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With winter approaching, it is imperative that your furnace works properly to ensure your family remains warm and comfortable, even on the coldest days. If you fire up your furnace and notice that the unit constantly turns on and off, your furnace will not able to heat your home to the desired temperature.

This issue might be a problem called short cycling. When you understand this common issue and the potential culprits that cause it, you can ensure that you and your family don’t suffer a single cold morning this winter.

Here is some valuable information about furnace short cycling, including potential reasons why your furnace may have this issue.

Furnace Short Cycling

A functional furnace will turn on and continue to run until the temperature set by the thermostat is reached. Short cycling occurs when the furnace will turn on and turn off again within a few seconds. In addition to not properly heating your home, short cycling is also hard on your furnace and can cause your furnace components to wear prematurely.

Luckily, there are several common causes of furnace short cycling and many do not require an expensive fix. No matter what the cause of short cycling, however, you should always work with a licensed HVAC technician to determine the reason why your furnace is short cycling, fix the problem, and ensure your furnace does not short cycle again in the future.

Dirty Furnace Filter

Your furnace filter serves a simple but critical purpose: the filter eliminates allergens, dirt, dust, and other impurities from the air before the impurities enter your furnace. A dirty air filter — whether the filter is a more cost-effective filter that should be replaced monthly or a costlier washable filter that will last for several months — is a common reason why your furnace will short cycle.

A dirty air filter does not allow proper airflow through your furnace, which in turn will cause your furnace to turn on for a few seconds and turn off again. If your furnace is short cycling, check the furnace filter first. Swap out the filter for a new model or, if the filter is washable, clean out the filter according to the manufacturer’s directions.

Often, simply swapping out a furnace filter will stop short cycling. Change your filter on a regular basis to prevent short cycling in the future as well.

Obstructed Exhaust Vent

Natural gas furnaces feature an exhaust vent that is typically found on your home’s exterior wall or roof. When the vent becomes blocked, typically with a bird’s nest, snow in the winter, or large pieces of debris, the furnace overheats and causes the unit to short cycle. Your HVAC technician can examine the exhaust vent to determine if there is an obstruction that causes the furnace to overheat and short cycle.

Never leave an obstruction in your furnace’s exhaust vent. In addition to causing short cycling, a blocked exhaust vent does not allow dangerous gases to be eliminated from your home. These gases, including carbon monoxide, can build up in your home and make your family very sick.

Improperly Placed Thermostat

The placement of your thermostat is critical to ensure that your home is heated evenly. When the furnace is placed next to another heating source, such as a space heater, a large appliance, or electronics that produce their own heat, the thermostat will turn off prematurely because the thermostat has reached its desired temperature.

Move your thermostat to a place that is not near any other heat sources, and move any appliances or electronics that produce heat away from the thermostat.

Short cycling is a common problem with several potential fixes. Contact the professionals at Carrano Air HVAC Contractors, Inc, with any of your HVAC related questions.

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