tracking pixel Gas Furnaces Won't Come On? Here's What to Check Before You Call a Pro
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If you’ve noticed your house is suddenly getting colder or you can hear your gas furnace click on but no warm air is coming out of the vents, your first instinct may be to pick up the phone. But before you call your HVAC professional, it’s worth taking a few minutes to check your gas furnace for some common causes of these conditions. Here are four problems that could be at fault and that you can easily fix on your own.

Check the power supply. You don’t have to lose electricity to your entire home just for the power to go out on your furnace. First, check the power switch on your furnace and make sure it’s in the on position. Next, check the electrical box to see if a fuse was blown or a breaker was tripped. Replace the fuse or reset the breaker if that’s the case, and you should be good to go.



Check the thermostat settings. Make sure your system is set to heat and that the temperature setpoint is lower than the ambient temperature in the room. The furnace will not come on unless the ambient temperature drops below the setpoint. To test the furnace, temporarily set the thermostat five to ten degrees higher than you normally would to see if it comes on, then return the thermostat to its normal setting when the test is complete.


Check the gas supply. Make sure your gas supply line is open. No gas. No heat.





Check the furnace filter and supply vents. If you haven’t kept up with changing your furnace filter, it may have gotten extremely dirty and started to block airflow, which negatively affects your furnace’s ability to heat your home. Another contributor may be blocked vents. Moving furniture, boxes, or other large items in front of supply vents restricts airflow and can cause some areas of your home to be colder, even when the furnace is doing its job. Replace the filter if needed, and make sure all supply vents are unobstructed.


If you’ve checked all of these possible causes, and your gas furnace still won’t start up, then it’s time to call your service provider. It may be a pilot light issue or a dirty ignitor or sensor, but correcting these more complicated causes is best left to the pros. Also, it’s important to have your gas furnace serviced annually. A routine tune-up will give you peace of mind that your system is ready for the heating season, and it will ensure all components are functioning correctly and operating at peak efficiency.

To learn more, call HB McClure at 717-232-HEAT (4328) or schedule an appointment online.