Home

Service Handbook - AO Smith Water Heaters

1. BL BLUE i IF ANY OF THE ORIGINAL WIRE AS SUPPLIED W WHITE m 1 MUST BE REPLACED USE ONLY TYPE 105 C THERMOPLASTIC OR EQUIVALENT Figure 10 A WARNING Disconnect from electrical supply before servicing unit Replace all doors and panels before operating the water heater Servicing should only be performed by a Qualified Service Agent 14 AND SERVICE OPERATING SEQUENCE FLOW CHART Power On Call for Heat Self diagnostic check is performed Correct state of Blower Prover Switch and ECO is verified polarity earth ground and Igniter presence are verified YES Blower Draft Inducer Motor is Energized Blower Prover Switch N O Contacts Close at 2 85 W C 0 13 W C YES Y Ignition Control Board Sends Voltage 80 120 VAC to Igniter for 17 20 Seconds Ignition Control Board Energizes Gas Valve 24 VAC Igniter De energized After 3 Seconds Ignition Control Board Waits 3 More Seconds For Strong Flame Sense Signal 2 0 uA DC or more YES Tank Heated to Set Point I NO NO gt Control Locks Out LED Displays 2 6 or 8 Flash Error Code See Error Code Chart Control Locks Out Displays 3 Flash Error Code Below 0 1 uA DC Flame Sense Heater Will Try to Ignite 3 Times Control De energizes Gas Valve
2. 5 6 Flashes x uiia usada ata ete eoe 24 Air REQuireMentt aderi 2 6 FE 24 e 6 RENE 25 Insufficient Make up Air Negative Air Pressure Continuous 25 Downdrafts 7 ee Ee te del Ae 25 Makeup Ac Dect Communication wih ege Heater Conto Display Contaminated Air 9 EE Pr Clearances Water Heater ccccccccssssssssssssssseeeee 9 Test 2 Polarity 28 Clearances 10 Test 3 Conunuity Check of High EE es Nee T ee OPERATION AND SERVICE 12 Test e Calling for Heat eNo Blower Operation 31 Sequence of 12 Test 6 Blower On No 1 32 Electrical 13 Test 7 Blower On Blower Prover Switch Closed Wiring Diagra EE 14 No Igniter Operation 33 Operating Sequence Flow Chart 15 Test 8 Igniter Heats No Main Burner 34 GontrolValVe ec E es 16 Test 9 Igniter Heats No Main 35 Measuring Gas Pressures 16 Test 10 Main Burner Ignition for Less than Manifold P
3. resolution 0 01 W C Recommend UEI model EM200 TPI model 620 or equivalent Servicing should only be performed by a Qualified Service Agent 4 INSTALLATION CONSIDERATIONS INSTALLATION CONSIDERATIONS Installation information given in this service manual IS NOT a complete installation instruction Installation information covered in this service manual has a limited focus as it applies to servicing This service manual does not replace or supersede the Instruction Manual that came with the water heater Always refer to the instruction manual that came with the water heater for complete installation instructions If the instruction manual that came with the water heater is not on hand copies can be obtained from the manufacturer s web site or by calling the toll free phone number shown on the back cover of this service manual WATER PIPING Closed Water Systems Water supply systems may because of code requirements or such conditions as high line pressure among others have installed devices such as pressure reducing valves check valves and back flow preventers Devices such as these cause the water system to be a closed system Thermal Expansion As water is heated it expands thermal expansion In a closed system the volume of water will grow when it is heated As the volume of water grows there will be a corresponding increase in water pressure due to thermal expansion Thermal expansion can cause premature tank fai
4. Blower Runs for Post Purge Period Control Locks Out for 1 Hour Displays 1 Flash Error Code Between 2 0 and 0 1 uA DC Flame Sense Heater Will Continue to Operate Displays 7 Flash Error Code Weak Flame Sense Ignition Control Board De energizes Gas Valve Blower Runs 60 Seconds Post Purge Cycle and Shuts Off Blower Prover Switch Contacts Ignition Control Board Goes into Standby Mode Figure 11 Servicing should only be performed by a Qualified Service Agent 15 AND SERVICE GAS CONTROL VALVE This gas valve is a 24 volt AC combination step opening valve It includes two valves assembled in parallel connected by a wiring harness Note that the valves have fixed pressure regulation and are not adjustable However the manifold outlet pressure is adjustable as described on the next page IMPORTANT For complete device shut off both gas control knobs must be in the OFF position Both gas control knobs must be in the same position for operation or shutoff Do not alter or remove the wiring harness Do not apply a jumper across the valve lead wires or short them together Inlet Pressure Taps TAZ Main Gas Gas Control Knobs 2 O27 ZU Regulators Outlet Pressure Adjustment Manifold Pressure Taps Wiring Harness Outlet TOP VIEW OF GAS VALVE Figure 12 Measuring Gas Pressures The supply gas pressure is measured at
5. OFF BELOW SETTING Water Temperature Circuit Check Continuity Continuity check pin to pin of lower temperature See Test 4 probe shows 1 or 0 E4 e check wiring and plug connections to heater control board receptacle E4 replace lower temperature probe Continuity check red wire pin to red wire pin on See Test 4 upper temperature sensor shows 1 or 0 E3 check wiring and plug connections to heater control board receptacle replace upper temperature probe All above checks are okay Check wiring and plug connections to heater control board receptacle Replace upper temperature probe Servicing should only be performed by a Qualified Service Agent 37 NOTES Servicing should only be performed by a Qualified Service Agent 38 NOTES Servicing should only be performed by a Qualified Service Agent 39 fe 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 Copyright 2010 Smith Corporation All rights reserved
6. P2 Temperature To Upper e Temp O Push Reset Adjustment Dial Probe Ra ECO Manual Reset Button To Ignition Le C Control rh 120 VAC from Board NN T 2 Ignition Control Board To Lower Pin Number Temp Probe Label Figure 17 WHITE RODGERS IGNITION CONTROL BOARD Diagnostic LED Error gt Flash Codes are Displayed Here 120 VAC Hot to Thermostat 120 VAC Hot from On Off Switch 120 VAC Neutral from On Off Switch 1 3 6 From Thermostat 4 2 To Igniter 80 120 VAC 2 Flame Probe 3 1 To Blower 120 VAC 7 10 Blower Prover Switch 8 Ground 120 VAC Neutral 9 12 To Gas Valve 24 VAC to Thermostat Figure 18 Servicing should only be performed by a Qualified Service Agent 21 OPERATION AND SERVICE PRE SERVICE CHECKLIST Use the following checklist BEFORE you begin servicing the water heater 1 Have you removed the cover from the controls Did you take notice of the status lights on the upper water heater control Did you take notice of the red LED in the upper left corner of the lower ignition control 2 Did you note conditions of the room Where does the supply air come from s the room clean What is stored with the heater How is the heater vented Are all water and gas shut off valves open Are there room exhaust or air intake fans 3 Did you note the condition of the heater Is the ON OFF switch e What is the temperature of the
7. as burners igniters flue baffles and vent system components Propellants of aerosol sprays beauty shop supplies water softener chemicals and chemicals used in dry cleaning processes that are present in the combustion ventilation or ambient air can cause such damage Vapors from volatile compounds such as solvents cleaners chlorine based chemicals and refrigerants in addition to being highly flammable in many cases can also react to form highly corrosive substances such as hydrochloric acid inside the water heater s combustion chamber The results can be hazardous and cause product failure Contaminated Air Causes Aggressive Corrosion of Water Heater Components Burners Igniters Flue Baffles Vent System Sheet Metal Parts A D S Rust Chips Wi Figure 4 CLEARANCES WATER HEATER A 24 inch clearance for all serviceable parts is recommended See also Figure 5 and Table 2 You may also refer to the instruction manual or to the label on the water heater for clearances applicable to your specific model Minimum Clearances to Combustible Surfaces ENES N L PAJ Te ben Ei ry y TOP VIEW OF BTR BOTTOM VIEW OF BTR Figure 5 Servicing should only be performed by a Qualified Service Agent 9 INSTALLATION CONSIDERATIONS Table 2 MINIMUM CLEARANCES TO COMBUSTIBLE SURFACES A Right Side Left Side 5 12 7 cm 5 12 7 cm 5 12 7 cm A B and C clearances to non combust
8. plug connections to hot surface igniter HSI ground replace HSI if needed Voltage is present Note ignition board flash code LED Hot surface igniter HSI should work Servicing should only be performed by a Qualified Service Agent 33 TROUBLESHOOTING TEST 8 IGNITER HEATS NO MAIN BURNER E1 Plug to Pin 9 E1 disc to Pin 12 Figure 27 short heat up time of igniter check control box grounding Normal warm up Approximately 20 seconds check for 24V from E1 Pin 12 to ground during 4 second trial If Yes continue If No No ignition replace Ignition Board No voltage present E4 Pin 12 to ground replace ignition board 24 Volt was present from E1 Pin 12 to ground check that air has been purged from gas circuit but no main burner check that wiring and connections to gas valve and E1 Pin 9 are correct check for 24 VAC at E1 Pin 9 to ground during 4 second trial for ignition Servicing should only be performed by a Qualified Service Agent 34 TROUBLESHOOTING TEST 9 IGNITER HEATS NO MAIN BURNER Conditions Test 8 completed Turn off power Disconnect wires from gas valve Manifold e e Manifold Pressure M Pressure Tap Measure Resistance Between Gas Valve Terminals Main Valve Solenoid Connections Outlet Figure 28 TEST 9 IGNITER HEATS NO MAIN BURNER Meter reads 0 or 1 Check meter scale setting verify that it is set to read between 550 and 650 Ohms repl
9. results in needless down time unnecessary parts replacement and customer dissatisfaction Servicing should only be performed by a Qualified Service Agent REQUIREMENTS REQUIREMENTS INSTRUCTION MANUAL Have a copy of the instruction manual that came with the water heater on hand for the model being serviced Instruction manuals can be obtained at the A O Smith web site www hotwater com or by calling technical support at 800 527 1953 Installation information given in this service manual is not a complete installation instruction Installation information covered in this service manual has a limited focus as it applies to servicing the water heater This Service Manual does not replace or supersede the instruction manual that came with the water heater Always refer to the instruction manual that came with the water heater for complete installation instructions TOOLS REQUIRED Phillips head screwdriver standard screwdrivers 3 8 and 7 16 inch open end wrench set of marked drill bits electrical multimeter tester capable of measuring continuity AC voltage and DC voltage gas pressure gauge or manometer gauge AOS pt no 9005033105 water pressure gauge AOS pt no 9004792105 thermometer AOS pt no 9005423105 range 0 220 degrees F 1 2 inch socket with extension for removal of the clean out cover 1 1 16 inch socket with extension for anode removal TOOLS OPTIONAL Two digital manometers range 20 00 to 20 00 W C
10. stored water Test at T amp P valve or nearby faucet s the thermal expansion tank installed 4 Did you write down the complete model and serial number of the water heater If so what are they 5 Does the heater have a good ground wire connection If not the blower draft inducer will typically come on for a short time 3 5 seconds then go off and the red LED will flash 8 times Servicing should only be performed by a Qualified Service Agent 22 TROUBLESHOOTING TROUBLESHOOTING IGNITION CONTROL BOARD ERROR CODES The White Rodgers ignition control board will display a flashing error code with an LED light located on the upper left corner of the Ignition Control Board Figure 18 when there is a problem There is a distinctive pause between a series of on off flashes 1 to 8 flashes when there is a problem The following information describes the meaning of these error flash codes and what should be checked and or repaired The 5 flash error code is not used with this application NOTE The Ignition Control Board varies the voltage to the Igniter to decrease wear Lower voltage results in a longer life for the Igniter For this reason voltage to the Igniter may vary from 80 VAC to 120 VAC FLASH System has locked out after 3 trials for ignition Check voltage 80 120 VAC to igniter Check flame sense rod alignment Check igniter and flame sense rod wiring Check flame sense rod for corrosion clean wit
11. the venting has been installed per all instruction manual requirements Installation must also conform with the current edition of the National Fuel Gas Code NFPA 54 ANSI 2223 1 Costs to correct installation errors are not covered under the limited warranty Chimney A minimum of 1 4 rise per foot of horizontal vent is required Figure 7 For larger applications BTR 500 water heaters can be common vented together either in a tapered manifold or a constant size manifold See Figure 8 In such cases follow the National Fuel Gas Code requirements for the sizing and installation of fan assisted products The BTR 500 model may be common vented only with other Category appliances Tapered Manifold TR 4 Constant Size Manifold Figure 8 Servicing should only be performed by a Qualified Service Agent 11 AND SERVICE OPERATION AND SERVICE SEQUENCE OF OPERATION 1 Call for heat is activated when temperature sensed from Thermistor Probes falls below the Thermostat setting 2 Blower Draft Inducer is energized 3 Ignition Control Board verifies that the Blower Prover Switch is closed and that the Blower Draft Inducer is operating 4 Igniter is energized 5 Gas Valve is energized and burners ignite 6 Ignition Control Board verifies flame at burners 7 Water is heated to Thermostat set point 8 Gas Valve is de energized 9 Blower runs for purge perio
12. 25 VAC black wire to ground 115 VAC check to E13 Terminal and 2B receptacle voltage is not present from on off switch center check conditions above black wire to ground check wiring from switch to break box Power is present from center on off terminal check power from on off switch to ignition board terminal E13 Voltage is not present at E13 to ground check wiring from on off Left outside terminal to E13 Replace on off switch Power is present at E13 check power from E14 to water heater control E2 receptacle Voltage is not present from water heater control check wiring from ignition control board E14 to water heater control receptacle E2 black to ground receptacle E2 Replace ignition control board Power is present at E2 green LED should be on Servicing should only be performed by a Qualified Service Agent 2f TROUBLESHOOTING TEST 2 POLARITY CHECK Conditions No hot water Green Power LED is on Tank is more than 5 F below temperature dial setting Red ignition control board diagnostic LED is flashing 6 times between pauses Red diagnostic Call for Heat LED OFF Diagnostic Indicator red LED ES x A Figure 20 EARTH 1 9 1 GROUND HOT 120 VAC 77 NEUTRAL p EARTH GROUND 1 1 E rz IGNITOR FLAME SENSOR R R 120 VAC CIRCUIT FACTORY INSTALLED w ta3 Ll BY INSTALLER Figure 21 Polarity Check T
13. EST 2 TER Check from on off switch center and white wire terminals to ground Ground Voltage is present white right terminal to ground reverse supply wire connections Polarity is reversed but not black center terminal to ground Servicing should only be performed by a Qualified Service Agent 28 TROUBLESHOOTING TEST 3 CONTINUITY CHECK OF HIGH LIMIT ECO Conditions e Power On No Hot Water Red heater control Call for Heat LED on Red ignition control board diagnostic LED 4 Flashes Note LED Flash Code before resetting water heater control e See Ignition Control Board Error Codes Turn Power OFF Figure 22 Continuity check of ECO energy cut off high limit TEST 3 Black to Black wires of upper probe Power is off continuity is indicated opens at 203 F closes at 193 F If water is below 193 F continuity is correct ZERO 0 0 Resistance continuity is not present replace ECO sensor if water temperature is below 193 F meter reads 0 L water is less than 120 F reset status LED should be on replace heater control if control will not manually reset Servicing should only be performed by a Qualified Service Agent 29 TROUBLESHOOTING TEST 4 UPPER TEMPERATURE PROBE CONTINUITY CHECK Conditions Power On Water below temperature set point Red water heater control Reset Statu
14. ONSIDERATIONS Table 1 Po NATURAL GAS PROPANE LP GAS Maximum Supply Gas Pressure 10 W C 2 49 kPa 12 W C 2 99 kPa t Minimum Supply Gas Pressure 5 2 W C 1 29 kPa 11 W C 2 74 kPa Manifold Gas Pressure 3 5 W C 0 87 kPa 10 W C 2 49 kPa i Maximum supply pressure readings are taken while gas is not flowing static pressure AND while gas is flowing dynamic pressure Supply pressure must never exceed this maximum value T Minimum supply gas pressure readings are taken while gas is not flowing static pressure AND while gas is flowing dynamic pressure Supply pressure must never fall below the minimum values Supply gas pressures should be measured with all gas fired appliances conencted to a common main firing at full capacity If supply pressure drops more than 1 5 W C as gas begins to flow the supply gas system gas line regulator may be restricted or undersized See the instruction manual for more information Manifold gas pressure reading can only be taken while gas is flowing Reading taken should be 0 3 W C of the listed value These water heaters are certified for use without modification for altitudes up to 10 000 feet For elevations above 10 000 feet 3 048 meters see High Altitude Installations section of instruction manual AIR REQUIREMENTS Carefully review the requirements for combustion and ventilation air in the instruction manual that came with the water heater Failure to m
15. Service Handbook A m MODEL BTR 500 A SERIES 120 121 A SI h INSTALLATION CONSIDERATIONS PRE SERVICE CHECKS OPERATION amp SERVICE TROUBLESHOOTING 500 Tennessee Waltz Parkway Ashland City TN 37015 SERVICING SHOULD ONLY BE PERFORMED BY A QUALIFIED SERVICE AGENT PRINTED IN THE U S A 0510 318349 000 COMMERCIAL GAS WATER HEATER SERVICE MANUAL TABLE OF CONTENTS INTRODUCTION heeds alin teer 3 Gas Control Valve Burner Area 18 Qualifications ice etre gend 3 Blower Prover Switch Settings 19 Service E Un D 3 Thermostat and Ignition control Board View 20 Service Reminder i dete rete ed 3 White Rodgers Integrated Control Thermostat 21 REQUIREMENTS eet ee 4 White Rodgers Ignition Control Board 21 Instruction Manual eee 4 Pre Service 22 Tools Required eB Aeneas 4 TROUBLESHOOTING n 23 Tools Optional A Ignition Control Board Error Codes 23 INSTALLATION CONSIDERATIONS 5 G EE 23 Water PIPING cide hand men 5 2 Flashies eee tete 23 Closed Water 5 BS FlASNCS uomen edat eet 24 Thermal Expansion 5 4 Flashes iie ecu 24 Gas Pressure Requirements
16. ace the gas valve Meter indicates pilot and main coil have valve should be okay However if there is still no gas to the main burner the coil continuity may be stuck Replace the gas valve Servicing should only be performed by a Qualified Service Agent 35 TROUBLESHOOTING TEST 10 MAIN BURNER IGNITION FOR LESS THAN FIVE SECONDS Conditions Power On plug connected Main Burner ignites for approximately five seconds then goes out Tests 8 and 9 completed Note the flash code on the ignition board LED Hot Surface Igniter HSI HSI Mounted on Main Burner E1 Pin 2 From Flame Proving Rod Figure 29 TEST 10 MAIN BURNER IGNITION FOR LESS THAN FIVE SECONDS no extended main burner ignition check wiring and plug connections of hot surface igniter HSI assembly plug and ignition board receptacles E1 Pin 2 verify that HSI assembly is not cracked or dirty verify that flame prover will be in main flame replace HSI assembly still no extended main burner ignition replace ignition control board Servicing should only be performed by a Qualified Service Agent 36 TROUBLESHOOTING TEST 11 WATER HEATER SHUTTING OFF BELOW SETTING Conditions Main burner ignited e Stored water is below temperature setting more than 5 F Tank Average Power off Plug disconnected from heater control board receptacle E3 and E4 GO eat Figure 30 TEST 11 WATER HEATER SHUTTING
17. arity in power supply 1 Interchange hot and neutral wire connections to the water heater 7 FLASHES Flame sensing is marginal flame sense signal is below 2 0 micro amps Water heater will continue to fire with flame sensing current over 0 1 micro amp below this the control will close the gas valve and ignition failure will occur 1 Check flame sense rod alignment 2 Clean flame sense rod with steel wool 3 Check ceramic insulator on igniter flame sensor for cracks Replace if damaged Servicing should only be performed by a Qualified Service Agent 24 TROUBLESHOOTING 4 Check molex plug connector between igniter flame sensor assembly and control board Also check flame sense 12 pin plug connection at control board 8 FLASHES Igniter not sensed and or water heater not grounded 1 Test igniter resistance It should should be 11 20 ohms Replace igniter if open continuity 2 Ensure that the water heater is grounded Check all ground wires on heater and controls 3 Check molex plug connector between igniter flame sensor assembly and control board Also check igniter 4 pin plug connection at control board CONTINUOUS FLASH Flame sensed out of sequence continuous flame sensed for more than 5 seconds without gas valve being energized 1 Ensure that the gas valve is not failing to close at the end of the heating cycle CONTINUOUS ON Internal control board failure 1 Replace ignition control board Serv
18. d and is de energized 10 Ignition Control Board goes into standby mode and Blower Prover Switch Opens Blower Draft Inducer Ce taMaster its Thermistors _ probes Main Gas gt gt ej Valve Main Hot Surface Igniter Burner Not Shown Figure 9 Servicing should only be performed by a Qualified Service Agent 12 AND SERVICE ELECTRICAL SEQUENCE 1 Switch Power on to unit 2 Thermostat calls for heat 3 Ignition Control Board performs diagnostic check on system components 4 On completion of diagnostics check the Ignition Control Board energizes the Blower Draft Inducer 5 The Blower Draft Inducer begins drawing air through appliance closing the Blower Prover Switch 6 On completion of Blower Prover Switch engagement the Ignition Control Board begins the ignition cycle 7 The Ignition Control Board provides power to the Silicon Nitride Igniter 8 The Silicon Nitride Igniter heats up for approximately 17 to 20 seconds 9 Atthe end of Silicon Nitride Igniter s warm up the Ignition Control Board opens the Gas Valve 10 From the time the Gas Valve opens the Ignition Control Board waits 3 seconds and then shuts off power to the Silicon Nitride Igniter 11 From the time the Silicon Nitride Igniter s power is shut off the Ignition Control Board waits 3 more seconds to monitor the Flame Sensor 12 If the Ignition Control Board does not detect flame at the burners it wi
19. d nearby Downdraft Caused by Kitchen Vent Hood Figure 2 One common example is in a restaurant installation where exhaust vent equipment was not considered in sizing make up air requirements This condition may result in air being back drafted by the restaurant exhaust equipment through the water heater causing the draft proving switch to open and or erratic heater shutdown See Figure 2 Down drafts can cause poor mixing of fuel gas and combustion air in the burners Down drafts can cause flue gases to spill into the installed space Down drafts can cause common service problems such as ignition failure Down drafts can sweep pilot gas away from the spark igniter during ignition and prevent ignition of the pilot Down drafts may cause extremely dangerous conditions such as flame rollout where the flames from the main burner roll out of the combustion chamber Servicing should only be performed by a Qualified Service Agent 7 INSTALLATION CONSIDERATIONS Make up Air Direct Communication with Outdoors A fresh supply of make up air for combustion can be supplied to the water heater through make up air ducts which directly communicate with the outdoors Not Direct Vent Two openings are required one within 12 inches of the top of the enclosure and one within 12 inches of the bottom of the enclosure Each opening must have a free area of notless than 1 square inch per 4 000 BTUH of the total input of all applianc
20. eet these requirements when the water heater is installed or overlooking their importance when servicing the water heater often results in operational problems some are listed below needless down time unnecessary parts replacement and customer dissatisfaction Ensure additional air for combustion and ventilation is provided when additional gas fired appliances are installed to increase hot water supply in an existing location Air Supply Stoichiometric or theoretical complete combustion requires 10 cubic feet of air per 1 000 BTUH of gas supplied The National Fuel Gas Code also recommends an additional 2 5 cubic feet of excess air For information on minimum make up air opening sizes for various building installations refer to the National Fuel Gas Code NFPA 54 ANSI Z223 1 ch 1 000 BTU 2 5 CUBIC FEET EXCESS AIR Figure 1 Servicing should only be performed by a Qualified Service Agent INSTALLATION CONSIDERATIONS Insufficient Make up Air Negative Air Pressure and Downdrafts A lack of combustion and ventilation air can create a negative ambient air pressure in the installed space The vent system on one or more gas fired appliances can experience down drafts due to the outdoor air pressure being greater than the ambient air pressure in the installed space Where multiple gas fired appliances are installed one or more gas fired appliances can pull air through the vent system s of other appliances installe
21. ell Gas yt Rollout Shield Main Burner gt Shield de Radiation Shield Main Burner with Hot Surface Igniter HSI mounted Figure 14 Table 3 HOT SURFACE IGNITER HSI Volts AC Nominal 80 VAC Ohms Resistance 11 0 20 0 77 25 NOTICE FLAME ROD CROSSES PATH OF FLAME 0 1 to 0 25 Servicing should only be performed by a Qualified Service Agent 18 AND SERVICE BLOWER PROVER SWITCH SETTINGS Vent Connection Blower Prover Switch Exhaust Outlet 3 Optional Hot Water Outlet Blower Draft Inducer Figure 15 Table 4 BLOWER PROVER SWITCH TABLE BTR Model Pressure Setting to Close Switch Inches W C 500 A 2 85 0 13 NOTE The Blower Prover Switch contacts are normally open and will close a fall in pressure This will be a negative pressure e a vacuum Servicing should only be performed by a Qualified Service Agent 19 OPERATION AND SERVICE THERMOSTAT AND IGNITION CONTROL BOARD VIEW Temperature Display Adjustment LEDs Dial Integrated Heater Control Diagnostic Reset Board also called Indicator CS i Th tat SUD 297 ermosta red LED RN 2 2 E14 HSI Ignition Control Board ON OFF Switch Figure 16 Servicing should only be performed by a Qualified Service Agent 20 OPERATION AND SERVICE WHITE RODGERS INTEGRATED CONTROL THERMOSTAT Display LED Label Display
22. es within the enclosure The lower opening primarily provides combustion air The upper opening provides vent dilution air and acts as a relief opening for flue gases should the vent become obstructed or a downdraft condition occur 1 SQUARE INCH PER 4 000 BTUH FOR EACH OPENING Figure 3 Additionally when the water heater is installed in a confined space and communicating with the outdoor air one permanent opening beginning within 12 inches 30 cm of the top of the enclosure must be permitted where the equipment has clearances of at least 1 inch 2 5 cm from the sides and back and 6 inches 16 cm from the front of the appliance The opening must directly communicate with the outdoors and must communicate through a vertical or horizontal duct to the outdoors or spaces crawl or attic that freely communicate with the outdoors and must have a minimum free area of a 1 square inch per 3 000 BTUH 7cm per kW of the total input of all equipment located in the enclosure and b not less than the sum of the areas of all vent connectors in the confined space Servicing should only be performed by a Qualified Service Agent 8 INSTALLATION CONSIDERATIONS Contaminated Air Carefully review the warnings concerning contaminated combustion and ventilation air in the instruction manual that came with the water heater Combustion air that is contaminated can greatly diminish the life span of the water heater and water heater components such
23. h steel wool Check igniter resistance It should be 11 20 ohms A Check ceramic insulator igniter flame sensor assembly for cracks Replace if damaged Check manifold gas pressure N 8 Check all molex plug connections on integrated control ignition control board and between the various components Check the pin to pin contact between plugs gently wiggle suspected plug connections during operation 2 FLASHES Blower Prover Switch circuit was closed during self diagnostic check at the beginning of the heat cycle Contacts should have opened at the end of last heat cycle Blower Draft Inducer will not start call for heat Status LED will be illuminated on integrated control 1 Test continuity of blower prover switch it should be open in normal state blower not running wires removed 2 Replace blower prover switch if continuity is present between terminals in normal state Check blower prover switch wiring making sure that there are no jumpers on blower prover switch Servicing should only be performed by a Qualified Service Agent 23 TROUBLESHOOTING 3 FLASHES Blower prover air pressure switch failed to close its normally open contacts after blower draft inducer was energized Blower will run indefinitely waiting for the blower prover switch circuit to close 1 Check air pressure reading at blower prover switch sensing port on blower fan housing with manometer digi
24. ible surfaces is 0 inches A 20 clearance to cover remains unchanged CLEARANCES EXTERIOR The illustration below shows the required clearances for venting units using natural draft venting The vent must extend at least 3 feet above the highest point where it passes through a roof of a building and at least 2 feet higher than any portion of a building within a horizontal distance of 10 feet for vents of 12 inches in diameter or less Reference NFPA 54 ANSI Z 223 1 More Than 10 Than 10 Height Above Any Roof Surface NOTE Within 10 No Height Above Horizontally Parapet Required E 3 when Distance from E 3 9 3 3 Min Walls or Parapet 15 More than 10 Wall or E Parapet More Than 10Feet 10 or Less Height Above Any Q or Less Roof Surface qud Within 10 Horizontally 2 Min 1 1 E 3 Min 10 Feet or Less Copyright by the American Gas Association Used by permission of the copyright holder Figure 6 Servicing should only be performed by a Qualified Service Agent 10 INSTALLATION CONSIDERATIONS VENTING The BTR 500 water heater is classified by ANSI as a Category non condensing negative pressure venting appliance It is approved for type B vent The blower draft inducer does not pressurize the exhaust NOTE This section of the service manual is not a complete venting installation instruction Refer to the instruction manual that came with the water heater ensure
25. icing should only be performed by a Qualified Service Agent 25 TROUBLESHOOTING INTEGRATED HEATER CONTROL DISPLAY LIGHTS Power Energy Cut Off Status O Call for Reset Heat Status LED INDICATION ACTION STATUS e Calling for heat Normal status No action required Check for excessively hot water e The ECO Energy Cut Off has 203 F or higher opened Correct the problem No power Check the breaker Tank is at a set temperature No action required 2 Tank has cooled Push the manual reset button below 120 E Refer to Figure 17 by ECO Open Troubleshoot for the reason that the ECO indication opened Servicing should only be performed by a Qualified Service Agent 26 TROUBLESHOOTING TEST 1 120 VAC TO HEATER CHECK Conditions No Green Display Power LED on Plugs are in receptacles Supply power breaker is not open On Off heater switch is on White Rodgers Integrated Control 9 1 Display 4 7 LEDs Fr pg HOT 120 VAC NEUTRAL des EARTH GROUND 8 eat Ignition Control i 120 VAC CIRCUIT i FACTORY INSTALLED BY INSTALLER i From Heater Control N E13 To ON OFF Switch Supply Neutral 9 Not Used Figure 19 120 V AC check to water heater ON OFF switch TEST 1 Check for 115 1
26. ll de energize the Gas Valve and run the Blower for approximately 20 seconds to purge the combustion chamber The Ignition Control Board then restarts at Step 7 for up to 2 more trials for ignition After the third failed trial for ignition the Ignition Control Board locks out for one hour At the end of this lock out period the Ignition Control Board will restart at Step 3 for three more trials NOTE The one hour lock out period can be reset by cycling power to the water heater off and on again 13 If the Ignition Control Board detects a strong flame from the Flame Sensor it will remain in the heating mode until the Thermostat is satisfied 14 When the Thermostat is satisfied the Ignition Control Board will de energize the Gas Valve and run the Draft Inducer for approximately 20 seconds to purge the combustion chamber The Ignition Control Board will then go into standby mode Servicing should only be performed by a Qualified Service Agent 13 AND SERVICE WIRING DIAGRAM BLOWER PROVER PRESSURE SWITCH 120 NEUTRAL EARTH GROUND NOTE Must be properly grounded and have correct polarity connections IGNITER FLAME SENSOR 120 VAC CIRCUIT FACTORY INSTALLED BY INSTALLER BK BLACK BR BROWN WIRING DIAGRAM FOR BTR 500 R RED 8 Le 850 WHEN EQUIPPED WITH WHITE RODGERS IGNITION Y YELLOW QU 2 BOARD DIGITAL THERMOSTAT AND CONTROLS G GREEN
27. lure leakage This type of failure is not covered under the limited warranty Thermal expansion can also cause intermittent temperature pressure relief valve operation water discharged from the valve due to excessive pressure build up This condition is not covered under the limited warranty The temperature pressure relief valve is not intended for the constant relief of thermal expansion A properly sized thermal expansion tank should be installed on all closed systems to control the harmful effects of thermal expansion Contact a local Qualified Service Agency page 3 to have a thermal expansion tank installed GAS PRESSURE REQUIREMENTS Table 1 shows supply and manifold gas pressure requirements for BTR 500 A 120 121 model water heaters Supply gas pressure is the pressure of fuel gas being supplied to the water heater Manifold gas pressure is the pressure of the gas being supplied to the water heater s burners Supply gas pressure should be measured twice One measurement while the water heater is not firing static and again while the water heater is firing dynamic If the supply gas pressure drops more than 1 5 W C between the static and dynamic pressure measurements this may indicate the gas line and or gas regulator to the water heater is undersized See the gas line requirements in the Instruction Manual that came with the water heater Servicing should only be performed by a Qualified Service Agent 5 INSTALLATION C
28. ressure Adjustment 47 5 iode ER eie 36 Main Valve Solenoid Connections 17 TEST Water Heater Shutting Qi Below Setting 37 Servicing should only be performed by a Qualified Service Agent INTRODUCTION INTRODUCTION This Service Manual is designed to be an aid in servicing and troubleshooting A O Smith Master Fit models BTR 500 Series 120 121 commercial water heaters The instructions and illustrations contained in this service manual will provide you with troubleshooting procedures to verify proper operation and to diagnose and repair common service problems This Service Manual does not replace or supersede the instruction manual that came with the water heater Always refer to the instruction manual that came with the water heater for complete installation instructions If the instruction manual is not available copies can be obtained from the manufacturer s web site or by calling the toll free phone number shown on the back cover of this service manual QUALIFICATIONS Servicing the products referenced in this manual requires the ability in the field involved equivalent to that of a Qualified Service Agent as defined by the American National Standards Institute ANSI below Installation skills such as plumbing air supply venting gas supply electrical supply are required in addition to diagnostic and electrical testing skills ANSI 2223 1 2006 Sec 3 3 83 Q
29. s LED OFF Call For Heat LED off Upper Temperature probe continuity check TEST 4 Red wire to red wire Turn supply power Off for this test Test indicates no continuity replace probe Continuity is indicated Probe should be okay Also verify Ohms resistance for water temperature Reading will be approximate Figure 23 Table 4 OHMS RESISTANCE TABLE 70 11 884 3 759 Servicing should only be performed by a Qualified Service Agent 30 TROUBLESHOOTING TEST 5 CALLING FOR HEAT NO BLOWER OPERATION Conditions Power on Plugs in Receptacles Red Call for Heat LED ON Blower Draft Inducer off Note flash code on ignition control board diagnostic LED Call for Heat LED Indicator Diagnostic LED Indicator reset control by interrupting power Note possible reasons for this from flashing LED code replace ignition board Pin 1 to ground has voltage Pin 3 to ground has no voltage check wiring harness and plugs replace blower Servicing should only be performed by a Qualified Service Agent 31 TROUBLESHOOTING TEST 6 BLOWER ON NO IGNITION Conditions Power on Plugs in receptacles Blower Draft Inducer operating No power to Hot Surface Igniter HSI Note LED flash code Blower Exhaust Blower Prover Switch Hot Water Outlet Blower Draft Inducer Figure 25 TEST 6 24 VAC Check of Blower Prover Switch Circui
30. t ignition board receptacles E1 Pin 7 to ground replace Ignition board shows no voltage E1 Pin 7 has 24 Volt to ground check wire connection to and from blower draft inducer voltage check of each blower switch terminal to Switch is open Check for proper draft should also see LED 3 flash code ground shows voltage to only 1 terminal check for blocked exhaust check that blower outlet exhaust damper is open replace blower prover switch Servicing should only be performed by a Qualified Service Agent 32 TROUBLESHOOTING TEST 7 BLOWER ON BLOWER PROVER SWITCH CLOSED NO IGNITER OPERATION Conditions Power on but no power to igniter Plugs in receptacles Blower Draft Inducer on e 24V at ignition board E1 Pin 10 Check E4 pin 4 to Ground Check E4 pin 2 to Ground Continuity cwm EN Test 9 USB LIE Vy 7 4 E4 Plug Figure 26 Voltage check and continuity check of hot surface igniter circuit Continuity check Power off Plug removed from E4 receptacles Nominal 80 VAC check Plug in E4 Power on Continuity is not indicated between E4 plug check wiring and connection from E4 plug to HSI receiving plug pin 2 to 4 replace HSI Assembly Continuity is present Resistance should be between 11 and 20 Ohms at a temperature of 77 F Voltage is not present between E4 Pin 2 to ground Replace ignition board Voltage is not present between E4 Pin 4 to check wiring and
31. tal preferred blower must develop at least 2 85 W C negative pressure before blower prover switch contacts will close Replace blower prover switch if pressure reading at the sensing port does drop to at least 2 85 W C and contacts remain open If pressure reading taken does not drop to at least 2 85 W C check vent system for obstruction debris and excessive elbows Ensure vent system complies with manufacturer s and NFGC venting requirements for fan assisted Category appliances Ensure there is neither a negative or positive air pressure in the equipment room open doors to outdoor atmosphere This can cause the blower prover switch to malfunction Alleviate air pressure imbalance between the equipment room and the outside atmosphere 5 Check the condition of the blower wheel in the blower clean or replace as necessary 4 FLASHES ECO cutout Energy Cut Off Tank temperature has risen above 203 and caused lockout ECO status LED on integrated control will also be illuminated See Figure 17 1 Determine if tank temperature is excessive and if so the possible cause i e temperature control failing to cut out at set point 2 Cool tank to below 120 F to reset ECO reset status LED will illuminate on the integrated control when the control can be reset Push reset button on integrated control See Figure 17 3 Check continuity resistance of temperature probes clean off calcium build up 6 FLASHES Reversed pol
32. the inlet pressure tap when the gas is flowing The manifold gas pressure is measured at the manifold pressure tap when the gas is flowing Servicing should only be performed by a Qualified Service Agent 16 AND SERVICE Manifold Pressure Adjustment The main gas regulators are found beneath the silver or black cap screws Natural Gas valves have silver caps Propane valves have a black caps Remove the caps to access the outlet manifold pressure adjustment screw IMPORTANT Ensure that the outlet pressure matches the manifold pressure that is listed on the water heater rating plate Natural Gas valves are factory preset to 3 5 inches W C The full rate outlet pressure range is between 3 and 5 inches W C Propane LP valves are factory preset to 10 0 inches W C The full rate outlet pressure range is between 8 and 12 inches W C Caution Always test the manifold pressure at the outlet when the gas is flowing Wiring Harness PEUT Main Gas Y Regulators Outlet Pressure Adjustment Lead Wires 24 Volt Main Valve Solenoid iA TOP VIEW OF GAS VALVE Figure 13 Main Valve Solenoid Connections The figure above shows the two 24 volt main valve MV solenoid connections The two yellow wires from the 12 pin ignition board plug connect to these leads Servicing should only be performed by a Qualified Service Agent 17 AND SERVICE GAS CONTROL VALVE BURNER AREA VIEW Honeyw
33. ualified Agency Any individual firm corporation 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 qualified as defined by ANSI above and licensed or certified as required by the authority having jurisdiction to perform a given task do not attempt to perform any of the procedures described in this manual If you do not understand the instructions given in this manual do not attempt to perform any procedures outlined in this manual SERVICE REMINDER When performing any troubleshooting step outlined in this service manual always consider the wiring and connectors between components Perform a close visual inspection of all wiring and connectors to and from a given component before replacement Ensure wires were stripped before being crimped in a wire connector ensure wires are crimped tightly in their connectors ensure connection pins in sockets and plugs are not damaged or worn ensure plugs and sockets are mating properly and providing good contact Failure to perform this critical step or failing to perform this step thoroughly often

Service Handbook - AO Smith Water Heaters

Contents

Download Pdf Manuals

Related Search

Related Contents