How do you reset a high limit switch on a furnace?

How do you reset a high limit switch on a furnace?

How to Reset a Furnace Limit Switch

1. Locate your furnace’s heating duct.
2. Locate the white limit switch.
3. Look at each arm to identify the settings.
4. Identify the component (setting) located in between the two arms.
5. Set the temperature on the middle component to approximately 105 to 115 degrees Fahrenheit.

What causes high limit switch on furnace?

If the supply air is too hot, the interior of the furnace overheats, which can cause damage to components. The limit switch trips when temperatures are too hot, effectively shutting down the system and locking furnace operation until the unit cools.

How do you turn off the limit switch on a furnace?

This is best left to a furnace repair specialist when trying to troubleshoot problems. The standard settings for most furnace fan limit switches are 200°F to shut off the burner, 130°F to turn off the blower, and 100°F to turn the blower back on.

Can I bypass a high limit switch?

Yes, you can bypass the high limit switch for testing. It’s as trivial to do as it sounds.

How much does a high limit switch cost?

Average Cost of a New Furnace Limit Switch You will need to buy a high limit switch that is produced by the same manufacturer as your furnace unit. Depending on who your OEM is, this component could roughly cost you anywhere from $4 to $25.

Should a limit switch be open or closed?

The limit switch is a normally closed switch in series with the sail switch and the thermostat. Being temperature actuated, it is designed to “snap open” when an over temperature condition occurs. Thus the switch is normally opening under full load conditions and that causes arcing of the contacts.

What will cause a limit switch to open?

Limit switch codes The limit switch shuts off the burner when the temperature exceeds a preset temperature. When the temperature reduces to normal, the burner will come back on. The most common reason for limits to open is a plugged filter or a dirty blower wheel.

What does open limit device mean on a furnace?

In modern furnaces an open limit switch will always bring on the main blower as a safety feature when there is a call for heat but it is not the blower control which usually operates on a timer built in to the. The limit switch will open periodically to prevent over heating.

What happens when a furnace overheats?

The most serious risk of an overheating furnace is stress cracks in the heat exchanger caused by overheating. The vast majority of premature heat exchanger damage is due to overheating as the heat stress causes cracks near the welds and bends.