Our Blog

Gas Furnace on the Fritz? How to Troubleshoot Your Home Heating Equipment


These tips for troubleshooting a gas furnace might help you get your system running quickly when it starts malfunctioning. It might have something as easy to fix as a dirty air filter, or a thermostat that needs a different setting. Conversely, you might find the problem is one best addressed by your trusted HVAC contractor.

Furnace Produces No Heat

Check the thermostat to see that it’s set to “heat” and turn it up and wait a few minutes. If it doesn’t start, open the furnace and look for signs of ignition or that the pilot light is burning. If yours has auto-ignition, you may have a problem that requires professional assistance. If yours uses a pilot and it goes out, clean the thermocouple and the pilot and try relighting it.

Furnace Turns On and Off Frequently

A dirty filter slows the airflow through the air handler and triggers a safety switch that shuts the furnace off shortly after it starts. The burner where combustion occurs may be covered with soot, which also causes the system to shut down quickly. If both are clean, it might be a problem with the thermostat.

Runs but Produces Inadequate Heat

If your furnace is too small for your home, it won’t be able to keep up with the need for heat during exceptionally cold weather. Ask your HVAC contractor to help with troubleshooting a gas furnace if you suspect this is the problem. You may be able to solve the problem by increasing attic insulation and sealing the air leaks to avoid furnace replacement for an otherwise functioning system.

Setting the thermostat to “on” will make the fan run continuously. After the heating cycle is finished, it’ll continue to blow air, and as it does, the air will feel cooler and cooler. Switching the setting to “auto” will turn the fan off between cycles.

Noisy Operation

The blower motor may need oiling or the fan belts need adjustment or replacement.

For more assistance troubleshooting a gas furnace, contact the pros at HVAC & Plumbing Unlimited Heating & Air Conditioning, providing top-notch HVAC services for Alexandria-area homeowners.

Image Provided by Shutterstock.com

HVAC Unlimited Inc.
Great job!
Chuck - Bristow, VA
Ask about our special financing for 3 years with approved credit!
Accreditations & Affiliations