Takagi 100 Series Service Handbook Download | Manualshive

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On-Demand Water Heater Service Handbook for 240, 340 & 540 Condensing Models • 11

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Error Codes

All units have self-diagnostics. If there is a problem with the unit, a numerical error code will display on the temperature controller
of indoor models or on the TM-RE42 Remote Controller (if installed). 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. (The green
LED is located beside the DIP switches as shown in Figure 3)

Table 2: Error and Flash Codes

ERROR CODE

GREEN LED ON

COMPUTER BOARD

SYMPTOM OR ISSUE

TROUBLESHOOTING PROCEDURE (PAGE NUMBER)

031

One Flash

Incorrect DIP switch

setting

Code 031: Incorrect DIP Switch Settings, p. 14

101

Five Flashes

Abnormal Combustion

(lockout is imminent)

Code 101: Abnormal Combustion, p. 14

.

111 or 121

Three Flashes

Ignition failure / Loss of

flame

Code 111 or 121: Ignition Failure / Flame Loss, p. 14

.

311

Two Flashes

Outlet thermistor failure

(240/340 models)

Heat Exchanger

Thermistor Failure

(540 models)

Code 311, 321, 331 or 341: Thermistor Failure, p. 16.

NOTE:

If you are working with a water heater that is part of an Easy-Link or multi-unit system, we recommend that you

troubleshoot the unit as an individual unit and not as part of the system. Follow these steps prior to troubleshooting

a child unit: 1. Shut off power to the heater. 2. Close the isolation valves to the heater. 3. Disconnect both linking

wires from the bottom of the heater. 4. If the unit is not an end unit, take the ends of both linking wires which you

unplugged and connect them together. One end is male and the other is female; they will connect together.

5. Turn power to the heater back on, then troubleshoot as necessary.

Error code on the computer board

240 (T-H3J) and 340 (T-H3S) models

Green LED

540 (T-H3) model

Green LED

Error code indicator on

the temperature controller

Error code indicator on the remote

controller

Figure 3

.

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Summary of Contents for 100 Series

Page 1: ...ndoor T H3J DV 240 Outdoor T H3J OS 340 Indoor T H3S DV 340 Outdoor T H3S OS 540 Indoor T H3 DV 540 Outdoor T H3 OS THIS SERVICE HANDBOOK IS FOR USE BY QUALIFIED SERVICE PROFESSIONALS ONLY IF YOU NEED ASSISTANCE CALL TECHNICAL SUPPORT IN USA CALL AT 877 737 2840 IN CANADA CALL 888 479 8324 Series 100 101 ...

Page 2: ...gnition Failure Flame Loss 14 Code 311 321 331 or 341 Thermistor Failure 16 Code 391 Air Fuel Ratio Rod Failure 17 Code 441 Flow Sensor Failure Easy Link or Multi Link System Only 17 Code 510 Abnormal Main Gas Solenoid Valve MV 17 Code 551 Abnormal Solenoid Gas Valve SV1 SV2 and or SV3 18 Code 611 Abnormal Fan Motor 18 Code 651 Flow Adjustment Valve Fault Easy Link or Multi Link System only 18 Cod...

Page 3: ...tion Components 39 Easy Link Connections with Previous Models 540 T H3 Only 43 DIP Switch Setting on the 540 T H3 Computer Board 43 Temperature Settings 44 Diagnostic Mode 45 Individual Unit 45 Multiple Units in a Linked System 540 T H3 Models Only 45 MAINTENANCE 49 Flow Sensor Control Valve Removal and Installation 51 Removal 51 Installation 51 Burner Removal and Installation 52 Burner Removal 52...

Page 4: ...67 NAT 2 4 0 60 LP 3 2 0 80 NAT 2 8 0 70 LP 3 2 0 80 NAT 2 9 0 72 Min inch W C kPa LP 0 6 0 15 NAT 0 7 0 17 LP 0 7 0 17 NAT 0 7 0 17 LP 0 6 0 15 NAT 0 7 0 17 LP 0 7 0 17 NAT 0 7 0 17 LP 0 6 0 15 NAT 0 7 0 17 LP 0 7 0 17 NAT 0 7 0 17 Weight lbs kg 58 26 3 58 26 2 58 26 3 58 26 2 59 26 8 59 26 9 Dimension inches H 22 4 x W 17 7 x D 10 7 mm H 570 x W 450 x D 272 Ignition Electric Ignition Electric Su...

Page 5: ...ed order Here is how to use this manual First refer to the Installation Manual as the primary source of information Refer to it along side this manual throughout the troubleshooting process Before troubleshooting if you are unfamiliar with how a tankless unit operates read Normal Operation on page 6 Before troubleshooting a new installation use the installation manual Before troubleshooting first ...

Page 6: ...models only Figure 1 The purpose of this diagram is to illustrate tankless water heater design concepts and may not be accurate to the unit s physical description Operation 10 The proportional gas valve and fan will modulate based on the amount of hot water demanded and the temperature rise needed 11 You may notice that only partial sections of the burner will be lit This is normal operation There...

Page 7: ... heater must sense water flow to initialize operations Water flowing through the heater backwards will not activate the flow sensor A dirty inlet filter A dirty inlet filter can either prevent water from flowing through the water heater entirely or create turbulence that can prevent the flow sensor from measuring the water flow Misconfiguration of the Easy Link system if applicable Gas line that h...

Page 8: ... The gas line may be sized improperly The gas supply pressure may be too low This may be caused by a malfunctioning gas supply regulator so check to see if the regulator is working properly See Check gas supply later in this section If a recirculation system is installed ensure that a check valve is installed between the pump discharge and the connection to the cold water supply Inspect the check ...

Page 9: ...et per hour This number must be less than the maximum ratings shown on the gas meter s rating plate If the maximum energy input of all appliances exceeds the maximum rating of the gas meter consult your local gas utility For LP models there may not be enough propane left in the tank Verify that the supply gas pressure is within specification not only when the heater is in standby but also while th...

Page 10: ...ow on the display points toward IN Refer to error code indicator in Figure 3 p 11 Check that the gas line is open and is purged of air page 33 Are the hot and cold water connections to the water heater reversed hooked up backwards Water flowing in reverse through the heater will not be detected by the flow sensor and the water heater will not operate See page 33 for details on checking for a rever...

Page 11: ...121 Three Flashes Ignition failure Loss of flame Code 111 or 121 Ignition Failure Flame Loss p 14 311 Two Flashes Outlet thermistor failure 240 340 models Heat Exchanger Thermistor Failure 540 models Code311 321 331or341 ThermistorFailure p 16 NOTE If you are working with a water heater that is part of an Easy Link or multi unit system we recommend that you troubleshoot the unit as an individual u...

Page 12: ... SV3 Code 551 Abnormal Solenoid Gas Valve SV1 SV2 and or SV3 p 18 611 Four Flashes Fan motor fault Code 611 Abnormal Fan Motor p 18 651 Four Flashes Flow adjustment valve fault Easy Link or Multi Link System Code 651 Flow Adjustment Valve Fault Easy Link or Multi Link System only p 18 661 Four Flashes Bypass valve fault Code 661 Bypass valve fault 540 T H3 model only p 19 701 One Flash Computer bo...

Page 13: ... Models 13 ERROR CODE GREEN LED ON COMPUTER BOARD SYMPTOM OR ISSUE TROUBLESHOOTING PROCEDURE PAGE NUMBER 941 Five Flashes Abnormal exhaust temperature Indoor model only Code 941 Abnormal Exhaust Temperature p 21 991 Five Flashes Imperfect Combustion Code 991 Abnormal Combustion p 21 ...

Page 14: ...d was not able to establish a flame after three failed ignition attempts code 121 These codes can appear due to a component in the heater or due to an external cause such as no gas supply Also these codes will automatically reset when water flow through the heater stops or when the power is interrupted 1 Verifythatthegassupplypressureis withinspecificationswhentheheateris instandby andverifythegas...

Page 15: ...y and in place while a weak spark will jump around 5 1 If no spark or a weak spark is observed check the purple igniter wire connections at both the igniter and at the computer board Unplug and reconnect them to clean the electrical connections 5 2 Check the igniter rod to make sure the black wire is properly attached and that the rod doesn t move If the rod moves replace the igniter rod part numb...

Page 16: ...re connections are secure and free of burns or cuts 4 Check the thermistor s resistance value See Table 4 for a list of normal resistance values 5 Clean the thermistor as follows a Drain the unit of water See Unit Draining and Filter Cleaning on page 32 b IF you are testing the outlet thermistor remove the screw that secures the computer board Move the computer board out of the way without disconn...

Page 17: ...ly is turned on 3 Check the flow sensor control valve wires to see if they are broken or disconnected Refer to Figure 41 p 49 or Figure 42 p 50 4 Verify the flow rate using the water heater s controller To do so select Flow Rate by pushing the INFO button until the arrow on the left side of the display points toward Flow Ensure that the controller displays a flow rate during operation If a flow ra...

Page 18: ...ure that there are no contaminants inside the water heater cabinet Correct any issues that are found 3 Visually check for breakages in the fan motor wiring or burn marks on the computer board PCB Repair replace as needed 4 Check for leaks at the heat exchanger 5 Check the fan housing for water 6 If you found water in the fan housing clean and dry the fan To remove the fan make sure that power to t...

Page 19: ...utlet thermistor as follows 3 1 Push the on off button on the temperature controller or remote controller so the orange STAND BY LED turns off 3 2 Run water through the heater 3 3 Check the reading of the outlet thermistor by pushing the INFO button on the temperature remote controller two times Compare it to the inlet thermistor The readings should be similar and it should be reading the temperat...

Page 20: ...connected to the remote controller properly 4 Power surges can cause this fault If frequent power surges occur install adequate surge protection to prevent nuisance faults 5 Check the voltage across the wires coming to the remote Normal voltage should be 10 25 VDC If within normal range replace the remote part 100209924 If the voltage is out of range replace the computer board PCB Code 751 Tempera...

Page 21: ...ere to any or all safety procedures specifically in regards to electrical and gas safety 1 Check the rating plate to verify that the gas type of the water heater matches the gas type applied to the unit Next make sure that the gas type DIP switch setting is correct See page 23 2 Verify that the venting meets the requirements specified in the installation manual e g vent diameter and length 3 Verif...

Page 22: ...will become gas rich and trigger the 101 or 991 code To check and clean the fan see Cleaning the Combustion Components page 39 To check and clean the burner refer to Cleaning the Combustion Components page 39 NOTE Do not proceed to the next step until this one has been completed and these causes have been ruled out Improperly installed venting incorrect dip switch settings and obstructions in the ...

Page 23: ...ation of the exhaust temperature control Enable Disable Default 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 2 3 4 5 6 7 8 9 10 Outdoor models No 6 OFF No 7 ON OFF ON 1 2 3 4 5 6 7 8 9 10 Set DIP switches shown in the table below OFF POSITION WARNING Do not adjust DIP switch No 10 without guidance from the technical service...

Page 24: ...control This switch is for a specialized purpose only Enable Disable Default 7 N A Do not change switch position N A N A Default 8 Deactivation of the freeze protection ﬁring system Enable Disable Default Outdoor models No 3 OFF No 4 ON OFF ON 1 2 3 4 5 6 7 8 Vent settings Indoor model only 3 ventings 5 to 20 ft DEFAULT 21 to 40 ft 41 to 70 ft 4 ventings 5 to 50 ft DEFAULT 51 to 100 ft N A No 3 ON...

Page 25: ...0 T H3 Model Computer Board Figure 11 No Functions ON position OFF position 1 Parent Child setting for Easy Link Systems Parent Child Default 2 3 4 FM FM and Input Fan motor speed is increased automatically 5 Output temperature settings Default 120 F 140 F 60 C 120 F 49 C Default 6 Easy Link connections with previous models Enable Disable Default DEFAULT No 2 OFF NO 3 OFF No 4 OFF OFF ON 1 2 3 4 5...

Page 26: ...peed change No 3 No 4 No 5 0 to 2 000 ft 0 DEFAULT OFF OFF OFF N A N A 2 000 to 3 000 ft 1 OFF ON OFF N A 6 3 000 to 5 000 ft 2 ON ON OFF 6 10 3 OFF OFF ON 9 14 5 000 to 7 500 ft 4 ON OFF ON 12 18 5 OFF ON ON 15 22 7 500 to 10 100 ft 6 ON ON ON 18 26 Special function ON OFF OFF N A 7 The settings are not listed in the Installation Manual of 240 T H3J 340 T H3S and 540 T H3 models Table 9 Indoor mo...

Page 27: ...N OFF OFF N A 7 Elevation Level DIP switch settings Output reduction Fan motor speed change No 3 No 4 No 5 0 to 2 000 ft 0 DEFAULT OFF OFF OFF N A N A 1 OFF ON OFF N A 6 2 000 to 4 000 ft 2 OFF OFF ON 9 14 4 000 to 6 000 ft 3 ON OFF ON 12 18 Special function ON OFF OFF N A 7 Table 11 Outdoor model 240 T H3J 340 T H3S Natural Gas Apply the altitude setting by adjusting DIP switches 3 4 and 5 as des...

Page 28: ...e lower bank See Figure 14 Figure 14 Lower bank of DIP switches 540 T H3 Elevation Level DIP switch settings Output reduction Fan motor speed change No 2 No 3 No 4 0 to 2 000 ft 0 DEFAULT OFF OFF OFF N A N A 2 000 to 3 000 ft 1 OFF ON OFF N A 6 3 000 to 5 000 ft 2 ON ON OFF 6 10 3 OFF OFF ON 9 14 5 000 to 7 500 ft 4 ON OFF ON 12 18 5 OFF ON ON 15 22 7 500 to 10 100 ft 6 ON ON ON 18 26 Special func...

Page 29: ...n motor speed change No 2 No 3 No 4 0 to 2 000 ft 0 DEFAULT OFF OFF OFF N A N A 1 OFF ON OFF N A 6 2 000 to 4 000 ft 2 OFF OFF ON 9 14 4 000 to 6 000 ft 3 ON OFF ON 12 18 Special function ON OFF OFF N A 7 Table 15 Outdoor model 540 T H3 Natural Gas Apply the altitude setting by adjusting DIP switches 2 3 and 4 on the lower bank See Figure 14 page 28 If the abnormal sound problem persists even with...

Page 30: ...t Switch BL Gas Propor Valve W R BL BL BL BL P BK BK W BK BK Outlet thermistor Inlet thermistor Surge box Hi limit switch for exhaust Exhaust thermistor W W W W BK W BL R BK Temperature controller Heater Heater Heater 240 340 Outdoor Heater BK Bank of DIPswitches Y Y Y Y Y Y W W W Y Flame rod AFR rod BK W Thermostat Heater Heater Heater 240 340 Indoor Green LED SV3 SV2 SV1 MV IG Flow Adjust ment V...

Page 31: ...R Y BL Gas Propor Valve R Y O BL W FM IG Igniter rod P P exchanger Heat thermistor Inlet thermistor Outlet thermistor Temperature remote controller optional accessory Parent 1 2 Flow Sensor Flow Adjust ment Valve Heater Heater 540 Outdoor Heater Y Y Heater Y Y Heater Heater 540 Indoor Hi switch limit O H C F MV SV1 SV2 SV3 BL BL BL BL LB G O R BL 540 Indoor Only 540 Indoor Only DIPswitches Note Th...

Page 32: ...in port then open their valves to drain the water 6 3 Go to step 8 7 Place a bucket or pan under the water filter drain plug to catch the water when it drains Figure 17 You may also drain the water to the outdoors 8 Open the drain port by turning it counter clockwise for two turns The drain port is shown at the far left hand side of Figure 17 There is no need to remove the drain port plug 9 Remove...

Page 33: ...culation ensure that they are turned off 2 Turn on hot water at one fixture in the structure Make sure that it is located at the highest point possible If possible use the hot side of a two handle fixture If you must use a single handle fixture make sure that it is open to the hot side only After a brief time the water should drain completely If water continues to run the fixtures and plumbing sys...

Page 34: ...cking the Manifold Gas Pressure 1 Verify that the gas supply pressure is within the correct operating range when the heater fires at maximum combustion Incorrect gas supply pressure will affect the gas manifold pressure 2 Ensurethattheunitisnotinoperation 3 Remove the screw from the manifold port Figure 22 4 Connect a manometer to the manifold port using a tube Ensure that this connection is secur...

Page 35: ...erify proper operation Adjusting Minimum Manifold Pressure WARNING Complete the following procedure ONLY if you have been instructed to do so by the Technical Service Department See WARNING text at the beginning of this section 1 Ensure that the water heater is not in operation 2 Remove the screw from the manifold test port Figure 22 page 34 See also page 49 or page 50 3 Connect a manometer to the...

Page 36: ...ill display flow if the flow sensor is working properly 2 Remove the flow sensor as described in Flow Sensor Control Valve Removal and Installation page 51 3 Blow into the inlet of the flow sensor Watch to see if the impeller spins It should spin freely for a few seconds If it comes to rest abruptly or doesn t spin at all it should be inspected for blockage NOTICE Do not try to disassemble the flo...

Page 37: ...inside of the burner Use 100 grit sandpaper or other suitable abrasive Be sure to remove any oxidation or contaminates 5 2 Clean the portion of the air fuel ratio rod that extends to the inside of the burner Use 100 grit sandpaper or other suitable abrasive Be sure to remove any oxidation or contaminates 6 Reassemble the unit in reverse order gasket rods and metal cover Be sure to connect all 3 wi...

Page 38: ...valves C D 5 Pour the white vinegar 3 gallons into the five gallon bucket 6 Connect one hose to the transfer pump s discharge outlet Connect its opposite end to the service connection at the cold water inlet s isolation valve B 7 Place the pump in the bucket of vinegar 8 Connect the second hose to the service connection at the hot water outlet A Place its loose end into the bucket with the vinegar...

Page 39: ...m the computer board 2 Remove the computer board from the water heater according to the following steps See also Figure 41 p 49 or Figure 42 p 50 2 1 INDOOR MODELS ONLY Unplug the wire connectors for the exhaust high limit switch item 472 p 74 and the exhaust thermistor item 718 p 74 See also Figure 41 page 49 2 2 Disconnect these wires from the front of the burner Flame rod wire orange See Figure...

Page 40: ... from the manifold plate assembly 5 8 Inspect the gaskets on the manifold plate for any tears If compromised replace with part number 100074229 item 113 and or 100074230 item 114 See p 73 5 9 Inspect the o ring item 151 p 73 and gas inlet ring item 119 p 73 at the gas connection for cuts or breaks If damaged replace with part number 100074242 item 151 and or 100074526 item 119 6 Remove the burner ...

Page 41: ...ater from the burner with compressed air 7 5 Inspect the gasket Minor surface tears are acceptable If the gasket shows major separations replace the gasket before the unit is returned to service 8 Clean the fan 8 1 Remove the fan from the bottom of the combustion chamber as follows 8 1 1 Remove the two Phillips hex head screws pointing down from the fan using an 8 long 2 Phillips head screw driver...

Page 42: ...hconnectstothe gasproportionalvalveisnotlabeled withanumber Ithastwowires red andwhite Seeschematicsonpages 30or31 NOTICE If necessary refer to the exploded assembly views which start on page 71 Inspect all gaskets Ensure that the black O rings and mesh filter on the gas valve inlet are not pinched or otherwise damaged during reinstallation ALL screws must be hand tightened only especially around ...

Page 43: ...rect Easy Link connections Temperature remote controller 9008172005 TM RE40 540 T H3 Previous model Previous model Previous model Case 1 Temperature remote controller 9007603005 TM RE30 Previous model Previous model 540 T H3 Previous model Case 2 Temperature remote controller 9007603005 TM RE30 Previous model 540 T H3 540 T H3 Previous model Case 3 In each case Previous model indicates a 520 T H2 ...

Page 44: ...emperature remote controller 100112155 TM RE30 See Figure 37 page 43 The 520 T H2 or 710 T M32 can be connected with temperature remote controller 9007603005 TM RE30 but they cannot be connected with temperature remote controller 9009069005 TM RE42 See Figure 37 page 43 F 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 C 38 40 43 45 50 52 55 57 60 63 65 68 70 75 77 80 Temperatures ...

Page 45: ...nostic mode press and hold the HOT and COLD buttons simultaneously for at least five seconds NOTE You may exit diagnostic mode by pressing the ON OFF button Also if left alone the display will exit diagnostic mode automatically after 30 minutes Multiple Units in a Linked System 540 T H3 Models Only 1 To enter diagnostic mode press the HOT button and the COLD button simultaneously for at least five...

Page 46: ...number Figure 40 shows that mode number 6 is selected See Table 18 page 47 for a list of mode numbers and their meanings Figure 40 Whole diagnostic mode Unit no Mode no Information This example shows the steps for displaying the outlet temperature for unit 2 in a linked system 6 Press the INFO button to select the mode number The data will be displayed on the controller Figure 40 shows that the ou...

Page 47: ... current rotation 0 to 720 minutes After 720 the next rotation occurs Air Fuel ratio rod current 0 to 999 μA 8 ON OFF cycles during current rotation 0 to 100 cycles After 100 the next rotation occurs Flow rate 0 to 999 0 1 GPM 9 N A Energization time of the unit 0 to 999 100 hours 10 Integrating ﬂow of the unit 0 to 999 10 000 gallons 11 Error code history displays the most recent error code 12 In...

Page 48: ...SERVICE PROCEDURES 48 On Demand Water Heater Service Handbook for 240 340 540 Condensing Models This page is left blank to preserve facing pages ...

Page 49: ...s Screw Secures the Computer Board Assembly Fuse Box Computer Board PCB High Limit Switch Exhaust Exhaust Thermistor See also Component Diagrams Item Numbers which starts on page 71 Air Fuel Ratio Rod Connector for Overheat Cutoff Fuse Blue Wires Manifold Plate Igniter Assembly not visible Brass Manifold Test Port Screw Power Cord Mounting Tab Gas Proportional Valve GPV Main Gas Valve Brass Screw ...

Page 50: ...Heat Exchanger Igniter Rod Wire Connection Secondary Heat Exchanger Over heat Cutoff Fuse OHCF Flame Rod AFR Wire Connections This Screw Secures the Computer Board Assembly Fuse Box Computer Board PCB Exhaust Vent See also Component Diagrams Item Numbers which starts on page 71 Air Fuel Ratio Rod Connector for Overheat Cutoff Fuse Blue Wires Manifold Plate Igniter Assembly not visible Brass Manifo...

Page 51: ...tems 460 461 page 74 6 2 Pull the cold connection tube item 466 page 74 from the outlet of the flow sensor control valve then lift the valve off the inlet connection You may have to twist the valve off inlet connection 7 Inspect the o rings on the inlet water connection and the cold connection tube for cuts or wear Replace as needed O ring on inlet water connection part no 100076308 O ring on cold...

Page 52: ...igure 42 p 50 2 1 INDOOR MODELS ONLY Unplug the wire connectors for the exhaust high limit switch item 472 p 74 and the exhaust thermistor item 718 p 74 See also Figure 41 page 49 2 2 Disconnect these wires from the front of the burner Flame rod wire orange See Figure 41 p 49 or Figure 42 p 50 center of picture Air fuel ratio rod AFR wire yellow NOTICE The connector is locked onto the spade To rem...

Page 53: ... item 113 and or 100074230 item 114 See p 73 5 9 Inspect the o ring item 151 p 73 and gas inlet ring item 119 p 73 at the gas connection for cuts or breaks If damaged replace with part number 100074242 item 151 and or 100074526 item 119 6 Remove the burner assembly according to the following steps 6 1 Remove the five 5 pan head Phillips screws that secure the burner to the combustion chamber There...

Page 54: ... If you removed the white connectors from the solenoids reconnect them Match the printed number on the wire to the corresponding number that is stamped on the solenoid body See Figure 46 For example if 73 is printed on a wire its pin should plug into the side of the connector that has the number 73 stamped closest to it 3 2 Slide the gas valve manifold plate onto the gas inlet connection The gas i...

Page 55: ...Connections in the figure noted above 9 INDOOR MODELS Connect the wires from the temperature controller item 722 page 71 to the computer board The correct receptacle is shown in one of these schematics 240 T H3J and 340 T H3s Models Page 30 See Temperature Controller 540 T H3 Models Page 31 See Temperature Controller 10 Verify that all water connections are tight and that there are no Gas Valve Po...

Page 56: ... 472 p 74 and the exhaust thermistor item 718 p 74 See also Figure 41 page 49 2 2 Disconnect these wires from the front of the burner Flame rod wire orange See Figure 41 p 49 or Figure 42 p 50 center of picture Air fuel ratio rod AFR wire yellow See Figure 41 p 49 or Figure 42 p 50 center of picture NOTICE The yellow wire is locked onto the rod s conductive spade To release the flame rod connector...

Page 57: ...ts or breaks If damaged replace with part number 100074242 item 151 and or 100074526 item 119 Gas Valve Manifold Plate Installation 6 Install the gas valve manifold assembly See item 102 p 73 6 1 Attachawireconnectorto eachofthesolenoidvalvesas described There are a total of five connectors to be reinstalled Each connector has a dark blue wire except for the proportional valve The other wire color...

Page 58: ...ection in the figure noted above Insert the connector from the power supply cable to its port on the fuse box See Fuse Box in the figure noted above Reinstall the flame rod AFR wires See Flame Rod AFR Wire Connections in the figure noted above 12 INDOOR MODELS Connect the wires from the temperature controller item 722 page 71 to the computer board The correct receptacle for your model is shown in ...

Page 59: ...MAINTENANCE On Demand Water Heater Service Handbook for 240 340 540 Condensing Models 59 MAINTENANCE This page is left blank to preserve facing pages ...

Page 60: ... easier 1 Shut the unit down as follows 1 1 Shut Off power and gas supply as follows 1 1 1 Shut off Power by disconnecting the power cord or shutting off the power disconnect 1 1 2 Shut off the gas supply to the water heater at the manual gas shutoff valve 1 2 Drain the water from the heater as follows 1 2 1 Close the shutoff valves on the hot and cold side of the heater 1 2 2 IF isolation valves ...

Page 61: ...have a 540 model with a bypass valve you must remove an additional fastener See item 458 at connection point A two places page 74 5 2 Pull the cold connection tube item 466 page 74 from the outlet of the flow sensor control valve Example Freeze Protection Heaters with Clips Figure 54 NOTICE If you have a 540 model you must pull a portion of the tube out of the bypass valve as well 5 3 Turn the flo...

Page 62: ... Figure 41 p 49 9 5 Disconnect the air tube off the left side of the gas valve Figure 57 See also Clear Plastic Tube in Figure 41 p 49 Manifold Screws DO NOT remove the screws indicated by the white crossed out circles Remove the screws indicated by the white arrows Figure 56 9 6 Disconnect the connector on the left side blue wires which goes to the overheat cutoff fuse See Connector for Overheat ...

Page 63: ... High Limit Switch wires clip the zip tie to separate them Figure 60 NOTICE Do not cut nick or damage the wires when clipping the zip tie 11 Remove the burner from the combustion chamber 11 1 Remove two screws below the burner at the back Figure 61 11 2 Remove three screws across the front of the burner See Figure 61 Do not remove the screws around the flame sensor AFR and igniter rods 11 3 Remove...

Page 64: ... out of the copper pipe 12 6 INDOOR MODELS Disconnect the venting from the exhaust flue 12 7 IF you have a 540 model disconnect the bypass valve wiring as follows Heat Exchanger Thermistor 540 Models Only View Right Side of Heat Exchangers Figure 62 12 7 1Locate the bypass valve wires on the left side of the heat exchangers Wire colors Red Yellow White Blue Brown 12 7 2 Disconnect the white connec...

Page 65: ...t 2 Remove the following items from the primary heat exchanger and INSTALL THEM IN THE SAME LOCATIONS ON THE NEW PRIMARY HEAT EXCHANGER High limit switch on the left side item 412 page 74 Over heat Cutoff Fuse OHCF and its six clips See Figure 64 Figure 65 and item 413 on page 74 See also Over heat Cutoff Fuse in Figure 41 page 49 Air tube and its connector nipple on the bottom of the combustion c...

Page 66: ...st on a flange on the inside of the case INDOOR MODELS Make sure that the flue gasket item 154 page 74 is on the inside of the case 5 Insertandhandtightenthree 3 screwsasshowninFigure63 page 64 Thiswillsecuretheheat exchangerassemblytotheheatercase 6 Reconnect the cold pipe as follows 6 3 1 Install the cold pipe as shown on page 74 See item 466 NOTICE 240 340 MODELS Reconnect the top termination T...

Page 67: ...ip See item 462 on page 74 11 Attachthetopofthecondensate draintubetotheportonthebottom ofthesecondaryheatexchanger See Item416onpage74 12 Install the fan with the air inlet facing toward the front as follows 12 1 Slide the fan s flanges into the slots on the bottom of the combustion chamber The fan s air inlet must face outward 12 2 Line up the holes then insert and hand tighten two 2 hex head sc...

Page 68: ... tabs at the connection Hand tighten only See Brass Screw Securing Gas Valve in Figure 41 p 49 13 5 Attach the air tube from the bottom of the combustion chamber to the port on the left side of the gas valve See Figure 69 NOTICE If the air tube is not connected to the bottom of the combustion chamber connect it now as shown in Figure 58 p 63 14 INDOOR MODELS ONLY Secure the power cord to the manif...

Page 69: ...it by hand tightening both mounting screws 20 Reconnect the freeze protection heater wiring Connect each male female pair of connectors that have YELLOW wires When you finish you will have reconnected five 5 pair of connectors with YELLOW wires Location of each connection One near the cold water inlet Two near the hot water outlet One on the right side above the gas valve One at the top left hand ...

Page 70: ...ons inside the cabinet Locate the two unsecured ground wires green Secure them with screws as shown in Figure 72 Locate the plug and receptacle with blue wires Plug them together at the left hand side of the cabinet See Over heat Cutoff Fuse OHCF in Figure 41 p 49 or Figure 42 p 50 This blue wire assembly has male and female plugs that you must plug together There are also two separate wires on th...

Page 71: ...g Models 71 COMPONENT DIAGRAMS ITEM NUMBERS Indoor model Outdoor model Case assembly 052 052 003 007 002 050 006 704 005 052 702 704 008 052 050 052 717 702 713 004 002 001 001 004 Temperature remote controller 724 723 722 056 Temperature controller Indoor model 722 722 722 722 ...

Page 72: ...OMPONENT DIAGRAMS ITEM NUMBERS CONT Computer board assembly Surge box assembly 540 T H3 model 240 T H3J and 340 T H3S model 710 701 713 103 709 402 707 708 714 721 407 408 701 714 403 715 721 707 722 715 402 402 103 713 708 710 709 716 716 722 402 061 121 713 703 706 063 709 053 703 701 703 ...

Page 73: ... assembly 101 104 115 106 107 108 110 109 111 712 112 062 053 053 709 053 401 103 105 065 054 113 114 102 708 119 151 118 055 051 150 057 055 063 117 053 116 062 121 714 719 707 711 117 540 T H3 model Manifold Assembly Burner assembly Gas Valve Combustion Chamber 709 113 114 151 119 112 burner assembly 112 102 Combustion Chamber 54 ...

Page 74: ...assembly D A E 459 454 411 412 058 F 413 452 450 414 451 414 418 416 009 C 453 468 468 052 455 463 455 469 052 463 462 467 064 462 462 473 466 466 415 451 465 418 414 464 471 064 D 472 153 152 053 718 470 415 401 B E F 473 451 540 T H3 model 240 T H3J and 340 T H3S models 458 458 458 154 540 T H3 model 451 415 Primary Secondary 407 408 402 402 406 402 460 461 466 456 458 466 460 461 472 718 406 46...

Page 75: ...cord assembly 007 N A EK161 Back guard panel 008 N A EK160 Chamber fixing plate 009 100074203 EKH23 Condensate drain port 050 N A EW000 Truss screw M4x12 w washer SUS410 051 N A EW001 Truss screw M4x10 w washer SUS410 052 N A EW002 Truss screw M4x10 Coated SUS3 053 N A EW003 Truss screw M4x10 SUS 054 N A EW004 Hex head screw M4 12 W Washer SUS3 055 N A EW005 Hex Head screw M4x8 FeZn 056 N A EW018 ...

Page 76: ...4230 EKK2K Manifold gasket B 115 100074217 EKK0G Burner holder gasket 116 100074227 EKK2D Pressure port 117 N A EX019 Combustion chamber tube 118 100074616 EK117 Gas inlet 119 100074526 EX00D Gas inlet ring 121 100074677 EK163 Surge box plate 150 100074533 EZP18 O ring P18 NBR Black 151 100074242 EK042 O ring P20 NBR Black 152 100074678 EK157 Silicon ring for Outdoor model 153 100074679 EK177 Exha...

Page 77: ...K333 Overheat cut off fuse 414 100074682 EK209 Pipe heater 415 100074683 EK210 Inlet heater for Indoor model 100074684 EK211 Inlet heater for Outdoor model 416 100074685 EK231 Drain tube 417 100074629 EK105 Inlet heater 418 100074700 EK251 Secondary heat exchanger for Indoor model 100074701 EK256 Secondary heat exchanger for Outdoor model 450 100074273 EKK27 Pipe heater fixing plate 451 100074310 ...

Page 78: ...100076100 EK280 Surge box 704 100074601 EK146 120 VAC wire for Indoor model 100074697 EK143 120 VAC wire for Outdoor model 706 100074326 EKK4V 120 VAC Power ON OFF switch 707 100074649 EK189 Remote controller wire for 240 T H3J and 340 T H3S models 100074650 EK165 Remote controller wire for 540 T H3 model 708 100074651 EK168 Gas valve wire 709 100074652 EK166 Flame rod wire 710 100074653 EK172 EH ...

Page 79: ...0 340 540 Condensing Models 79 COMPONENT ITEM NUMBERS CONT Item Part Description 240 340 and 540 models T H3J T H3S and T H3 models 723 N A EK178 Fixing plate 724 100112572 TM RE40 Temperature remote controller 100209924 TM RE42 Temperature remote controller ...

Page 80: ...80 On Demand Water Heater Service Handbook for 240 340 540 Condensing Models Copyright 2016 A O Smith Corporation All rights reserved ...

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