HD Air truck

Comfort is on the Horizon

Furnace Short Cycling

Furnace Short Cycling

When you turn on your HVAC system to warm your home in the winter, you don’t expect it to turn off and on every few minutes. Leaving a furnace in the “auto” setting will cause the system to shut down once it reaches the desired temperature on the thermostat before starting again. However, the heating cycle should take longer than a few minutes to complete. 

Our expert technicians are here for youSchedule Online Today

Furnace short cycling happens when the heating unit only fires up for a few minutes at a time. A short-cycling furnace can lead to heating and energy inefficiencies, so you need to address the root of the problem quickly to ensure you can adequately heat your house in the winter. 

Short Cycling Symptoms

Inconsistent Heatingwoman trying to turn heat up on a short cycling furnace

Varying temperatures inside your house can signify many problems, including HVAC issues, drafty windows, and air leakage. However, short cycling usually causes inconsistent heating if the room’s temperature never matches the one on the thermostat. 

When a furnace has a short heating cycle, the unit will never run long enough to generate the warmth needed to reflect the set temperature on the thermostat. It will likely shut down before reaching the desired temperature. Even though the cold air and thermostat settings will trigger the furnace to restart, it still won’t produce sufficient heat.

Heater Starts Up and Then Stops

If the heater starts up and then stops, or if your furnace won’t turn on when the temperature drops or lasts only for a minute or two, short cycling is likely the problem. As a result, the furnace can start and stop up to eight times in an hour on cold days, especially if your house doesn’t have great insulation to retain the warmth the furnace manages to produce. 

Increased Energy Bills

Short cycling can have detrimental effects on your energy consumption. One of the biggest energy consumers for most households is the HVAC system. Still, your energy usage can quickly spike if the furnace runs inefficiently for long periods. 

Any time a furnace doesn’t run at its optimal performance level, it will consume excess energy to produce the desired temperatures on the thermostat. The extra strain on the system can cause parts to wear down more quickly, forcing the unit to consume more fuel. Unless you identify the cause of the short cycling problem, your monthly energy expenses could spike. 

Why Is My Furnace Short Cycling?

A short cycling furnace is a common problem for HVAC systems. The term describes the short heating cycles that occur due to several furnace problems. Instead of the furnace running for several minutes to efficiently warm up a residence, the system will work for a few seconds or a minute before stopping. 

Heating units can start short cycling for several reasons, including the ones below. 


a woman cold in her house because of her short cycling furnace

Air filters are an integral aspect of HVAC equipment because they trap airborne particles. With clean filters in place, your home will have fresher air, and the furnace’s internal components won’t get dirty too quickly. A clean filter also helps prevent blower problems by ensuring the fan can get enough air to the heat exchanger.

Unfortunately, dirty air filters restrict airflow to the heat exchanger. This causes the furnace to overheat due to the extra strain on its other components. 

Thermostat Issues

Your thermostat controls the furnace. The heater won’t turn on or off unless the thermostat’s settings and sensors dictate it. As such, faulty thermostats commonly cause furnace short cycling. 

Sometimes, these devices aren’t faulty. They simply don’t have enough power to accurately read temperatures and trigger the HVAC unit. Changing the batteries can help with this problem. 

Clogged Burners

Without regular furnace tune-ups, your system burners and flame sensors can quickly accumulate debris. The burners work to burn oxygen and gas, oil, or propane to produce heat that blower fans disperse through vents. If the burners clog with dust, dirt, and other debris, the furnace can shut off quickly or fail to produce enough heat to activate the blower fan.

Dirty Air Ducts or Obstructed Vents

Air filters aren’t the only furnace parts that can restrict airflow. Your furnace’s warmth travels around your home through air ducts and vents.

Ductwork can collect debris as an air filter does, and it can develop gaps and tears that prevent enough air from reaching the furnace. Airflow restriction also occurs when vents fill with debris or become blocked by furniture. 

How To Fix a Short Cycling Furnace

Troubleshooting Steps

Sometimes, furnace short cycling stems from an easily fixable problem. If you need to know how to fix a short cycling furnace, consider these steps to troubleshoot your heating unit:

  1. Check the air filter and replace it if necessary.
  2. Inspect the thermostat to see if the batteries are dying or if the device has another problem.
  3. Ensure your vents are clean, open, and free of blockages.

DIY Solutions for Minor Problems

One of the best things you can do to make your furnace function more efficiently is regularly changing your air filter. Ideally, you should change the filter every 30 to 90 days. Yet, if your household includes pets or members with allergies or asthma, it may be best to replace the filter once a month since the screens can get dirty more quickly.

By changing your air filters regularly, you ensure your HVAC system gets enough airflow to work properly. It also keeps debris inside the furnace at a minimum. Otherwise, you could need furnace repair more often due to premature wear and tear of your furnace’s components.

When You Need a Professionalhvac technician trying to fix a short cycling furnace

If your troubleshooting efforts don’t rectify your furnace’s short cycling problem, seek professional help from a qualified HVAC company. Furnace technicians have the skills, equipment, and experience to inspect the unit to uncover the underlying problem causing the system to short cycle. 

For example, if your home has an improper furnace size, the system will likely short cycle. However, that’s not a problem you can fix yourself; the technician can determine if you have a wrong-sized furnace and proceed with the furnace replacement. 

Importance of Regular Furnace Maintenance

Routine furnace maintenance is a must if you want to keep your heating unit running smoothly throughout the winter season. Professional furnace tune-ups in the fall will ensure your system operates efficiently, experiences fewer breakdowns, and provides reliable warmth throughout the winter months.

Maintenance also helps with your energy consumption. When your furnace runs correctly, it consumes less energy, decreasing monthly utility expenses.

The Takeaway

HD Air and our team of local HVAC technicians can help with furnace short cycling and keep your furnace in great condition. Thanks to our decades of experience and comprehensive HVAC services, we offer 100% satisfaction and same-day services. Contact our team today to schedule a repair