water lighter than cold water and causing it to rise by means of convection currents This effect is used in circulating water heaters which are used with storage tanks fitted with hot and cold connections In these installations the hot water rises from the heating unit up the hot outlet to the storage tank and cold water flow from the tank down the cold inlet to the heating unit The third effect is that hot water being less dense than cold water will float on top of cold water without much mixing for some time This principle is used in all displacement water heaters and allows cold water to enter the tank while hot water is taken from the top without mixing with the hot water Thermal Input The rate at which heat energy is supplie
38. ducts will not be applied when the product has been damaged among other things by flood Any claims made will be declined if it is deter mined the cause of failure is the product being damaged as a result of flood INSTALLATION SERIES AND PARALLEL The installation drawings in this section are typical Check local code requirements for vacuum breaker devices and cold water inlet check valves If you install a check valve in any of these systems you must install a thermal expansion tank The majority of commercial water heater installations involve the delivery of water at one temperature only The exceptions or two temperature systems are restaurants convales cent homes and special process applications In most of these general purpose applications the water heater thermostats are adjusted to deliver water at a temperature ranging from 130 F to 150 F The simplest of the single temperature systems is one using a single free standing water heater This design uses an automatic storage tank type water heater and is piped directly with a cold in and hot out The heated water is delivered directly to its point of use and is mixed at the sink tub or faucet In many cases a single water heater may not have enough capacity to handle the hot water demand In this case two or more heaters can be piped together in a piping arrangement called manifolding Manifolding multiple heaters or a heater with storage tanks will increase the quantity o
39. e 100 effective because bacteria is still allowed to grow inside the tank CHLORINATION OF WATER HEATER TANKS 1 Turn off the manual electrical switch or shut off the gas supply 2 Close the cold water inlet valve at the heater 3 Open a nearby hot water faucet and the T amp P valve to relieve tank pressure 4 Drain the heater of enough water to compensate for the bleach Use a hose connected to the drain valve if an open drain is not adjacent to the heater 5 Remove relief valve anode rod or disconnect the hot water outlet pipe from the heater 6 Pour one gallon of bleach for every 30 gallons of water heater tank capacity Use the relief valve anode rod or hot water outlet pipe opening Re pipe the heater and close the T amp P valve 7 Open the cold water inlet valve at the heater and fill the tank with water Observe the water level through the closest hot water faucet Close inlet valve when the tank is full 8 Leave the bleach mixture in the heater for one hour 9 After one hour open all the hot water faucets and allow the bleach mixture to clean the hot water supply pipes Drain the remaining bleach mixture from the tank through the heater drain valve 10 Close the heater drain valve make sure the cold water inlet valve is open and com pletely fill the tank with fresh water Leave the water in the tank for 15 minutes 11 After 15 minutes purge the hot water supply lines and drain the water from the tank through the heat
40. e and Pressure T amp P Relief Valve Safety device that vents extreme pressure and excessively hot water outside the tank to prevent tank rupture and explosion Commonly called the T amp P valve it is designed to operate at approximately 150 PSI or 210 F Temperature Rise The difference in temperature between the desired hot water and the incoming cold water expressed in degrees Fahrenheit If the desired temperature at the faucet is 120 F and the 51 Fundamentals Training Manual Rev 1 incoming cold water is 70 F the required temperature rise is 50 F 120 70 50 Temperature rise is the number of degrees Fahrenheit that the water must be raised either from the inlet water temperature or a pre heat water temperature In short the temperature rise is the difference between existing water temperature and desired water temperature Thermal Expansion When water is heated it expands However water is not compressible Therefore the expanded water along with a closed water system creates a dangerous pressure in the water heater and system piping The closed condition is usually due to a check valve or backflow preventer installed in the system This pressure will cause the T amp P valve to open at approximately 150 PSI The T amp P however is not designed to open on a regular basis and could eventually fail If the T amp P does not function properly there is a potential safety hazard Expansion tanks are the most wi
41. e extending from the cold water inlet to a predetermined area near the bot tom of the tank that feeds cold water into the water heater The length of the dip tube will vary based on the tank dimensions and efficiency of the heater The length of the tube is precisely measured in order to prevent excessively high temperatures at the top of the tank stacking during short draws of water Direct Vent Designed to use outside air for combustion rather than the inside air from within a home or building The term balanced flue refers to the fact they draw in the same amount of air as they exhaust Two types of direct vent products are offered A horizontal direct vent which handles both combustion air and discharge gases through a single coaxial vent The mobile home direct vent brings in combustion air from below the floor and discharges combustion products vertically through a roof jack Displacement Hot water is much less dense than cold water and this is used in the displacement principle on which most storage water heaters operate If cold water is fed into the bottom of a tank full of hot water it will displace an equal quantity of hot water out of the top of the tank and if the heater is correctly designed the hot water will float on the cold water for a considerable time without mixing Draft Diverter vent hood Capping device that connects the water heater to the venting system The draft diverter aids in the venting by providing a higher
42. e shown that the peak period of hot water usage will occur once or twice a day in residential applications Peak periods for commercial applications are dramatically different By contrast a peak period in a school gymnasium shower may occur ever hour Temperature Rise The difference in temperature between the desired hot water and the incoming cold water expressed in degrees Fahrenheit For example the desired temperature at the faucet is 120 F and the incoming cold water is 70 F The required temperature rise is 50 F 120 70 50 Temperature rise is the number of degrees Fahrenheit that the water must be raised either from the inlet water temperature or a pre heat water temperature In short the temperature rise is the difference between existing water temperature and desired water temperature Another factor in proper sizing is recovery time A smaller gallon capacity heater with a high recovery time heats water faster may prove as effective as a larger capacity heater with a nominal recovery time NOTES 22 Fundamentals Training Manual Rev 1 Galiono hoi Gallons avail Shower Time Available Water Heater able within 10 Based of gallons per minute flow of shower water available Gallons 120d degrees of head 5 Perce thermostat 3 GPM 6 GPM 9 GPM 30 21 27 9 4 1 2 3 40 28 36 12 6 4 50 35 45 15 7 1 2 5 66 46 59 20 10 6 2 3 80 56 72 24 12 8 120 84 108 36 18 12 Table 3 Shower Time Available
43. e the building See also Direct Vent Cold Inlet Temperature The temperature of outside water coming into a water heating system Throughout most of the U S this temperature is considered to be 40 F during the coldest months Combustion Combustion takes place when gaseous liquid or solid fuels react at an elevated temperature with oxygen by burning thus releasing heat For good combustion an adequate supply of oxy gen must be available and all the carbon in the fuel will be converted to carbon dioxide and all the hydrogen to water vapor The presence of carbon monoxide in the flue gases and or sooting indicates imperfect combustion Condensation Condensation can form on the tank when it is first filled with water The condensation might also occur with a heavy water draw and very cold inlet water Drops of water falling on the burner can produce a sizzling or pinging sound and water may also be seen beneath the heater This condition is not unusual and will disappear after the water in the heater becomes heated Undersized water heaters can result in excessive water condensation Convertible Thermostat Control The type of control used on manufactured housing mobile home gas water heaters This con trol is designed so it can use either natural gas or liquid petroleum LP gas as its fuel source This type of control is not permitted on standard gas water heaters Cycle The number of times per second that a conductor carrying AC
44. e to a safer level of 115 degrees or less Table 1 Scalding Temperature Time to Scald 125 F 1 1 2 to 2 minutes 130 F About 30 seconds 135 F About 10 seconds 140 F Less than 5 seconds 145 F Less than 3 seconds 150 F About 1 1 2 seconds 155 F About 1 second Fundamentals Training Manual Rev 1 Electrical Shock Electric water heaters may pose a risk of electrical shock When installed properly all exposed wires to the thermostat and heating elements are protected and covered The risk of shock exists when these service panels are removed to adjust the thermostat setting or to reset the energy cut off switch Power supply must be shut off before removing access panels prior to adjusting thermostat s or resetting the temperature limiting control Flammable Vapors Vapors from flammable liquids will explode and catch fire causing death or severe burns Do not use or store flammable prod ucts such as gasoline solvents or adhesives in the same room or area near the water heater Flammable vapors cannot be seen are heavier than air travel a long way on the floor and can be carried from other rooms to the pilot Flammable Vapors flame by air currents Keep flammable prod ucts far away from the heater in tightly A DANGER Vapors from flammable Water heater has a main closed and approved containers and out of liquids will explode and burner and pilot flame i i A A The pilot flame reach of children Do not inst
45. eased steadily As a result the last water heater purchased by the homeowner now may be too small to satisfy household needs In addition rising energy costs have become a concern Operating costs now can be just as important in making the buying decision as the initial price of the new water heater itself How many family members will routinely take a shower in any given hour For instance if all four of the children take a shower between 7 8 PM daily to get ready for bed you may have a high usage demand If both parents take their showers in the morning Mom gets a load of clothes in the washing machine and turns the dish washer on before everyone leaves for school and work you may have a high usage demand Focus on the customer s usage pattern and consumption factors Peak Hour Demand is the key Peak hour demand is the busiest one hour usage period This may be in the morning evening or some other time during the day Accurate calculation of the demand is essential to proper water heater sizing Look at the following sample of a typical peak hour demand for this family of three Avg Gallons Times per Total Hot Household Activity per activity hour Water used Shower or bath 20 3 60 Shave 2 1 2 Washing hands or face 4 Shampoo hair 4 1 4 Washing dishes by hand 4 1 4 Automatic dishwasher 14 Food preparation for a meal 5 Automatic clothes washer 32 Total Peak Hour Demand 70 gallons Table 6 Sample Peak Hour Demand Calculation 26
46. eaters the ASHRAE Standard 90A 1980 was used as a standard for high efficiency water heaters While no longer applicable residential water heaters continue to meet this standard ASME American Society of Mechanical Engineers May be required on commercial water heaters over 120 gallons or over 200 000 BTUs The ASME code is generally adopted on a state by state basis Automatic Storage Commercial Heater A water heater that heats and stores water within the appliance at a thermostatically controlled temperature for delivery on demand and which has an input rating of less than 4 000 BTU per hour per gallon of stored water Input rating is above 75 000 BTUH Backflow Device Backflow Preventer A device valve which allows water to flow in only one direction In order to comply with the provisions of the Safe Water Drinking Act Municipal Water Systems or local plumbing codes may require these devices to be installed in the cold water inlet line to prevent water from back ing up into the central main Backflow devices cause a closed loop system which can become a potentially dangerous situation due to the effects of thermal expansion See Check valve thermal expansion expansion tank Boiling Point The boiling point refers to the temperature at which a liquid changes to vapor by the addition of heat The boiling point depends on the pressure at which the liquid is held and it increases as the pressure increases BTU British Thermal Un
47. ection the valve automatically closes Chemical Rinse A chemical sanitation rinse used in some dishwashers which allows the maximum rinse water temperature to be 140 F instead of 180 F Circulating Tank Heaters There are two types as follows a Automatic Circulating Tank Water Heater A water heater which furnishes hot water to be stored in a separate vessel Storage tank temperatures are controlled by means of a ther mostat installed on the water heater Circulation may be either gravity or forced b Non automatic Circulating Tank Water Heater A water heater which furnishes hot water to be stored in a separate vessel Storage tank temperatures are controlled by means of a thermostat installed in the storage vessel The Non automatic is normally a tube type of heater Circulating Tank System A water heating system in which a water heater is connected to a separate storage tank so that large amounts of hot water may be built up for use during relatively short periods of peak demand The ratio of recovery to storage is approximately 1 GPH recovery 100 F Rise to gallon stored 39 Fundamentals Training Manual Rev 1 Coaxial Vent A vent system which provides for both outside air for combustion as well as venting of the combustion exhaust gases in a single vent system Combustion air enters through the outer air tube and flows to the combustion chamber Flue gases are discharged through the inner exhaust tube and released outsid
48. er drain valve Close the drain valve Check anode rod for serviceability replace with a new R TECH anode rod if there are signs of deterioration 12 Make sure you purge all the air from the hot water lines from the open hot water faucets Close the hot water faucet after all the air is out of the system 13 Check for water leaks at all fittings used repair as necessary 14 Turn on the manual electrical switch or gas supply from step 1 above 15 Check for normal water heater operation 13 Does your water have a strange appearance Does your water have a strange taste Fundamentals Training Manual Rev 1 DIAGNOSING YOUR WATER PROBLEM Turbid or cloudy Blue green stains on sink or around fix tures Brown red stains or discolored clothing Yellowish color Black stains on fix tures or clothing Blacking and pitting of stainless steel sinks Milky Salty or brackish Metallic taste Alkali taste Sharp chemical taste Potential Causes organic or suspended matter defective well screen inadequate public treatment corrosive water reacting with brass and copper fittings naturally occurring iron in the water iron bacteria leached from old iron pipes water passing through peat soil and vegetation well water naturally occurring manganese usually found with iron excess salt improper treatment excess chlorine Potential Contaminants dirt sand clay silt organic matter brass
49. ermine first hour delivery To determine the ballpark first hour delivery use the following formula tank capacity x 70 recovery first hour delivery For instance You have a 40 gallon 40 000 BTU gas water heater 40 x 7 36 64 gallons first hour delivery You can find the recovery rate in gallons per hour for your heater in the following charts Check the rating plate of your water heater for the input in watts electrical or BTUs gas Water Heater Recovery Rates in Gallons per Hour Degrees F Rise Input KW BTUs 40 50 60 70 80 9 100 110 120 1 000 3 413 10 8 7 6 5 5 4 4 3 1 500 5 120 16 12 10 9 8 7 6 6 5 2 000 6 826 21 17 14 12 10 9 8 8 7 2 500 8 533 26 21 17 15 13 12 10 10 9 3 000 10 239 31 25 21 18 16 14 12 11 10 3 500 11 946 36 29 24 21 18 16 15 13 12 4 000 13 652 41 33 28 24 21 18 17 15 14 4 500 15 359 47 37 31 27 23 21 19 17 16 5 000 17 065 52 41 34 30 26 23 21 19 17 5 500 18 722 57 46 38 33 28 25 23 21 19 6 000 20 478 62 49 41 35 31 27 25 22 21 9 000 30 717 92 74 61 53 46 41 37 34 31 12 000 40 956 123 98 82 70 61 55 49 45 41 Table 5 Water Heater Recovery Rates in Gallons per Hour 25 Fundamentals Training Manual Rev 1 SIZING OF A RESIDENTIAL WATER HEATER Like any household appliance the water heater has a very specific job to perform and it must do its job to the homeowner s complete satisfaction 24 hours a day every day for years and years Water heating requirements for the home have incr
50. f hot water available or will allow for dual delivery temperature requirements The only aspect of the heater that will make the unit heat water faster is the BTU input rating The second method of installation is to manifold more than one water heater or storage tank in series or parallel Manifold means to pipe together with several apertures that make multiple connections That is what manifolding is all about With commercial water heaters you may manifold one heater to two or more storage tanks or you may manifold two three or four water heaters together There are two methods of manifold installation series and parallel 29 Fundamentals Training Manual Rev 1 SERIES INSTALLATION Series installation uses heaters that are not identical in both BTU input and storage capacity An example might be when a commercial business expands or adds on a facility that will require additional hot water The existing system will not handle the demand and a new water heater must be installed The new heater is not identical to the existing heater In this example series installation may be appropriate When installing water heaters in series the heater with the largest BTU input should be the first heater in the series at the cold water inlet side of the system Series installation draws hot water from one tank at a time As hot water is drawn it is taken from the last heater in the series For every gallon of hot water drawn preheated water is i
51. f the benefits of The EverKleen system is that it greatly reduces peak temperatures and stacking effects thus increases first hour deliverability Stand Kit Raises gas water heater 18 above floor level as required by many codes Standby Loss The heat energy lost during standby mode operation of the water heater Most standby loss in gas water heaters occurs through the flue system Electric water heaters standby loss occurs through the exterior jacket Storage Water Heater A water heater incorporating a storage tank such that water can be heated whether water is flowing through the heater or not as contrast to instantaneous Water Heater System Temperature This refers to the temperature of the water actually in the water heater i e 140 F 180 F 180 F etc This is as opposed to the inlet temperature water coming into heater or the use temperature the water as it is used from the heater either at heater temperature or mixed with cold Temperature This is a measure of hotness or coldness or the ability to transmit heat outward or receive heat inward Heat and Temperature can be compared to water and heights As water will flow naturally down hill so heat flows from the higher temperature to the lower The flow in the reverse direction requires the application of energy in some way Temperature is normally measured in Fahrenheit degrees F but in scientific literature it may be quoted as Celsius C Temperatur
52. from full on to a minimum by pass flow and vice versa Some thermostats combine a modulating function from full on to low fire then snap action to off The differential of a snap action thermostat is the temperature difference between the opening and closing functions Transformer Used in PowerVent water heaters and Universal commercial gas water heaters to activate the electrical components Two Temperature System This is a system that uses one heater to supply two different water temperature requirements with the use of a mixing valve The way it works is that the application requiring the hottest water is fed directly from the heater while water for the lower temperature application goes through a mixing valve to be combined with cold water to achieve the desired lower tempera ture This is most often found in food service applications U B C Uniform Building Code U L Underwriters Laboratory An independent laboratory for testing and listing products which meet standards set by UL and the American National Standards Institute U L 307b The standard which govern the Direct Vent Mobile Home product Unvented As applied to most gas appliances this means that the unit is not connected to a secondary flue As applied specifically to water heaters this means that there is no open exhaust or vent pipe in the hot water system open to atmosphere at all times Use Temperature This is the temperature of the water as it is actually
53. g valves without a bypass being installed expanded water from a water heater cannot return to the city supply It is now a closed system and the expanding water has no place to go Dangerous conditions exist during thermal expansion long before the temperature and pressure relief valve operates Internal pressures repeatedly occurring during recovery peri ods can stress the tank causing the tank welds and fitting connections to the tank to weaken Remember water heat pressure closed system potential explosion As a result the expanding water creates a rapid and dangerous pressure increase in the water heater and system piping inside the residence Eventually the combination of temperature pressure and the closed system will activate the T amp P valve The setting on the safety relief is quickly reached and the relief valve opens losing heater water down the drain or all over the floor Even though the T amp P valve operates dur ing each recovery period internal high pressures occurring over and over again can accelerate tank leakage and shorten water heater life A good indication of thermal expansion is when the T amp P valve releases about one cup of water for each ten gallons of heater capacity with each heating cycle The best solution to thermal expansion is to control the pressure the heat ed water generates within normal safe operating range well below the emergency setting of a T amp P valve This wi
54. gher the pressure the more dissolved gasses in the water Significant pressure drops may occur at the inner radius of elbows and fittings under high pressure This rapid pressure drop may release gas bubbles These gas bubbles have an abrasive effect on pip ing and are an important factor in corrosion erosion The release of dissolved gas also creates air pockets and air locks in plumbing systems The spurts of air or gas when opening a hot water faucet can be attributed to the release of dis solved gasses in the water Other gasses such as hydrogen can be a by product of severe corro sion activity in a plumbing system SMELLY WATER AND THE ROTTEN EGG ODOR The incidence of rotten egg odor or black water in hot water lines is due to the reaction of sulfates and micro organisms in the water This condition is a water problem rather than a water heater problem A quick check for the cause of the odor is to draw enough hot water to notice the odor Then move to another faucet or wait until the smell dissipates and draw cold water The source of the odor may be in the cold water supply such as untreated rural water systems or well water For many years the regular magnesium anode was and is the standard anode for use in water heater tanks In general it is a very good anode however the performance is dependent on water chemistry In waters where the conductivity is low the anode operates at very low current levels Conversely where the wate
55. h the effects of a closed loop condition First Hour Rating The calculated amount of hot water a fully heated water heater can deliver in the first hour peri od 42 Fundamentals Training Manual Rev 1 Fatigue Just as the human body can break down if exposed to an adverse environment or repeated stress so can materials fail due to fatigue A material can fail by repeated exposure to a stress well below its normal breaking point purely by cycling the stress on and off Water heaters can be exposed to repeated pressure fluctuations during their life and must be designed to resist the effects of fatigue Flow Control Valve These are devices that are installed between the supply pipe and the plumbing fixture shower head faucet etc to reduce the flow of water to a constant level They are highly recommend ed for large shower installations because they can often reduce the flow of water more than half without disturbing the spray pattern This of course results in a savings of water and the ener gy required to heat the water Flow Rate Flow rate is the amount of water in gallons flowing in a plumbing fixture or pipe over a period of time normally minutes Flow rate is normally given in gallons per minute GPM Flue Baffle A device inside the flue that restricts the flow of the heated combustible air to allow for better heat transfer between the flue and water inside the tank GPH Gallons per Hour The term used to measu
56. ing Similarly a polypropylene ball lighter than water in the cold water inlet fitting floats up to seat during the standby mode Heat Unit A measure of heat energy In English speaking countries it is the BTU British Thermal Unit In Europe it is the calorie also spelled Calorie or Kalorie Hertz Hz A measure of freguency One Hertz eguals one cycle per second 60 cycles AC is also called 60 Hertz AC High Altitude As related to water heaters the orifice is changed to help aerate the gas supply to the heater so that it will operate properly in areas of higher altitude thinner air Standard water heaters are designed to operate safely up to 2 000 ft Per the reguirements of ANSI and the National Fuel Gas Code the de rate above this level is 4 per 1 000 feet altitude Rheem generally de rates gas products to a 5 000 ft elevation which results in a 20 reduction in BTU input 44 Fundamentals Training Manual Rev 1 High Watt Density Element The watt density of an element is the amount of heat transferred from any point on the surface of the element of the water A high watt density element has less surface area of heating ele ment than a low watt density element but is transferring the same amount of energy into the water Input Rate A measure of heat input to a water heater BTU s per hour of gas WATTS per hour of electrici ty The higher the input rate the more hot water it will produce Input Rating The gas b
57. ions for corrosion pin holes in the tank and finally tank failure Cathodic protection is accomplished in the glasslined water heater through the use of an auxiliary magnesium anode with a patented Rheem resistor Due to the relative position of magnesium to steel in the electromotive series of metals magnesium will corrode producing an abundance of electrons which flow much the same as an electrical cur rent to the exposed steel surface and maintaining it in the electro nega tive state As current flow takes place the anode rod attracts the electro magnetic current and reacts chemically to corrode at a rate faster than the steel inner tank This process stops tank corrosion by substituting the sacrificial magnesium anode rod in place of the steel tank As long as the magnesium anode rod remains in the tank in an active state there will be no corrosion of the minute areas of exposed steel inside the tank The life of the anode in turn depends on water temperature amount of water used and the quality of the glass lining However the most important factor in the life of the anode rod is the water chemistry and the hardness or softness of the water Also check the manufacture and installation date of the water heater If the heater is more than five 5 years old and the anode rod has not been replaced inspect the anode rod The anode should be replaced when there is six 6 inches or more exposed core wire at either end Fig 7 Fully
58. ired to clean and wash clothing The following are some of the tell tale signs of hard water Difficult to remove soap scum on tubs showers basins and faucet fixtures Reduced sudsing and cleaning capabilities of some soaps and detergents Scale build up around faucet fixtures and on the inside of a water heater Scale build up is one of the most serious prob lems caused by hard water mineral deposits These deposits commonly called lime build up may clog water pipes collect in the bottom of water heaters or collect on electrical heating elements immersed inside the water heater The build up on the electrical heating elements will insulate the elements and reduce their efficiency Eventually the elements will fail If this sediment is allowed to remain in the tank it will gradu a ally sink to the bottom where it will harden into an insoluble scale This will lead to a reduction in the efficiency of the heater clogging of the drain valve and may lead to eventual tank failure Fig 4 Sediment Build up Hydrogen Sulfide Hydrogen sulfide HS is a gas present in some waters Hydrogen sulfide is a gas that is present in two forms depending on the pH of the water At higher pH levels H2S is present in the alkaline sulfide form and at lower pH levels it is present in the gaseous form There is never any doubt when it is present due to its offensive rotten egg odor in concentrations as low as one part per million A
59. it A measure of energy used to determine the input ratings for natural and LP water heaters The amount of energy required to raise one pound of water one degree Fahrenheit 38 Fundamentals Training Manual Rev 1 Carbon Monoxide A by product of gas combustion which is generated as the result of the burning of fossil fuels natural and LP gas For safety purposes the ANSI Z21 standards set specific limits for the amount of carbon monoxide that can be emitted from gas burning water heaters Cast Iron Burner A burner made of cast iron material used today on the higher input water heaters of 60 000 BTU s up to 75 500 BTU s Previously cast iron was the preferred burner material used on LP water heaters until the development of stainless steel burners in the mid 80 s Catch Pan A pan usually metal placed under the water heater to help prevent water damage in the event the water heater should begin to leak Most catch pans have either a side or bottom drain fitting which should be piped to a suitable floor drain or piped to the outside of the home Local codes may govern the type of catch pan required and how it is to be piped Cathode The negative electrode or an electrical cell the opposite to anode See also under galvanic Action Check Valve Also know as a non return valve a check valve is intended to allow a fluid to flow in only one direction in a pipe Should conditions occur which might lead to flow in the reverse dir
60. l treatment of dishes and utensils Sanitization is based on the principle of heat build up at the surface of dishware Temperatures at the surface of the clean dishes must be hot enough 180 F in the final rinse cycle of dishwashers to com plete effective sanitation that is destruction of harmful microorganisms or germs Further 180 F rinse temperature effectively air dries chinaware glassware and utensils Sediment Build Up Sediment or scale build up is one of the most serious problems caused by hard water mineral deposits These deposits commonly called lime build up may clog water pipes collect in the bottom of water heaters and collect on electrical heating elements immersed inside the water heater The build up on the electrical heating elements will insulate the elements and reduce their efficiency Eventually the elements will fail If this sediment is allowed to remain in the tank it will gradually sink to the bottom where it will harden into an insoluble scale This will lead to a reduction in the efficiency of the heater clogging of the drain valve and may lead to eventual tank failure Self Contained Commercial Storage Heater A water heater that heats and stores water at a thermostatically controlled temperature for deliv ery on demand Input rating above 75 000 BTUH They are ideally suited for applications where there are several short peak period draws Basically they can re heat a volume of water equal to their storage ca
61. lationship to the pilot burner ports Pilot Light The flame designed to be continuously lit that ignites the main burner when the thermostat demands heat Pilot Orifice A cup shaped part in the pilot which contains precisely sized openings which control the amount of gas to the pilot Pilot Ports The openings through which the gas or gas and air mixture passes before burning 47 Fundamentals Training Manual Rev 1 Pipe Losses Certification tests of a water heater are carried out on an isolated heater not connected to hot or cold water lines Note Stand by losses determined do not apply to the installed heater Additional losses take place when installed These are called pipe losses and are made up of 1 Conduction of heat along the hot and cold water pipes This effect is generally limited in extent 2 Convection of water in the hot water line above the heater This effect can be quite large but can be reduced considerably by introducing a heat trap in the hot water line at the heater 3 Radiation from the hot water pipes and fittings These are reduced by insulating 4 Between uses the water in the hot water line gets cold This has to be run off before hot water can be drawn from the fixture The overall effect is reduced by the following means 1 Fit a heat trap in the hot water lines 2 Use small diameter pipe 3 Use short runs of pipe 4 Insulate hot water pipes particularly the section nearest the heater P
62. ll allow thermal expansion to occur but without causing a dangerous increase in pressure This is accomplished by adding an expansion tank As the water temperature increases the expanded water is received by the expansion tank As the temperature and pres sure reaches its maximum the diaphragm flexes against the air cushion air is compressible to allow for increased water expansion By adding a Rheem THERM X GUARD thermal expansion tank with a sealed in compressible air cushion space is provided to store and hold the additional expanded water volume When the water is heated the expand PRECHARGED ed volume is consumed by the expansion tank When AIR hot water is used in the system the expansion tank returns the water back into the system for use Fig 9 Thermal Expansion Tanks Service Tip Thermal expansion tank pressure must be 10 15 psi above service pressure There are sizing issues when selecting the proper expansion tank Consult the expansion tank manufactures specifications 17 Fundamentals Training Manual Rev 1 TEMPERATURE AND PRESSURE RELIEF T amp P VALVES Temperature and Pressure Relief Valves also called T amp P valves are emergency safety limit devices that will prevent or relieve overheated water and pressure Without a T amp P valve during an unsafe condition the pressure inside the tank would rise to the point the tank may rupture or explode This would cause potential damage to both people and proper
63. lumbing fixtures especially inside a toilet tank Service tip Check the inside of a porcelain toilet tank for colored stains The color of the stains may indicate the mineral content of the water Manganese Manganese is rarely found alone in a water source but is usually paired with iron At concentrations of 0 05 parts per million manganese can cause black staining of fixtures laun dry or masonry It is hard to treat because of the complexes it can form which are dependent on the oxidation state pH bicarbonate carbonate OH ratios and the presence of other minerals particularly iron Concentrations higher than 0 05 mg l cause manganese deposits and staining of clothing and plumbing fixtures The stains are dark brown to black in nature The use of chlorine bleach in the laundry will cause the stains to set The chemistry of manganese in water is similar to that of iron High levels of manganese in the water produces an unpleasant odor and taste Organic materials can tie up manganese in the same manner as they do iron therefore destruction of the organic matter is a necessary part of manganese removal Deposits of man ganese can collect in plumbing systems and produce a dark brown or black sediment and black turbidity suspension of particles in the water Like iron manganese can also produce favor able growth conditions for manganese bacteria and clog screens and plumbing lines Together with iron manganese bacteria cause a general
64. mon cause for taste and odor in surface water supplies In treated water supplies chlorine can react with organics and cause odor problems ANODE RODS AND CATHODIC PROTECTION Corrosion can be defined as the destructive attack of a metal by an electrochemical reac tion with its environment Steel exposed to moisture and oxygen will rust and corrode Corrosion is defined as the eating away of metal by electrochemical means There are four main factors affecting water s ability to corrode i a 1 Acidity Water is made acidic by naturally occurring dissolved gases such as carbon dioxide and hydrogen sulfide 2 Temperature Temperature speeds up the corrosive process Chemists have a rule of thumb that for every 49 F increase in temperature chemical reactions increase two fold 3 Electrical conductivity The more dissolved mineral solids in the water the greater its ability to carry electrical current When dissimilar metals are in the water Electrical current flows between metals One of the metals gradually corrodes faster than the other 4 Amount of dissolved oxygen Free oxygen dissolved in the water pro motes corrosion Fig 5 New Anode Rod Fundamentals Training Manual Rev 1 Dissimilar metals are present in the interior steel tank surfaces of all water heaters in several forms such as the drain nipples heating ele ments inlet and outlet nipples and the anode rod These metals and oth ers present in the w
65. n On this basis thermal efficiency is the percentage of the potential heat content of a fuel which becomes available as hot water or hot air in the case of a space heater Thermal effi ciency is a measure of performance under stated conditions and the efficiency will vary as con ditions are varied Accordingly official or test thermal efficiencies should not be quoted or used unless the circumstances are comparable to the method of test See also Pipe Losses Electronic Ignition Also called intermittent ignition system The ignition system of the residential power vent water heater Helps reduce standby losses by igniting the pilot only during the burner cycle Also prevents nuisance pilot outage due to down draft conditions Energy Factor A measure of the overall efficiency rating of a water heater the higher the number the more efficient the water heater EverKleen Specially developed inlet tube that creates a high velocity spiraling water stream which helps dislodge sediment and prevent buildup in the tank It also creates better mixing throughout the water heater tank which reduces the effects of stacking Expansion Tank A tank with a sealed in compressible air cushion which will compress as thermal expansion occurs providing a space to hold and store the additional expanded water volume Expansion tanks are used when check valves back flow preventers or pressure reducing valves are installed in a water system to deal wit
66. n see under galvanic action or as a source of material in electroplating Annual Cost of Operation An estimate of the yearly operating cost for residential gas and electric water heaters The U S averages for gas and electric fuel rates are provided yearly by the Department of Energy and this information is used to compute the yearly operating cost data which appears on the Energy Guide label Anode Rod The active metal within a steel glass lined tank which sacrifices itself in order to prevent any 37 Fundamentals Training Manual Rev 1 exposed steel cathode from corrosion The patented R Tech anode rod used by Rheem is made of magnesium and is designed to last longer and offer greater tank protection than those used by other manufacturers ANSI Z21 10 1 American National Standards Institute The testing and safety standards which govern all residential gas fired water heaters up to 100 gallon capacity and up to 75 000 BTU s Anti Siphon Hole A small hole located in the dip tube approximately six inches from the top The anti siphon hole is designed to prevent the siphoning of water through the cold water line in the event of a reverse water flow or siphon condition ASHRAE American Society of Heating Refrigeration and Air Conditioning Engineers An association which recommends standards and test methods used today primarily for com mercial water heaters Prior to the NAECA law which now governs residential water h
67. n mind lets investigate the more common complaints in a hot water system Fig 3 Water Hardness pH Acidity vs Alkalinity The term pH is used to indicate acidity or alkalinity of a given solution It is not a measure of the quantity of acid or alkali but rather a measure of the relationship of the acid to the alkali The pH value of a solution describes its hydrogen ion activity The pH scale ranges between 0 and 14 Typically all natural waters fall within the range of 6 0 to 8 0 pH A value of 7 0 is con sidered to be a neutral pH Values below 7 0 are acidic and values above 7 0 are alkaline Water with a pH value of 3 5 or below generally contains mineral acids such as sulfuric or hydrochlo ric acid Water Hardness Hard water is found in more than 85 of the United States Water hardness is due to the presence of two dissolved minerals calcium and magnesium So common are these two min erals in water that practically no supply can be found that does not contain at least one or two 6 Fundamentals Training Manual Rev 1 grains per gallon The hardness of a water supply is determined by the content of calcium and magnesium salts Calcium and magnesium combine with bicarbonates sulfates chlorides and nitrates to form these salts Mineral concentrations may be expressed as grains per gallon or parts per million When you have high levels of calcium and magnesium in your water more scrubbing power and more detergent is requ
68. ndamentals Training Manual Rev 1 Musty or earthy Chlorine Detergent Rotten eggs Fishy sweet or per fume Oil or gas Gritty or abrasive Scum or white deposits Potential Causes algae vegetation excess chlorine or inadequate de chlori nation septic discharge into water supply sewage sulfate reducing bacteria industrial chemicals waste gasoline or oil leaks into water supply Potential Causes defective well screen inadequate public treatment elevated levels of calcium and magne sium salts Potential Contaminants organic matter such as leaves chlorine detergents hydrogen sulfide gas sulfates volatile organics semi volatile organ ics Suggested Treatment Options contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility contact local health agency or public water utility gasoline oil benzene contact local health Potential Contaminants fine sand grit hard water agency or public water utility Suggested Treatment Options contact local health agency or public water utility contact local health agency or public water utility water softener OPEN AND CLOSED WATER HEATER SYSTEMS Water heater systems may be installed as either an open or closed system Water in an ordinary
69. nside the tank This effectively will prolong the anode life and protect the tank for a longer period especially in areas with aggressive water conditions Lime Buildup Mineral deposits usually found in hard water See sediment build up 45 Fundamentals Training Manual Rev 1 Lint Screen Removes lint and dirt from primary air before it enters the primary air opening Also traps par ticles on the inlet side of a gas control valve Low Nox Term that refers to natural gas water heaters required in select areas of California which are built with a special burner to help reduce or limit the amount of nitrous oxides Nox released during the combustion process Low Watt Density Element The watt density of an element is the amount of heat transferred from any point on the surface of the element of the water A low watt density element has more surface area of heating ele ment than a high watt density element but is transferring the same amount of energy into the water A low watt density element will generally last longer than a high watt density element Maintenance Rate Stand by losses The maintenance rate is the rate which heat or energy has to be supplied to an appliance to maintain its temperature at the required level when the unit is not being used In the case of a storage heater it is the heat input required to hold the unit at the required temperature general ly 80 F above ambient on gas heaters and 100 F above ambient
70. ntroduced into the last heater in the series and cold water is introduced into the first heater in the series In a series configuration the first heater piped to the cold water inlet will do the majority of the work The second or remainder heaters will not work as hard because they receive preheated water not cold water The last heater in the series will do very little work In the example the commercial installation shows a series system with a booster heater The larger tank type heater is supplying the 120 to 140 hot water demands to sinks and lavato ries The booster heater is supplying hot water to a dishwasher that requires 180 water for the sanitizing rinse If the dishwasher consumes less than the recovery capability of the booster heater the booster heater is considered to be an instantaneous heater Fig 13 Series Installation TEMPERATURE AND PRESSURE GAUGE COLD WATER SUPPLY EXPANSION TARK Fundamentals Training Manual Rev 1 PARALLEL INSTALLATION Parallel installation uses heaters that are identical in both BTU input and storage capaci ty Normally parallel installation is used when there is a demand for large quantities of hot water over a shorter period of time Equipment being equal two or more heaters connected in parallel will deliver more hot water than the same heaters connected in series In a parallel con figuration the
71. ocedure This procedure involves a water heater that is put through a 24 hour simulated use test The simulat ed use test is used by all water heater manufacturers All of the test procedures are mandated by the DOE Test procedures include the length of the test the thermostat setting the water tem perature of the cold water delivered into the water heater and the quantity of hot water drawn from the heater during the 24 hours of testing The final number is displayed in a decimal equivalent It is not meant to be a percent age This number called the Energy Factor EF represents the efficiency of the water heater The higher the EF the more efficient the unit The Energy Factor represents two major condi tions when determining water heater efficiency How efficiently the unit uses fuel gas or electric How efficiently the unit retains heat during stand by How useful is the Energy Factor The EF aids the consumer is making comparison shopping easier When shopping for a new water heater the consumer can compare the EF rating of the unit against like units Like units is not a relative term When comparing the EF consumers must compare water heaters with the same fuel source gas or electric and the same water storage capacity Comparing the EF between a natural gas unit and an electric unit is not comparison shopping Comparing 50 gallon electric units to each other is comparison shopping VACATIONS AND LONG TERM IDLE TIME
72. om the heater This setup is generally used when there is a large quantity of hot water drawn in a single use When a single heater is used with multi ple storage tanks you will experience a longer recovery time 31 Fundamentals Training Manual Rev 1 PERCENTAGE OF HOT AND COLD WATER MIX Many consumers do not realize how much hot water they are using in a given draw This chart shows the percentage of hot water used given the thermostat setting the cold water inlet tem perature and the temperature of the hot water For example A water heater with a thermostat setting of 120 F and the cold water inlet temperature is 50 F and the shower temperature is 110 F would use 86 HOT water and 14 COLD water Thermostat 120 Mixed Temperature 100 105 110 115 120 Cold Inlet 40 75 81 88 94 100 45 73 80 87 93 100 50 75 81 88 94 100 55 73 80 87 93 100 60 75 81 88 94 100 65 73 80 87 93 100 70 75 81 88 94 100 75 73 80 87 93 100 Thermostat 125 Mixed Temperature 100 105 110 115 120 125 40 71 76 82 88 94 100 45 69 75 81 88 94 100 50 67 7 80 87 93 100 55 64 71 79 86 93 100 60 62 69 77 85 92 100 65 58 67 75 83 92 100 70 55 64 73 82 91 100 75 50 60 70 80 90 100 Thermostat 130 Mixed Temperature 100 105 110 115 120 125 130 40 67 72 TBP 83 89 94 100 45 65 71 76 82 88 94 10
73. on electric heaters The main tenance rate may be measure in BTU per hour for gas or kilowatts per 24 hours for electricity The temperature above ambient must always be quoted Multiple Heater Installation This is an installation where a number of heaters are used to supply the total building hot water requirements The heaters are manifolded together in one location and the installation can be defined as a central water heating system This is one of the easiest systems to service and maintain When one heater is being serviced the remaining heater s will continue to supply hot water Multi Watt Element An element that has the capability to function at two different wattages The Multi Watt ele ment offered by Rheem is convertible from 3800 to 5500 watts NAECA National Appliance Energy Conservation Act of 1987 The Federal Law enacted by Congress which sets minimum energy efficiency standards for residential water heaters and other prod ucts Effective with water heaters produced on or after January 1 1990 NAECA supersedes all previous state and local energy efficiency requirements NPT National Pipe Thread Nipples Can be made of various materials Used to connect the water heater to the piping system 46 Fundamentals Training Manual Rev 1 Nitrous Oxide By product produced in the combustion process of natural gas water heaters Off Peak Metering Required by some electric utilities to reduce excessive electricity
74. pacity 1 12 to 2 Y2 times each hour Simultaneous Wiring A double element heater may be wired for simultaneous operation This means both elements will heat at the same time during the initial fill or during heavy water draws This can be use ful when there is a requirement for a rapid recovery time This does not mean that both ele ments will always fire simultaneously During normal water draws only the bottom element will fire similar to a non simultaneous heater Smelly Water Hydrogen sulfide H S is a gas present in some waters There is never any doubt when it is present due to its offensive rotten egg odor in concentrations as low as one part per million Hydrogen sulfide is present in the incoming cold water supply and normally found only in 50 Fundamentals Training Manual Rev 1 ground water Hydrogen sulfide gas can produce a favorable condition for the growth of organ isms referred to as sulfate reducing bacteria This favorable condition is enhanced with the application of heat such as in a hot water heater The smell is most noticeable with the first hot water draw in the morning or maybe when you get home from work Stacking Occurs when frequent small draws of water create different temperatures throughout the tank resulting in increased peak temperatures at the top of the tank ANSI AGA certification testing sets specific limits as to the temperature differential between the bottom and top of the tank One o
75. r conductivity is high an excessive amount of cur rent is produced with inefficient operation In addition some of these waters have excessive sulfate content along with various strains of sulfate reducing bacteria These bacteria harmless to health will grow in the presence of the highly active magnesium anode and will produce hydrogen sulfide gas utilizing the hydrogen ion from the anode cathode reaction The greater activity of the anode the greater amount of the hydrogen ion and hydrogen sulfide gas These bacteria can be killed with adequate additions of chlorine and or ozone This will usually elimi nate the odor problem 12 Fundamentals Training Manual Rev 1 Although there is very little literature associating odors and sulfate reduction with mag nesium there is reference to sulfate reducing bacteria known as desulfovibrio These bacteria cannot grow in the presence of atmospheric oxygen which may account for their not being noticed in cold water supplies When the same water is heated they become noticeable There are two ways to eliminate an odor or black water problem They are listed in the order of preference 1 Chlorination by means of a continuous chlorine feeder or periodic flushing with a com mon household bleach This process is 100 effective only if a continuous chlorine feeder 1s installed 2 Install a new R TECH anode rod after the water heater has been flushed with household bleach This process may not b
76. re 7 000 grains in one pound Hardness of water Natural waters contain impurities in various proportions Some of these impurities affect the lathering of soap in such water The main impurities are the soluble slats of magnesium and calcium The hardness of a water is its difficulty in raising a lather Hardness is measured in terms of the equivalent amount of calcium carbonate in a solution which would cause equal dif ficulty in lathering It may be quoted as grains per gallon or parts per million or parts per 100 000 The hardness is generally determined by finding the quantity of a specially prepared soap solution It is necessary to add to a known quantity of the water in order to establish a permanent lather To convert parts per million to grains per gallon divide by 17 A general classification of waters would be Type Hardness Grains per Gallon Soft 0 49 ppm 0 3 grains Fairly soft 50 99 ppm 3 6 grains Fairly Hard 100 149 ppm 6 9 grains Hard 150 249 ppm 9 14 5 grains Very Hard 250 plus ppm 14 5 plus grains Heat Loss A hot body looses heat by the combined effects of conduction convection and radiation Heat Trap Fittings A device that helps reduce heat transfer from the water heater to the pipes It contains a ther moplastic ball that seat themselves in place to help restrict heat transfer when hot water is not running A Teflon ball heavier than water seats to trap standby heat on the hot outlet fitt
77. re heated Water This is the water that has been heated in one water heater before going to another water heater to be raised to an even higher temperature For instance in restaurants there will often be one heater that will heat incoming water to 140 F general purpose water This pre heated water will go into a booster heater to be heated to 180 F for the sanitizing rinse cycle of some dish washers Pressure Reducing Valve A valve which automatically reduces inlet water pressure to a specified value at its outlet under static cold water conditions Primary Air Intake The hole or opening through which air is drawn to mix with a gas for burning Polyurethane Foam Insulation The foam used to insulate the water heaters for high energy efficiency POWERGLO Name given to ignition system on Rheem power vent products Power Vent Gas water heater that uses a blower to vent the flue gases out of the heater The power vent water heater can be vented horizontally rather than vertically as required by conventional atmospheric water heaters This allows you to vent directly outside through a wall May also refer to an after market blower kit that may be attached to a natural draft gas heater 48 Fundamentals Training Manual Rev 1 R Foam Insulation Rigid polyurethane foam insulation has been proven to be a more effective insulating material in reducing the standby loss through the jacket than previously used fiberglass Generally
78. re the recovery rate of a water heater A water heater at a certain input rate will recover x amount of gallons per hour at a certain temperature rise The higher the temperature rise needed the less a water heater will supply in GPH GPM Gallons per Minute This stands for gallons per minute and refers to the amount of water flowing through a plumb ing fixture or pipe Galvanic Action If two unlike metals are immersed in an electrolyte an electrical potential will exist between them If the two are in electrical contact an electrical current will flow The metal which becomes the anode of this cell will corrode and dissolve while the cathode will be protected from corrosion The two metals do not have to be vastly different for this effect to take place It can occur with copper and a copper alloy It can even occur with two different parts of the same sheet tube or rod Glass lined A coating of enamel bonded to the inside of the tank to help protect the tank from corrosive ele ments in the water This is a coating of vitreous enamel bonded to an iron or steel surface by firing at red heat The enamel is a special formulation resistant of hot water and is not the same type of glass as that used in windows and glassware Glass lined heater may be referred to as glass enamel lined glass enameled vitreous enameled or bonded vitreous enamel 43 Fundamentals Training Manual Rev 1 Grain A measure of weight There a
79. rods will react before a steel water tank Service conditions have also accelerated water heater corrosion problems The increasing demand for hot water coupled with the trend toward higher temperatures have suggested corrosion increases as temperature and water throughput increases 10 Fundamentals Training Manual Rev 1 In a water heater corrosion is protected by a glass actually a porcelain enamel lining in the steel tank and the use of auxiliary anode rods During the manufacturing process the inside water tank and both the top and bottom heads are sprayed with a liquid glass material Glass technology allows the glass to adhere to the steel interior and is accomplished by apply ing a precise thickness of glass mixture to the tank and heating for a precise time period This material is fired in a furnace and when cooled resembles a porcelain lining This glass pro vides a long life to the steel tank otherwise the tank would fail or corrode in a relatively short time Every glasslined water tank no matter how carefully 1t is manufactured has some bare metal exposed This is due to the inability to effectively cover sharp corners and the radius around the fittings There is a chance that a crack or chip in the porce lain lining will allow the water to come in contact with the steel tank Over time water a universal solvent that becomes more aggressive with temperature breaks down the interior tank lining This will create con dit
80. t 40 50 58 67 75 83 92 100 50 45 55 64 73 82 91 100 60 40 50 60 70 80 90 100 70 33 44 56 67 78 89 100 Thermostat 170 Mixed Temperature 100 110 120 130 140 150 160 170 40 46 54 62 69 77 85 92 100 50 42 50 63 67 75 83 92 100 60 36 45 59 64 73 82 91 100 70 30 40 55 60 70 80 90 100 Thermostat 180 Mixed Temperature 100 110 120 130 140 150 160 170 180 40 43 50 57 64 71 79 86 93 100 50 38 46 52 62 69 77 85 92 100 60 33 42 48 58 67 75 83 92 100 70 27 36 43 55 64 73 82 91 100 Cold Inlet Cold Inlet 33 Fundamentals Training Manual Rev 1 FORMULAS AND FACTS 1 gallon of water weighs 8 33 lbs 1 gallon of water has a volume of 231 cubic inches 1 cubic foot of water weighs 62 38 lbs and contains 7 48 gallons of water 100 feet of 3 4 copper pipe contains 2 5 gallons of water 1 pipe contains 4 3 gallons 8 33 BTU will raise 1 gal of water 1 F at 100 efficiency electricity 11 BTUs are required to raise gallon of water 1 F at 70 efficiency gas 3 412 BTU equals 1 kilowatt hour Kwhr 1 Kwhr will raise 410 gallons of water 1 F at 100 efficiency 1 BTU X 0 293 watts 1 KW 1000 watts 2 42 watts are required to raise 1 gallon of water 1 F 1 Kwhr will raise 10 25 gal of water 40 degrees F at 100 efficiency 1 Kwhr will raise 6 8 gal of water 60 degrees F at 100 efficiency 1 Kwhr will raise 5 1
81. ty Rheem water heaters are pressure tested to 300 pounds per square inch PSI and have a working pres sure of 150 PSI The T amp P valve is designed to open when the pressure inside the tank exceeds 150 PSI allowing pressure to vent safely The T amp P valve will also open if the water temperature reaches 210 F The valve will remain open allowing cold water into the tank until the unsafe condition is over Why is hot water over 212 F dangerous The containment vessel or stor age tank used to store the hot water causes the danger This tank is under pres sure the normal working pressure caused by the cold water supply As water is heated under pressure the boiling point rises For example with a nominal incoming supply pressure of 50 PSI water will not boil under pressure until the temperature reaches approximately 297 F The energy potential in the super heated water is called latent heat energy and will flash to steam when exposed to normal atmospheric pressure This flash to steam has the explosive potential of over two million foot pounds of energy Fig 10 Temperature amp Pressure Relief Valve The Temperature and Pressure Relief Valve is the safety device that prevents these con ditions from happening It is a 2 in 1 device that responds to both pressure increases and tem perature increases When actuating by pressure the T amp P valve will open and allow the tanks internal pressure to drop below 150PSI Generally when
82. urning capacity of a water heater in BTU s per hour Water heater input ratings are based on sea level operation and need not be changed for operation up to 2 000 feet elevation For operation at elevations above 2 000 feet input rating should be reduced at a rate of 4 for each 1 000 feet above sea level For instance a gas heater with a 40 000 BTU input rating installed at 4 000 feet above sea level would have a reduced BTU rating of 33 600 BTU s Instantaneous Water Heater A water heater which has an input rating or at least 4 000 BTU per hour per gallon of stored water Intermittent Ignitor Also referred to as an LI D Intermittent Ignition device The ignition system of the residen tial power vent water heater This is used to light the pilot during the heating cycle Junction Box The place in electric water heaters where the power supply is connected to the water heater Water heaters wired for 3 phase operation will require a separate external junction box Kilowatt kW A measure of the rate of supply of energy or power and is equal to 1 000 watts A kilowatt equals 3 412 BTU per hour Lifeguard Element A trade marked registered heating element offered by Rheem The element has a stainless steel outer sheath of INCOLY 800 the same material found in electric range elements The LIFE GUARD element is a low watt density design and contains a small resistor built into the ele ment to reduce cathodic reaction with the water i
83. used For instance water for showers may be stored in the heater at 140 F but is mixed with cold near the point of use to arrive at use temperature of 95 F to 110 F Vacuum Switch Or pressure switch Used in power vented water heaters The vacuum switch verifies that the vent motor is running after which gas is allowed to flow to the main burner 53 Fundamentals Training Manual Rev 1 Volts V The voltage is a measure of the electrical pressure between two conductors Open circuit volt age is the voltage measured between two conductors when no appliance or other load is con nected to them Closed circuit voltage is the voltage as measured across the terminals of an appliance with the appliance is turned on and is operating Generally speaking the closed cir cuit voltage will be lower than the open circuit voltage Water Hammer A loud pounding usually caused by high water pressure when a faucet is turned off or washer valve is closed Watts A measure of the rate of consumption of energy Watts are calculated from volts and amps sin gle phase only as follows Watts volts x amps Weeping T amp P The Temperature and Pressure relief valve opening due to high pressure 150 PSI or high tem perature 210 F NOTES 54 Fundamentals Training Manual Rev 1 NOTES 55 Fundamentals Training Manual Rev 1 NOTES
84. verage water usage involves the hot water heating system in our homes Hot water is a complex environment that enhances the existing capability of naturally occurring minerals to cause corrosion scale deposits and odor problems These minerals are already present in the cold water supply When water is heated it acts differently than cold water For example Water changes volume expands when heated and it is virtual ly incompressible We all know that when water freezes it expands and may burst household plumbing fixtures and pipes Water also expands when it is heated That is why water heaters have a Temperature and Pressure Relief valve installed One of the common effects of such expansion is that hot water backs into the cold water supply lines of the water heater or causes the T amp P valve to dribble if the system is closed Heating water releases gasses present in the water Water naturally contains dissolved gasses such as oxygen chlorine carbon dioxide and hydrogen sulfide At a given pressure such as a normal 40 PSI household the amount of gas that water can hold is less as the temper ature increases This is exactly what happens inside a water heater With a normal household pressure the water is heated The heated water releases the gas causing the faucet to spit when there is a hot water draw One of the common occurrences may be a complaint of milky water from the tap Allowing the water to stand for several
85. water heater through a given temperature rise in a given amount of time Recovery capacity is usually expressed in terms of gallons per hour GPH at 100 F temperature rise Generally the higher the BTU or wattage input rate the faster the recovery rate is Recovery rates are also a component of the First Hour Rating First Hour Rating The calculated amount of hot water a fully heated water heater can deliver in the first hour peri od The output on a water heater is normally given in gallons per hour at a 100 F temperature rise It is the quantity of water that the heater will deliver at 140 F when the cold start temper ature is 40 F This does not mean the water heater will provide hot water for 60 continuous minutes This quantity of hot water is based on initial storage plus the ability to heat water as it is being drawn The temperature of this water must be within 10 F of the thermostat setting to be considered usable Input The amount of fuel electricity consumed by a water heater in a given period of time It is usually expressed in terms of British Thermal Units per hour BTUH or Kilowatt hours KWH Hot Water Demand The total volume of hot water in gallons required during a peak load or maximum usage peri od of time The peak load may vary from a few minutes to a few hours depending on the user Draw Rate The rate at which water is drawn from a water heating system usually expressed in gallons per minute GPM
86. wo sub systems the hot water supply and the cold water supply The modern home or a remodeled older home will most likely have at least one mixing or single handle type faucet installed Most homes today have an automatic laundry washing machine Both of these are examples of appliances and fixtures that have a mixing valve Any mixing valve can allow a cross over to occur should they become defective A defective mix ing valve will allow a cross over of hot and cold water even though there are no visible signs of trouble or leak Plumbing cross overs can cause a complaint such as water not hot enough Testing the hot plumbing system for a cross over can be accomplished by using the following procedure 1 Close the cold water shut off valve supplying cold water to the heater 2 Using a faucet with separate HOT and COLD spigots open the hot faucet only 3 With the cold water to the heater shut off once the pressure is relieved the water should stop running completely Should the water continue to flow but at a slower than normal rate you have one of two conditions If the slower flow continues but stays HOT the cold water shut off valve is defective and the test will not be valid Replace the cold water shut off valve and continue the test If the water turns COLD you have cold water crossing over to the hot water plumbing system 4 To locate the cross over first shut off the hose bibb service valves to the laundry wash er
87. you see a T amp P valve weeping or drib bling it is due to pressure thermal expansion or foreign material such as calcium buildup in the valve seat This material on the valve seat will prevent the valve from closing tightly If the valve is discharging large quantities of water then the release is due to temperature Remember the T amp P is installed in the top six inches of the tank If the temperature probe on the T amp P sens es water temperatures of 210 F it will open the valve The valve will stay open until the tem perature probe cools With cold water entering the bottom area of the tank you can see a large volume of water gallons will be discharged before the temperature probe cools T amp P valves should be inspected and tested on every service call When checking the valve also check the rating plate on the valve Many changes may take place in a plumbing system after the original installation Through a systemic reinspection program we can insure that the safety device is working properly The 18 Fundamentals Training Manual Rev 1 T amp P Valve must be capable of discharging more BTUs than the heater is capable of putting into the water Installation of a temperature and pressure relief valve is critical to the safe operation of a water heater The basic rule is that the T amp P valve must be installed so that the temperature sensing probe is immersed in the hottest water which is in the top six inches of the

Fundamentals of Water Heating

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