Gas Furnace High Limit Switch

Limit switches turn off the burner and turn on the circulating fan if there is a high temperature condition in the furnace.

Gas furnace high limit switch.

Fan limit switches are used on all types of building heating furnaces. Some furnaces provide extra safety features by wiring two or three high limit switches in a series that check the temperature in the furnace at different points. The high temperature limit switch is a small but important device used in forced air furnaces powered by natural gas lp or heating oil. Additionally when the plenum gets too hot the high limit switch will shut off the gas supply to the furnace burners.

In this episode of repair and replace vance shows how to replace the high limit switch in a gas furnace. As a safety the high limit switch turns the gas off when the temperature becomes too high. When the temperature reduces to normal the burner will come back on. The limit switch is a safety switch that monitors t.

It reads the temperature of the plenum and waits until it gets appropriately warm. For example if the blower motor stopped running then no air would move through the unit. A high limit switch is a protective part of a furnace designed to keep the mechanism from overheating itself. This control also provides a safety limit that turns off the burner or furnace if temperatures at the furnace are too high.

This safety feature prevents your furnace from overheating. A furnace is at a risk of overheating any time airflow is limited from passing through the heat exchanger. There is a difference between a limit switch and a rollout switch. Once the plenum reaches a specific temperature the limit switch sends a signal to the air handler to begin running and delivering warm air to your home.

Fan control limit switch. The fan limit switch on a heating furnace controls when the furnace blower fan turns on and off. High limit switch a high limit control switch will turn off the gas to a furnace if the temperature becomes too high. The limit switch shuts off the burner when the temperature exceeds a preset temperature.

A limit switch is a device that s located under your furnace s supply plenum. Also known as the fan limit switch or simply the limit switch it has two functions in the furnace s operation.