You trust your furnace to keep your home at the perfect temperature without having to think about it. Sometimes, however, you may notice the furnace turning on and off frequently. This behavior is known as short cycling. Short cycling can cause uneven heating, more expensive utility bills, and damage to your furnace. If your furnace is short cycling, it’s time to find the problem and get it corrected. The following are some of the common reasons your furnace may be short cycling.


1. Your Furnace is Overheating

Overheating is one of the main reasons that short cycling occurs. Overheating happens when the heat exchanger gets too hot and must shut down to prevent further damage. When it has cooled down, it will turn back on and start the cycle all over again. Overheating can be caused by a number of different problems. 

  • Dirty Air Filter- If your air filter is blocking air from entering your furnace because of dust and other buildup, the heat exchanger may get too hot. It is a good idea to check your filter and change it if necessary. Try our Worry Free Filter Program if you don’t want to deal with the hassle of trying to remember to change it.
  • Blocked or Closed Vents- If air flow is restricted in your ducts, the pressure will increase and the heat exchanger may not be able to transfer enough heat. It will get too hot and have to turn off. This can be caused by blocked/closed interior vents or by a blocked exhaust vent. 


air filter

Air filters should be replaced regularly to prevent overheating

by Donar Reiskoffer [CC BY-SA 3.0 (] via Wikimedia


2. Your Furnace is Improperly Sized

If your furnace is new, your problem may be a result of it being too large for your needs. An oversized furnace will be able to quickly heat up the house, and then it will turn off abruptly. This very fast heating will likely result in uneven heating throughout your house. Not only is the constant on and off bad for your furnace, but it also requires a lot of energy to start up such a big motor. This will mean larger utility bills. An HVAC technician can perform tests to determine the correct furnace size for your home. 


3. Your Thermostat is Malfunctioning

Another explanation for short-cycling may be due to a broken thermostat. The thermostat is the main control center of the HVAC system that tells the other components what to do. If the thermostat isn’t working properly, it may be telling the furnace to turn on and off too often. Your thermostat may have battery or wiring issues, or it may be installed too close to your heat source. 


Meridian Heating and Cooling

A short cycling furnace should be examined and fixed as soon as possible. Damage to the furnace can be costly if it is left unchecked. For Meridian furnace repair, trust Snowflake Air to get the job done in a timely and professional manner. Visit for all your Treasure Valley heating and cooling needs.