Why Does My Furnace Keep Turning Off?

December 2, 2024

The average furnace heats a home in Sharpsburg, GA, in 10 to 15 minutes. It typically cycles like this two to three times an hour. Something is wrong if your furnace is cycling more frequently and for much shorter periods, even if it’s blowing hot air. Short cycling in a furnace can be the result of overheating, which could be caused by a furnace that is not correctly sized for your home. Check to see if your ductwork is sized correctly or a mismatch between the furnace size and the size of the evaporator coil. A furnace that keeps overheating will lead to the dreaded result of a cracked heat exchanger.

Furnace Is Overheating:

Anything that obstructs the flow of air through the vents will put pressure on the furnace motor. As a result, the blower motor will have to work harder to circulate the air. Such stress on the motor can cause it to overheat, in which case the system will automatically shut down for safety’s sake. If you smell something burning throughout your house check the motor in your furnace to see if has stopped running. Be careful if you touch the motor because it could be very hot and could burn your hands. Check to see that you’re not blocking any of the supply vents with rugs or furniture. Don’t forget the number one cause of overheating, old faithful, the dirty filter. Overheating may also occur because dirt and dust have entered the furnace and created an insulating layer on the motor and heat exchanger. 

The Thermostat Isn’t Calibrated Correctly:

Thermostats need calibration now and then. That means adjusting the sensor inside them so that they read the temperature correctly. When a thermostat loses its calibration, it may think your home is already warm enough and shut the furnace down prematurely. This is more common in non-digital thermostats.

Heating System Is Too Big:

We touched on this briefly earlier, but the worst-case scenario is that whoever installed your furnace put something in that’s designed for a much larger home. With a furnace that is able to produce such a large amount of BTUs, your system will warm your home too fast and give you uneven results. The only way to solve this is to replace the furnace with one that will work correctly.