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Your Furnace’s High Limit Switch Explained

This article explains the so-called furnace high limit switch.

Each of the components in your gas furnace must be capable of operating correctly else your furnace may cease to provide heat. Unfortunately, many homeowners find the multitude of different components a source of serious confusion.

Here’s what you need to know.

The Basics

The furnace high limit switch is one of the most important safety features in your furnace. In the event that your blower system ceases to function correctly, the furnace high limit switch’s job is to shut down the furnace.

It does this because, without a working blower system to send it out into your home, the furnace’s heat would soon build up to potentially explosive levels.

The furnace high limit switch regulates your furnace’s operation by closely monitoring the temperature inside of the combustion chamber.

A Closer Look 

As you may be able to gather from the information above, the furnace high limit switch contains a thermostat capable of reading your furnace’s internal temperature.

Should this temperature exceed a pre-set safety threshold, the furnace high limit switch will kick into action and close off the gas valve allowing gas into your furnace.

High combustion chamber temperatures are most commonly associated with a non-functioning blower system.


Like all furnace components, it is possible for the furnace high limit switch to begin causing problems should it become miscalibrated or broken.

Perhaps the most commonly encountered issue is a furnace high limit switch that shuts off the gas flow even when the temperature is still within the safe range.


If you believe that your furnace high limit switch may be experiencing unintended issues, feel free to Contact Us at (651) 294-7798 to tell us what you need us to do.

We cover Blaine, Bloomington, Brooklyn Park, Eagan, Edina, Hastings, Maplewood, Minneapolis, Minnetonka, Roseville, North Saint Paul, Saint Paul, Saint Paul Park, South Saint Paul, Stillwater, West Lakeland, West Saint Paul, White Bear Lake, Woodbury,  and many more locations.

Can’t find your town listed? Contact us at (651) 294-7798 to tell us where you live, so we can help you.

Schedule a HVAC repair anywhere in the Minneapolis or St. Paul area today by calling (651) 294-7798 or by requesting an estimate online.


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1220 Cope Avenue East, Maplewood, MN 55109