Short Cycling

You may not notice it right away, but short cycling of your furnace can be an indication of problems that need to be addressed. Not only to prevent your furnace from getting to the point of a costly breakdown, but to also make sure that you aren’t losing value on inefficient heating at higher energy costs. Your furnace runs as a system, and if even one component of the system is damaged or hindered, it could ultimately end up being reflected in your energy bills. 

So, why is your furnace short cycling? Let’s take a look at some of the common causes of short cycling and what you can do about it!

Deterioration To Flame Sensors

Deterioration of the flame sensors can be a cause of short cycling that is urgent to address. Over time, corrosion and rust can occur from small amounts of water that are produced during furnace operation. As corrosion builds up, this triggers short cycling. This can be detrimental to not just your system, but the overall safety of your home. 



This is one of the most common causes of short cycling. If your components that sense the and monitor the temperature are not working properly it leaves room for the furnace to overheat and shut down. Most contemporary furnaces come with built-in safety devices that regulate the temperature of the furnace. Sometimes, short cycling is a result of a faulty heat exchanger. In some cases, a cracked heat exchanger will emit heat into the other components of your furnace, heating other components and resulting in short cycling. 


Blocked Air Filters

Believe it or not, even a dirty air filter can cause short cycling of your furnace. Clogged air filters block airflow and cause a backup eventually. When this happens, the warm air will remain in the furnace instead of exiting and distributing among the different areas of your home. The present air will cause the furnace temperature to rise and your system will shut off, causing more frequent cycling. 

Clogged Flue

A clogged flue is not only a cause of short cycling, but it can also be dangerous for your safety. Your system will cycle off to prevent carbon monoxide poisoning to the people in your home. It is critical that your system is able to detect this for your safety, even if the root of the cause is from a clogged flue.  Birds, pests, debris, and other objects blocking the vent can cause this, so checking the vent regularly is a good idea. However, it is best to rely on the experience of our professional HVAC team.

Furnace Size Too Large For Your Home 

If your furnace is too large for your home, your home will heat up much quicker than that of an appropriately sized furnace. Some areas of your home will likely heat faster than others, leaving cold spots and higher bills. Part of the issue with this is that your furnace will expel more energy when ramping up to provide the heat. You will get a quick blast of heat, working your system hard, and then having it completely shut off, only to be restarted again shortly after. Rather than, your furnace ramping up in a normal cycle and steadily pumping in the right amount of heat to complete a normal cycle. The former uses more fuel in the frequent starting process rather than a spaced out, smooth steady flow of heat. 


A faulty thermostat can be a big cause of short cycling. A thermostat that is not performing properly or is faulty may result in short cycling. If the thermostat is unable to properly function and read the temperature of the room it may be kicking on and off sporadically, causing your system to constantly fire up and burn through more energy, driving up your bills. The thermostat plays an important role in temperature detection, telling your system when to operate. Therefore, making sure the thermostat is functional properly is a critical inspection point. Oftentimes, you will want to rely on a trained professional to do this for an accurate assessment of the issue. 

Contact Us

Contact us today if you are having short cycling issues. We want to educate you on what might be causing short cycling, but it is best to let trained professionals diagnose and fix the problem. Rely on our trained and experienced professionals. Call for a free estimate!

Diamond Elite Contractor

The only Diamond Elite contractor in over 400 miles.