How to fix the thermocouple on Reliance?

by Dan

I have a Reliance gas water heater and it seems that the thermocouple is out. I suspect that there is a thermocouple malfunction because pilot light doesn’t remain lit and the burner doesn’t ignite. How to test the thermocouple and fix the problem?

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Oct 27, 2013
troubleshooting thermocouple
by: Pit

As you might know, thermocouple is used to determine is the pilot flame present or not; and if it is not, than the system shuts down. It is a safety feature and any malfunction usually leads to pilot and burner outage.

How to replace the thermocouple if it is broken and how to test the element?

Removing the thermocouple is easy and it requires only a screwdriver. Turn off the main gas shut off valve that supplies the water heater. It is usually located beside the unit. At the base of the gas water heater there is a gas valve with the thermostat. Turn the thermostat to its lowest setting and put the gas control knob to the off position. Remove the outer door and two screws that hold the manifold door assembly.

Now you can dismantle the thermocouple, pilot tube and other elements from the gas control valve. Take the burner assembly and remove it from the gas combustion chamber. Take out the wire connector from the manifold door by unclipping the retainer clip. Remove the two screws to dissemble the burner and get the thermocouple out from the pilot assembly.

Putting the thermocouple back requires precision and some knowledge. When dealing with this element it is important to protect it from damaging. It must be inserted into the pilot bracket hole where its base must be flushed with the base of the bracket, and it can be bended by hands for routing purposes, as long as it is not damaged. The installation of other elements should be done in the opposite order.

How to test the thermocouple?

Once the thermocouple is separated, use the multimeter to measure the millivolts. Put one end of the clip lead to the thermocouple copper body and the other end to the end where it connects to the valve. Try to light the pilot. If after a minute or so, the reading doesn’t show 12 mV or more, than the element is broken and has to be replaced. If it passes the test, check other elements, such as the gas valve.

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