Understanding Your Furnace's Thermocouple
For the most part, a gas powered furnace represents a fairly simple mechanical system to understand. Yet certain components remain a mystery even to those with fairly comprehensive HVAC knowledge. If you own a gas furnace and would like to learn more about one of its most important components, read on. This article will provide a helpful overview of the role and importance of the thermocouple.
The Basics
The thermocouple is one of the most important parts of your furnace's safety system. Its job is to stop the flow of gas to the pilot orifice if the pilot light goes out. Otherwise that gas would pass out into the air of your home. If the problem were to go on too long, and the gas levels to become too high, this would represent a serious threat of explosion or suffocation to you and your family.
How A Thermocouple Works
A thermocouple is a type of electrical device especially designed to detect and respond to changes in temperature. It is located in such a position that the flame of the pilot light will directly touch it. When the pilot light is on, two metal strips at the tip of the thermocouple will become heated. This results in the generation of an electrical charge.
The idea is that, when the pilot light is on, and the thermocouple heats up, the resulting electrical charge will tell the gas valve to stay open. But if the pilot light were to go off, the thermocouple would soon cool down and cease to generate a voltage output. This would cause the valve to close, thus preventing any gas from escaping into the air of your home.
Thermocouple Problems
Thermocouples have a tendency to become problematic over time. The most common way this manifests is as a pilot light--and thus a furnace--that won't stay lit. The problem here is that, even when the pilot light is re-lit, the thermocouple won't generate the voltage needed to keep the gas valve open.
Oftentimes, this problem is caused by a pilot light whose directional orientation is off. In other words, if the pilot light is not pointed directly enough at the thermocouple, it will not heat up enough to generate an electrical charge. Likewise, the metal strips may become covered by a layer of soot over time. This can impede their ability to create a voltage output. Cleaning the strips is often enough to get the furnace working once more.
Finally, it may simply be the case that some internal part of your thermocouple has ceased to function properly. In that case, the necessary fix is to remove the faulty thermocouple and replace it with a new one. Those who don't feel comfortable undertaking this moderately difficult maintenance task should call heating services in their area.