Beware of Furnace Short Cycling

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As the temperature outside continues to drop, you’re going to be relying on your furnace more and more often to keep warm. At some point, you may start to notice your furnace turning itself on and off every few minutes. If you notice this happening, don’t ignore it. That behavior is called short cycling and it can do an incredible amount of damage to the system if you aren’t careful. Read on to find out what causes short cycling, and the kind of damage it can do if it is allowed to continue.


Furnace short cycling is caused most often by heat becoming trapped in the furnace plenum. The plenum is the central part of the furnace. Typically, air flow gets cut off in the furnace due to a clogged air filter or a broken air handler. Regardless of the cause, though, the consequences are what you really need to worry about. Without a way to rid itself of the heat it generates, the internal temperature of the furnace will rise above safe levels. This will cause the limit switch to activate and shut down the furnace as a precaution. Once the furnace has cooled down enough, it will restart in an attempt to heat the home. If the core issue isn’t dealt with, though, it will simply overheat again and shut down again.


The furnace will continue to short cycle until the core problem is resolved. As the system continues to short cycle, it will experience dramatically increased wear and tear. The furnace will wear down faster as a result, and will have its lifespan shortened by a substantial number of years. If you notice your furnace short cycling, shut it down and call for repairs as soon as possible.

Bell Plumbing and Heating provides a full range of furnace repair services throughout Denver, CO.

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