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What Is Short Cycling



Senior man is standing in the kitchen of his home with bills in one hand and a cup of tea in the other. He has a worried expression on his face.


Short cycling basically means short run times and short off times, that your furnace is turning on and off quickly and thus not providing the heat that your home needs.

It can happen for a number of reasons.  A furnace that is too big for your home is often the culprit.  When your home heats too quickly, it also cools down too quickly causing your furnace to turn on and off too much. If this is a new problem with an older furnace that has worked for you well in years past, size probably isn’t your issue.

Another problem is a dirty air filter.  You must make it a habit to check your air filters.  If your filter is dirty and clogged, it restricts air flow which makes your whole furnace less efficient and is one of the leading causes of short cycling.  Change your air filter according to the manufacturers instructions and make sure to check it once a month.  If is dirty change it again.

A faulty thermostat can cause a unit to short cycle.  Double check your settings and make sure that it is working correctly.  Take note of the environment that your thermostat is in.  Is it in the sun?  Is it in the shade?  The warmth of the room will affect the readings on the thermostat. 

Less likely but still possible reasons for your furnace short cycling is a corroded flame sensor or foreign objects getting lodged in your vents.  

Short cycling can cause irreparable damage to your furnace if not investigated and corrected right away.  It also leads to and increase in your utility costs.  

Call Glenn Aire Company or request service online today! For preventive maintenance before your furnace starts to short cycle, or call us to repair a furnace that isn’t performing the way it should.

Need HVAC Service?

Contact the experts at Glenn Aire Co.

Call us at 817-736-1012!