A.O. Smith T-H2-DV Service Manual
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A.O. Smith T-H2-DV Service Manual

A.O. Smith T-H2-DV Service Manual

On-demand water heater
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CONFIDENTIAL
T-H2-DV/T-H2-OS Service Manual
Ver. 1.01
T-H2-DV/ T-H2-OS
On-Demand Water Heater
Service Manual
Flash Water Heater
Flash Water Heater
Model T-H2-OS
Model T-H2-DV
A.O. Smith Water Products Company
500 Tennessee Waltz Parkway
Ashland City, TN 37015
Toll Free: 1-877-737-2840
1

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  • Page 1 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 T-H2-DV/ T-H2-OS On-Demand Water Heater Service Manual Flash Water Heater Flash Water Heater Model T-H2-OS Model T-H2-DV A.O. Smith Water Products Company 500 Tennessee Waltz Parkway Ashland City, TN 37015 Toll Free: 1-877-737-2840...

  • Page 2: Table Of Contents

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Table of Contents 1. Specifications…………………………………………………..…………………………………………………..…… 3 2. Exterior view……………………...…….………………………………………………………………………………. 4 3. Interior view…………………………….……………………………………………………………………………….. 6 4. List of main components in the interior view…….………………………………………………….…… 8 5. Schematic diagram…………………………………………………………………………………………………..11 6. Wiring diagram…………………………………………………………………………………………………………. 12 7. Wiring diagram checkpoints for diagnosis………………………..………………….………………….… 13 (A) Resistance values of the temperature thermistors……..…………………………………………...

  • Page 3: Specifications

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 1. Specifications Model T-H2-DV T-H2-OS Dimensions H25.6"×W18.5"×D12.4" Weight 73 lbs. 71 lbs. 199,000 INPUT BTU/h 13,000 Combustion System Power vent Installation Direct-vent Outdoor Fan motor PWM turbo fan LP 4.9” WC LP 4.6” WC Manifold Natural 3.6”...

  • Page 4: Exterior View

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 2. Exterior view T-H2-DV Front view Side view Bottom view Top view...
  • Page 5 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 T-H2-OS Front view Side view Bottom view Top view...

  • Page 6: Interior View

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 3. Interior view T-H2-DV...
  • Page 7 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 T-H2-OS...

  • Page 8: List Of Main Components In The Interior View

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 4. List of main components in the interior view Item# in Takagi Common parts Description components Part # For other models diagram Manifold assembly with gas EKH6T (LP model) T-K4-IN/OS, T-D2-IN/OS valve assembly EKH6U (NA model)
  • Page 9 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Item# in Takagi Common parts Description components Part # For other models diagram T-K3, T-K3-Pro, T-K3-SP/OS, Gas inlet EKK1E T-KJr2-IN/OS, T-K4-IN/OS, T-D2-IN/OS Pipe heater EKJ47 Water control valve EKH32 T-M50, T-M32 Secondary heat exchanger...
  • Page 10 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Item# in Takagi Common parts Description components Part # For other models diagram Exhaust thermistor assembly EKH6E Inlet drain plug (water filter) EX006 T-M50, T-M32 Flat heater EX13P 3 array heater EX13R EKH5B (T-H2-DV)

  • Page 11: Schematic Diagram

    The T-H2-OS doesn’t have fan motor for exhaust, exhaust thermistor and hi-limit switch for exhaust. 1. When a hot water tap is opened, cold water enters the T-H2-DV or T-H2-OS. 2. The water flow sensor detects this water flow and sends this information to computer.

  • Page 12: Wiring Diagram

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 6. Wiring diagram The diagram below refers to both the T-H2-DV and T-H2-OS. TM-RE30...

  • Page 13: Wiring Diagram Checkpoints For Diagnosis

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 7. Wiring diagram check points for diagnosis The table below applies to both the T-H2-DV and the T-H2-OS. Check- Part and Description Color of wires Normal range point White – Black (A) A, A1...
  • Page 14 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Check- Part and Description Color of wires Normal range point Mixing thermistor Black - Black Output thermistor Black - Black See table on p. 14 Inlet thermistor Black - Black Remote controller 11 to 25 VDC Fan motor Red –...

  • Page 15: A) Resistance Values Of The Temperature Thermistors

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 8. (A) Resistance values of the temperature thermistors The T-H2-DV and the T-H2-OS use the same thermistors. Resistance values at different temperatures ºF Temperature ºC Resistance kΩ 23.76 19.08 15.43 12.56 10.28 8.47 7.02 5.85...

  • Page 16: B) Resistance Values Of The Temperature Exhaust Thermistors

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 8. (B) Resistance values of the temperature Exhaust thermistor Only the T-H2-DV is equipped with the exhaust thermistor. Resistance values at different temperatures ºF Temperature ºC Resistance kΩ 30.04 24.12 19.50 15.87 13.00 10.71 8.87...

  • Page 17: Operational Flow Chart

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 9. Operational flow chart The diagram below refers to both T-H2-DV and T-H2-OS.

  • Page 18: Component Specifications

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10. Component specifications 10-1. Burners……………………..………………………………….………………………………..………. 19 10-2. Gas manifold………….………………………………………………..……………………………..20 10-3. Fan motor……………………………………………………………………………………….……...… 21 10-4. Fan motor for exhaust………………………………………………………………………………. 10-5. Gas valve assembly………………..……………………….………………………………..………. 23 10-6. Flame rod………………………………………………………….………………………………………. 24 10-7. AFR rod……………………………………………………………………………………………….……. 10-8. Heat exchanger………………………………………………………………………………..……….. 26 10-9.

  • Page 19: Burners

    Visual inspection: excessive dust deposit on the burner surface and/or Diagnostic unstable flame conditions during operation. Color/Number of wires The burner for the T-H2-DV and T-H2-OS has the “46V” mark as shown below. Burner damper (#111 / EKH5G) The burner damper is not included in EKH5W.

  • Page 20: Gas Manifold

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-2. Gas manifold Included EKH6T (LP model) Unit Part # Takagi Part # Checkpoint in #118 EKH6U (NA model) 1. The manifold distributes gas from the gas valves to the burners. The manifold has two types of the nozzles: one type for gas-rich burners (16...

  • Page 21: Fan Motor

    13 to 17 VDC (Input) Orange-Blue 2.0 to 6.5 VDC (Input) Verify the fan motor speed using the Diagnostics Mode of White-Blue the T-H2-DV/T-H2-OS computer board or the TM-RE30 temperature remote controller. See Section 12-1 for details. PWN turbo fan motor...

  • Page 22: Fan Motor For Exhaust

    Orange-Blue 2.0 to 6.5 VDC (Input) Color/Number of wires Verify the fan motor speed for exhaust using the Diagnostics Mode of the T-H2-DV computer board or the White-Blue TM-RE30 temperature remote controller. See Section 12-1 for details. The fan motor for exhaust of the T-H2-DV has the “46”...

  • Page 23: Gas Valve Assembly

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-5. Gas valve assembly Included EKH6T (LP model) Unit Part # Takagi Part # Checkpoint C,H1 in #118 EKH6U (NA model) Opens and closes the gas pathways of the water heater (main and solenoid...

  • Page 24: Flame Rod

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-6. Flame rod Unit Part # #106 Takagi Part # EKK0E Checkpoint To detect flames while unit is in operation. Function 1. Unable to detect flames when flames actually do occur Failure events 2. Detecting a false flame when no flames actually occur 1.

  • Page 25: Afr Rod

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-7. AFR rod Unit Part # #106 Takagi Part # EKK0E Checkpoint Checks flame conditions during combustion. Function When AFR rod detects unexpected flame conditions, the computer of the water heater makes adjustments in the fan motor speed to compensate.

  • Page 26: Heat Exchanger

    B. Inspect for scale buildup inside the heat exchanger pipes. Scale buildup obstructs proper heat transfer to the water, thereby overheating the heat exchanger and causing damage. Color/Number of wires The heat exchanger of the T-H2-DV and T-H2-OS has the “Pro” mark as shown below. T-H2-DV T-H2-OS...

  • Page 27: Secondary Heat Exchanger

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-9. Secondary heat exchanger Unit Part # Takagi Part # EKH6X Checkpoint Absorb latent heat from exhaust gas and transfer the water through the Function secondary heat exchanger pipes, which can improve heat efficiency of the unit by approximately 10%.

  • Page 28: Flow Sensor

    Failure event Effects on the water Ignition sequence does not start heater if flow sensor (T-H2-DV/T-H2-OS will not initiate any operation) fails Error codes when the 441 (Within Easy-link systems only) flow sensor fails 1. Visual inspection: connection / breakage of wires and/or debris on impeller.
  • Page 29 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-11. Water control valve (flow adjustment valve and bypass valve) Unit Part # #423 Takagi Part # EKH32 Checkpoint The water control valve in the water heater has three functions of water control: flow adjustment, bypass, and two-way) This valve is exactly the same as the water valve in the T-H1.

  • Page 30: Water Control Valve

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-11. Water control valve (flow adjustment valve and bypass valve) Blue-Brown 13.0 to 16.0 VDC Color/Number Orange-Brown ON: 12.5 to 16.0 VDC OFF: 0 to 1 VDC wires Red-Brown (0° position) 1 VDC less...

  • Page 31: Thermistors

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-12. Thermistors #422 (Inlet) EKK38 (Inlet) E1 (Mixing) Unit Part # #433 (Output) Takagi Part # EKK2T (Output) Checkpoint E2 (Output) #418 (Mixing) EX00H (Mixing) E3 (Inlet) Measure cold/hot water temperatures in the water heater.

  • Page 32: Exhaust Thermistor

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-13. Exhaust thermistor Unit Part # #706 Takagi Part # EKH6E Checkpoint Measure the exhaust temperatures in the exhaust chamber. Function Unable to measure exhaust temperature in the exhaust chamber properly. Failure events If the thermistors fail open or short, error code appears before starting Effects on the water heater operation.

  • Page 33: Hi-Limit Switch

    "111" or "121" error code will display. Error codes when hi-limit The T-H2-DV / T-H2-OS Outdoor don't have the "141" error code that was used switch fails in our previous models. This error code is now replaced by the "111",the "121"...

  • Page 34: Hi-Limit Switch For Exhaust

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-15. Hi-limit switch for exhaust Unit Part # #442 Takagi Part # EKH6G Checkpoint -Based on bi-metal thermal expansion. Function -Detects excess temperature (more than 151˚F or 66˚C) of exhaust gas in the exhaust chamber.

  • Page 35: Overheat Cutoff Fuse

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-16. Overheat cutoff fuse Unit Part # #404 Takagi Part # EX02A Checkpoint -The overheat cutoff fuse contains solder with a melting point of 430˚F (221˚C). -Detects excessive temperatures within the water heater, especially around...

  • Page 36: Freeze Protection Heaters

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-17. Freeze protection heaters #405 EX002 #415 EKK2P Unit Part # #426 Takagi Part # EKJ47 Checkpoint #453 EX13P #454 EX13R Prevents the heat exchanger, water valves, and water pipes within the water Function heater from freezing.

  • Page 37: Computer Board

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-18. Computer board Unit Part # #701 Takagi Part # EKH4E Checkpoint Controls the functions of most of the parts in the water heater. Function Malfunctioning computer Failure events -A component(s) may not operate within the water heater. In most cases...

  • Page 38: Transformer

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-19. Transformer Unit Part # #702 Takagi Part # EM296 Checkpoint A1,A2 -To transform input voltage from 120VAC to 100VAC. -Every electrical component of the water heater is designed to only work Function with a 100VAC power supply, therefore, the water heater comes equipped with this transformer.

  • Page 39: Igniter

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-20. Igniter Unit Part # #123 Takagi Part # EKN74 Checkpoint -To ignite the gas/air mixtures when the water heater is ready to burn gas on Function its burner surface. -The output voltage of the igniter is more than 14kV.

  • Page 40: Freeze Protection Thermostat

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-21. Freeze protection thermostat #704 EKH79 (T-H2-DV) Unit Part # Takagi Part # Checkpoint #719 EKH7A (T-H2-OS) Temperature detecting device which prevents the pipes within the water heater from freezing. When this device detects temperatures below 36.5˚F Function (2.5˚C) inside the water heater, power is supplied to the electric heaters to...

  • Page 41: Fuse Box

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 10-22. Fuse box Unit Part # #715 Takagi Part # EKH67 Checkpoint Protects the unit from high voltage and/or high electric current caused by lightning. Function There are 2 types of surge absorbers in the water heater. Surge absorber A is activated by voltage higher than 220 V, the other one is activated by voltage higher than 680 V.

  • Page 42: Fault Analysis & Specifications

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 11. Fault Analysis & Specifications Remarks: 1. Proper range of values of voltage & resistance shown below. 2. Please refer to the wiring diagram for checkpoint positions. Remove power to the water heater when checking for continuity, disconnections, resistance values, etc.
  • Page 43 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Natural of Fault Diagnosis Checkpoint 5 Check that the filter on the cold water inlet is clean. The hot water is not 6 Check whether or not the unit is frozen. available when a fixture 7 Check if there is enough gas in the tank.
  • Page 44 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Natural Diagnosis Checkpoint Fault 4 Fault of PCB in the water heater Fluctuation [1] No voltage to gas solenoid valve (SV of hot water Normal: 78 to 100 VDC between COM (blue) & #9 (green)
  • Page 45 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Error Code Diagnosis Checkpoint 6 Check if there is any blockage in the intake air and/or exhaust. 7 Check if there is dust and lint in burner and heat exchanger, when the water heater has been installed in laundry room.
  • Page 46 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Error Code Diagnosis Checkpoint 5 Disconnected/damaged O.H.C.F. (Refer to section 10-16) V isual inspection: connection/breakage of wires. Normal: 1 Ωor less between blue & blue 6 Disconnected/damaged hi-limit switch. (Refer to section 10-14) V isual inspection: connection/breakage of wires.
  • Page 47 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Error Code Diagnosis Checkpoint 4 Check for soot on the flame rod [1] Clean the flame rod [2] PCB fault During operation: more than 1 μA through the flame rod wire (orange) 5 Disconnected/damaged O.H.C.F.
  • Page 48 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Error Code Malfunction description Cancellation method Disconnected/short-circuited exhaust thermistor Turn off the power or water supply (T-H2-DV only) Diagnosis Checkpoint 1 Exhaust thermistor fault (Refer to section 10-13) V isual inspection: connection/breakage of wires and/or debris on thermistor.
  • Page 49 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Error Code Malfunction description Cancellation method Fault of driving circuit for main gas solenoid valve (MV, SV , SV and/or SV (The computer checks the condition of the main Turn off the power supply...
  • Page 50 Normal: 2.0 to 6.5 VDC between orange & blue (during operation) Verify fan motor speed of the water heater using the "diagnostics mode" of the T-H2-DV/T-H2-OS computer board or the TM-RE30 temperature remote controller. See the "12-1. How to diagnose the water heater using the TM-RE30”.
  • Page 51 Checkpoint Verify fan motor speed for exhaust of the water heater using the "diagnostics mode" of the T-H2-DV/T-H2-OS computer board or the TM-RE30 temperature remote controller. See the "12-1. How to diagnose the water heater using the TM-RE30”. V isual inspection of PCB: connection/breakage of wires and/or burn marks on the computer board.
  • Page 52 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Error Code Malfunction description Cancellation method Water control valve fault Turn off the power or water supply (Bypass valve function) Diagnosis Checkpoint 1 PCB and bypass valve fault (Refer to section 10-11 & 10-18) V isual inspection of Water control valve: connection/breakage of wires, motor drive locked due to scale buildup, and/or water leakage.
  • Page 53 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Error Code Malfunction description Cancellation method 1. Hi-limit switch trip / Overheat cutoff fuse compromised NOTE: When these components are compromised, Turn off the power supply the “711” error code may appear instead of the “111”...
  • Page 54 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Error Code Malfunction description Cancellation method Restoring proper cable connections among all the water heaters. When the Miscommunication between Parent and Child computer detects proper connections units for Easy-Link systems. among all the water heaters, "761" error code will cease to display.

  • Page 55: Controls And Settings

    12-12. High Altitude Region Support Software (FM+, FM++ and FM+++)…..………………….…………… 12-13. How to convert unit of set temperature.……………………………………………………………………………. 12-14. Control for exhaust temperature (T-H2-DV only)……..……………………………………………..…………. 12-15. Relay selection for the pump control connection………………………………………………………………. 12-16. Alarm port terminal…………………………………………………………………………………………………………… 12-17. Adjusting manifold gas pressure………………………………………………………………………………………... 81 12-18.

  • Page 56: A) Diagnosis Using The Computer Board

    When selecting information, please refer to the table on p.59 and p.61 for the proper mode #. In the tables on p.58 to p.60 say the followings; d1 to d18 (p.59 to p.60) : Unit information of Individual T-H2-DV or T-H2-OS h1 to h15 (p.61) : Information of whole Easy-Link system NOTE: The “h1”...

  • Page 57: B) Diagnosis Using The Tm-Re30

    2. Scroll up or down to the needed information (mode #) of the Button T-H2-DV or T-H2-OS by pressing the “HOT” or “COLD” buttons (Fig.1 shows mode #5 being selected.) When selecting information, please refer to the table on p. 58 and p.59 for the proper mode #.
  • Page 58 2. "0" will be displayed on the TM-RE30. (See Fig. 1) 3. Scroll to the desired T-H2-DV or T-H2-OS unit # in the easy-link system by pressing the "HOT" or the "COLD" buttons to scroll up or down. (Fig. 2 shows that unit #2 is being selecting) NOTE: The definition of the unit #’s:...
  • Page 59 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 <Description of mode numbers in “Diagnostics Mode” for individual unit> 3-digit 7-seg LED on the TM-RE30 computer board Diagnostics information Mode Mode unit information (#1 to #4) unit information (#1 to #4) Total operation time 0 to 999 (×100 hours)
  • Page 60 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 3-digit 7-seg LED on the TM-RE30 computer board Diagnostics information Mode Mode unit information (#1 to #4) unit information (#1 to #4) Current value of Proportional 0 to 999 0 to 9,999 (×0.1mA) valve “1”...
  • Page 61 NOTE: The “h1” to “h15” can be selected only in parent unit. ***When the dipswitch No.4 (the right bank) on the T-H2-DV/T-H2-OS computer board is set to the “OFF” position, press and hold the “Number display” button on the computer board while in mode# P3 for at least 3 seconds to display the “Pon”.

  • Page 62: Verifing Functionality Of Computer Board, Displaying Error Code History, And Clearing Error Code History Memory

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 12-2. Verifying functionality of computer board, Displaying error code history, and Clearing error code history memory A. Check if the computer board works properly Check the 100 VAC power supply on the computer board. Refer to part “A” on p. 11. Check the voltage at “A”.
  • Page 63 1. Briefly press the “Error-call button” (do not hold down the button). 2. If the T-H2-DV or T-H2-OS has had prior error codes, the 3-digit 7-seg LED will display the most recent error code first. Pressing the button again will display the 2...

  • Page 64: Clearing The "101" And "991" Error Code

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 12-3. Clearing the “101” and “991” error code The “101” and “991” error codes signify imperfect (abnormal) combustion, caused by insufficient intake air and/or obstructions in the exhaust. A. If the “101” and “991” error code occurs, please check the following: 1.

  • Page 65: Afr Rod Function

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 12-4. AFR rod function <Function> The AFR rod checks flame conditions during combustion. When the AFR rod detects unexpected flame conditions, the computer board of the 520 models adjusts the fan motor speed to ensure that air and fuel are always at a proper mixture ratio, minimizing emissions.

  • Page 66: Dipswitch Settings

    Ver. 1.01 12-5. Dipswitch settings Right bank of dipswitches The computer board in the T-H2-DV is the same as one in the T-H2-OS. There are two banks of dipswitches (right and left bank) on the computer board. The left bank has certain special functions as shown on the following table and generally should not need adjustment.
  • Page 67 No. 5 OFF position ON position OFF position +6 % No. 6 ON position +12 % +18 % Fan motor for exhaust (T-H2-DV only) No. 5 OFF position ON position OFF position +3.6 % No. 6 ON position +7.3 % +11.4 %...

  • Page 68: Assigning Unit Numbers In The Easy-Link System

    3. Press and hold “Number display” button again. New unit # will be assigned in order as you proceed through every unit. Each T-H2-DV or T-H2-OS in an Easy-link system is assigned a random unit #, except for the Parent unit, which is always assigned as unit #1.

  • Page 69: A) On/Off Conditions: Overview

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 12-7. (A) ON/OFF conditions: Overview The following table shows the ON/OFF conditions of the water heater. ON/OFF Conditions The BTU requirement is more than 14,880 BTU/h Conditions needed to turn ON. The water flow rate is more than 0.5 GPM...

  • Page 70: B) On/Off Conditions: Btu Requirements

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 12-7. (B) ON/OFF conditions: BTU requirements A. Calculating the ON/OFF conditions of the T-H2-DV or T-H2-OS Condition needed to turn the T-H2-DV or T-H2-OS ON – T ) × GPM × 500 > 14,880 Condition needed to turn the T-H2-DV or T-H2-OS OFF –...

  • Page 71: A) Pump Control On/Off Conditions (Only For Single And Easy-Link System)

    12-8. (A). Pump control ON/OFF Conditions (Only for single and Easy-link system) To run circulation pumps efficiently and effectively, the T-H2-DV/T-H2-OS offers four different modes of pump control. The following table shows the pump control ON/OFF conditions for different modes. To change pump control modes, see section 12-5 for dipswitch settings.

  • Page 72: B) Pump Control On/Off Conditions: Btu Requirements

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 12-8. (B). Pump control ON/OFF conditions: BTU requirements A. Calculating the ON/OFF conditions of the T-H2-DV or T-H2-OS Condition needed to turn the pump ON – T ) × GPM × 500 > 14,880...

  • Page 73: Multi-Unit System On/Off Conditions

    T-H2-DV/T-H2-OS Service Manual Ver. 1.01 12-9. Multi-unit system ON/OFF conditions FLOW In an Easy-Link system, the amount of T-H2-DV or T-H2-OS’s called on to activate depends on the RATE SET TEMPERATURE. and the 1. Condition required to activate an additional T-H2-DV or T-H2-OS: Flow rate required to activate additional T-H2-DV or T-H2-OS= A ×...

  • Page 74: Operation Time For Unit Rotation

    Ver. 1.01 12-10. Operation time for unit rotation The unit that turns on first is whichever unit the T-H2-DV/T-H2-OS decides is the primary unit. The priority unit will rotate when it reaches 100 ON/OFF cycles or after 12 hours of operation.

  • Page 75: Individual Unit Operation In Easy-Link System While Parent Unit Is Under Abnormal Conditions (Individual Operation Mode)

    If this happens, the minimum flow rate of the system changes from 0.5 GPM to 0.5 GPM multiplied by the number of T-H2-DV/T-H2-OS. Refer to the following example: Ex: Minimum flow rate of a four unit easy-link system.

  • Page 76: High Altitude Region Support Software (Fm+, Fm++ And Fm+++)

    If the abnormal sound problem persists even with a “Level 4” setting, please contact our Technical Service Department. for advice. Note that there are many high risks associated with manually changing the manifold pressures. *T-H2-DV/OS installation manual doesn’t mention this function for safety purposes.

  • Page 77: How To Convert Unit Of Set Temperature

    This function offers a method for displaying the temperature in Celcius instead of Fahrenheit. On T-H2-DV/T-H2-OS, changing the unit of temperature can be done simply by using the No.1 dipswitch of Light bank of dipswitches. See section 12-5 for dipswitch settings.

  • Page 78: Control For Exhaust Temperature (T-H2-Dv Only)

    The exhaust gas temperature is controlled by the exhaust fan motor. T-H2-DV is equipped with a thermistor and hi-limit switch for, detecting excess temperatures of the exhaust gas within the flue and enabling the unit to safely stop operations if needed.

  • Page 79: Relay Selection For The Pump Control Connection

    Ver. 1.01 12-15. Relay selection for the pump control connection The maximum current capacity of T-H2-DV or T-H2-OS pump control connection is 1 amp. Before using any relay with the pump control, please check the specifications of that particular relay to ensure that the current value through the coil will not exceed 1 amp.

  • Page 80: Alarm Port Terminal

    This function is to alert end-users of any error codes that may occur by using an alarm lamp and/or the buzzer and connecting it to the T-H2-DV/T-H2-OS computer board. When the T-H2-DV/T-H2-OS computer detects any error codes, the alarm port terminal on the T- H2-DV/T-H2-OS computer will activate the connected lamp or buzzer.

  • Page 81: Adjusting Manifold Gas Pressure

    3. Connect a manometer to the manifold port using a tube (Figure 2). Ensure that this connection is secure enough to prevent gas leak. 4. Run water through the T-H2-DV or T-H2-OS to activate its operation. If presence of a gas leak is detected, immediately shut off the T-H2-DV or T-H2-OS and inspect the tube/manifold connection;...
  • Page 82 (Figure 3). Refer to the manometer to verify that pressure has been set to desired value. 6. After gas pressure has been set, deactivate the T-H2-DV or T-H2-OS, remove the manometer tube, and replace the port screw. Figure 1...

  • Page 83: Manually Adjusting The Fan Motor Speed

    4. After fan speed has been set, set dipswitch No.4 back to the “OFF” position. Adjusting minimum fan motor speed 1. While T-H2-DV or T-H2-OS is in operation, set dipswitch No.4 on T-H2-DV/T-H2-OS to the “ON” position. (Figure 1) 2. On the temperature remote controller, display mode #3 (fan motor speed) by entering the “Diagnostics mode”...
  • Page 84 “Increase” button NOTE: The dark square is the direction “Decrease” button the dipswitch should be set to. Figure.1 Left bank of dipswitch settings Figure.2 T-H2-DV/T-H2-OS Computer board For example; (Unit: %) Variation for fan motor speed Fan motor for combustion -10.0...

  • Page 85: Freeze Protection System

    The five kind of heating blocks focus on protecting the inlet, outlet and drain piping inside the T-H2-DV or T-H2-OS, as well as the front drum pipe. The conditions to activate either feature are different from each other. However, the two features are not mutually exclusive, because they focus on different areas of the T-H2-DV or T-H2-OS.
  • Page 86 The blocks will only activate based on what the freeze protection thermostat senses. The thermostat is located on the intake port for T-H2-DV and left side of compter board for T-H2-OS. Electrical power is required for this feature to operate.

  • Page 87: Freeze Protection For Recirculation Systems

    12-20. Freeze protection for recirculation systems The T-H2-DV or T-H2-OS has the freeze protection function for a re-circulation system by using a pump installed in the system. Basically, this function is only ON / OFF control of the pump from the computer in the T-H2-DV or T-H2-OS.
  • Page 88 <How to set the Freeze protection pump > To set the Freeze protection pump mode in T-H2-DV/T-H2-OS, please follow the procedures below: 1. Change the dipswitch No.4 of the right bank on the computer board to the “OFF” position (Individual operation mode should be oFF position) .

  • Page 89: Draining The Unit And Cleaning The Inlet Water Filter

    12-21. Draining the unit and cleaning the inlet water filter Close the manual gas shut off valve. 2. Turn off power to the T-H2-DV or T-H2-OS, wait a few seconds. And then turn on again. Wait 30 seconds for water valves starts to completely open. Then turn off power to the T-H2-DV or T-H2-OS, yet again.

  • Page 90: Components Diagrams

    T-H2-DV/T-H2-OS Service Manual Ver. 1.01 13. Components diagrams Case assembly Other than the case assembly (No.15) and front cover (No.16), all of the T-H2-OS’s parts are the same as the T-H2-DV. The T-H2-OS doesn’t have fan motor for exhaust (No.124). T-H2-DV T-H2-OS...

  • Page 91: Computer Board Assembly

    Computer board assembly Other than Part# 719, the T-H2-DV and the T-H2-OS share the same components. T-H2-OS doesn’t have exhaust thermistor assembly (No.716) and exhaust fan motor wire (No.720). Burner assembly The T-H2-DV and the T-H2-OS share the same components.
  • Page 92 T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Water way assembly Other than Part# 456, Part# 459, Part#460 and part# 461, the T-H2-DV and the T-H2-OS share the same components. The T-H2-OS doesn’t have hi-limit switch for exhaust (No.442) and exhaust thermistor assembly (No.706).

  • Page 93: Parts List

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 14. Parts list Item # Part # Description Common parts for other models EKH5B Case assembly (DV) EKH5M Front cover (DV) EV00K Intake air port assembly EM335 Brackets T-M50 EKH5D Back guard panel T-K3, T-K3-Pro, T-K3-SP/OS, T-KJr2-IN/OS, T-K4-IN/OS,...
  • Page 94 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Item # Part # Description Common parts for other models T-K3, T-K3-Pro, T-K3-SP/OS, T-KJr2-IN/OS, T-K4-IN/OS, EKK2W Rod holder gasket T-D2-IN/OS, T-M50, T-M32 T-K3, T-K3-Pro, T-K3-SP/OS, T-K4-IN/OS, T-D2-IN/OS, EKK0E Flame rod T-M50, T-M32 T-K3, T-K3-Pro, T-K3-SP/OS, T-K4-IN/OS, T-D2-IN/OS,...
  • Page 95 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Item # Part # Description Common parts for other models T-K3, T-K3-Pro, T-K3-SP/OS, T-KJr2-IN/OS, T-K4-IN/OS, EKK1B Igniter plate T-D2-IN/OS, T-M50, T-M32 T-K3, T-K3-Pro, T-K3-SP/OS, T-KJr2-IN/OS, T-K4-IN/OS, EKN74 Igniter T-D2-IN/OS, T-M50, T-M32 EKH5T Fan motor for exhaust...
  • Page 96 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Item # Part # Description Common parts for other models EM222 Filter plug T-M50, T-M32 EZF25 O-ring P25 FKM EX006 Water inlet filter T-M50, T-M32 EZH21 O-ring JASO# 1021 FKM EM404 Water inlet T-M32...
  • Page 97 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Item # Part # Description Common parts for other models EKJ02 Water outlet T-M32 EZH17 O-ring JASO# 1017 FKM EZF14 O-ring P14 FKM EKH6H Drain tube Secondary heat exchanger EKH4H plate gasket A Secondary heat exchanger...
  • Page 98 CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 Item # Part # Description Common parts for other models EKH65 Exhaust chamber assembly Secondary heat exchanger EKH62 plate EKH38 Heater fixing plate 20 T-M50 EK031 Heater fixing plate 16 T-KJr2-IN/OS, T-K4-IN/OS, T-D2-IN/OS, T-M50, T-M32...

  • Page 99: Revisions

    CONFIDENTIAL T-H2-DV/T-H2-OS Service Manual Ver. 1.01 15. Revisions Version Description of changes Date 1.00 First edition 10/09/09 1.01 Revised by the R&D and Japan 11/01/10...

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