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Why Does the Pilot Light Keep Going Out?

The pilot light is notorious for being the most temperamental part of a gas-powered system. It is known for going off all the time for no apparent reason, prompting a relighting procedure either by yourself or your HVAC professional. There is a difference, however, between a pilot light that goes out frequently and one that simply won’t stay lit. If your pilot light doesn’t stay lit for any appreciable length of time, it is very likely that you have a bad thermocouple.

What is a Thermocouple?

A thermocouple is a long metal wire or rod made of two different metal conductors. One end of the thermocouple is installed right next to the pilot light, while the other is connected to the gas valve responsible for feeding the pilot light. When metal is subjected to uneven levels of heat, it generates an electric current. Thus, when the pilot light end of the thermocouple is exposed to the heat of the flame, it produces a current that runs down the wire to the other end, where it serves to keep the gas valve open. This ensures that, once lit, a pilot light will stay lit by consuming a constant flow of gas. Essentially, the thermocouple is a heat sensor designed to regulate the flow of gas to the pilot light.

Bad Thermocouple

When a thermocouple goes bad or is faulty, it loses its ability to generate a current when exposed to heat. This means that when you attempt to light the pilot light, the thermocouple will not be able to open the gas valve to keep the flame alive. When this happens, there isn’t really a way to repair it. Chances are you’ll have to replace the thermocouple. It is possible that part of the thermocouple could have simply been bent away from the flame, as sometimes happens during installation or poor maintenance. The best way to tell, however, is to have a professional look at it for you.

If your pilot light is not staying lit, call At Your Service Plumbing, Heating & Air. We conduct heating repairs throughout the entire Salt Lake City area.

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