Furnace High Limit Switch

The limit switch is a safety switch that monitors t.

Furnace high limit switch. It reads the temperature of the plenum and waits until it gets appropriately warm. A pair of wires is connected to the switch. High limit switch a high limit control switch will turn off the gas to a furnace if the temperature becomes too high. I believe high limit switches are normally closed and.

This is the role it plays in every cycle of your furnace s normal operation. The limit switch includes a sensor in the heat exchanger to. 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. The high limit switch in your gas furnace is a small part with two very important jobs.

They will be mounted near where the flame may rollout the front of the furnace due to venting blockages heat. Some of these parts are shown on the left. The high temperature limit switch is an important device used in forced air furnaces powered by gas or heating oil. For example if the blower motor stopped running then no air would move through the unit.

Note that the limit switch has nothing to do with the thermostat. A limit switch is a device that s located under your furnace s supply plenum. Rather it is wired in series with the 24 volt control circuit of your furnace. If the blower came on at the same time as the burner it would pump cold air through the house at first.

It s also known as a fan limit switch or simply a limit switch. As a safety the high limit. Turning the fan motor on and off is the high limit switch s main job. In this episode of repair and replace vance shows how to replace the high limit switch in a gas furnace.

This switch plays a role in the normal operation of your furnace. Remove the cover by lifting it upwards or pulling it off to reveal the body of the switch and two metal arms. Locate the white limit switch. Rollout switches and high temperature fuses are different from limit switches in that when they open they will not close again unless reset as in the case of the rollout switch or replaced as in the case of the high temperature fuse.

Depending on your furnace model the switch will be surrounded by a silver or white cover. It will be located at the top of the panel. The blower will continue to run until either the system is reset or the limit switch closes. The switch makes sure the furnace is operating safely and at its desired settings.

If the high limit switch was bad the furnace should not fire.