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Professional Heating & Air Blog

What Is a Thermocouple?

Every combustion heating system needs a number of safety mechanisms to ensure that the unit runs safely. One area that has to be highly monitored with both furnaces and boilers is the pilot light. In a furnace that has a standing pilot light, the component responsible for monitoring the pilot is known as a thermocouple.

What It Is

A thermocouple is an instrument made from two differing metals; these metals are soldered together at a single point for the purpose of monitoring temperature. When the metals are heated at the point of contact, a voltage is generated; this is known as the Seebeck effect. As the heat on the metals increases, the voltage also increases; the voltage coming from the thermocouple is what indicates to your furnace that there is a pilot and that it is viable and good for lighting your furnace. The thermocouple is placed so that the point of contact, which is encased in a stainless steel encasement, is right in the flame; this is so the thermocouple can accurately measure the pilot.

How It Works

The thermocouple not only measures the standing pilot flame, it also acts as a gatekeeper to the gas line valve. When your thermostat calls for heat, the thermocouple checks the pilot light; if there isn’t a pilot light, or the flame isn’t strong enough, the thermocouple won’t allow the main gas valve to open. This helps ensure that gas won’t flow unless it can be lit. If the standing pilot is viable, the thermocouple allows the main gas valve to open and your furnace’s burner is successfully lit.

Common Problems

Thermocouples are exposed to very high temperatures, and then cool off; this kind of prolonged wear and tear can cause the thermocouple to crack. Additionally, the metal strips can corrode, which also cause operational issues. A dirty thermocouple may not be able to accurately read the flame, and a thermocouple that shifts position or is positioned incorrectly will be too far away to correctly read the flame. Any of these problems can result in ignition problems with your furnace.

The safety mechanisms on your furnace are critical; as such, they should only be repaired by professionals. Having problems with your furnace? Call A–Professional Heating and Air Conditioning today and schedule an appointment with us! We offer quality furnace repair services in the Hammond area.

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