A Thumping Noise From the Attic Fan

Quality Issues

• If your attic fan is making regular thumping noises, the problem could be the size of the fan in relation to the job that it has to do. Fans are designed to move air effectively throughout a certain space. If your attic fan is too small to work in your attic or home space effectively, its motor will run longer and harder trying to do the job. The result is often a pounding or thumping noise as the fan runs harder than it is supposed to.

Vents

• Fan vents can also cause problems when it comes to noise. Attic fans are protected by shutters or screens that help keep larger debris away from the ductwork and help control air flow. If these shutters are attached loosely to their supports, the air from the fan can move them. Often, shutters can fall into a cycle of movement that corresponds with the turning of the fan blades, thumping with each new wave of air that comes in.

Vibration and Mounting

• An attic fan is mounted in place with a series of screws and bolts. Over time, the vibration of the fan can work these mounting brackets loose. The result is a loose fan that can vibrate itself back and forth as it works. This can create bumping or thumping noises echoing down from your attic. Fortunately, tightening or replacing the screws can easily fix this problem.

Lubrication

• In some fans, the fan blades turn around a central core or are tightly controlled by a framework designed to properly channel air. Over time, however, the lubrication of the fan can wear away. This can cause the fan blades to develop an erratic spin as they move. They may back into the sides of the fan frame or wobble around their axis. Either problem can cause the thumping noise you are hearing.