3 Tips for Finding the Cause of the Noises Coming from Your Home's Gas Furnace

7 March 2016
 Categories: Construction & Contractors, Articles


If you have noticed that your gas furnace has started making odd noises, you may decide to try to find the cause of them. If so, use the following tips for investigating the sounds to determine any potential problems.

Make Note of When You Hear the Sound

When trying to find the source of your furnace's noises, make note of when you hear the sounds. This could give you a clue as to what is causing them and whether or not the problem is serious.

For example, if you hear a faint bang every time the furnace starts or stops, this could be normal. Whenever the furnace kicks on, the motor starts abruptly, sometimes causing the casing to shift. However, if you have never noticed this noise before, there could be an issue with the bracket holding the motor in place.

Another time you may start hearing strange sounds is a few minutes after the furnace kicks on. A whirling sound for a few seconds could be the fan rotating because the blower has started. However, if you hear rattling noises along with the whirl, this could be a sign that the fan has become loose.

Look at the Fan If You Hear Rattling Noises

If you do hear rattling noises and suspect the fan is causing the sounds, you can check to see if it is still secure. Turn off the furnace and let the unit cool down for about 15 to 30 minutes.

Once the furnace has cooled off, open the access panel and locate the fan. Grab one of the blades and wiggle it. If it seems secure, the fan might not be the issue. There could be a belt inside the motor that has become loose or dislodged. In this case, you may want to have an HVAC professional take a look at it.

However, if the fan shifts when you grab it, the bolt may have become loose, and you may be able to fix it yourself. To do this, find the center bolt and use an adjustable crescent wrench to hand tighten it. Test the looseness of the fan. If it still wiggles, tighten the bolt again.

Once the fan feels tight, replace the access panel and turn on the furnace to see if you still hear the rattling noises. If not, the fan was likely the issue.

Turn Off the Heater If You Hear Any Noises Accompanied by a Strange Odor

Whenever you hear noises coming from the furnace, inhale deeply to see if the sounds are accompanied by a strange odor, such as burning metal or rotten eggs. If so, this could indicate a serious problem that needs to be checked out by a professional as soon as possible. Turn off your furnace and do not restart it until it has been checked out.

A burning metal odor could indicate a problem with the wiring. If there is a short in the electrical system, it could be coming into contact with the motor's casing or inner circuits. This could present a fire hazard, especially if a spark comes into contact with the gas flowing through the furnace during operation.

If you start smelling rotten eggs, this is a sign of a gas leak. The odor is caused by mercaptan, an additive in natural gas that helps in the detection of leaks since natural gas is normally odorless. When this odor is present, turn off your furnace immediately, open your windows, and call a repair service that provides emergency assistance.

If you are unable to find the cause of your furnace's noises or feel the problem could pose a potential safety hazard, you may want to have a professional look at it right away. Contact a furnace repair service to have the unit inspected and to discuss your options for either repairing or replacing it.