A.O. Smith 710 ASME Service Manual Download Page 6

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710 / 710 ASME Service manual

Ver. 1.00

CONFIDENTIAL

List of main components in the interior view

No.

Description

Items# in

components

diagram

AOS

Part #

Common parts

For other models

Case assembly

001

319143-287

Manifold assembly with gas

valve assembly

120

319143-305 (LP model)

319143-306 (NA model)

Computer board

701

319143-279

Igniter

125

319143-052

520, 110, 310, 510,

910

Transformer

702

319143-309

Water inlet

411

319143-074

520

Water outlet

435

319143-098

Mixing thermistor

418

319143-081

520

Inlet thermistor

422

319143-085

520, 510, 910

Output thermistor

433

319143-096

520, 510, 910

Overheat cut-off fuse

403

319143-286

Burner assembly (Burners)

101

319143-299

Hi-limit switch

432

319143-095

520, 510, 910

Fan motor

115

319143-043

520, 310, 510, 910

Freeze protection thermostat

117

319143-185

110, 310, 510

Flow sensor

429

319143-092

520, 910

210

319143-302

(Regular model)

Heat exchanger

211

319143-314

(ASME model)

Gas inlet

123

319143-307

Heater

410

319143-068

520, 910

Water control valve

423

319143-086

520, 910

GFI

712

319143-227

910

Summary of Contents for 710 ASME

Page 1: ...E Service manual Ver 1 00 1 CONFIDENTIAL 710 710 ASME On demand Water Heater Service manual A O Smith Water Products Company 500 Tennessee Waltz Parkway Ashland City TN 37015 Toll Free 1 877 737 2840...

Page 2: ...ts in the interior view 6 5 Schematic diagram 8 6 Wiring diagram 9 7 Wiring diagram checkpoints for diagnosis 10 8 Resistance values of the temperature thermistors 12 9 Operational flow chart 13 10 Co...

Page 3: ...p 100 F to 185 F default set 120 F Temperature dipswitch setting 100 F 115 F 120 F 135 F 145 F 155 F 165 F 185 F Bypass valve Yes Water control Thermistors 3 thermistors In Out Mixing Available remote...

Page 4: ...7 8mm COLD 3 1 8 80 8mm HOT 4 5 8 118 3mm GAS 6 1 4 159 mm 8 7 8 226mm 120 VAC 5 1 2 142mm 5 1 2 1 4 2m m 5 3 4 147mm COLD 1 5 8 4 0 9mm 120 VAC 1 5 8 42m m GAS 5 7 8 1 47 9 mm HOT 5 7 8 149mm G A S 6...

Page 5: ...710 710 ASME Service manual Ver 1 00 5 CONFIDENTIAL 3 Interior view 16 20 1 3 4 5 6 7 8 9 10 11 12 13 14 15 17 18 19 21 2 22 23 24 25 26 27 28 29...

Page 6: ...7 Water outlet 435 319143 098 8 Mixing thermistor 418 319143 081 520 9 Inlet thermistor 422 319143 085 520 510 910 10 Output thermistor 433 319143 096 520 510 910 11 Overheat cut off fuse 403 319143...

Page 7: ...s 22 Outlet drain plug 416 319143 079 520 23 Air fuel ratio rod AFR rod 106 319143 035 520 310 510 910 24 Flame rod 106 319143 035 520 310 510 910 25 Igniter rod 108 319143 037 520 310 510 910 26 Surg...

Page 8: ...er 6 Water circulates through the heat exchanger and is heated up to the set temperature 7 Using thermistors to measure temperatures the computer modulates the gas and water valves to ensure proper ou...

Page 9: ...Y G W BK BL Water Control valve O H C F B L B L B L B L Y G O R B L Y O W P P P P Gas Propor tional Valve Flow Sensor W R B K W R WR BK R W BL BL BL L B G O R Parent W W BK BK BL BL R R Remote control...

Page 10: ...C Gas valves Red blue at COM SV3 78 to 100 VDC during operation 0 9 to 1 7k C1 Hi Limit switch Blue Blue Less than 1 VDC and less than 1 C2 Overheat cutoff fuse Blue Blue Less than 1 VDC and less than...

Page 11: ...l ratio rod Yellow AFR rod Between AFR rod and the computer board More than 0 5 A during operation I Flame rod Orange Flame rod Between flame rod and the computer board More than 1 A during operation...

Page 12: ...8 47 7 02 5 85 4 90 4 12 Temperature F 122 131 140 149 158 167 176 185 194 203 212 C 50 55 60 65 70 75 80 85 90 95 100 Resistance k 3 49 2 96 2 53 2 16 1 86 1 60 1 39 1 21 1 05 0 92 0 81 Temperature...

Page 13: ...Remove cause Opeartion lamp OFF Operation stop YES NO YES NO NO YES YES NO 20sec later YES NO NO YES YES NO YES NO 5sec later 3sec later YES YES NO YES NO 20sec later YES NO NO NO YES FM speed Above...

Page 14: ...mbly 18 10 5 Flame rod 19 10 6 AFR rod 20 10 7 Heat exchanger 21 10 8 Flow sensor 22 10 9 Water Control valve 23 10 10 Thermistors 25 10 11 Hi limit switch 26 10 12 Overheat cutoff fuse 27 10 13 Freez...

Page 15: ...le to initialize sustain combustion 2 Dust or soot deposit on the burner surface 3 Cracks of the burners 4 Gas leakage from the burners Effects on the water heater if burners fails 1 Unexpected combus...

Page 16: ...low from the manifold which can cause poor combustion in the combustion chamber In this case the AFR rod will detect an improper flame condition and computer will take safety measures 2 Gas leakage fr...

Page 17: ...s not function properly 2 Failure to ignite or abnormal ignition 3 Unstable combustion conditions Error codes when the fan motor fails 101 111 121 611 991 Diagnostic 1 Visual inspection connection bre...

Page 18: ...e valves fails 111 121 510 701 Diagnostic 1 Visual inspection connection breakage of wires 2 Listen for clunk sounds from the gas valves opening right after fan motor initiates 3 Check voltages and re...

Page 19: ...error code s will display 2 The water heater will not initiate the ignition process The 721 error code will display Error codes when the flame rod fails 111 121 721 Diagnostic 1 Visual inspection conn...

Page 20: ...heater will not initiate the ignition process The 721 error code will display 2 The fan motor speed cannot be modulated properly under abnormal flame conditions which can result in excessive CO emissi...

Page 21: ...tect this event and immediately stop the water heater from operating 3 Abnormal sounds during combustion Error codes when the heat exchanger fails N A Diagnostic 1 Visual inspection soot deposits crac...

Page 22: ...sensor fails Ignition sequence does not start water heater will not initiate any operation Error codes when the flow sensor fails 441 only within Easy link and Multi unit systems Diagnostic 1 Visual i...

Page 23: ...ion The function of the bypass valve 4 Prevents water from flowing through the heat exchanger when water heater is not in operation to protect the heat exchanger The function of the two way valve Fail...

Page 24: ...d bypass valve Blue Brown 13 0 to 16 0 VDC Orange Brown ON 12 5 to 16 0 VDC OFF 0 to 1 VDC Color Number of wires Red Brown 0 position 1 VDC less The water control valve contains the flow adjustment va...

Page 25: ...heater will have temperature fluctuations in hot water Error codes when thermistors fails 311 Output 321 Inlet 331 Mixing Diagnostic 1 Visual inspection connection breakage of wires and or debris on...

Page 26: ...rom the heat exchanger exceeds 194 F 90 C Note The mixing and output thermistors always act as backup hi limit detectors to detect excessively high water temperatures in the heat exchanger 2 The water...

Page 27: ...own the water heater instantly The 111 or 121 error code will display Failure event 1 Unable to detect the excessively high temperatures within the water heater Effects on the water heater if the over...

Page 28: ...eramic heaters do not activate allowing water contained in the heat exchanger to freeze up possibly causing the heat exchanger to burst Error codes when hears fails N A Diagnostic 1 Visual inspection...

Page 29: ...ect correct signals from any all water heater sensors 3 Unable to control water valves which may cause output temperature fluctuations 4 Errors in its self diagnostics In order to self diagnose proper...

Page 30: ...r if transformer fails 1 The water heater does not operate due to lack of power from transformer 2 A failed transformer can cause electrical damage to other electrical components within the water heat...

Page 31: ...tect electrical leakage within the water heater 2 OFF failure the water heater does not receive any power from the GFI which means the water heater cannot operate Error codes when the GFI fails N A Di...

Page 32: ...cannot ignite during the ignition process and the 111 or 121 error codes will display 2 No effects on the water heater however the durability of the igniter wears down Error codes when Igniter fails 1...

Page 33: ...thermostat fails 1 The freeze protection heaters will always be ON causing heat damage to components inside the water heater 2 The freeze protection heaters will never be able to turn on even under fr...

Page 34: ...ilure of the absorber Effects on the water heater if the Surge box fails 1 Unable to protect the computer board if high voltage gets applied to the unit The computer board can short out stopping all o...

Page 35: ...display on temperature remote controller even when remote is turned on 7 Fault of PCB of remote control 1 Check for normal voltage at terminal It takes long time to get hot water at the fixtures 1 Th...

Page 36: ...r heater 1 Check the gas type of the water heater 2 Check how long the water heater has been installed and in use 3 Check the installation place 4 Check the altitude elevation of area of where the wat...

Page 37: ...brown J Fluctuation of hot water temperature 7 Fault of Water control valve Normal 0 09 to 0 2 k between red black J Error Code Malfunction description Cancellation method Incorrect dipswitch setting...

Page 38: ...etween burner igniter rod Normal gap 0 16 4mm 3 PCB fault Normal 90 to 110 VAC at 7 purple purple during ignition B 3 PCB fault 1 No voltage to main gas solenoid valve MV Normal 78 to 100 VDC between...

Page 39: ...ption Cancellation method Loss of flame Turn off the power or water supply Diagnosis Checkpoint 1 Check gas supply and pressure Refer to section 1 2 PCB fault 1 No voltage to gas main solenoid valve M...

Page 40: ...nnection breakage of wires and or debris on thermistor Check voltage resistance between black black 12 Refer to Section 8 for proper range of values E2 Error Code Malfunction description Cancellation...

Page 41: ...0 8 Visual inspection connection breakage of wires andor debris on impeller Check voltage resistance between red black or white black H2 Error Code Malfunction description Cancellation method Fault of...

Page 42: ...onnection breakage of wires and or burn marks on the computer board 2 Gas solenoid valve fault SV1 SV2 and or SV3 C Error Code Malfunction description Cancellation method Fan motor fault Turn off the...

Page 43: ...buildup and or water leakage Normal 13 0 to 16 VDC between blue brown Normal ON 12 5 to 16 0 VDC OFF 0 to 1 V Normal 1 V Less than 0 position Visual inspection PCB connection breakage of wires and or...

Page 44: ...of wires of the gas proportional valve Normal 20 to 40 between white red H1 Error Code Malfunction description Cancellation method False flame detection Turn off the power or water supply Diagnosis C...

Page 45: ...er or water supply Abnormal burning Refer to section 12 3 If not possible press and hold the INC and DEC buttons on the computer board simultaneously for more than 3 sec Diagnosis Checkpoint 991 1 Che...

Page 46: ...d Easy link system 58 12 8 B Pump control ON OFF Conditions BTU requirements for Re circulation mode 59 12 9 Multi unit system ON OFF conditions 60 12 10 Operation time for unit rotation 62 12 11 Indi...

Page 47: ...T or COLD buttons Fig 1 shows mode 5 being selected When selecting information please refer to the table on p 49 for the proper mode 3 Press the INFO button to fix the mode and the information to whic...

Page 48: ...710 models a maximum of twenty units can be linked together For the Easy link system a maximum of four units can be linked as well 4 Press the INFO button to fix the desired unit 5 When the desired u...

Page 49: ...12 Inlet temperature of the priority unit 0 to 999 F Error code history displays 2nd most recent error code 13 Mixing temperature of the priority unit 0 to 999 F Error code history displays 3rd most...

Page 50: ...seg LED will light in a circular 0 pattern one segment at a time B Displaying error code history 1 Briefly press the Error call button do not hold down the button 2 If the 710 has had prior error code...

Page 51: ...re there any obstructions in the intake air and or exhaust Damper sticking Vent Flaps installed on the Terminator Snow build up around Terminator Installed in a closet No Ventilation or lack of combus...

Page 52: ...be confirmed in Diagnostic Mode Section 12 1 The relationship between the AFR stage and the 101 and 991 error codes 16 15 6 0 Gas type LPG Natural gas Installation Outdoor Indoor Direct vent Outdoor...

Page 53: ...ut is reduced automatically See section 12 12 10 Maximum input Disable Default 4 Allow adjustments of fan motor speed Changing the FM speed is similar to changing the manifold pressure See section 12...

Page 54: ...n a 710 Two priority units One priority unit 8 Parent Child setting on Easy link systems Parent Child Default MST DIRE OUT TMP3 TMP2 TMP1 1 2 3 4 5 6 7 8 MODE D PRT N O MST DIRE OUT TMP3 TMP2 TMP1 1 2...

Page 55: ...y button on the computer board of all child units for at least 5 seconds 2 The 7 seg LED on the computer board of all child units will display 0 to signify that the computer memory has been erased of...

Page 56: ...onditions For Every pump modes Conditions needed to turn ON The BTU requirement is more than 14 880 BTU h AND The water flow rate is more than 0 5 GPM Conditions needed to turn OFF The BTU requirement...

Page 57: ...5 2 0 2 5 3 0 3 5 4 0 ON 40 5 70 2 80 2 85 1 88 1 90 1 91 5 92 6 100 OFF 52 4 76 2 84 1 88 1 90 5 92 1 93 2 94 1 ON 55 5 85 2 95 2 100 1 103 1 105 1 106 5 107 6 115 OFF 67 4 91 2 99 1 103 1 105 5 107...

Page 58: ...enable the re circulation pump to be controlled by the following conditions ON OFF Conditions Re circulation mode Energy conserving re circulation mode Conditions that activate the pump The BTU requir...

Page 59: ...on example Set temperature Tset 120 F Flow rate 2 5 GPM Condition needed to turn the pump ON 120 Tin 2 5 500 14 880 Tin 108 1 F Condition needed to turn the pump OFF 120 Tin 2 5 500 14 880 Tin 108 1 F...

Page 60: ...l 710 Flow rate required to activate additional 710 A n Where n number of currently activated 710 and A is dependent on the set temperature See table below Set temperature Factor A F C GPM L min 100 1...

Page 61: ...26 No 18 OFF 55 208 No 4 ON 10 39 No 17 OFF 52 195 No 5 ON 14 52 No 16 OFF 48 182 No 6 ON 17 65 No 15 OFF 45 169 No 7 ON 21 78 No 14 OFF 41 156 No 8 ON 24 91 No 13 OFF 38 143 No 9 ON 27 104 No 12 OFF...

Page 62: ...urs of operation NOTE The priority unit is the unit that turns on first when there is a hot water demand When there is a black out and or cut off for over 50 minutes priority unit will switch back to...

Page 63: ...unit multi unit system Under normal conditions 0 5GPM When the multi unit controller fails 0 5 5 2 5GPM Minimum flow rate of the multiple system depends on the number of the units installed in the mu...

Page 64: ...s even with a Level 3 setting please contact our Technical Service Department for advice Note that there are many high risks associated with manually changing the manifold pressures Level Function Set...

Page 65: ...for the computer board and flow sensor diagnostic purposes Using the function 1 When in Standby mode right before ignition cannot be in combustion forced combustion or the FM adjustment modes press an...

Page 66: ...ed 1 amp For example To the right there is a sample of relay specifications from an arbitrary brochure You can select either the 120 VAC or 240 VAC relay because their current values are less than 1 A...

Page 67: ...otherwise proceed onto the next step 5 Press and hold down the MAX button on the computer board While holding down the MAX button press either the Increase or Decrease button to increase or decrease t...

Page 68: ...AL desired value 6 After gas pressure has been set deactivate the 710 remove the manometer tube and replace the port screw Manifold port Figure 1 Tube To Manometer Figure 2 MAX button MIN button Incre...

Page 69: ...computer board While holding down the MAX button press either the Increase or Decrease button to increase or decrease the fan motor speed respectively Figure 2 Refer to the remote controller display...

Page 70: ...met it is possible for both features to operate at the same time Ceramic heating blocks The blocks will only activate based on what the freeze protection thermostat senses The thermostat is located on...

Page 71: ...eeze protection the Automatic fan motor system will deactivate if Tout Tin 3 6 F OR Tin 50 F and Tout 50 F and TMIX 50 F OR Tin 39 F and Tout 39 F and TMIX 39 F and Flow sensor detects flow rate for 1...

Page 72: ...ng on its screen In order to detect the temperature of the system accurately The computer makes the pump work every two minutes during the freeze protection operation A Activation conditions all 3 con...

Page 73: ...5 seconds or longer to start a display of A at 7 seg LED on the computer board 2 While A is displayed press the Number display button The 7 seg LED will display o F F and then repeat the 3 letters oF...

Page 74: ...all water flow has ceased close all hot water taps 6 Have a bucket or pan to catch the water from the drain plugs of the 710 models Unscrew the drain plugs to drain all the water out of the 710 7 Wai...

Page 75: ...03 709 0 52 708 115 703 707 719 712 706 705 For T M32 706 For T M32 ASME 13 Components diagrams Case assembly Computer board assembly Other than Part 706 the 710 and the 710 ASME share the same compon...

Page 76: ...Burner assembly The 710 and the 710 ASME share the same components 103 101 102 401 104 105 152 707 152 106 107 151 108 109 110 152 152 111 152 112 113 153 114 115 154 116 117 155 118 119 121 704 152...

Page 77: ...09 410 052 052 417 416 418 427 415 435 420 430 421 428 429 436 420 431 414 420 423 420 405 426 425 401 402 403 411 412 413 427 419 422 419 150 424 432 437 434 419 433 414 414 414 414 414 414 414 211 1...

Page 78: ...3 017 Fastener 520 51 319143 325 Screw M4 10 W Washer 52 319143 026 Screw M4 10 Coated 101 319143 299 Burner assembly 102 319143 300 Burner gasket 103 319143 301 Guide plate gasket 104 319143 033 Burn...

Page 79: ...7 Gas inlet 124 319143 051 Igniter plate 520 110 310 510 910 125 319143 052 Igniter 520 110 310 510 910 151 319143 059 Pan screw M4 8 152 319143 060 Screw M4 10 153 319143 061 Pan screw M4 12 W Washer...

Page 80: ...9143 079 Outlet drain plug 520 417 319143 080 O ring P6 EPDM Purple 520 110 310 510 910 418 319143 081 Mixing thermistor 520 419 319143 082 O ring P4 EPDM Purple 520 110 310 510 910 420 319143 083 O r...

Page 81: ...ow sensor Gas proportional valve connection and Thermistors wire 706 319143 324 Flow sensor Gas proportional valve connection and Thermistors wire for 710 ASME 707 319143 292 Flame rod wire 708 319143...

Page 82: ...710 710 ASME Service Manual Ver 1 00 82 CONFIDENTIAL 15 Records of revision of this manual Version Changes Date 1 00 First edition 11 19 10...

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