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5 Reasons Why Your Furnace Keep Turning On and Off

It can happen at any time of day or night. You hear your heating system kick on — and then a few minutes later, the entire unit shuts off without completing a heating cycle. This frustrating problem is referred to as “short cycling.”

Unfortunately, there can be many reasons your furnace keeps turning off and on. This issue can sometimes have quick, easy fixes. However, there are some instances where the only solutions are to schedule a professional repair. or sign up for an annual service plan.

So, what causes a furnace to short cycle? Read on for a list of possible reasons your furnace may be acting strangely, and some great advice on what to do about it.

Diagnosing Your Furnace Problems

Your thermostat is a master at regulating the temperature in your home, sending signals back and forth between your heating or cooling equipment, depending on the time of year. When you set the desired temperature, the thermostat senses the current room temperature, and calls upon thefurnace once it dips below the set point. During normal operation, your furnace cycles off and on between three, and six times per hour. More frequent, brief periods of off and on activity, is known as short cycling, and should it continue undetected for a significant period of time, can cause irreversible damage to your furnace components, and an unwelcome rise in energy costs. Without scheduling an appointment for furnace repair with an HVAC specialist, you run the risk of your furnace dying on the coldest day of the year.

Why Is My Furnace Short Cycling?
Restricted Air Flow

If the airflow through your HVAC system is hampered, due to blocked supply or return vents, or most commonly, because of a dirty air filter, the heated air from your furnace will have nowhere to go. As it accumulates within your air ducts and back towards the furnace, your heating system receives a message that sufficient hot air has been deployed, and shuts off. Minutes later, the thermostat calls for more heat, the furnace starts up again, and the cycle continues. The solution? Change your air filter regularly, and ensure there are no objects blocking return or supply vents.

Malfunctioning Thermostat

While it may seem obvious, make sure your thermostat is set to “heat” before calling for service. Next, try changing the battery, and finally, ensure the unit is shielded from direct sunlight, drafts, or an alternate heat source such as a lamp.

Dirty Air Filter

Do you keep up with your heating system’s maintenance needs? If not, you certainly should. For example, a dirty or clogged air filter can spell a lot of trouble for your furnace — and it can also be one of the reasons your furnace keeps turning off and on.

When the filter is coated in a layer of dirt and debris, it becomes impossible for air to pass through it. This lack of airflow can make it difficult for the heated air inside your furnace to make its way through the air ducts. As a result, your heating system can overheat — and it will shut down as a safety precaution. Overheating is a common issue that can lead to a short-cycling furnace.

Most heating and air conditioning systems have air filters that need to be replaced regularly. You should consider changing the filter once every three months or more often, depending on your needs. Many local furnace repair companies stress the importance of this simple maintenance task, so don’t ignore it!

Deteriorating Flame Sensor
This built-in safety feature can rust over time, and may require periodic cleaning, which is best left to a professional.

Improperly Sized Furnace
A furnace that is too large for your home may heat it quickly, but your interior will cool down just as fast, causing a series of continual on and off cycling. In addition to wasting energy, this repeated action will shorten the lifespan of your equipment, and result in more frequent repairs.

At Wulf Brothers, we want to help you and your family to stay warm and toasty this winter without having to spend any more than you have to on heating your home. We have been helping Door and Kewaunee County homeowners like you for more than 50 years. If you’re experiencing any type of heating problem, our team is more than happy to help.
For furnace repair in Door and Kewaunee County, schedule an appointment or call us at 800-854-5587.

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