RETURN AIR VENT BANGS

[rbm328]

just bought a house in east central Alabama. house was built in '88 but hvac unit is ~5yo. been living in it for a week and just today wife heard banging every so often. after chasing it down when I got home, we determined noise is coming from a return vent. it sounds like typical trunk line expansion/contraction, but after living in 8 houses in my life, I have NEVER heard a vent make this noise.
any thoughts? questions?
thanks all!
Rich

 

[Jeff Handy]

Post a recording of it.

Where is the noisy vent?

Behind drywall?
In a basement?
Crawlspace?
Attic?

More info please.

 

[rbm328]

give me a couple days to research further. right now, all we know is that the sound is coming from the return air vent that's under the stairs.
thanks

 

[Jeff Handy]

I slept over a vent like that my whole childhood.
Tick...tick....clunk....tick... all year round.

 

[slownsteady]

....that could explain a lot of things:lil guy::lil guy::lil guy:

 

[Jeff Handy]

Yes, for sure!

 

[rbm328]

well, I found out whats making the noises. the return vent is under the side of the stairs. they built a box with galvanized metal that surrounds the return ducting. the right sides of galv. box has a slight buckle in it. it doesn't feel like there is a backer board I can screw it too. after I go under the house and investigate further, i'll decide what to do. maybe I can install a backer or if I have to get a small piece of angle iron. those are my thoughts.
anyone else have any ideas? I have a picture, but can't find the cable to download it. hopefully tomorrow.
thanks

 

[rbm328]

you're not going to believe this, but I replaced the filter with a better and more rigid filter and the noise has gone away!

 

[Rusty]

Turn up your TV.