Nothing is more annoying than having a furnace at your home that turns on and off repeatedly, especially during the winter season. This problem is called short-cycling, which can lead to a premature furnace breakdown. It can also cause a steep increase in your energy bills.
Three Reasons Your Furnace Turns On and Off Frequently
Dirty Air Filter
A dirty air filter is the most common reason why a furnace turns on and then off after a few minutes. When the air filter is dirty, it blocks the airflow, and the unit gets overheated. It causes the furnace to shut off automatically as a safety precaution. You can turn the heater off and replace the clogged air filter with a new one to prevent it from short-cycling.
A faulty thermostat is the second most common reason why a furnace turns on and off repeatedly. In such cases, check the battery of your thermostat. Try replacing the batteries and see if that fixes the problem. In the case where your thermostat is not battery powered, open its panel, and examine the low-voltage wires inside. If the wires are damaged, then make sure to call a professional to fix it.
In some instances, the thermostat device is not at fault, but the location of the thermostat is causing the problem. It is because thermostats, which are kept too close to a heat source, such as direct sunlight, tend to misread the house temperature and shut off the furnace too early. You may need to move the thermostat in a shadier place in the room.
The Furnace Is Improperly Sized
The third and most expensive reason is having an improperly sized furnace. In such cases, the only solution is the replacement of your furnace with an appropriately sized one. A furnace having a larger capacity will heat your house too quickly and will shut off early, and it can also overheat. Similarly, a furnace that is too small in capacity can also cause short-cycling.
Troubleshooting Guide – Furnace Turns On and Off Frequently
Here is a quick troubleshooting guide to help you deal with a furnace that turns on and off frequently.
- Check your furnace's air filter and make sure it's not clogged or dirty.
- Check the thermostat to make sure it is functioning correctly.
- Check the furnace blower motor.
- Check the furnace flue.
- Check the flame sensor and ensure it’s working correctly.
After completing all the above steps, if your furnace is still turning on and off, you may have an improperly sized furnace.
Also read: Furnace Maintenance: Things You Should Know
When to Call an HVAC Professional?
In case you are not able to resolve the short-cycling problem of your furnace on your own, call an HVAC expert from White Mechanical Inc. You can schedule a free consultation with us to ensure that you don't end up with a faulty furnace during the coldest time of the year.