A.O. Smith 110 Indoor Service Manual
A.O. Smith 110 Indoor Service Manual

A.O. Smith 110 Indoor Service Manual

Direct vent on-demand water heater

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110 Direct Vent Indoor
and Outdoor Models
110 Indoor
On-Demand Water Heater
Service Manual
110 Indoor / 110 Outdoor Service Manual
110 Outdoor
A.O. Smith Water Products Company
500 Tennessee Waltz Parkway
Ashland City, TN 37015
Toll Free: 1-877-737-2840
1
CONFIDENTIAL
Ver. 1.01

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Summary of Contents for A.O. Smith 110 Indoor

  • Page 1 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 110 Direct Vent Indoor and Outdoor Models On-Demand Water Heater Service Manual 110 Indoor 110 Outdoor 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 110 Indoor / 110 Outdoor 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……………………………………………………………………………………………………. 10 6. Wiring diagram…………………………………………………………………………………………………………. 11 7.
  • Page 3: Specifications

    Surge absorber and Power ON-OFF switch control Freeze protection Ceramic heaters Self-combustion Air-Fuel Ratio Detection System improvement Easy-Link system Multiple-system * The 310 Direct Vent Indoor means the 110 Indoor in the text. **The manifold pressure measurement is base on conditions without front cover.
  • Page 4: Exterior View

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 2. Exterior view 110 Indoor Side view Front view Bottom view Top view...
  • Page 5 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 110 Outdoor Side view Front view Bottom view Top view...
  • Page 6: Interior View

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 3. Interior view 110 Indoor...
  • Page 7 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 110 Outdoor...
  • Page 8: List Of Main Components In The Interior View

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 4. List of main components in the interior view Item# in Common parts Description components Part # for other models diagram 319143-159 (110 Indoor) Case assembly 319143-172 (110 Outdoor) Manifold assembly with...
  • Page 9 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Item# in Common parts Description components Part # For other models diagram Surge box 319143-168 310, 510 Outlet drain plug 319143-199 310, 510, 910 Air-fuel ratio rod (AFR rod) 319143-339...
  • Page 10: Schematic Diagram

    The diagram below refers to both the 110 Indoor and 110 Outdoor. 1. When a hot water tap is opened, cold water enters the 110 Indoor or 110 Outdoor. 2. The water flow sensor detects this water flow and sends this information to computer.
  • Page 11: Wiring Diagram

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 6. Wiring diagram The diagram below refers to both the 110 Indoor and 110 Outdoor. 9007666005...
  • Page 12: Wiring Diagram Checkpoints For Diagnosis

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 7. Wiring diagram check points for diagnosis The table below applies to both the 110 Indoor and 110 Outdoor. Check- Part and Description Color of wires Normal range point White – Black (A)
  • Page 13 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Check- Part and Description Color of wires Normal range point 1 to 15 VDC (during operation) Gas proportional valve White - red 20 to 40 Ω Red - Black 4 to 5.5 VDC...
  • Page 14: Resistance Values Of The Temperature Thermistors

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 8. Resistance values of the temperature thermistors The 110 Indoor and 110 Outdoor use the same thermistors. Resistance values at different temperatures ºF Temperature ºC Resistance kΩ 23.76 19.08 15.43 12.56...
  • Page 15: Operational Flow Chart

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 9. Operational flow chart The diagram below refers to both 110 Indoor and 110 Outdoor.
  • Page 16: Component Specifications

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10. Component specifications 10-1. Burners……………………..…………………………………………………….......………. 17 10-2. Gas manifold………….…………………………………………………………......18 10-3. Fan motor………………………………………………………………………...…………………………… 19 10-4. Gas valve assembly………………..……………………….…………………………………………….. 20 10-5. Flame rod………………………………………………………….………………………………………….. 21 10-6. AFR rod…………………………………………………………………………………………………………. 22 10-7. Heat exchanger……………………………………………………………………………………………… 23 10-8.
  • Page 17: 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 110 Indoor and 110 Outdoor has the “46B” mark as shown below. Burner damper (#112 / 319143-170) The burner damper is not included in 319143-161.
  • Page 18: Gas Manifold

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-2. Gas manifold Included 319143-169 (LP) Unit Part # AOS Part # Checkpoint in #102 319143-165 (NA) 1. The manifold distributes gas from the gas valves to the burners. The...
  • Page 19: Fan Motor

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-3. Fan motor Unit Part # #103 AOS Part # 319143-347 Checkpoint Function To provide combustion air into the burner chamber and to exhaust flue gas. 1. Fan speed failure, causing abnormal sounds with or without combustion during operation.
  • Page 20: Gas Valve Assembly

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-4. Gas valve assembly 319143-169 (LP) Unit Part # #102 AOS Part # Checkpoint C,H1 319143-165 (NA) Opens and closes the gas pathways of the water heater (main and solenoid...
  • Page 21: Flame Rod

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-5. Flame rod Unit Part # #108 AOS Part # 319143-339 Checkpoint To detect flames while the water heater is in operation. Function 1. Unable to detect flames when flames actually do occur Failure events 2.
  • Page 22: Afr Rod

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-6. AFR rod Unit Part # #108 AOS Part # 319143-339 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 23: Heat Exchanger

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-7. Heat exchanger 319143-162 (IN) Unit Part # #401 AOS Part # Checkpoint 319143-166 (Out) Absorbs heat from combustion and transfer it to water through the heat Function exchanger pipes.
  • Page 24: Flow Adjustment Valve

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-8. Flow adjustment valve Unit Part # #402 AOS Part # 319143-167 Checkpoint Controls water flow to properly control the output hot water temperature. Function 1. Water leakage from valve.
  • Page 25: Flow Sensor

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-9. Flow sensor Unit Part # #402 AOS Part # 319143-167 Checkpoint Detects and measures water flow rate using a spinning impeller and Function magnetic pick-up. Unable to detect or measure any water flow rate.
  • Page 26: Thermistors

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-10. Thermistors #407 (Inlet) 319143-214 (Inlet) E1 (Outlet) Unit Part # AOS Part # Checkpoint #408 (Outlet) 319143-218 (Outlet) E2 (Inlet) Measures cold/hot water temperatures in the water heater. Function Unable to properly measure water temperatures within the water heater.
  • Page 27: Hi-Limit Switch

    "11" or "12" error code will display. Error codes when hi-limit The 110 Indoor / 110 Outdoor don't have the "14" error code that was used in switch fails our previous models. This error code is now replaced by the "11" and the "12"...
  • Page 28: Overheat Cutoff Fuse

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-12. Overheat cutoff fuse Unit Part # #413 AOS Part # 319143-149 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 29: Freeze Protection Heaters

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-13. Freeze protection heaters #414 319143-200 Unit Part # AOS Part # Checkpoint #415 319143-078 Prevents the heat exchanger, water valves, and water pipes within the water Function heater from freezing. The heaters are but one of the freeze protection devices in the water heater.
  • Page 30: Computer Board

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-14. Computer board Unit Part # #701 AOS Part # 319143-164 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 31: Transformer

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-15. Transformer Unit Part # #702 AOS Part # 319143-182 Checkpoint A1,A2 -To transform input voltage from 120 to 100 VAC. -Every electrical component of the water heater is designed to only work...
  • Page 32: Igniter

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-16. Igniter Unit Part # #711 AOS Part # 319143-052 Checkpoint -To ignite the gas/air mixtures when the water heater is ready to burn gas on Function its burner surface.
  • Page 33: Freeze Protection Thermostat

    ON mode: 90 to 110 VAC and less than 1 Ω Color/Number of wires (itself) OFF mode: less than 1 VAC and more than 1M Ω Activation and deactivation temperature of the 110 Indoor’s or 110 Outdoor’s freeze protection system ON mode: 36.5˚F (+6.3˚F -2.7˚F) 2.5˚C (+3.5˚C -1.0˚C) OFF mode: above 46.4˚F...
  • Page 34: Surge Box

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 10-18. Surge box Unit Part # #703 AOS Part # 319143-168 Checkpoint A2,A3 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 220V, the other one is activated by voltage higher than 680 V.
  • Page 35: Fault Analysis & Specifications

    CONFIDENTIAL 110 Indoor / 110 Outdoor 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 36 CONFIDENTIAL 110 Indoor / 110 Outdoor 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.
  • Page 37 CONFIDENTIAL 110 Indoor / 110 Outdoor 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 38 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Error Code Diagnosis Checkpoint 7 Check if there is dust and lint in burner and heat exchanger, when the water heater has been installed in laundry room. 8 Check if there is grease and dirt in burner and fan motor, when the water heater has been installed in restaurant.
  • Page 39 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Error Code Diagnosis Checkpoint 6 Disconnected/damaged hi-limit switch. (Refer to section 10-11) V isual inspection: connection/breakage of wires. Normal: 1 Ω or less between blue & blue 7 Inspect flame rod [1] Check for any soot on the rod.
  • Page 40 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Error Code Diagnosis Checkpoint 5 Disconnected/damaged O.H.C.F. (Refer to section 10-12) V isual inspection: connection/breakage of wires. Error code is Normal: 1 Ω or less between blue & blue shown after 6 Check if hi-limit switch is properly functioning.
  • Page 41 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Error Code Malfunction description Cancellation method Fault of driving circuit for main gas solenoid valve (MV) Turn off the power supply (The computer checks the condition of the main gas valve immediately after every operation)
  • Page 42 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Error Code Malfunction description Cancellation method Fan motor fault Turn off the power or water supply Diagnosis Checkpoint 1 PCB and fan motor fault (Refer to section 10-3 & 10-14)
  • Page 43 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Error Code Malfunction description Cancellation method Restoring proper cable connections between the water heater and the Remote controller (9007666005). When Miscommunication between water heater and the computer detects proper connections...
  • Page 44: Controls And Settings

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 12. Controls and settings 12-1. Diagnosis using the 9007666005…..…….………………………………………………………….…………….…… 45 12-2. Verifying functionality of computer board and…..............… 12-3. Display patterns for error codes…………………………………………………………………………………………. 47 12-4. Clearing the “10” and “99”error code….…………………………………………………………………….………. 48 12-5.
  • Page 45: Diagnosis Using The 9007666005

    Fig.2 For example, mode #3 will display of the Inlet temperature. Description of mode numbers in “Diagnostics Mode” Mode # Individual 110 Indoor or 110 Outdoor unit information Total operation time 0 to 99 (×1,000 hours) ON/OFF cycles 0 to 99 (×10,000 cycles) Inlet temperature 32 to 210 (°F).
  • Page 46: Verifying Functionality Of Computer Board And

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 12-2. Verifying functionality of computer board How to check if the computer board works properly 1. Check the power ON-OFF switch of the water heater. The factory setting is ON position.
  • Page 47: Display Patterns For Error Codes

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 12-3. Display patterns for error codes Display patterns for error codes The red LED will blink in the patterns shown below when the water heater has an error code. When the water heater does not have an error code and is operating under normal conditions, the red LED will remain solidly lit during operation and will remain completely OFF during stand-by.
  • Page 48: Clearing The "10" And "99"Error Code

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 12-4. Clearing the “10” and “99” error code The “10” and “99” error codes signify imperfect (abnormal) combustion, caused by insufficient intake air and/or obstructions in the exhaust. If the “10” and “99” error code occurs, please check the following: 1.
  • Page 49: Afr Rod Function

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 12-5. 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 110 adjusts the fan motor speed to ensure that air and fuel are always at a proper mixture ratio, minimizing emissions.
  • Page 50: Dipswitch Settings

    110 Indoor / 110 Outdoor Service Manual Ver. 1.01 12-6. Dipswitch settings The 110 Indoor shares the computer board with the 110 Outdoor. Each dipswitch has a special function shown on the following table. The gas type and model type should not need adjustment.
  • Page 51: A) On/Off Conditions: Overview

    CONFIDENTIAL 110 Indoor / 110 Outdoor 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 29,800 BTU/h. Conditions needed to turn Inlet temperature is lower 5.4°F than the set...
  • Page 52: B) On/Off Conditions: Btu Requirements

    110 Indoor / 110 Outdoor Service Manual Ver. 1.01 12-7. (B) ON/OFF conditions: BTU requirements alculating the ON/OFF conditions of the 110 Indoor or 110 Outdoor A. C Condition needed to turn the 110 Indoor or 110 Outdoor ON – T ) ×...
  • Page 53: High-Altitude Region Support Functions (Fm+, Fm++ And Fm+++)

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 12-8. High-Altitude Region Support Functions (FM+, FM++ and FM+++) Using these functions The high-altitude region support functions have four operation levels, with the appropriate level being set up by the installer until the abnormal sound problem is solved.
  • Page 54: Adjusting Manifold Gas Pressure

    4. Run water through the 110 Indoor or 110 Outdoor to activate its operation. If presence of a gas leak is detected, immediately shut off the 110 Indoor or 110 Outdoor and inspect the tube/manifold connection;...
  • Page 55 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 desired value. 6. After gas pressure has been set, deactivate the 110 Indoor or 110 Outdoor, remove the manometer tube, and replace the port screw. Figure 1 Manifold port Figure 2...
  • Page 56: Freeze Protection System

    The ceramic heating blocks will heat up whatever portion of the heat exchanger the blocks are strapped The two heating blocks focus on protecting the inlet and outlet piping inside the 110 Indoor or 110 Outdoor, as well as the front drum pipe.
  • Page 57: Draining The Unit And Cleaning The Inlet Water Filter

    12-11. Draining the unit and cleaning the inlet water filter Close the manual gas shut off valve. Turn off power to the 110 Indoor or 110 Outdoor, wait a few seconds. And then turn on again. 3. Wait 30 seconds for water valves starts to completely open.
  • Page 58: Components Diagrams

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 13. Components diagrams Case assembly 110 Indoor 110 Outdoor...
  • Page 59 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Burner assembly 110 Indoor/Outdoor Burner assembly Manifold assembly Only 110 Indoor...
  • Page 60 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Computer board assembly 110 Indoor /Outdoor Water way assembly 110 Indoor /Outdoor Exhaust section (OS model) Water outlet section Water inlet section...
  • Page 61: Parts List

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 14. Parts list Item # Part # Description Common parts for other model 319143-159 Case assembly (IN) 319143-172 Case assembly (Out) 319143-163 Front cover (IN) 319143-173 Front cover for (Out)
  • Page 62 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Item # Part # Description Common parts for other model 319143-341 Burner holder gasket 319143-031 Burner gasket 520, 310, 510 319143-033 Burner window 520, 310, 510, 910, 710 319143-034 Rod holder gasket...
  • Page 63 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Item # Part # Description Common parts for other model 319143-194 Water outlet 310, 510 319143-199 Outlet drain plug 310, 510, 910 319143-228 Hi-Limit switch 319143-149 Overheat-cut-off fuse 310, 510, 910...
  • Page 64 CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 Item # Part # Description Common parts for other model 319143-052 Igniter 520, 310, 510, 910, 710 319143-039 High voltage igniter cable 520, 310, 510, 910 319143-185 Freeze protection thermostat...
  • Page 65: Revisions

    CONFIDENTIAL 110 Indoor / 110 Outdoor Service Manual Ver. 1.01 15. Revisions Version Description of changes Date 1.00 First edition 11/01/10 1.01 Revision of wrong information in the section 1, 4 and 12-6 12/22/10...

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