Reasons Your Furnace Won’t Turn On

The last thing you want to find out on the first chilly night of the season is that your furnace isn't turning on. Here are five common reasons why you might be left in the cold. 

1. An Ignition Is Faulty

If your ignition sensor is damaged or dirty, it could fail to start the furnace. The best way to know if this is the problem is to stand near the furnace when it's trying to turn on. If you hear the ignition click but not ignite, there is something wrong with the ignition mechanism. 

If the ignition simply needs to be cleaned, you can turn off the gas, remove the front panel, remove the ignition sensor, and very gently clean it of dirt and debris. If the furnace still will not turn on after you've cleaned everything, the ignition sensor may need to be replaced. 

2. The Gas Turned Off

If this is the first time you're turning on the furnace for the winter season, you may need to check that your gas line is turned on. Find the shut-off valve outside and verify that it is in the ON position.

If other gas-powered appliances in your home are working, check that the gas line to the furnace itself is not obstructed. If you ever smell or suspect a gas leak, call for professional help and seek fresh air immediately. 

3. The Electricity Supply Is Interrupted

Even if your furnace is powered by oil or gas, it may still need electricity to run. Make sure a breaker has not been tripped and that the furnace is still connected to power. 

If the furnace trips the breaker again after you turn the electricity to the furnace back on, you'll need to call a repair technician to find out why. 

4. The Air Filter Is Clogged

Furnace air filters need to be changed regularly as part of their normal maintenance. If you're not sure of the last time your furnace's filter was changed, it's worth checking to see if a clogged or dirty filter is preventing it from turning on. 

Furniture or household belongings could also be blocking the registers in your home, further hindering air from circulating through the furnace. Once you've replaced the air filter, check to make sure heat registers are open and clear. 

5. The Thermostat Is Malfunctioning

It may not be a problem with the furnace at all, but instead, perhaps the thermostat is not functioning as it should. Most digital thermostats will give an error message, so check there first. 

The thermostat may not be connected or communicating with the furnace itself. If you're adjusting your thermostat but hearing absolute silence from your furnace, this may be the reason. 

To learn more, contact a company that offers residential HVAC services.


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