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Why Does My Furnace Keep Turning On and Off?

Last updated on September 28th, 2021

One of the most common furnace troubleshooting questions we hear from our customers is, “Why does my furnace keep turning on and off?”. Normally, furnaces should cycle on only when the temperature in your home is lower than the pre-set temperature you have input at the thermostat. When the desired temperature is achieved, your furnace should turn off and only turn back on when required to bring the temperature back up.

However, some homeowners may find that their furnace is constantly cycling on and off, which can become more than just an annoyance – it can also indicate a serious problem. Luckily, there are some simple explanations for why this might be happening with your furnace:

Thermostat Errors
If your thermostat is faulty or is set incorrectly, your furnace may be signalled to turn off and on more frequently than necessary. Carefully review your thermostat’s settings and make sure they are correct. Next, consider the placement of your thermostat in your home, and move it if it is close to a heat source or direct sunlight, which may be signalling your furnace to shut off. A furnace turning on and off can also be the result of a faulty thermostat, so it may need to be completely replaced.

Short Cycling
Short cycling is often the number one answer to the question, “Why does my furnace keep turning on and off?”. Short cycling usually involves issues with the furnace itself, starting with a simple dirty air filter to a major issue with the circuit board. There are many other serious furnace issues that can cause short cycling, such as:

  • Cracked heat exchanger
  • Improper or clogged venting
  • Malfunctioning inducer
  • Dirty flame rods
  • Improperly sized furnace
  • And more

These are just some of the issues that can cause your furnace to overheat, thereby triggering safety measures which shut off your furnace. Once it cools down, the furnace will start up again and the cycle will repeat over again until the problem is resolved.

Our team recommends seasonal furnace maintenance to avoid these potential furnace issues and to prevent short cycling from occurring in the first place. Regular tune-ups and/or replacement of broken and damaged components can ensure your furnace keeps running efficiently.

If you are still left asking, “Why does my furnace keep turning on and off?” we are here to solve the problem. Evam Canada is pleased to offer emergency furnace repair services to Mississauga and GTA residents. Our technicians are available around the clock to quickly respond to your furnace issues when you need us most!

Call us at 1-905-642-5544 for fast and friendly emergency furnace repair now.