Why Does My Gas Furnace Keep Turning On and Off?

Your gas furnace is designed to turn on for as long as it takes to keep your home at the temperature you’ve set on your thermostat. But sometimes, it turns on and off too often, putting strain on your furnace that can cause premature wear and tear on your equipment, plus breakdown and diminished efficiency and performance.

This too-frequent start-and-stop dance is called “short cycling,” and it is typically caused by one of three things:

• A dirty air filter – Your air filter is designed to block dirt, dust, and other air contaminants from entering your duct system and circulating throughout your home. But after a while, it will become so clogged that it will actually block airflow into your furnace. That’s not good: your furnace’s heat exchanger needs that air to stay cool, otherwise it will shut down until it cools down (hence the cycling).

  This is one of the many reasons why you should check your air filters every 30 days or so during heating season, cleaning or changing them when needed (keep in mind that an expert technician will replace your air filters during a routine annual heating inspection – if you haven’t had one yet this year, now’s the perfect time).

• A problem thermostat – One of two thermostat issues could be contributing to a short cycling problem with your heating system: either the thermostat isn’t working properly, or it has been placed too close to a heat source (such as a heating vent or a window that gets lots of daytime sun). In the latter case, the thermostat sensor thinks you home is too warm and turns off the furnace.

  Thermostats are like any other appliance in your Connecticut home: they wear out over time. Be sure to have a heating expert check your thermostat when you have your annual heating maintenance.

• A mismatched furnace – When it comes to choosing a furnace, bigger isn’t always better. If you choose a furnace that is too large for your home, it heats the space too quickly and shuts off; all those starts and stops wear down your heating equipment quickly, possibly years before its time. In the meantime you’ll get diminished efficiency (which means higher heating bills) and poor airflow in your home (which means less comfort and uneven heating).

  Unfortunately, the only real fix for this problem is to replace your heating system with a properly sized high efficiency propane or natural gas furnace. If your current furnace is more than 10 years old, it could be the perfect time to do just that.

If your furnace is short cycling, start by checking and changing or cleaning (depending on the model) your air filter first. If that doesn’t work, contact the pros at Hocon for expert heating service in CT right away. And remember, if you haven’t scheduled your routine heating maintenance, it’s time!