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Why Does My Furnace Turn On & Off

A frustrated homeowner bundled up in her winter coat while inside her Hazelwood, MO, home because her furnace is not working properly.


Does your finicky furnace turn on and off, over and over again? This problem is called furnace short cycling, and it can be exhaustively annoying, but more importantly, it could signify a bigger problem with your system. In Hazelwood, MO, frigid winters can exacerbate the problem to the point that your furnace is turning on and off every minute or so. The good news is you don’t have to put up with furnace short cycling. The bad news is there could be multiple problems causing it to happen. Luckily, your local heating contractor Academy Air will always have the parts and tools needed to diagnose and solve your furnace short cycling problems. Here’s some more information about this issue to help point you in the right direction.


What is Short Cycling?

Furnace short cycling is a problem that occurs in furnace units and may get worse as the weather gets colder. This term simply refers to a furnace that turns on and off repeatedly. When the weather gets cold, it’s normal for the furnace to turn on a few times per hour. However, your furnace shouldn’t be shutting on and off at more frequent intervals, like every minute – this indicates a problem. If you’re having issues with the temperature in your home, know you can always rely on our experts at Academy Air for our professional heating services. While this problem could have a few simple fixes, you’re more likely to need to call for furnace repairs. Read on for more about the causes of this problem as well as the solutions.


Short Cycling Causes

Short Cycling could be caused by multiple things, making it difficult for you to tell just how to resolve it. First, you should check the obvious problems and move on to calling your local heating specialist when you find yourself out of answers. Here are a few problems that may cause furnace short cycling:

  • Air Filters – Severely dirty air filters may cause this issue because they restrict the airflow to your system. Replace the filter and set a reminder to do this regularly.
  • Blocked Vents & Registers – This is another easy fix you can try. Make sure that nothing (furniture or décor) is sitting on top of or in front of your air vents. This restricted airflow could also cause this problem.
  • Heat Exchanger Obstruction – When the coils inside the heat exchanger are blocked by dust or other debris, the restriction of airflow could cause the short cycling you’re experiencing.
  • Thermostat – If the thermostat has shorted out or is set to the wrong settings, you could experience some short cycling.
  • Safety Switches – Most systems are built with safety switches that will shut the system off if the temperature reaches a certain heat or the pilot light extinguishes. A problem with the safety switches on your system could be the problem.

A heating technician examines and administers repair to a central gas furnace in a Hazelwood, MO, residence.

Signs of Short Cycling

-Cold House

A cold house can be caused by a variety of factors, including inadequate insulation in the walls or attic, an insufficient furnace, and faulty windows. If the temperature you want in your home is never reached, your furnace could be short cycling.

-Short Heating Cycles

The length of furnace heating cycles is determined by the temperature requirements. In the cold season, a house that has been shut down for months may require the furnace to run for hours. Heating cycles in a well-insulated, heated home may be as short as five minutes. If the time between cycles is less than five minutes, the furnace is most likely short-cycling.

-Frequent Heating Cycles

Heating cycles that run for shorter periods of time produce more frequent heating cycles. Depending on the outside temperature and how well-insulated your home is, these short cycles may occur five to eight times per hour.

-Room and Thermostat Difference

When the two temperature readings on the thermostat, room temperature and thermostat set temperature, never match, you have a short-cycling furnace. If the room’s temperature steadily rises during the heating cycle, but falls short of the set temperature—and does so repeatedly—then the furnace is short cycling.


Short Cycling Solutions

The first thing that has to be done is to determine the cause of your short cycling problem. If the issue is a dirty air filter, that is an easy, do-it-yourself fix. Simply remove the old filter and replace it with a new one, making sure the arrows on the frame point in the same direction as your unit’s airflow. If the problem is a faulty thermostat, it could be improperly set or need new batteries, which is another easy fix. If the thermostat is dead or defective, call in our professionals to replace it so the comfort of your home can be restored. Something else that could trigger your furnace to shut down too often is a clogged flue. The furnace flue is constructed to remove hazardous gases. If it’s clogged, the furnace will shut down to prevent those gases from building up inside your home. You can fix this by turning off the furnace and taking apart the flue to check for clogs and remove them before reassembling. You can also call our experts to handle this for you. Other causes, like a dirty flame sensor or defective fan limit switch, can also be fixed or replaced by our qualified team at Academy Air.

Tackling these problems by yourself may not be the best option. Of course, you should check your furnace filter and air vents to ensure they aren’t blocked. However, the rest of these problems are best left to a professional. Luckily, Hazelwood, MO, residents can contact Academy Air for 24-hour repairs that keep the heat on all season long!

3 pairs of hands are extended over a heater to feel the warmth from the home’s furnace in Hazelwood, MO.

When you’re experiencing problems with the heat in your home, you can rely on our experts at Academy Air in Hazelwood, MO, to provide superior service when you need it most. Call us today at (314) 377-7057 and start collaborating with us so we can restore the comfort level of your home.


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