Perform Gas Leak Test
WARNING
Fire or Explosion Hazard.
Can cause severe injury, death or property damage.
Check for gas leaks with soap and water solution any time work is done on a gas system.
CAUTION
Water Damage Hazard.
Can damage electrical components in the WT8840.
Do not spray soap and water solution on the WT8840 housing. Do not use an excessive amount of soap and water to perform the gas leak test.
Gas Leak Test
1.Paint pipe connections upstream of the water heater control with a rich soap and water solution. Bubbles indicate a gas leak.
2.If a leak is detected, tighten the pipe connection.
3.Stand clear of the burner while lighting to prevent injury caused from hidden leaks that could cause flashback in the appliance burner compartment.
4.With the burner in operation, paint the pipe joints (including adapters) and the control inlet and outlet with a rich soap and water solution.
5.If another leak is detected, tighten the adapter screw, joints, and pipe connections.
6.Replace the part(s) if a leak cannot be stopped.
Check the gas input and burner flow rate
WARNING
Fire or Explosion Hazard.
Can cause severe injury, death or property damage.
Follow these warnings exactly:
1.Do not exceed input rating stamped on appliance nameplate or manufacturer recommended burner orifice pressure for size of orifice(s) used. Follow instructions of appliance manufacturer.
2.IF CHECKING GAS INPUT BY CLOCKING GAS METER: Make certain there is no gas flow through the meter other than to the appliance being checked. Other appliances must remain off with the pilots extinguished (or that consumption must be deducted from the meter reading). Convert flow rate to Btuh as described in form number 70-2602, Gas Controls Handbook, and compare to Btuh input rating on appliance nameplate.
3.IF CHECKING GAS INPUT WITH MANOMETER: Make sure the manual gas shutoff switch is in the OFF position before removing outlet pressure tap plug to connect the manometer (pressure gauge). Also, move the manual gas shutoff switch to the OFF position when removing the gauge and replacing the plug. Also shut off gas supply before disconnecting manometer and replacing plug. Repeat Gas Leak Test at plug with main burner operating.
WT8840 TRADE WATER HEATER CONTROLS
Procedure to check the gas input and burner flow rate
1.Check the full rate manifold pressure listed on the appliance nameplate. Water heater control full rate outlet pressure should match this rating.
2.With burner operating, check the water heater control flow rate using the meter clocking method or check pressure using a manometer connected to the outlet pressure tap on the water heater control. See Fig. 5.
MAINTENANCE
WARNING
Fire or Explosion Hazard. Can cause severe injury, death or property damage.
Do not attempt to take apart or clean the gas valve inside the WT8840 control. Improper cleaning or reassembly can cause gas leakage.
The maintenance program should include regular checkout of the control as outlined in the Startup and Checkout section, and the control system as described in the appliance manufacturer literature.
Maintenance frequency must be determined individually for each application. Some considerations are:
1.Cycling frequency. Appliances that may cycle 10,000 times annually should be checked monthly.
2.Intermittent use. Appliances that are used seasonally should be checked before shutdown and again before the next use.
3.Consequence of unexpected shutdown. Where the cost of an unexpected shutdown would be high, the system should be checked more often.
4.Dusty, wet or corrosive environment. Since these
environments can cause the control to deteriorate more rapidly, the system should be checked more often.
The system should be replaced if:
•It does not perform properly on checkout or troubleshooting.
•The control is likely to have operated for more than 150,000 cycles.
•The control is wet or looks as if it has been wet.
TROUBLESHOOTING
Troubleshooting With Status
Indicator Assistance
1.Pilot burner must be lit. If not, push and hold Pilot knob and light pilot with piezo. Error code will be displayed when thermopile heats up. Error code can be recognized by counting the number of flashes of the status indicator after a three second pause. One single flash (with set point knob in PILOT position) indicates that the control is in normal operation.
2.Observe status indicator on control; check and repair the system as noted in Table 3 on page 6. Flash codes are displayed with a three-second delay between cycles. A continuous solid light indicates system shutdown when knob is turned from a temperature setting to OFF position. When the solid light is present, the pilot and
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34-00013EF—03 |
WT8840 TRADE WATER HEATER CONTROLS
main valve will not hold. When the status indicator goes out, the user can restart the system. (Approximate shutdown time is one minute.)
3.After status indicator analysis and appliance repair is complete, turn device knob to OFF, wait until the indicator goes out, then perform lighting procedure.
4.Status indicator light should be in normal mode (1 flash) with the knob in the PILOT position. Turn the device knob past the water temperature in the tank should turn on the main burner. The Status indicator light will strobe every three seconds when there is a call for heat.
5.In the event of multiple failure codes, the next failure code follows the previous failure code by approximately three seconds with higher flash count first.
Table 3. Troubleshooting with status light visual indication.
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LED |
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Error |
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Code** |
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Number of LED Flashes* |
Detected Failure |
Recommended Action |
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Normal |
1 flash |
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Not an error; |
You can now turn the knob to a |
operation. |
every 3 |
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indicates the |
desired setpoint temperature. LED |
No action |
seconds |
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electronics is holding |
will continue to flash 1 time every 3 |
required. |
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the Pilot Valve open |
seconds while in Idle mode (no call |
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and the Main Valve |
for heat). |
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closed. |
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Strobe |
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Not an error; |
None. |
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every 3 |
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indicates call for heat |
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seconds |
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during normal |
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operation, Main valve |
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open. |
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Action |
2 flashes |
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Low thermopile |
Check thermopile and its |
required. |
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voltage; main valve |
connections. Check pilot flame. |
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not turned ON. |
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4 flashes |
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Temperature cut-out |
Check the valves and the water |
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limit reached. |
temperature sensor. Reduce the |
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water temperature setpoint. |
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Thoroughly check out main valve |
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operation and water temperature |
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control before walking away. |
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5 flashes |
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Water temperature |
Check water temperature sensor |
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sensor failure. |
and its connection for open |
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circuits, shorts, or differences in |
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resistance between the two sensor |
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elements. |
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6 flashes |
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Tank leakage |
Control recovers after receiving |
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detected by |
message from accessory module. |
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accessory module. |
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7 flashes |
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Electronics Failure |
Replace control module. |
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8 flashes |
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This is just a warning; |
Check valves. |
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The control does not |
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see power decaying |
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with the knob in the |
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OFF position. |
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Solid ON |
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Not an error— |
None; wait until LED turns off if you |
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indicates that the |
want to restart the system. |
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control is in OFF |
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mode. |
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* LED Error Codes are flashed once per second, with a three-second pause between repeating the error code. **Maximum two different errors can be displayed simultaneously if more than one error has been detected.
34-00013EF—03 |
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