Noise on a Gas Furnace Blower

Common Fan Noises

• If you have just bought a new gas furnace or have installed a new blower system (or moved into a new house), do not be surprised if the furnace makes noises. Some fans are louder than others, especially if you have upgraded to a more powerful furnace. Open your furnace and examine the fan. Sometimes new fans have pieces of paper stuck to them; the air blowing past the paper can create a surprising amount of noise that echoes through your ductwork.

Problematic Noises

• If your blower system starts to make noise where once it was quiet, this indicates a developing problem. If your blower starts rattling or vibrating loudly, part of your furnace may be working its way loose of its bolts. If so, the bolts need to be tightened. Your fan may have become slightly warped over time, so you might need to switch it for a new fan that does not create as much noise.

Motors

• Fan motors power the blower. At low settings with variable-speed blowers, the motor is typically quiet. However, the noise from many motors increases noticeably when settings move higher. This is normal and does not indicate a problem. However, any sudden and unexpected noises from a motor could indicate that it is developing problems and may be close to failing.

Corrosion and Other Factors

• Some fan blades become corroded over time due to condensation and frequent use. If the fan blades start to rust, the blower can become noisier and efficiency will be impaired. Replacing the fan blades can solve this problem. Noise can also be created by a dirty fan that has never been cleaned, so inspect the fan carefully and wipe it down with a cloth to see if this helps reduce the noise.