How to Stop a Forced Air Furnace From Making a Bang When it Shuts Down

If your forced air furnace is making popping or banging sounds, a few screws may be all that is needed to make your home quiet again. The noises you hear are typically from the expansion and contraction of the duct work as it warms with heated air, and when the duct work cools to room temperature.

Instructions

Difficulty: Easy

Things You’ll Need:

• screwdriver
• you may also need: insulation and duct tape.

1. Isolate the area of your duct work that is making noise. You may want to recruit a few friends or family numbers if you have a large area to cover. You will need to stand and watch your duct work when the furnace begins its cycle and for a few minutes after. If you notice the sound when the furnace turns off, be prepared to watch for a few minutes after the cycle ends.
2. Once you know the area of the duct work that is making the popping noises, check the screws on the duct work itself and the mounting hardware that attaches it to the ceiling/wall. If you can tighten them, do so at this time. This may solve the problem if the duct work was too loosely joined and flexing at the seams.
3. If tightening the screws in the noisy area does not help, try insulating the area of the duct for noise reduction. Wrap the duct in several inches of insulation if it is accessible using heat safe insulation, or layer a few inches of insulation on the exposed surfaces of the duct. Cover the insulation completely with duct tape until you cannot see the insulation.

Tips & Warnings

• Have a Phillips head and a regular head screwdriver available.
• Wear gloves and long sleeves when using insulation. Tuck your sleeves into the gloves.
• If your duct work is in a cold area, you may want to consider insulating it even if it isn't making noise, the savings can be considerable!
• Insulation itches! Wear long sleeves, gloves and be sure to protect your eyes.
• Do not use materials that are unsafe when exposed to heat.