On Feb 20, 12:22*pm, Dom wrote:
Hello everyone.

The ducts in my house make a loud booming noise when the heat turns on
and again after it cools down. *Sounds like someone is banging a metal
trash can with a hammer. *It's so loud that I'm ashamed to have
friends over.

My house is on a crawl space, and I have no easy way to reach the
ducts. *Can I do anything to fix this? *I just got a new heater and
decided not to get a humidifier (since the old one didn't do much
good). *Will a humidifier help the problem?

If you manually turn the blower on and off, without the furnace
heating up, is the noise there? You need to tell if it is an
expansion problem due to heating the metal, or if it is the duct
flexing under the air pressure. You should be able to hear which wall
it is coming from, and then locate it better using a listening tool, a
rod held to the wall and the other end to your ear.

Once you are suspicious as to the location, cycle it several times to
be more sure. Then insert a stiff wire or knitting needle thru the
wall till it touches the duct. Listen again while the noise
reoccurs. If you are close, you should be able to feel a vibration in
the wire/needle. If you do, then you know where the problem is. From
the attic, maybe you can slide a piece of wood down into the opening,
along the side of the duct, to push against the duct and stop the
noise.