Noises From the Single Intake Vent on a Furnace

Bolts

• Your intake vent is attached by either bolts or screws. The slight vibration that the furnace and blower system create can eventually cause these attachments to loosen. Rust can corrode your bolts and lead to a similar problem. As the mounting loosens, the intake vent starts to vibrate whenever the furnace is used and this creates loud noises. Replacing and re-attaching bolts and screws can solve this problem.

Clogs and Temperature

• Intake vents can become clogged over time due to dust and debris build up. Even if air can still make it through, it will not be able to do so efficiently, which can lead to strange noises coming up through your ducts. Temperature changes can also cause noise. The intake vent may be heated by its nearness to the furnace. In cold weather, this causes cold metal to quickly expand, leading to creaks and groans.

Fan

• Fan systems create power air currents that draw air in through the intake vent and expel it back through the house. Fan systems can be the noisiest part of your furnace. Small misalignments in the fan blades can lead to rattling. Vibration here can also knock bolts loose. The fan motor can run loud as it starts to age. Cleaning a fan and replacing any damaged parts can solve this noise issue.

Liners and Insulation

• If your vent is well secured and your fan is functioning correctly but the noise persists, consider investing in liners or insulation. There are vent liners and simple rubber pads you can use to stop the intake vent from vibrating against the wall. You can also wrap insulation around the vent to prevent the creaks and groans that occur when the cold metal meets heat.