Gas Furnace Pilot Light Thermocouple

It is a safety device that shuts off the gas if the pilot light goes out or the electric igniter fails.

Gas furnace pilot light thermocouple. Typically the thermocouple sensor is mounted right in the flame of the pilot light on gas fired heating equipment. This rod is connected to your furnace s gas valve. It contains a metal rod that is placed very close to your pilot light s flame. A thermocouple is a safety device that s used to detect whether or not your furnace s pilot light is lit.

If it determines that the pilot light is off it shuts down the flow of gas. Our photo left shows how you may spot the copper tubing of the thermocouple extending between its sensor at the pilot flame of a gas burning furnace and its connection to the gas control valve. When the sensor is not heated by the pilot flame the solenoid closes the gas supply line. A gas furnace s standing pilot in which the flame is lit at all times is sometimes referred to as a pilot light but no matter what you call it its purpose is to serve as a small ignition flame for the gas burner when the thermostat signals for gas to be delivered from the gas valve to the burner it is the standing pilot that ignites the gas flowing to the burners to heat the air in the.

While holding the pilot light button down i get a blue flame with a yellow tip that s over an inch in length. In this hvac training video i show up close how the thermocouple pilot light and gas valve work on a water heater furnace fireplace as well as other ap. Thermocouples detect pilot lights by sensing the heat they produce. The thermocouple which operates as a safety device turns the gas supply off when the pilot light goes out.

The thermocouple is below the pilot light but the flame is definitely touching it. A gas furnace thermocouple is in place to shut off the gas line when the pilot goes out or the flow of gas is interrupted on the way to the pilot it works as a type of sensor and if it fails your furnace will not light a thermocouple is the right hand man of the pilot light as it reads the pilots temperature on a rating which tells it to keep the gas flowing. It consists of a heat sensor connected to a solenoid. The thermocouple is a gas furnace component located near the pilot light burner.

The furnace is definitely over 30 years old and was likely installed in the 60 s. A slim rod shaped flame sensor sits in the path of your pilot flame where it collects and then transfers heat down via a flexible connector wire or tube to signal through an electrical charge that the main gas valve should open. While this is an excellent safety feature a faulty thermocouple may decide arbitrarily that your pilot light is off when you want it on shutting down your pilot light and your furnace. I ve held the button down for over the recommended 60 seconds.

When a thermocouple fails the pilot light won t stay lighted.