Duct noises can make it seem like your entire heating and cooling system is an echo chamber. Fabricated of thin sheet metal in long rectangular shapes, residential ductwork can amplify and transmit duct noises throughout the entire home.

From the moving parts in your furnace or A/C to the effects of temperature changes inside the ducts themselves, you may hear any number of duct noises emitted by the supply and return vents. Here’s what some of these duct noises may be telling you:

Cracking And Popping

As heated air flows through ductwork, the sheet metal expands and then contracts later as the ducts cool. When thin metal flexes, it frequently makes cracking and popping noises, which is amplified by the metal enclosure. Unreinforced “original equipment” rectangular ductwork can be replaced by reinforced ducts or by round ductwork that equalizes expansion stresses without generating noise.

Moving Parts

The furnace incorporates an electric motor with a belt and pulley drive system to rotate the blower. If the pulley or blower bearings are dry and squeaking, they need lubrication. A stretched drive belt may also squeal and require adjustment or a new belt. Continuous rumbling noises while the blower is running usually indicate a worn blower motor that needs to be replaced.

Burner Noises

Furnace burners that are dirty and partially clogged don’t ignite gas evenly. This causes a roaring sound like a torch burning as gas ignites further from the burner and is mixed with air. Conducted by the acoustics of the ductwork, burner noise may be quite audible. Incomplete combustion should be checked out by an HVAC technician ASAP as it may produce excessive carbon monoxide.

Hissing And Whistling

Depending on where they occur, duct leaks may cause air noises. Leaks in the supply ducts can produce an audible hissing sound, while return duct leaks are likely to make whistling noises as they suck air into the ducts.

For more information about the causes and cures of duct noises, contact Powers Heating & Air. We’ve been serving residents of Peachtree City since 1979.

Our goal is to help educate our customers in Peachtree City, Georgia and surrounding areas about energy and home comfort issues (specific to HVAC systems).

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