A.O. Smith ATI-140H-N Service Handbook
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A.O. Smith ATI-140H-N Service Handbook

Condensing, on-demand
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Condensing Models
On-Demand Water Heater
MODELS:
ATI-140H-N
ATI-140H-P
ATO-140H-N
ATO-140H-P
THIS SERVICE HANDBOOK IS FOR USE BY QUALIFIED SERVICE PROFESSIONALS ONLY.
IF YOU NEED ASSISTANCE, CALL TECHNICAL SUPPORT AT 877-737-2840.
Service Handbook
GTS-140-NIH
GTS-140-PIH
GTS-140-NEH
GTS-140-PEH
GT-140-NIH
GT-140-PIH
GT-140-NEH
GT-140-PEH
T-H3M-DV-NG
T-H3M-DV-LP
T-H3M-OS-NG
T-H3M-OS-LP
100267626
January 2016

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Summary of Contents for A.O. Smith ATI-140H-N

  • Page 1 Condensing Models On-Demand Water Heater Service Handbook MODELS: ATI-140H-N GTS-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 USE BY QUALIFIED SERVICE PROFESSIONALS ONLY. IF YOU NEED ASSISTANCE, CALL TECHNICAL SUPPORT AT 877-737-2840.

  • Page 2: Table Of Contents

    TABLE OF CONTENTS Specifications..........................................4 Introduction...........................................5 General Installation Guidelines ..................................5 Normal Operation .........................................6 Activation ........................................6 Operation ........................................6 Shutdown ........................................6 Troubleshooting ..........................................7 Preliminary Checklist .....................................7 Gas/Water/Electric: ..................................7 Remote Controller: ..................................7 High Altitude: ....................................7 Long Vent Run ....................................7 Hard Water: ....................................7 New Installations: ..................................
  • Page 3 Service Procedures ........................................24 Verifying DIP Switch Settings ..................................24 Unit Draining and Filter Cleaning .................................24 Checking for a Crossed Connection ................................25 Checking for a Reversed Connection ................................25 Checking Inlet Gas Pressure/Purging Air from Gas Line ..........................25 Checking and Adjusting the Manifold Gas Pressure ............................25 Adjusting Minimum Manifold Pressure ............................

  • Page 4: Specifications

    SPECIFICATIONS Table 1: 140 (T-H3M) Direct Vent Indoor and Outdoor* 140 lndoor 140 Outdoor Model (T-H3M-DV) (T-H3M-OS) Natural Gas Input Min.: 15,000 BTU/h (Operating Range) Max.: 120,000 Propane Input Min.: 15,000 BTU/h (Operating Range) Max.: 120,000 Gas Connection 1/2” NPT Water Connection 3/4”...

  • Page 5: Introduction

    INTRODUCTION Read and follow all safety messages intended order. Here is how to use procedures, consult the technical service and instructions in this handbook and this manual: department or the local service agent. on the product labeling. ● First, refer to the 140/T-H3M Installation Manual as the primary General source of information.

  • Page 6: Normal Operation

    NORMAL OPERATION Becoming familiar with how a tankless 2. The fan activates after the 1. The proportional gas valve and water heater normally operates may conditions in the previous step are fan will modulate based on the help to troubleshoot it. Assuming it met.

  • Page 7: Troubleshooting

    TROUBLESHOOTING High Al tude: code? If it runs well through the Preliminary hot isolation valve, the plumbing Is your location at an altitude of over 2,000 Checklist system is at fault. feet? This may cause a lack of air. See “Dip Switch Settings,”...

  • Page 8: Water Is Too Hot

    • resides in the plumbing line, Output temperature will be Temperature fl uctuates when a not in the tankless unit. affected if air flow is impeded. fi xture is opened. • Check for crossed plumbing between ◦ Make sure that the unit is installed Check for construction dust cold water lines and hot water lines.

  • Page 9: Unit Does Not Ignite When Water Goes Through It

    • • plate. If the maximum If the clear tube from the If the unit is in a recirculation energy input of all appliances proportional gas valve to the system, the return water exceeds the maximum rating bottom of the combustion temperature may be too close of the gas meter, consult chamber is disconnected,...

  • Page 10: Error Codes

    Error Codes All units have self-diagnostics for safety and convenience when troubleshooting. If there is a problem with the unit, a numerical error code will display on the TM-RE42 Remote Controller (if installed) or on the temperature controller of indoor models. Installation-related problems may also produce an error code. If the remote/ temperature controllers are not working, the green LED on the computer board will flash a code pattern.
  • Page 11 (Continued from previous page...) ERROR CODE GREEN LED ON SYMPTOM OR ISSUE TROUBLESHOOTING PROCEDURE COMPUTER BOARD Abnormal main OR Abnormal Main/Solenoid Gas Valve, p. 14. Six Flashes abnormal solenoid gas valve Six Flashes Abnormal solenoid gas Abnormal Solenoid Gas Valve, p. 14. valve Four Flashes Fan motor fault...

  • Page 12: Incorrect Dip Switch Settings

    Incorrect DIP Switch Se ngs gas line is cleared of debris. 3. Make sure that the clear plastic tube connecting the proportional • Error Code: 031 It is possible that there is a faulty gas valve to the combustion pressure regulator at the gas 1.

  • Page 13: Outlet Thermistor Failure

    freely in the ceramic insulator. Outlet Thermistor Failure o-ring that wraps around See “Cleaning the Rod Assembly this sensor. Error Code: 311 (Flame Sensor and Air/ Fuel Ratio Replace and test. Rod)” on page 28. See also “Wiring Diagram,” page 4.

  • Page 14: Exhaust Thermistor Failure

    Remove the computer Air-Fuel Ra o Rod Failure 5. Check the voltage across the main board to access the inlet gas valve wires (blue - light blue Error Code: 391 thermistor. The computer #3) during operation. The voltage 1. Ensure that the unit is plugged into is fi...

  • Page 15: Abnormal Fan Motor

    3. If the unit was recently rebuilt, within normal range, replace the computer board (PCB), or moisture. make sure that each gas valve wires computer board, part number If moisture is found, allow the are plugged into the proper place. 320273-369.

  • Page 16: False Flame Detection

    Propor onal Gas Valve / 5. Verify that supply gas pressure is False Flame Detec on Computer Board Fault within specifications. Error Code: 721 Error Code: 701 6. Check the resistance across the WARNING! Shut off all gas and proportional valve (red, white 1.

  • Page 17: Abnormal Exhaust Temperature

    Clear them if any professionals only. A.O. Smith is not Normal voltage should be 11- are found. liable for the actions of the technician if 25 VDC.
  • Page 18 burners will become gas rich and Press the on/off bu on on code as follows: trigger the 101 or 991 code. the remote/temperature controller so the amber Turn off the power to the ◦ To check and clean the standby light is off . heater using the switch burner, refer to “Cleaning the above the computer board.

  • Page 19: Dip Switch Settings

    DIP SWITCH SETTINGS Figure 9. Use this section to verify DIP switch settings. Each DIP switch has a specific function as shown in the following tables. Generally, they should not require adjustment. Verify the function of each DIP switch carefully before changing any settings. If you have questions, contact the technical service department.
  • Page 20 Table 6: Altitude-Specific DIP Switch Settings (Indoor Models) Indoor models: Propane DIPSWITCH SETTINGS OUTPUT FAN MOTOR ELEVATION LEVEL REDUCTION SPEED CHANGE NO.3 NO.4 NO.5 0 to 2,000 (DEFAULT) 2,000 to 3,000 -3 % 3,000 to 5,000 -5 % -7 % 5,000 to 7,500 -11 %...
  • Page 21 Table 7: Altitude-Specific DIP Switch Settings (Outdoor Models) Outdoor model 140 (T-H3M): Propane FAN MOTOR DIPSWITCH SETTINGS OUTPUT SPEED ELEVATION LEVEL REDUCTION NO.3 NO.4 NO.5 CHANGE 0 (DEFAULT) (DEFAULT) 2,000 2,000 -6 % 10 % 4,000 4,000 -9 % 14 % 6,000 Over 6,000 cal Ser...

  • Page 22: Wiring Diagram

    WIRING DIAGRAM Figure 10. Wiring Schematic and Check Point Locations W: WHITE BK: BLACK LB: LIGHT BLUE Indoor Model Only R: RED BL: BLUE Y: YELLOW Heater G: GREEN O: ORANGE BR: BROWN P: PURPLE (for the secondary heat exchanger) Heaters (for the heat exchanger and water pipes)
  • Page 23 Notes: Condensing Models: On-Demand Water Heater Service Handbook • 23...

  • Page 24: Service Procedures

    SERVICE PROCEDURES valves, follow these sub-steps: Verifying DIP Unit Draining and Switch Se ngs Filter Cleaning Place a bucket or pan underneath each isola on valve drain port. (There are two: one on the COLD line Incorrect DIP switch settings can 1.

  • Page 25: Checking For A Crossed Connection

    3. Remove the screw for the pressure Checking for Checking for port located on the gas inlet. See Figure 13. a Crossed a Reversed Connec on Connec on 4. Connect a manometer to the pressure port. 5. Slowly re-open the manual gas 1.

  • Page 26: Adjusting Minimum Manifold Pressure

    pressure during maximum 5. During this step, DO NOT press the combustion, press and hold the “Increase” or “Decrease” button for “MAX” button on the computer more than two seconds at a time. board. (See Figure 8, page 18). Press and hold down the “MAX” button on the computer board •...

  • Page 27: Checking The Overheat Cutoff Fuse (Ohcf)

    5. During this step, DO NOT press the 067). Replacing this part will require If you have a remote, you can check “Increase” or “Decrease” button for you to remove the heat exchanger. for flow rate by turning on power more than two seconds at a time.

  • Page 28: Cleaning The Rod Assembly (Flame Sensor And Air/ Fuel Ratio Rod)

    two screws on the bottom. Clean the flame sensor Figure 17. thoroughly with 100 grit 3. Remove the rod assembly as sandpaper or other suitable described below. (See Figure 17.) abrasive. Con nue un l it has a bright fi nish. Locate the yellow and Clean the air/fuel ratio rod orange wires located in the...

  • Page 29: Descaling The Unit

    cover. Be sure to connect all 3 hoses/pump to the drain ports of 6. Restart the water heater as wires on the front of the burner. the isolation valves (A and B). See described in its manual. Verify Also, inspect all gaskets to make page 28, Figure 18.
  • Page 30 715, p. 70). See also Remove the screws that Before you begin these procedures, Figure 24, page 35. secure the green ground consider removing the “Components” wires to the manifold plate. section from this manual. It starts on NOTE: Outdoor models Remove the screws that page 35.
  • Page 31 Remove the screw securing Unplug the wire connectors Note the orienta on of the the gas valve to the gas at the solenoid valve (SV3); damper, then remove the connec on. The screw is the solenoid valve is a ached damper (item 112, p.
  • Page 32 into the slots, star ng at the 7.1.3 Slide the fan toward you Use the air compressor to back and moving forward. to remove it from the rear blow air down through the Make sure that no contact slots that hold it in place. top of the heat exchanger is made with the gasket;...
  • Page 33 10. Reassemble all items in reverse order. Use this checklist: For example, if “73“ is printed on a wire, its pin □ If necessary, refer to the should plug into the side exploded assembly views of the connector that has which start on page 67.
  • Page 34 This page is inten onally le blank. The Maintenance sec on begins on the next page. 34 • Condensing Models: On-Demand Water Heater Service Handbook...

  • Page 35: Maintenance

    MAINTENANCE Indoor Model: High Limit Switch Exhaust (Exhaust) Thermistor Secondary Heat Over-heat Exchanger Cutoff Fuse (OHCF) Condensate Primary Heat Drain Tube Pipe Heater Exchanger High Limit Switch Flame Rod (Heat Exchanger) & AFR* Wire Connections Igniter Rod Wire Connection Clip for High Manifold Plate Limit Wires Connector for...
  • Page 36 Outdoor Model: Three Screws Secure the Secondary Heat Exchanger to the Case Secondary Over-heat Heat Exchanger/ Cutoff Fuse Exhaust Vent (OHCF) Condensate Pipe Heater Drain Tube Primary Heat Exchanger High Limit Switch Flame Rod (Heat Exchanger) & AFR* Wire Connections Igniter Rod Wire Connection Manifold Plate...

  • Page 37: Replacing The Heat Exchanger (Indoor Models)

    Removing Heat cause damage by electrostatic Replacing the Heat discharge. Exchanger Components Exchanger (Indoor Disconnect all wire (Indoor Models) Models) connectors from the computer board. 1. Shut the unit down as follows: Remove the screw at the Tools: top of the computer board Shut Off...
  • Page 38 Disconnect fastener 14-22 9. Remove the Gas Valve and inlet connec on. (The gas (item 458, page 70). Manifold Plate Assembly: valve and manifold are s ll connected together.) Remove two heaters and Unplug wire connectors clips (located at top and from the air/fuel ra o rod You may need to twist bo om of tube):...
  • Page 39 part number 319143-044 (item driver. There are 2 holes 11.4 Check the gaskets on the 113) and/or 319143-045 (item in the case directly below burner for any tears. If 114). See page 69. the screws to put the screw there are, replace the gasket driver through.

  • Page 40: Preparing The New Primary Heat Exchanger For Installation (Indoor Models)

    13. Follow these steps to remove the 13.2.1 Remove fastener 14-22 1. Make sure the gasket on top of heat exchangers: (item 458, p. 70) from the primary heat exchanger is the tube on the le -hand not compromised. If it is, contact 13.1 Slide the heat exchangers side.

  • Page 41: Preparing The New Secondary Heat Exchanger For Installation (Indoor Models)

    Preparing the Installing the (“14-22” is marked on the end of this clip; all such clips are marked on the New SECONDARY Heat Exchanger end in the same manner.) Heat Exchanger (Indoor Models) for Installa on 4. Install the heat exchanger assembly into the case, making (Indoor Models) 1.
  • Page 42 cabinet. You may need to 9. Install the fan with the air inlet a number stamped next push the assembly up some facing toward the front as follows: to it. During installation, in order to line up the holes. each wire number must Slide the fan discharge into match its solenoid valve Insert and hand ghten...
  • Page 43 • connec on. Hand-tighten 11.2 Slide the black igniter Two 14-22 fasteners. (“14- only. See Figure 24, page wire onto the igniter rod. 22” is marked on the end of See “Igniter Rod Wire each clip.) Connec on” in Figure 24, 10.5 A ach the air tube from the See both instances of item page 35.
  • Page 44 Figure 39. Figure 40. 13.2 Install pipe heaters just below connec on points “A” and “B.” (See page 70.) Secure each Install Plugs into Receptacles Below the fuse box location, connect plugs to receptacles. one with a clip (item 451). Three pair: Receptacles 13.3 Install a pipe heater just above...
  • Page 45 Figure 42. Figure 43 16.2 Insert the connector from the power supply cable to the top port on the fuse box. See Figure 43. Secure 16.3 Use screws to secure fuse box w/ three (3) green wires to 2 screws. the bo om, center of the manifold plate.

  • Page 46: Replacing The Heat Exchanger (Outdoor Models)

    Removing Heat Disconnect all wire Replacing the connectors from the Exchanger Components computer board. Heat Exchanger (Outdoor Models) (Outdoor Models) Remove the screw at the top of the computer board assembly, then remove the 1. Shut the unit down as follows: board (Figure, p.
  • Page 47 6. Remove the igniter assembly: Flame Rod Wire Connector: Example: To remove, pinch flat sides at end Freeze Protection Heaters Remove the screw that with your finger nails, then slide with Clips secures the igniter assembly connector off the spade. (Figure 25, page 36).
  • Page 48 Remove the brass screw (item 151) and/or 319143- 10. Disconnect and remove the securing the gas valve to the 049 (item 119). See page following items: gas connec on. The screw is 10.1 Disconnect the condensate located at the bo om, right- drain line (item 415, page hand side of the gas valve.

  • Page 49: Preparing The New Primary Heat Exchanger For Installation (Outdoor Models)

    • Three Screws Securing the secondary heat exchanger Air tube and its connector/nipple Secondary Heat Exchanger assembly, go to “Preparing on the bottom of the combustion the New Secondary Heat chamber (Figure 52). Exchanger for Installa on • Two (2) freeze protection heaters (Outdoor Models).”...

  • Page 50: Preparing The New Secondary Heat Exchanger For Installation (Outdoor Models)

    3. Disconnect and remove the fan 1. Remove the following items from Angled View of Primary and from the combus on chamber as the secondary heat exchanger, Example: Secondary Heat Exchangers follows: then INSTALL THEM IN THE SAME LOCATIONS ON THE NEW with Clips Insert tube into Remove the 2 Phillips/hex...
  • Page 51 Line up the holes, then insert Insert and hand ghten three A ach the wire connectors to and hand- ghten two (2) hex (3) screws along the top, each of the solenoid valves. head screws (item 54). See front por on of the burner. •...
  • Page 52 Secure the power cord to Figure 59. Figure 61. the gas valve as shown in Figure 25, page 36. (See Install Plugs into Receptacles Below the fuse box location, the “Power Cord Moun ng connect plugs to receptacles. Tab” callout.) Hand-tighten Three pair: Receptacles only.
  • Page 53 11. Install the fl ow sensor/control fully inserted at each see also Figure 62.) valve (item 402, p. 70) and cold connection point. Hand ghten two screws to secure connec on tube (item 462, p. 70) it to the manifold plate. as follows: 11.5 Verify that all of the fasteners on the water tubing are...
  • Page 54 • Item “I” in the schematic 19. Open the gas valve slowly and OUTDOOR MODELS: (p. 22) uses a separate check for leaks. If any gas leaks THREE OPEN CONNECTORS ON THE COMPUTER BOARD wiring assembly which appear, shut off the gas and includes three wires: disconnect power to the water yellow, green, and...

  • Page 55: Flow Sensor/Control Valve Removal And Installation

    5. Remove the computer board 459 on p. 70, which secures Flow Sensor/ (PCB). See Item 701, p. 68; see the inlet of the flow sensor/ also Figure 41. control valve to the inlet water Control Valve connection. “16A” is marked on Removal and Disconnect all wires from the end of this clip.

  • Page 56: Burner Removal And Installation

    • Outdoor Models: wires from the computer OPEN CONNECTORS ON THE COMPUTER BOARD: There are three (3) board. (These wires are • TWO FOR INDOOR MODELS receptacles on the black and white). • THREE FOR OUTDOOR MODELS computer board that will be open (Figure 65).
  • Page 57 Disconnect the freeze 8. Remove the Gas Valve and protec on heater wires. Manifold Plate Assembly: INDOOR MODELS have 6 sets Unplug wire connectors of white connectors with yellow from the air/fuel ra o rod wires (two above the assembly, (AFR), fl...
  • Page 58 Figure 69. Figure 71. part number 319143-044 (item 113) and/or 319143- Front View of Burner Assembly 045 (item 114). See page Install Plugs into Receptacles Three Screws Three Screws Receptacles 8.12 Inspect the o-ring (item 151, p. 69) and gas inlet ring (Yellow Wires) (item 119, p.

  • Page 59: Installation

    Installa on 3. Install the manifold plate/gas fuse box will be installed. (If valve assembly (item 102, p. 69) needed, refer to Figure 74, page to the combus on chamber: 60). 1. If a new burner is being installed, then you must complete one of A ach the white wire 6.
  • Page 60 • 7. Install the fuse box assembly to Indoor models: OPEN CONNECTORS ON THE COMPUTER BOARD: the le side of the manifold plate. One connector will be • TWO FOR INDOOR MODELS (See items 709 & 120, page 69.) unused (black and white •...

  • Page 61: Gas Valve/Manifold Plate: Removal And Installation

    14. Slowly open the gas valve and Disconnect all of the wires Gas Valve/ check for leaks. If any gas leaks from the computer board. appear, shut off the gas and turn Manifold Plate: Remove the screw at the top, off...

  • Page 62: Installation

    Unplug the wire connectors If compromised, replace with IMPORTANT: Remove only at the solenoid valve (SV3); part number 319143-057 (item the screws along the outside the solenoid valve is a ached 151) and/or 319143-049 (item edges of the manifold plate. to the corner of the manifold 119).
  • Page 63 • Install each connector to A ach the air tube from the NOTE: All connectors with the solenoid valve with bo om of the combus on yellow wires are connected the matching number. chamber to the port on the to the same circuit, so the le side of the gas valve order in which you connect •...
  • Page 64 Secure these wires with the 13.2 Insert the connector from OPEN CONNECTORS ON THE COMPUTER BOARD: cable clamp on the le side the power supply cable to • TWO FOR INDOOR MODELS of the cabinet. the top port on the fuse box. •...
  • Page 65 This page is inten onally le blank. The Components sec on begins on the following pages. Condensing Models: On-Demand Water Heater Service Handbook • 65...
  • Page 66 This page is inten onally le blank. The Components sec on begins on the following page. 66 • Condensing Models: On-Demand Water Heater Service Handbook...

  • Page 67: Component Diagrams/Item Numbers

    COMPONENT DIAGRAMS/ITEM NUMBERS Case assembly Indoor model Outdoor model 050 002 Temperature controller Temperature remote controller Indoor model Condensing Models: On-Demand Water Heater Service Handbook • 67...
  • Page 68 COMPONENT DIAGRAMS/ITEM NUMBERS Computer board assembly Indoor model Outdoor model Fuse box assembly 68 • Condensing Models: On-Demand Water Heater Service Handbook...
  • Page 69 COMPONENT DIAGRAMS/ITEM NUMBERS Burner assembly Burner assembly 111 709 Image of fuse box is hidden Manifold assembly Gas Valve 055 062 Condensing Models: On-Demand Water Heater Service Handbook • 69...
  • Page 70 COMPONENT DIAGRAMS/ITEM NUMBERS Waterway Assembly Outdoor Model Indoor Model Secondary Heat Exchanger Secondary Heat Exchanger 419 465 466 064 450 053 for Indoor model 411 058 Heat Exchanger (Primary) Chamber 451 413 052 453 Outlet Inlet 70 • Condensing Models: On-Demand Water Heater Service Handbook...

  • Page 71: Component Item Numbers

    COMPONENT ITEM NUMBERS Table 10: Component Descriptions and Part Numbers Part Number Item Number Description 140 Model T-H3M Model Case assembly for EK450 Indoor model Case assembly for EK451 Outdoor model Front cover for Indoor EK452 Front cover for Outdoor EK453 Intake air port assembly 320273-350...
  • Page 72 COMPONENT ITEM NUMBERS Table 10: Component Descriptions and Part Numbers Part Number Item Number Description 140 Model T-H3M Model Fan motor for Indoor 319143-443 EK109 model Fan motor for Outdoor 319143-043 EKK25 model Burner gasket 319143-031 EKK2X Fan damper for Indoor 320273-557 EK491 model...
  • Page 73 COMPONENT ITEM NUMBERS Table 10: Component Descriptions and Part Numbers Part Number Item Number Description 140 Model T-H3M Model Flow Sensor/ 319143-463 EK129 Control Valve Condensate drain port 319143-018 EKH23 Water inlet 319143-193 EKK1U Inlet drain plug 319143-197 EKK2B Inlet water filter 319143-198 EKK2C Inlet thermistor...
  • Page 74 COMPONENT ITEM NUMBERS Table 10: Component Descriptions and Part Numbers Part Number Item Number Description 140 Model T-H3M Model Flat heater 319143-535 EK217 Cold pipe for 140 model 320273-555 EK477 Header connection 320273-368 EK478 Thermistor fixing plate 319143-106 EX13H Exhaust thermistor 319143-111 EX13L gasket...
  • Page 75 COMPONENT ITEM NUMBERS Table 10: Component Descriptions and Part Numbers Part Number Item Number Description 140 Model T-H3M Model Exhaust high limit 319143-501 EK180 switch wire Temperature controller 320273-684 EK487 for Indoor model Fixing plate EK490 Temperature remote 319143-485 TM-RE40 controller Remote controller 320273-512...
  • Page 76 Copyright © 2016 A.O. Smith Corporation.

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