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Community and Q&A

How could we muffle or stop the cracking noise our forced air box makes?

Shawna Jonas | Posted in General Questions on

Every time our forced air turns off it cracks loudly while the pipes are cooling down I believe. Is there a way to fix that or muffle the noise? It’s right beside our guest room.

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  1. GBA Editor
    Martin Holladay | | #1

    Just to clarify: I'm pretty sure that when you wrote "forced air box," you meant to write either "furnace" or "plenum," and when you wrote about "the pipes" you meant to write "the ducts."

    Hot-air ducts shouldn't make loud noises when they expand and contract. There must be some type of installation problem: either the ducts are somehow a little too long (or a little too short), or there is unusual friction between the ducts and the straps or hangers used to support the ducts.

    An experienced HVAC contractor should be able to examine your ducts and figure out the puzzle (and then implement a solution).

    If you know which section of ductwork is causing the noise, one solution would be to remove the galvanized duct and replace it with properly sized flex duct. (I don't recommend this solution -- flex duct often introduces unacceptable static pressure to the system -- but it would work.)

  2. Chris Jorgensen | | #2

    I think it's a hydro-air handler with water pipes that Shawna is referring to.

  3. GBA Editor
    Martin Holladay | | #3

    You might be right. Shawna: Care to provide us more information on your equipment?

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