Why does my heat keep cutting off?

Does this sound familiar? Your furnace turns on, runs for a few minutes and then shuts off. Soon after, it turns back on and the process repeats.

What’s the problem?

Typically, a furnace keeps turning off and on (or “short cycling”) like this because of one of these problems:

• Heat exchanger is overheating due to low airflow
• Dirty flame sensor rod
• Oversized furnace

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Quick DIY fixes

• Change the furnace filter if it’s dirty
• Open all your air supply vents (yes, even in rooms you don’t use)

 If your heater stands on uneven or soft ground, the tip-over protection button may not be fully pressed, falsely leading the heater to believe it is tipped over.

For very sensitive heaters on uneven grounds, even a person walking past the heater could cause the tip-over protection to trigger. This can also happen if the tip-over protection is using a so-called accelerometer: A sensor measuring acceleration. When the heater senses movement, it shuts off. This can also happen by someone stomping past the space heater or a pet bumping into the heater if the sensor is too sensitive.

The automatic shut-off of the space heater, of course, should not be triggered by such small impacts. Faulty sensors can also cause repeated space heater shut-offs.

How to test it

You can easily test the tip-over protection by tapping the space heater when it is turned on. Does it turn off when you tap it? If yes, the fault is in the tip-over protection.

If your heater stands on uneven or too soft ground, a simple fix is to place it on a solid, even surface. 

Else if the issue persists, it is usually best, to get a new heater. Faulty electronics are hard to detect and it requires professional knowledge.

Conclusion

Oftentimes you can find the reason for your space heater shutting off by trying out different wall outlets, cleaning the air filter, or placing it on a different surface. Once you found the issue, however, it is usually the best solution to replace your space heater. When the issue is inside your space heater, I would not recommend trying to fix up the electronics. The risk of something going wrong is too high compared to saving the $50-$200 for a new space heater.

Why does my heat turn off after a few minutes?

How do I stop my heater from going short cycling?