“Short cycling” is a term that’s used to describe what happens when a heating and cooling system turns on and off too frequently. When it’s happening, your furnace will shut off before your home is adequately heated and your system will go through many more heating cycles than normal throughout the day. Short cycling puts your furnace through excess wear-and-tear, which can quickly lead to breakdowns. Today we’re going to talk about why furnace short cycling happens and what you can do to prevent it from happening in your home!

What causes furnace short cycling?

Some of the most common causes of a short cycling furnace include:

  • Dirty air filter. When your air filter is dirty, it will block airflow to your furnace and cause your system to overheat. This can trigger your furnace’s limit switch, which will shut down your furnace even if your home isn’t properly heated.
  • Other airflow issues. In addition to a dirty filter, other problems that lead to airflow issues (such as blocked or closed air registers, dirt buildup on your system or problems with your air handler) can cause your system to overheat and short cycle.
  • Oversized furnace. If your furnace is too large for your home, it will go through very brief and frequent heating cycles because it will heat some parts of your home too quickly while other parts might not yet be warm enough.
  • Malfunctioning safety devices. Your furnace has multiple safety devices (such as the thermocouple, draft pressure switch and limit switch) that will shut down your system when they detect problems. If any of these devices are malfunctioning, they can shut your furnace off prematurely even if everything else is operating just fine.
  • Cracked heat exchanger. If your heat exchanger has a crack, it can pull extra oxygen inside and cause the burners’ flames to flare up. This can cause your furnace’s plenum to overheat and shut down prematurely.
  • Thermostat issues. If your thermostat’s batteries are dying or if it’s getting bad readings of your home’s temperature, it can force your furnace to turn on and off at the wrong times.
  • Extremely cold weather. When it’s extremely cold outside, you might think your furnace is short cycling when in reality it is just going through more heating cycles than normal because there is more of a demand for heat in your home.

How can you prevent furnace short cycling?

Four of the best ways to prevent furnace short cycling include:

  1. Checking/changing your air filter every month to avoid airflow issues.
  2. Keeping all of your home’s air vents open and clear of furniture.
  3. Scheduling a furnace tune-up every year so that Jerry Kelly Heating & Air Conditioning can inspect your system’s thermostat, heat exchanger, safety devices and other vital components.
  4. Always working with a trusted heating and cooling professional like Jerry Kelly Heating & Air Conditioning so that your furnace is the right size and your installations and repairs are performed properly.

If you have any questions about furnace short cycling, or if you’d like a heating system serviced or installed in your home, contact Jerry Kelly Heating & Air Conditioning, your St. Louis area furnace installation and repair contractor. We serve the entire St. Louis area, including towns like Dardenne Prairie, Des Peres and Frontenac, MO.

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