This manual has been prepared especially for the The information
Contents
1. CONSERVATIONIST BURKAY BOILERS DURAMAX BOILERS MODEL NUMBER GALLONS UN LIME MODEL NUMBER GALLONS UN LIME HW 120 4 DW DB 720 5 HW 160 4 DW DB 840 5 HW 200 5 DW DB 960 5 HW 225 5 DW DB 1080 6 HW 300 5 DW DB 1210 6 HW 399 6 DW DB 1350 7 HW 420 6 DWI DB 1480 7 HW 520 8 DWI DB 1610 7 HW 670 8 DW DB 1810 7 Technical Literature Department Servicing should only be performed by a Qualified Service Agent 5 of 16 Ashland City TN 62009 ALL ABOUT DELIMING COPPER TUBE BOILERS Table 3 cont Gallons of Un Lime required by A O Smith boiler product model numbers GENESIS BOILERS LEGEND BOILERS MODEL NUMBER GALLONS UN LIME MODEL NUMBER GALLONS UN LIME GW GB 200 4 LW LB 500 6 GW GB 300 4 LW LB 750 6 GW GB 400 4 LW LB 1000 8 GW GB 500 5 GW GB 650 5 GW GB 750 5 GW GB 1000 8 GW GB 1300 8 GW GB 1500 8 GW GB 1850 9 GW GB 2100 9 GW GB 2500 10 DELIMING PUMP AND FITTINGS Table 4 Table 4 lists a suitable pump and some of the special Item Description Quan fittings and materials required to perform the Forced 7 a Circulation Deliming method beginning on page 7 and the 1 2X T12 PG threaded bushing 2 Stopper Kit Deliming method beginning on page 9 2 1 1 2 x 1 2 PVC threaded bushing 2 In addition to the items in Table 4 standard 2 1 1 2 and 3 1 1 4 x 1 2 PVC2. 1 Transfer rotate the stoppers to close the circuit s previously delimed and allow flow through the remaining circuits that have not been delimed as shown in Figure 6 through Figure 9 2 Delime remaining 2nd 3rd and 4th circuits depending on boiler model as outlined in the instructions for the first circuit 3 Test the deliming solution being used to ensure it is not exhausted after each water circuit is delimed see Testing Delimer on page 5 4 When all water circuits have been delimed drain the deliming solution from the boiler Test the deliming solution for reuse see Testing Delimer on page 5 Store for future use or dispose of as directed by the labeling on the deliming solution container or instructions provided by the deliming solution manufacturer Deliming The Second Circuit 2nd Circuit Outlet Manifold Coupling Plastic Bushing Hose Connection 3rd Circuit Discharge o Hose From Pump HW 300 670 Model Boilers Figure 7 Deliming 3rd and 4th Circuits Figure 8 and Figure 9 illustrate stopper configurations for HW 300 670 model boilers only 1st Circuit 2nd Circuit Outlet Manifold Plastic Bushing Hose Connection Plastic Plug Couplings Discharge Spy Hose From Pump HW 120 225 Model Boilers Figure 6 3rd Circuit HW 300 670 Model Boilers Figure 8 11 of 16 4th Circuit HW 300 670 Model Boilers Fi
3. Consider installing a bypass line and valve to raise the minimum inlet water temperature Call 800 527 1953 for technical assistance Technical Literature Department 13 of 16 Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS BOILER TEMPERATURE LOGt Date Time Outlet Temp Inlet Temp Temp Rise A Readings Taken By t Outlet Inlet A Outlet supply water temperature minus inlet return water temperature equals the temperature rise Delta T A through the boiler Readings should be taken daily or weekly When the temperature rise Delta T A increases by 5 F schedule deliming maintenance to prevent heavy lime accumulation which can greatly reduce efficiency and permanently damage coils and heat exchangers in a boiler t Sustained inlet water temperatures below 110 F can cause heavy condensation and the formation of copper oxide on copper coils and heat exchangers This can reduce the flow of flue gases inside the boiler and cause combustion problems Consider installing a bypass line and valve to raise the minimum inlet water temperature Call 800 527 1953 for technical assistance Technical Literature Department 14 of 16 Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS BOILER
4. outlet valve is throttled to set the proper temperature rise flow rate The return water inlet valve must remain 100 fully open during operation and must never be used to throttle water flow Bypass Lines amp Valves Bypass lines and valves installed between the boiler s outlet and inlet supply and return water lines are used to regulate raise the inlet water temperature This helps reduce the possibility of condensation forming on the copper tube coils and heat exchangers When the temperature rise is being initially set the bypass valve if present should be completely closed Once the temperature rise through the boiler has been set by throttling the outlet valve the bypass valve can be opened incrementally until the inlet water temperature is raised to the desired required temperature Generally a minimum inlet water temperature of 110 F to 120 F will greatly reduce or prevent condensation SCHEDULING DELIMING MAINTENANCE It is critically important to set the water temperature rise through the boiler according to the requirements given in the Instruction Manual that came with the boiler Once the water temperature rise through the boiler has been set mark the positions of the supply water outlet valve and the bypass valve if so equipped Remove the valve handles and store them nearby to prevent accidental changes Keep a boiler log see page 12 at the boiler to record inlet and outlet water temperatures Also
5. From Pump HW 120 225 Model Boilers Figure 4 3 Attach a plastic hose to the discharge side of the pump and the other end to the outlet manifold as shown in Figure 4 and Figure 5 Technical Literature Department 10 of 16 2nd Circuit Outlet Manifold Nipple Coupling Plastic Bushing 4 Hose Connection 3rd Circuit Discharge Hose From Pump HW 300 670 Model Boilers Figure 5 4 Ensure one end of the plastic return hose is connected to the inlet manifold on the boiler and the other end is inside the large plastic container as shown in Figure 2 on page 9 Secure the end of the hose in the large container so it will not pop out of the container when the pump is started 5 Add the proper amount of UnLime delimer to the large container See Table 3 on page 5 6 Start the deliming pump by inserting the pump plug into a GFCI protected 120 VAC wall outlet Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS Deliming The First Circuit cont 7 Allow the Un Lime Delimer to circulate for at least one hour and longer if foaming or air bubbles due to dissolving lime scale continue to appear After all foaming has stopped continue circulating the Un Lime Delimer for another 20 to 30 minutes to remove any remaining lime scale is removed and then unplug the pump Deliming The Remaining Circuits
6. the Instruction Manual that came with the boiler for specific operating requirements such as flow rates temperature rise e Make certain that the inlet and outlet thermometers have been installed per manufacturer s specifications For staged fire boilers the temperature rise should only be recorded when the boiler firing at 100 e Record temperatures after the outlet valve has been adjusted throttled to achieve the proper temperature rise flow rate per manufacturer s requirements for the particular model The inlet valve should remain 100 open at all times during operation Never use the inlet valve to throttle or regulate water flow Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS Neglecting to Delime Regularly A consistent deliming schedule will reduce the severity of lime scale accumulation Necessary cleaning intervals will vary Keeping a boiler temperature log pages 3 and 13 is the best way to schedule deliming maintenance If regularly scheduled deliming maintenance is neglected until a rumbling or pounding noise occurs the lime scale build up is severe Severe lime accumulation removal is more costly and the procedures are more time consuming than regularly scheduled deliming maintenance See the Heavy Lime Deposit Removal procedure for HW 120 670 boilers on pages 8 and 9 Water Impurities Severe lime accu
7. threaded bushing 2 1 1 4 NPT pipe couplings and short pipe nipples will also be required to perform the Stopper Kit Deliming method 4 1 x 1 2 PVC threaded bushing 2 beginning on page 9 See Figure 4 on page 10 through 5 1 2 PVC threaded pipe plug pa Figure 9 on page 11 The stopper kit A O Smith Part No 9004876115 is 6 3 4 PVC threaded pipe plug 2 required for heavy lime accumulation removal Stopper Kit 7 1 2 brass thread to 1 2 barbed hose adapter 2 Deliming method beginning on page 9 and can be ordered by calling 800 433 2545 8 10 foot sections 1 2 Plastic Hose 2 The Little Giant model 4RL36 submersible chemical 9 1 2 hose clamps 4 solution pump can be ordered from Grainger Inc online at www grainger com or by phone at 800 323 0620 Large Container plastic trash can 1 The remaining parts and materials can be obtained 11 Submersible Chemical Solution Pump 1 through your local plumbing supplies Little Giant model 4RL36 or equivalent 12 Stopper Kit AOS PN 9004876115 1 Technical Literature Department 6 of 16 Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS HOW TO DELIME 7 The maintenance procedures that follow and throughout this manual require the ability equivalent to that of a licensed tradesman in the field involved Plumbing air 8 supply a
8. 210 BASED ON 10 GRAINS HARDNESS PARARE CF DATA FROM PURDUE BULLETIN 74 BEEN ki POUNDS OF LIME DEPOSITED PER YEAR LI E Z a l l an mia 1500 21 TO a 3300 WATER USAGE IN GALLONS PER DAY This chart was prepared from research by Purdue University 3900 These three factors determine how much lime scale will fallout of solution in a hot water supply system 1 WATER HARDNESS The harder the water is the more mineral content the more lime scale will be accumulated The chart above is based on 10 grains of hardness 2 USAGE Each gallon of water used will have a certain amount of lime scale As the number of gallons used increases so will the amount of lime scale accumulation See the usage gallons per day shown horizontally across the bottom of the chart 3 WATER TEMPERATURE As shown in the chart above the rate at which lime scale will drop out of solution dramatically increases as the water or system temperature is increased Note the increase in pounds accumulated when the water or system temperature is increased from 140 F to 180 F With the same hardness and usage there is a seven fold increase in accumulation Temperature Rise And Flow Rate The flow rate of water GPM gallons per minute through a boiler is critical to it s operation performance and life Technical Literature Department 3 of 16 span Temperature rise through a boiler is inversely linked to the flow rate As the flow
9. ALL ABOUT DELIMING COPPER TUBE BOILERS This manual originally entitled All About Deliming Coil Type Water Heaters was prepared as a maintenance instruction for deliming A O Smith Burkay copper coil boilers This manual has been revised to include Light Lime Deposit Removal instructions for other A O Smith copper tube boilers such as DuraMax Genesis and Legend Heavy lime accumulation in DuraMax Genesis and Legend boilers may necessitate the removal of the heat exchanger and or removing the inlet and outlet manifolds from the heat exchanger for mechanical cleaning These procedures are beyond the scope of this manual Call 800 527 1953 for further technical assistance Deliming instructions for Burkay BC model boilers are no longer included in this manual request form 4778 revision 10 for instructions on deliming BC model Burkay boilers For deliming tank type water heaters request form 4800 Why When and How to Remove Water Scale From Tank Type Water Heaters These publications are available from your local A O Smith sales representative or can be downloaded from the A O Smith web site at www hotwater com CONTENTS INTRODUCTION 1 053 6 40 ccna ele alain eed eeeees 2 HOW TO DELIME abi cc aes ieee eee een ected 7 Qualifications And Warnings 2 Light Lime Deposit Removal All Boilers 0 0 0 eee 7 WEY DE NME koua kose diya ea ieena 2 Heavy Lime Deposit Removal 00urirrreerrrrrerrrerra
10. For All Boiler Models Forced Circulation Deliming Method Figure 1 ee Discharge Hose To Boiler Return Line Deliming T HEAVY LIME DEPOSIT REMOVAL Heavy lime accumulation in DuraMax Genesis and Legend boilers may necessitate the removal of the heat exchanger from the boiler cabinet or removing the inlet and outlet manifolds from the heat exchanger for mechanical cleaning These procedures are beyond the scope of this instruction Call 800 527 1953 for further technical assistance HW 120 670 Model Boilers It is possible to build up heavy lime deposits when scheduled deliming maintenance has not been performed regularly Heavy lime deposits are evidenced by a rumbling or pounding noise and or burner cycling off of the high limit control This condition could indicate one or more water circuits in the boiler s coil or heat exchanger are blocked causing insufficient water flow Technical Literature Department 8 of 16 If the Forced Circulation Deliming Figure 1 procedure has been performed and the symptoms of pounding noise and or burner cycling off of the high limit control continue deliming of the individual water circuits in the boiler s coil and heat exchanger may correct the problem When the stopper kit part number 9004876115 plugs are used correctly to isolate individual circuits partially blocked circuits can sometimes be cleared Completely blocked water circuits in a boiler s coil or hea
11. TEMPERATURE LOGt Date Time Outlet Temp Inlet Temp Temp Rise A Readings Taken By t Outlet Inlet A Outlet supply water temperature minus inlet return water temperature equals the temperature rise Delta T A through the boiler Readings should be taken daily or weekly When the temperature rise Delta T A increases by 5 F schedule deliming maintenance to prevent heavy lime accumulation which can greatly reduce efficiency and permanently damage coils and heat exchangers in a boiler t Sustained inlet water temperatures below 110 F can cause heavy condensation and the formation of copper oxide on copper coils and heat exchangers This can reduce the flow of flue gases inside the boiler and cause combustion problems Consider installing a bypass line and valve to raise the minimum inlet water temperature Call 800 527 1953 for technical assistance Technical Literature Department 15 of 16 Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent f Smith 500 Tennessee Waltz Parkway Ashland City TN 37015 Technical Support 800 527 1953 Parts 800 433 2545 Fax 800 644 9306 www hotwater com
12. a bypass valve is present and left open some or all of the UnLime solution will flow through the bypass line instead of flowing through the boiler where it is 18 needed 5 Depressurize the system Open the heat exchanger 19 drain valve if present or the pressure relief valve on the boiler Close the drain relief valve when water pressure in the boiler has been reduced to 0 PSI WARNING When relieving the pressure in the system direct the water to a suitable drain safely avoiding contact 6 Figure 1 shows a typical piping arrangement with deliming T fittings that permits gravity or forced circulation deliming Make connections using a submersible chemical feed pump large container fittings and hoses see Table 4 as shown in Figure 1 Technical Literature Department 7 of 16 Pour the proper amount of UnLime see Table 3 pages 5 and 6 for the model being serviced into the large container Start the deliming pump by inserting the pump plug into a GFCI protected 120 VAC wall outlet Allow the Un Lime Delimer to circulate for at least one hour and longer if foaming or air bubbles due to dissolving lime scale continue to appear After all foaming has stopped continue circulating the Un Lime Delimer for another 20 to 30 minutes to remove any remaining lime scale is removed and then unplug the pump Drain the Un Lime from the boiler Flush the unit with fresh water for at least 10 to 15 minutes Also flush and clean the d
13. astic hose that will return the UnLime solution to the large container see Figure 2 Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS Service Note A screwdriver straight and offset pliers will be needed to help wedge the stoppers in place when isolating the water circuits inside the outlet manifold The instructions that come with the stopper kit explain this in detail Figure 3 shows the components that make up the four water circuits in HW 300 670 models The smaller HW 120 225 models are constructed similarly except there are only two water circuits present one through the heat exchanger and one through the copper coil 1st Circuit Heat Exchanger 2nd Circuit Figure 3 3rd Circuit 4th Circuit Deliming The First Circuit 1 Insert the stoppers 9004876115 kit firmly into all but one of the water circuits of the outlet manifold as shown in Figure 4 and Figure 5 2 Using field supplied threaded couplings and nipples and the appropriate size bushings and hose adapter see Table 4 on page 6 prepare the outlet manifold on the boiler to connect the chemical feed discharge hose that will supply the UnLime solution to the boiler see Figure 2 on page 9 Figure 4 and Figure 5 2nd Circuit Outlet Manifold Stopper Plastic Bushing 1st Circuit Hose Connection Couplings Discharge rr Hose
14. ation 1 Technical Literature Department Locate the boiler s primary system control thermostat and record the current temperature setting and then lower it to the lowest set point Verify the boiler s is no longer firing and that all boiler circulation pumps have stopped Close the gas supply shut off valve to the boiler s Close the supply and return water valves to the boiler If a bypass line is present between the supply and return water lines note mark the position of the valve handle then close the valve This is a critical step If a bypass valve is present and left open some or all of the UnLime solution will flow through the bypass line 9 of 16 instead of flowing through the boiler where it is needed Depressurize the system Open the boiler drain valve or the pressure relief valve on the boiler until water pressure inside the boiler is reduced to 0 PSI WARNING When relieving the pressure in the system direct the water to a suitable drain safely avoiding contact Disconnect the supply outlet and inlet return water lines from the boiler Remove the automatic high limit temperature control s temperature sensing bulb from the temp probe well in the outlet manifold and plug the threaded opening with a plastic pipe plug see Figure 2 Use field supplied couplings and pipe nipples and the materials and fittings listed in Table 4 on page 6 prepare the inlet manifold on the boiler to connect the pl
15. e become less soluble As the water temperature rises these minerals will precipitate or fall out of solution See the chart on page 3 As water is heated inside a boiler the lime scale forms deposits on the inner walls of the copper tubes and waterways This accumulation of lime reduces water flow through a boiler a critical aspect of a boiler s operation and performance The following reasons for removing this lime scale build up from the copper tubes and waterways inside a boiler are much the same as they are for other water heating equipment Technical Literature Department 1 2 of 16 NOT ENOUGH HOT WATER Lime forms an insulating crust inside the boiler s tubes and waterways This reduces water flow through the boiler less GPM gallons per minute The amount of hot water delivered by a boiler is directly proportional to the flow rate through the boiler As flow rate is reduced the quantity will also be reduced NOISY OPERATION Severe lime accumulation can reduce water flow to a point that traps water in a section of the heat exchanger or prevents the rapid release of hot water from the source of heat The water can be heated above it s boiling point causing audible and sometimes alarming sounds as the water flashes to steam inside the boiler HIGHER UTILITY BILLS Heating surfaces lose direct contact with the water as lime accumulation builds up The accumulated lime acts as an insulation barrier and r
16. educes the rate of heat transfer This will cause extended heating cycles which increases operating costs SHORTENED UNIT LIFE As noted above when the heating surfaces lose direct contact with the water it will extend the heating cycles Extending the heating cycles also extends the wear and tear on the boiler The insulating effect of lime accumulation reduces the rate of heat transfer between the water and the heat transfer surfaces This will cause a rise in the surface temperature of the heat transfer surfaces Lime accumulation will cause greater heat stress higher surface temperatures for longer periods of time This will increase service costs and shorten the life of the boiler CUSTOMER DISSATISFACTION The customer soon becomes dissatisfied with less hot water higher operating costs increased service costs down time and shortened equipment life A regular planned deliming and maintenance schedule will e Improve performance e Reduce operating costs e Reduce service costs and down time Extend the life of the equipment Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS WHEN TO DELIME Lime Accumulation The amount of calcium and magnesium carbonate lime scale released from water is in direct proportion to water hardness temperature and usage see the chart below POUNDS OF LIME DEPOSITED VS TEMPERATURE AND WATER USAGE
17. eliming pump bucket and deliming fittings Restore the original piping and original fittings If a bypass valve was closed during the deliming set up procedure restore the bypass valve to its previous position Inspect all piping connections Slowly open the inlet valve valve B Figure 1 on page 8 while carefully purging all air out of the boiler through its pressure relief valve or other appropriate fitting or opening WARNING Direct this discharge to a suitable drain safely avoiding contact When all air is removed close the relief valve or opening used to purge the air from the boiler Open the outlet valve valve A in Figure 1 on page 8 Check for any water leaks and repair as necessary Follow the start up instructions in the Instruction Manual that came with the boiler Instruction Manuals can be obtained at A O Smith s web site www hotwater com or by calling technical support at 800 527 1953 Restore the boiler s primary system control thermostat to the setting recorded in Step1 Restore the boiler to service Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS To System Service Note The flow of UnLime solution through the boiler is in the opposite direction that water flows through the boiler during normal operation Large Container Submersible Pump Regularly Scheduled Deliming Maintenance Procedure
18. gure 9 Technical Literature Department Servicing should only be performed by a Qualified Service Agent Ashland City TN 62009 ALL ABOUT DELIMING COPPER TUBE BOILERS Flushing The Boiler 1 Reconnect the return water piping to the inlet bottom manifold on the HW model boiler as it was on arrival 2 Disconnect the plastic hose from the submersible pump and direct the disconnected end of the hose toa suitable drain leaving the other end of the hose connected to the outlet top manifold Firmly secure this hose to ensure it cannot move during flushing 3 Slowly and carefully open the return inlet boiler isolation valve partially to allow system water to flush the boiler for 5 minutes WARNING When flushing the boiler direct the water to a suitable drain safely avoiding contact 4 When flushing is completed close the return inlet boiler isolation valve Returning The Boiler to Operation 1 Reconnect the supply water piping to the outlet top manifold on the HW model boiler as it was on arrival Ensure the return water piping to the inlet bottom manifold of the boiler has also been reconnected as it was on arrival 2 Replace the automatic high limit temperature control s temperature sensing bulb removed in the preparation Steps on page 9 see Figure 2 on page 9 3 Slowly open the return inlet boiler isolation valve to its full open position Allow the boiler to fill with water 4 Ifa bypass line i
19. mulation may necessitate the removal of the heat exchanger from the boiler cabinet or removing the inlet and outlet manifolds from the heat exchanger for mechanical cleaning These procedures are beyond the scope of this instruction Call 800 527 1953 for further technical assistance Heat exchangers can become completely restricted with lime scale and in some cases not be salvageable This condition is not covered under the A O Smith limited warranty Table 1 PROBLEM MAY BE TERMS DESCRIPTION REMOVED BY REDUCED BY TLime Calcium and Deliming with Un Lime twater Softening or feeding Water Hard Water Magnesium Carbonate Professional Delimer glassy phosphates Scale P Cannot be eliminated but effect Other Silene Se Manually Scrapping can be reduced by regular Aluminates etc ye deliming with Un LIme Fine particles of soil or sand suspended in or deposited by water Silt Deliming with Un Lime Professional Delimer and Flushing Water Filtering t About 85 of this country s area is served by water containing concentrations of dissolved minerals suffi cient to cause lime scale Excessive lime scale formations can also be reduced by setting the water temperature control at the lowest possible temperature which will provide satisfactory hot water service Technical Literature Department 4 of 16 Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agen
20. n this manual Copies of Instruction Manuals can be obtained on the web site listed on the back cover of this manual or by calling 800 527 1953 Qualifications Performing any of the maintenance procedures covered in this manual requires ability equivalent to that of a Qualified Agency as defined by ANSI below in the field involved Installation skills such as plumbing air supply venting gas supply electrical supply are required in addition to electrical testing skills when performing service ANSI Z223 1 2006 Sec 3 3 83 Qualified Agency Any individual firm corporation or company that either in person or through a representative is engaged in and is responsible for a the installation testing or replacement of gas piping or b the connection installation testing repair or servicing of appliances and equipment that is experienced in such work that is familiar with all precautions required and that has complied with all the requirements of the authority having jurisdiction Service Warning If you are not licensed or certified to perform a given task do not attempt to perform any of the procedures outlined in this manual If you do not understand the instructions or do not feel confident in your abilities to perform a given task do not attempt to perform any procedures outlined in this manual WHY DELIME When water is heated dissolved minerals in the water such as calcium and magnesium carbonate lime scal
21. nd electrical work are required Do not perform any maintenance procedures if you do not meet the 9 Qualifications listed on page 2 LIGHT LIME DEPOSIT REMOVAL ALL BOILERS A O Smith recommends the Forced Circulation Deliming method as a regular preventative maintenance plan for the removal of light lime deposits This method uses a pump and fittings such as those listed in Table 4 on 10 page 6 11 Forced Circulation Deliming Boilers must be equipped with supply and return water isolation valves and deliming T fittings installed in the 12 supply and return water lines as shown in Figure 1 on page 8 When not in use the branch of the T fittings are plugged If these valves and fittings are not installed they will need to be installed before the forced circulation 13 deliming procedure outlined below can be performed Reference Figure 1 on page 8 for the following instructions 1 Locate the boiler s primary system control thermostat and record the current temperature setting and then lower it to the lowest set point Verify the boiler s is no longer firing and that all boiler circulation pumps have stopped 14 Close the gas supply shut off valve to the boiler s 3 Close the A supply and B return water shut off 13 valves to the boiler s See Figure 1 on page 8 16 4 Ifa bypass line is present between the supply and 17 return water lines note mark the position of the valve handle then close the valve This is a critical step If
22. rate is decreased the temperature rise will increase as the flow rate is increased the temperature rise will decrease A O Smith copper tube boilers will generally operate with a temperature rise of about 20 F to 40 F depending on model pump and piping configuration If the system is set to provide a 120 F supply the water temperature inside the boiler s heat exchanger may reach 140 F to 160 F As flow rate is reduced the water temperature inside the boiler will increase This will increase the rate of lime accumulation as noted in the previous chart Deliming Schedule Preventative maintenance helps eliminate the problems page 2 associated with lime scale build up One method to establish a deliming schedule is to record the temperature rise at the time of installation or immediately after deliming A sample boiler log is provided on page 13 A boiler log should be attached to each boiler and the temperature rise should be recorded weekly Record the outlet and inlet water temperatures at the same time with the boiler firing at 100 firing rate The difference between the two temperatures is the temperature rise through the boiler In this way the normal temperature rise can be established and used as a guide for when to schedule future deliming As the temperature rise through the boiler reaches 5 F higher than the original readings a deliming procedure should be performed Important Service Notes e Always refer to
23. record the water temperature rise through the boiler When the water temperature rise through the boiler increases by 5 F schedule deliming maintenance At this point the lime accumulation will not be heavy and can usually be removed with the less costly Light Lime Deposit Removal method outlined on page 7 Failing to implement regularly scheduled deliming often results in heavy lime accumulation that is more costly to remove and may completely block the copper tubes inside the boiler Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS BOILER TEMPERATURE LOGt Date Time Outlet Temp Inlet Temp Temp Rise A Readings Taken By t Outlet Inlet A Outlet supply water temperature minus inlet return water temperature equals the temperature rise Delta T A through the boiler Readings should be taken daily or weekly When the temperature rise Delta T A increases by 5 F schedule deliming maintenance to prevent heavy lime accumulation which can greatly reduce efficiency and permanently damage coils and heat exchangers in a boiler Sustained inlet water temperatures below 110 F can cause heavy condensation and the formation of copper oxide on copper coils and heat exchangers This can reduce the flow of flue gases inside the boiler and cause combustion problems
24. s present between the supply and return water lines on the boiler return the valve to the marked position that was noted in the preparation Steps on page 9 5 Open the supply outlet boiler isolation valve and check for water leaks repair any water leaks Restore the gas and power to the boiler Follow the start up lighting instructions in the Instruction Manual that came with the boiler Copies can be obtained at A O Smith s web site www hotwater com or by calling 800 527 1953 8 Return the boiler s primary system control thermostat setting to the value recorded in the preparation Steps on page 9 WATER FLOW AND TEMPERATURE RISE Ensure the water temperature rise through the boiler is within the requirements listed in the Instruction Manual that came with the boiler when placing the boiler back in operation Water temperature rise is determined by taking a water temperature reading at the outlet and inlet of the boiler while firing at full capacity The outlet temperature Technical Literature Department 12 of 16 minus the inlet temperature the boiler s water temperature rise Inversely Proportional Water temperature rise through the boiler is inversely proportional to the water flow rate through the boiler As the water flow rate is decreased the temperature rise through the boiler increases And as the flow rate increases the temperature rise will decrease Regulating Temperature Rise The supply water
25. sarenannne 8 WHEN TO DELIME 22 0000 aac ob keyes vi kie 3 HW 120 670 Model Boilers 0 00 eee eect eens 8 Lime Accumulation ccesesescseseseseseseseseseeeceesseseseceeseeeeseces 3 Stopper Kit Deliming Method eset eeeeetereteee 9 Temperature Rise And Flow Rate 3 Flushing The Boiler 0 00 0 eee a aeaa 12 Deliming SCHEdUIC cccccsscssstsseseseeseesceceseseseststeeseececeees 3 Returning The Boiler to Operation ee 12 Neglecting to Delime Regularly c ccccccsteseeeceeesteteeees 4 WATER FLOW AND TEMPERATURE RISE eee 12 Water ImpuritieSsjun oe a ea 4 Regulating Temperature RiS cccccsceesesseessteeeeeeees 12 DELIMER caduno neiaa tia ed aa ana TE aeiiae 5 Bypass Lines amp Valves Asni ne R 12 PALE ANS a bo toi es a e tla he aki 5 SCHEDULING DELIMING MAINTENANCE 00 cece 12 CQWANLNAY ea kiskeya eescedeecev eases ioe deeae Di PO papa kose anpe ap t 5 Boiler Temperature Log TemplatES v rerrrrrrrrerrerarons 13 DELIMING PUMP AND FITTINGS ceeceeseeeeeeeeeeeeeeeeeeees 6 PRINTED IN THE U S A 0609 Technical Literature Department PART NO 316645 000 Ashland City TN 2009 ALL ABOUT DELIMING COPPER TUBE BOILERS INTRODUCTION Instruction Manual Have a copy of the Instruction Manual that came with the boiler on hand for the model and series number you are working with before servicing Read the Instruction Manual before performing any of the procedures outlined i
26. t DELIMER Hydrochloric Muriatic acid type cleaners must not be ALL ABOUT DELIMING COPPER TUBE BOILERS used on any A O Smith boiler products Un Lime A O Smith recommends the use of Un Lime for deliming Un Lime is a patented Non Muriatic Delimer Un Lime is specifically formulated for this type of equipment and will not harm the copper coil or heat exchanger during or after removing calcium lime scale build up Un Lime is ready to use and should not be diluted Do not mix Un Lime delimer with any other chemicals Read and comply with all instructions warnings and cautions on the Un LimeQ container labels before use Un LimeQ is sold in 1 gallon plastic containers packed 4 per carton and in 5 gallon plastic containers packed 1 per carton See Table 2 for part numbers Table 3 Testing Delimer Delimer is easily tested for strength by placing some lime scale orwhite chalk into a glass with a small amount of the delimer If the material is vigorously dissolved by the solution the delimer can be reused Table 2 UN LIME DESCRIPTION 9005416105 4 1 gallon case 9005417105 1 5 gallon Contact your local A O Smith distributor or sales representative for information on how to order Quantity Table 3 shows the amount of delimer required to delime A O Smith boilers by model number Gallons of Un Lime required by A O Smith boiler product model numbers
27. t exchanger cannot be salvaged in most cases Follow the Stopper Kit Deliming Method instructions see page 9 using potable water to first test each circuit for complete blockage using the stopper kit part number 9004876115 If one or more water circuits are unable to maintain any flow during this test with potable water the coil or heat exchanger in the boiler will have to be replaced These procedures are beyond the scope of this instruction Call 800 527 1953 for further technical assistance Ashland City TN 2009 Servicing should only be performed by a Qualified Service Agent ALL ABOUT DELIMING COPPER TUBE BOILERS Heavy Lime Deposit Removal Procedure For HW 120 670 Model Boilers Stopper Kit Deliming Method Service Note The flow of UnLime solution through the boiler is in the opposite direction that water flows through the boiler during normal operation Heat Exchanger inside the top of boiler cabinet Manifold Copper Coil Inlet surrounds the inside of the boiler cabinet Manifold Figure 2 Automatic High Limit Outlet Manifold Detail View Submersible Pump Stopper Kit Deliming Method These instructions are for HW 120 670 model boilers only Properly inserted stoppers from the kit part number 9004876115 will plug all but one water circuit through the boiler s coil and heat exchanger Flow will occur through only one circuit at a time Stopper Kit Method Prepar
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