image of homeowner feeling chilly due to short cycling furnace

The winter brings a frigid chill in the air. As we approach the peak of the season, the temperatures will keep dropping, making it more uncomfortable outdoors. Do not let your family suffer from freezing nights. Take a look into your furnace to ensure that it is working correctly. Some problems can be resolved easily, while some can be a complex issue. One of these includes short cycling or when the furnace runs then shuts off and starts again. This article delves into what short cycling entails and what you need to do when you notice your furnace experiencing this problem.

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Is My Furnace Short Cycling?

Typically, a normal-working system will switch on and operate until the set thermostat temperature is reached. It will switch off to allow the room to maintain the heat and only resumes when the temperature drops again. A furnace that turns on and off in quick succession means that it is short cycling. It will fail to reach the desired temperature. Not only that, but your heating system will wear out faster, and, consequently, your home will still feel cold despite your furnace running all day.

Why Is My Furnace Short Cycling?

image of question mark depicting furnace short cycling questions

There are several reasons for furnace short cycling. The proper solution depends on the cause. Here are a few reasons that can trigger this problem:

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Furnace is Overheating

Overheating is usually caused by improper airflow. HVAC units are built with a safety measure to protect them from damages. For instance, if your system gets too hot, it will switch off automatically. This emergency measure is to ensure that your heating system does not sustain damages like a cracked heat exchanger. With a cracked heat exchanger, deadly gases like carbon monoxide can leak into your home. Fortunately, your system has built-in protection in place.

Bad Flame Sensor

image of a gas furnaceThe flame sensor in your furnace monitors the gas valve. It prevents raw gas from entering your home. It triggers your valve to shut off when no flame is present. A faulty sensor, however, switches the gas valve off even though the flame is necessary. A quick way to resolve this is by cleaning the sensor. If that does not work, then the bad flame sensor needs to be replaced. Seek a professional HVAC contractor to conduct the necessary replacements.

Furnace Filter Is Dirty

The HVAC filter gets caked with dust and other debris over time. This causes short-cycling as you’ll notice your furnace running for a short while before turning off. The air your furnace is pumping out might also be hotter than usual. This is because there isn’t any proper airflow, so the furnace does not cool down as it should. The heat will build up, and your furnace will shut down as a safety mechanism. Wash or replace your furnace filters when necessary.

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Heat Grates Are Blocked

hands in front of hvac air vents

The warm air is released into your home through the heat grates. If these are obstructed, the air cannot flow out properly. The heat is instead trapped inside the unit and causes overheating. This, inevitably, will cause short cycling and can be resolved by removing the blockages. It would help if you also kept in mind that at least 75 percent of all HVAC dampers should be open at all times. These mechanisms allow you to control whether a zone receives heated air or not. Closing a high number of these vents can only lead to overheating.

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Exhaust Vent Is Blocked

The exhaust vents should always be open. They can get blocked by nests, snow, shrub, and beehives, and more. These should be removed immediately. As part of the maintenance, it should be checked regularly. If dangerous animals are blocking the vents, contact animal control to assist you in the removal.

Thermostat Is In The Wrong Location


Thermostats have built-in sensors that measure the indoor temperature. This way, it can conduct proper furnace regulation as per the environment temperature. It cannot do its job correctly if the thermostat is located near any direct heat source. You might have placed it near a heating grate or a window, which can mess up with the sensor readings. The thermostat will conclude that the house has reached the set temperature and switch off the furnace. Make sure that the thermostat is away from anything that can affect its sensor readings.

Furnace Is Too Large For Your Home

You might think that having the biggest furnace you can afford for your home is the best option. However, this is not always the case. Having excess capacity can lead to short cycling. When this happens, wear and tear will happen prematurely, hot and cold spots will be prominent around your house, and you will have increased heating bills. You will need to replace your large furnace with a furnace size that best fits your home. A professional HVAC technician can conduct the proper calculations to help you.



Get your home winter-ready by ensuring that your furnace is in tiptop shape. If it is short cycling, look into the reason behind it using the clues provided in the list above. Seek professional assistance to ensure proper diagnosis, repairs, and replacements. This way, you will have a warm and safe winter using your longer-lasting furnace.

Call Hart Home Comfort For All Of Your HVAC Requirements

hart-logoHart Home Comfort offers high-quality HVAC services in Nassau County, Suffolk County, and Queens, New York. We have the best professionally certified technicians who conduct excellent heating and cooling repairs, replacements, installations, and maintenance. All our techs are friendly, knowledgeable, and experience in providing correct and timely HVAC services.

Rest assured that our company offers affordable HVAC service rates in the area. Our maintenance services help increase your home comfort and energy efficiency. When you need to replace your current system, our techs can recommend the best make and model within your budget. All our works are backed with a guarantee. Schedule a service appointment and call Hart Home Comfort today. We offer free, in-home estimates.

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For any questions about what Hart Home Comfort can do for you, give us a call today. Click here to contact us now or call us at (631) 667-3200 to find out more!