A.O. Smith ATI-140H-N Service Handbook Download Page 35

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Condensing Models: On-Demand Water Heater Service Handbook • 35

MAINTENANCE

Computer
Board

Figure 24.

High Limit Switch

(Exhaust)

Exhaust

Thermistor

Clip for High
Limit Wires

This Screw
Secures
Computer
Board
Assembly.

Manifold Plate

Brass Manifold
Test Port Screw

Main Gas Valve

Gas Proportional
Valve (GPV)

Flame Rod
& AFR* Wire
Connections

Igniter Rod Wire

Connection

Brass Screw Securing
Gas Valve to Gas
Inlet Connection.

Over-heat
Cutoff Fuse
(OHCF)

Igniter Assembly
(not visible)

Connector for

Overhead Cutoff

Fuse (Blue Wires)

See also “Component Diagrams/Item Numbers” which starts on page 67.

Flow Sensor/Control
Valve (Behind Wires)

* Air/Fuel Ratio Rod

Primary Heat

Exchanger

Secondary Heat

Exchanger

Ground
Connections

Condensate

Drain Tube

Power Cord
Mounting Tab

Pipe Heater

High Limit Switch

(Heat Exchanger)

Indoor Model:

MAINTENANCE

Fuse Box

Summary of Contents for ATI-140H-N

Page 1: ...140 NIH GT 140 NIH T H3M DV NG ATI 140H P GTS 140 PIH GT 140 PIH T H3M DV LP ATO 140H N GTS 140 NEH GT 140 NEH T H3M OS NG ATO 140H P GTS 140 PEH GT 140 PEH T H3M OS LP THIS SERVICE HANDBOOK IS FOR US...

Page 2: ...er is not hot enough 7 Water is too hot 8 Temperature fluctuates when a fixture is opened 8 Unit does not ignite when water goes through it 9 Abnormal sounds come from the unit 9 Error Codes 10 Incorr...

Page 3: ...cing the Heat Exchanger Indoor Models 37 Removing Heat Exchanger Components Indoor Models 37 Preparing the New PRIMARY Heat Exchanger for Installation Indoor Models 40 Preparing the New SECONDARY Heat...

Page 4: ...1 0 28 Max 3 0 0 75 Min 1 1 0 27 Max 1 6 0 40 Weight lbs kg 50 22 5 50 22 5 Dimension inch H 21 3 4 x W 14 x D 9 1 4 mm H 552 x W 352 x D 236 Ignition Electric Ignition Electric Supply VAC Hz 120 60 C...

Page 5: ...a tankless unit operates read Normal Operation on page 6 To double check or troubleshoot a new installation use the 140 T H3M installation manual When beginning troubleshooting first go through the Pr...

Page 6: ...perature rise needed 2 You may notice that only partial sections of the burner will be lit This is normal operation There are three sections on the burner assembly and the computer controls the number...

Page 7: ...s will gradually accumulate scale buildup on the heat exchanger and cause a leak Heat exchanger leaks due to hard water scale are not covered under the warranty New Installa ons A new installation tha...

Page 8: ...ture using the temperature controller or the remote controller The flow adjustment valve could be obstructed due to hard water scale or debris causing lower than expected water flow Verify water flow...

Page 9: ...does not ignite when water goes through it If you use the remote controller is the remote power button turned on Check to see if the Computer board is receiving power This can be verified by observing...

Page 10: ...Figure 3 Table 2 Error and Flash Codes ERROR CODE GREEN LED ON COMPUTER BOARD SYMPTOM OR ISSUE TROUBLESHOOTING PROCEDURE 031 One Flash Incorrect DIP switch setting Incorrect DIP Switch Settings p 12...

Page 11: ...l Gas Valve Computer Board Fault p 16 711 One Flash Gas solenoid valve drive circuit failure High Limit Switch Overheat Cutoff Fuse Circuit is Compromised p 16 721 Six Flashes False flame detection Fa...

Page 12: ...heater by disconnecting the power cord or external switch Locate the high limit switch item 411 p 70 See also Figure 24 on page 35 Push the button in the middle of it The switch was reset if you hear...

Page 13: ...uts The outlet thermistor is embedded in the water outlet connection See item 408 on page 70 2 Check the resistance value See page 15 for a list of normal resistance values 3 Clean the thermistor a Dr...

Page 14: ...o rod flame rod See Cleaning the Rod Assembly Flame Sensor and Air Fuel Ratio Rod on page 28 Abnormal Main Solenoid Gas Valve Error Code 510 Driving circuit fault for the main or solenoid gas valves i...

Page 15: ...letely before turning power back on 3 Check fan housing for water If found please dry the fan then test heater If there is a significant amount of water there may be a heat exchanger leak 4 To remove...

Page 16: ...F circuits If any of these are compromised this code will appear 1 Inspect the dark blue common wire to the high limit switch the OHCF and the gas valves for any breaks or cuts 2 Verify proper wiring...

Page 17: ...stance of the thermistor Refer to Exhaust Thermistor Failure page 14 Abnormal Combus on Error Code 991 See also Error Code 101 IMPORTANT Familiarize yourself with the components before attempting thes...

Page 18: ...e seconds They are the two lower bu ons Figure 8 page 18 7 4 Release the bu ons when the green LED on the control board turns o Figure 8 page 18 It will turn back on 7 5 Shuto power to the heater usin...

Page 19: ...49 C DEFAULT 140 F 60 C OFF ON 1 2 3 4 5 6 7 8 9 10 OFF ON 1 2 3 4 5 6 7 8 9 10 DEFAULT No 3 OFF No 4 OFF No 5 OFF OFF ON 1 2 3 4 5 6 7 8 9 10 Propane OFF ON 1 2 3 4 5 6 7 8 9 10 Natural Gas OFF ON 1...

Page 20: ...OFF ON 5 7 5 000 to 7 500 4 ON OFF ON 7 9 5 OFF ON ON 11 11 7 500 to 10 100 6 ON ON ON Special ON OFF OFF N A 7 Indoor models Natural Gas ELEVATION LEVEL DIPSWITCH SETTINGS OUTPUT REDUCTION FAN MOTOR...

Page 21: ...6 2 000 4 000 2 OFF OFF ON 6 10 4 000 6 000 3 ON OFF ON 9 14 Over 6 000 4 T cal Ser Special ON OFF OFF N A 7 Outdoor model 140 T H3M Natural gas ELEVATION LEVEL DIPSWITCH SETTINGS OUTPUT REDUCTION FAN...

Page 22: ...W W Y Flame rod BK W Thermostat Heater Heaters IndoorModelOnly Gas Valve W BK W BK controller Indoor Model Only W Y Y Y for the secondary heat exchanger for the heat exchanger and water pipes for the...

Page 23: ...Condensing Models On Demand Water Heater Service Handbook 23 TROUBLESHOOTING Notes...

Page 24: ...When the water flow stops close all hot water faucets 6 IF the installation includes isolation valves follow these sub steps 6 1 Place a bucket or pan underneath each isola on valve drain port There a...

Page 25: ...a faucet The unit should turn on and the gas in the pipe line should purge Leave the faucet on to keep the unit running until it shuts down due to lack of gas then shut the faucet off Ignore any erro...

Page 26: ...NG Complete the following procedure ONLY if you have been instructed to do so by the Technical Service Department 1 Ensure that the water heater is not in operation 2 Remove the screw from the manifol...

Page 27: ...he heat exchanger for any burn marks hot spots cracks etc 5 Restore power and test the unit Be very cautious during this step avoid contact with electrical components and wires Checking the Flow Senso...

Page 28: ...e spade connector pinch the flat surfaces together at the back of the connector Pinch and pull at the same me 3 2 Remove the three Phillips head screws holding the panel in place 3 3 Pull the assembly...

Page 29: ...s submersible place it into the bucket If it is not submersible place an inlet hose into the bucket 3 Open valves A and B See Page 28 Figure 18 4 Circulate the white vinegar until the water is clear o...

Page 30: ...range Item 708 page 69 See also page 35 Figure 24 Air fuel ratio rod AFR wire yellow See Figure 19 See also page 35 Figure 24 Igniter rod wire black Item 709 page 69 See also page 35 Figure 24 2 4 Rem...

Page 31: ...amber There are several at the top of the burner and two more at the bo om toward back of combus on chamber If the screws at the bo om are di cult to remove li the burner while turning the screws 5 2...

Page 32: ...an will rotate and dust will fly out of the fan housing NOTE You will reassemble these items in reverse order at the end of this procedure 8 Clean the heat exchanger 8 1 If you have a DV model remove...

Page 33: ...from gas valve to the bottom of the combustion chamber Reinstall the fan Verify that all components are reattached and are secure NOTICE Ensure that all wire connectors have been reconnected Some conn...

Page 34: ...34 Condensing Models On Demand Water Heater Service Handbook MAINTENANCE This page is inten onally le blank The Maintenance sec on begins on the next page...

Page 35: ...ire Connections Igniter Rod Wire Connection Brass Screw Securing Gas Valve to Gas Inlet Connection Over heat Cutoff Fuse OHCF Igniter Assembly not visible Connector for Overhead Cutoff Fuse Blue Wires...

Page 36: ...uring Gas Valve to Gas Inlet Connection not visible Over heat Cutoff Fuse OHCF Igniter Assembly not visible Connector for Overhead Cutoff Fuse Blue Wires See also Component Diagrams Item Numbers which...

Page 37: ...of the heater 1 2 2 IF isola on valves are installed open up the drain ports 1 2 3 IF isola on valves are not installed remove the filter item 405 page 70 and open the pressure relief valve 2 Remove...

Page 38: ...f the manifold plate 9 3 Remove the screw on the le side of the gas valve that secures the power cord 9 4 Disconnect the air tube o the le side of the gas valve See page 42 Figure 37 9 5 Disconnect th...

Page 39: ...rner See Figure 29 Do not remove the screws around the flame sensor AFR and igniter rods 11 3 Slide the burner out toward you You may need to use a small set of pliers to loosen the burner on the side...

Page 40: ...he primary heat exchanger is not compromised If it is contact technical support 2 Remove the following items from the primary heat exchanger and INSTALL THEM IN THE SAME LOCATIONS ON THE NEW HEAT EXCH...

Page 41: ...nnec on on the bo om of the secondary heat exchanger The tube from the primary heater will insert into the back elbow on the secondary heat exchanger Figure 31 page 40 2 Make sure that the screw holes...

Page 42: ...o the gas valve is s ll in place 10 2 A ach the wire connectors to each of the solenoid valves Eachconnectorhasadark bluewire exceptforthe proportionalvalve The otherwirecolorswillvary Each set of wir...

Page 43: ...2 Installtheflowsensor control valveontotheinletwater connec on Figure24 page 35 12 3 Inserttheendofthecold connec ontubeintotheoutlet oftheflowsensor controlvalve Seeconnec onpoint D on page70 showni...

Page 44: ...cable clamp on the le side of the cabinet 16 Install the computer board PCB Small feet at the bottom must fit into the corresponding holes in the case Insert the screw at the top of the computer boar...

Page 45: ...hand corner of the cabinet Plug in the flame rod wire connectors 2 See Flame Rod AFR Wire Connections in Figure 24 page 35 Plug in the high limit switch and exhaust thermistor connectors See Figure 24...

Page 46: ...ollows 1 2 1 Close the shuto valves on the hot and cold side of the heater 1 2 2 IF isola on valves are installed open up the drain ports 1 2 3 IF isola on valves are not installed remove the filter i...

Page 47: ...the screws that secure the green ground wires to the manifold plate 8 3 Remove the screws that secure the manifold plate Figure 46 IMPORTANT Remove only the screws along the outside edges of the mani...

Page 48: ...item 151 and or 319143 049 item 119 See page 69 9 Remove the burner from the combus on chamber 9 1 Remove two screws below the burner at the back See Figure 48 9 2 Remove three screws across the front...

Page 49: ...er page 70 A plate attached at the top with a gasket surrounding the flue gas connection to the secondary heat exchanger See Heat Exchanger Primary on page 70 1 Make sure the gasket on top of the prim...

Page 50: ...eat exchangers making sure that the flange on top of the primary heat exchanger male connector goes into the connec on on the bo om of the secondary heat exchanger The tube from the primary heater wil...

Page 51: ...point E onp 70 9 Install the manifold plate gas valve assembly item 102 p 69 to the combus on chamber 9 1 Make sure the screen on the inlet to the gas valve is s ll in place 9 2 A ach the wire connect...

Page 52: ...The fuse box will be mounted later 10 Install the igniter assembly to the lower right hand corner of the manifold plate See Igniter Assembly and Igniter Rod Wire Connection on page 36 see also item 7...

Page 53: ...installed See the following pipe heaters on page 70 item 413 three instances and item 414 two instances If installation is still needed 12 1 Install the long pipe heater to the bo om of the secondary...

Page 54: ...n Figure 25 page 36 There are two mounting holes for these wires The three green wires can be identified as follows One green wire comes from the power cord Two green wires come from connectors on the...

Page 55: ...wear Replace as needed O ring on inlet water connection part no 319143 083 O ring on cold connection tube part no 319143 100 Installa on 1 Install the flow sensor control valve item 402 p 70 onto the...

Page 56: ...Restore power to the water heater 7 Open the gas valve slowly checking for leaks If gas leaks appear shut o the gas supply and disconnect power to the water heater 8 Turn on water to the heater and t...

Page 57: ...ly the screws along the outside edges of the manifold plate DO NOT remove the screws securing the manifold plate to the gas valve DO NOT remove the screws along the interior of the manifold plate 8 4...

Page 58: ...the burner at the back Figure 69 9 3 Slide the burner out toward you If it is di cult to remove try the following 1 Grasp an oval air vent on the front of the burner at the edge on either side 2 Pull...

Page 59: ...up the manifold plate with the holes on the burner and combus on box 3 3 Insert and hand ghten the top center screw on the manifold plate Do not overtighten 3 4 Secure the manifold plate by hand ghte...

Page 60: ...used later to connect the temperature controller to the computer board 9 Verify that all manifold screws have been reinstalled and hand ghtened 10 Complete the wiring Reinstall all three ground wires...

Page 61: ...ors that go to the computer board 5 Remove the computer board as follows See Figure 24 page 35 5 1 Disconnect all of the wires from the computer board 5 2 Remove the screw at the top then remove the b...

Page 62: ...h See High Limit Switch Heat Exchanger in Figure 24 page 35 The wires are locked onto the connectors Pinch the sides of each connector to release it 8 10 Li the gas valve upward to remove it from the...

Page 63: ...ing hole is located on the left side of the gas valve 9 7 Lineupthemanifoldplatewith theholesontheburnerand combus onbox Insertand hand ghtenthetopcenter screwonthemanifoldplate See ManifoldPlate page...

Page 64: ...75 page 60 13 3 Use screws to secure three 3 green wires to the bo om center of the manifold plate See Ground Connec ons in Figure 24 page 35 There are two moun ng holes for these wires The three gree...

Page 65: ...Condensing Models On Demand Water Heater Service Handbook 65 MAINTENANCE This page is inten onally le blank The Components sec on begins on the following pages...

Page 66: ...66 Condensing Models On Demand Water Heater Service Handbook MAINTENANCE This page is inten onally le blank The Components sec on begins on the following page...

Page 67: ...ok 67 COMPONENTS COMPONENT DIAGRAMS ITEM NUMBERS Caseassembly Temperature remote controller Indoor model Outdoor model 702 704 052 052 052 006 704 005 052 004 004 001 007 003 050 002 001 714 002 Tempe...

Page 68: ...r Heater Service Handbook COMPONENTS Computer board assembly Fuse box assembly 709 710 103 708 402 707 701 711 716 402 407 408 060 713 706 for Indoormodel for Outdoormodel 701 710 703 120 053 705 712...

Page 69: ...bly 101 401 116 053 117 103 105 064 054 104 115 053 053 106 107 108 708 110 061 109 111 709 112 053 114 113 707 102 053 120 709 150 057 055 062 053 711 117 055 119 151 118 051 Manifold assembly Burner...

Page 70: ...451 052 409 457 460 453 408 059 454 410 416 455 458 402 459 457 404 406 456 405 052 453 407 059 416 053 417 A B A B 401 154 E E 467 463 063 455 458 455 467 463 063 455 458 A 455 455 468 B 467 463 063...

Page 71: ...rew M4 12 W Washer 319143 025 EW000 051 Screw M4 10 W Washer 319143 325 EW001 052 Screw M4 10 Coated 319143 026 EW002 053 Screw M4x10 319143 060 EW003 054 Hex head screw M4 12 W Washer 319143 326 EW00...

Page 72: ...holder 319143 036 EKK32 111 Rod cap 320273 358 EK462 112 Burner damper Indoor 320273 359 EK463 Burner damper Outdoor 320273 360 EK464 113 Manifold gasket A 319143 044 EKK2Y 114 Manifold gasket B 31914...

Page 73: ...fuse 319143 067 EX02A 413 Pipe heater 320273 364 EK468 414 Inlet heater 320273 365 EK469 415 Drain tube 320273 366 EK470 416 Inlet heater 319143 468 EK105 417 Secondary heat exchanger for Indoor mode...

Page 74: ...02 Rubber grommet 319143 426 EX148 703 Surge box 320273 128 EK280 704 120 VAC wire for Indoor model 319143 427 EK146 120 VAC wire for Outdoor model 319143 546 EK143 705 120 VAC Power ON OFF switch 319...

Page 75: ...s and Part Numbers Item Number Description Part Number 140 Model T H3M Model 716 Exhaust high limit switch wire 319143 501 EK180 721 Temperature controller for Indoor model 320273 684 EK487 722 Fixing...

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