Temperature Talk: 5 Common Gas Furnace Problems (and Solutions)

Welcome back to our guest bloggers series! Today’s post comes to us courtesy of Thompson Plumbing, Heating, & Cooling. Thompson is located in the Greater Cincinnati/Northern Kentucky area, and graciously allowed us to republish this list of five problems people commonly encounter with gas furnaces. We hope that these tips are helpful in keeping your home comfortable this winter!

It’s that time of year — temperatures have dipped and you’re using your heating system on a regular basis. Unfortunately, many people find that their natural gas-powered furnace isn’t operating properly once they start using it again in the fall or winter. The problem may be fixed with something as simple as relighting the pilot light or replacing the filter, or you may need a more complex furnace repair. Here are five common gas furnace problems, along with possible causes and repairs.

1. Furnace is not producing heat.

Possible causes include a broken thermostat; the thermostat being set too low; an out pilot light; a blown fuse or circuit breaker; a closed gas valve; or electronic ignition problems.

Depending on the cause of the problem, you may need to make sure the thermostat is in “heat mode” and adjust it up a few degrees; relight the pilot light; replace a blown fuse or tripped circuit breaker; troubleshoot the thermostat; or troubleshoot electronic ignition problems.

2. Furnace is not producing enough heat.

This may be caused by obstructed airflow or dirty or misaligned gas burners. In some cases, airflow is obstructed by a dirty furnace air filter, and if it is replaced, the problem is solved.

To troubleshoot the problem, try replacing the air filter, and if that doesn’t solve the problem, have a technician come out to clean/adjust the burners and make sure airflow to the combustion air chamber isn’t obstructed.

3. Blower always running

The thermostat may be set to the “fan continuous” setting, or, in cases where the thermostat has no fan setting, your furnace may have a faulty fan limit control switch.
To fix the problem, you might only need to adjust the thermostat fan setting, or it may be necessary to reset or replace the fan limit control switch on your furnace.

4. Furnace coming on and off too quickly

This behavior could be caused by a problem with the heat anticipator in the thermostat, a problem with the blower motor, or a dirty furnace air filter.
Start by replacing the air filter. If this doesn’t solve the issue, you may need to adjust the thermostat heat anticipator or troubleshoot the blower motor. The blower motor may need to be oiled at lubrication points, or have its belt adjusted (if it is too loose) or replaced (if it is frayed).

5. Noisy Operation

You may be able to determine the cause of a loud furnace by the pitch of the sound it is making: a high-pitched noise may indicate shaft bearings need oiling or that the blower belt is slipping; a low-pitched sound can mean that the pilot light is poorly adjusted or that the gas burners are dirty.

To troubleshoot, try oiling blower motor lubrication ports and checking for proper belt tension and that the belt is not frayed. You can also try adjusting the pilot light and having a furnace service technician clean or adjust your gas burners.

In many cases, troubleshooting and furnace repairs will require the services of an HVAC systems professional. Even if your gas furnace seems to be operating fine now, it’s important to schedule an annual heating tune-up to ensure that it will continue to function properly throughout the entire cold season.

Thanks again to Thompson for contributing this article! To learn more about the Thompson company, please visit their website.