ticking, popping, and clanging/banging in ductwork below bedroom


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Old 05-08-21, 03:24 PM
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ticking, popping, and clanging/banging in ductwork below bedroom

We recently moved into a home and noticed immediately that the ductwork is noisy when the heat kicks in. We sometimes notice it in other rooms, but for the most part the problem is limited to the master bedroom. We have a zoned system (3 floors, one zone per floor), and when any of the zones calls for heat, we hear ticking in one particular spot under the master bedroom floor, along with banging/clanging sounds in a couple different areas under the floor. It's quite frustrating and we'd like to find a definitive solution to this problem.

We first called in a contractor who "thought" he knew how to fix it. That involved pulling up the carpet in the master bedroom, cutting up the floor, and adding padding between the ductwork and the floor. I think he made some other adjustments as well, but none of that changed the situation at all.

I've called a number of other HVAC companies. Most tell me they have no idea how to fix, but could look if we have someone first remove the drywall in the room(s) below the master bedroom. One company told us that sealing the ductwork should fix it, but they are quoting $3.5k to do it, and I'm hesitant to sink that much money into the problem unless i have a guaranteed solution.

So at this point, I'm trying desperately to figure out the cause of and solution to this problem. Ideally someone who has dealt with this before who can come in and say "here's the cause, here's how i'll fix it, and it will cost x dollars".

Any ideas? Anyone know how to proceed?
 
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Old 05-08-21, 04:21 PM
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No one can say "here's the problem" without seeing it and that isn't going to be easy to find if it's buried in the floors and walls.

Leaky ductwork does not make any noise so sealing up the ductwork will yield no improvement.
You say you have a zoned system and from your description it sounds like a loose damper.
That would certainly make noise. Typically the dampers are installed so as to be able to service them.
Do you know where they are ?
 
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Old 05-08-21, 07:02 PM
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Thanks for the quick response!

Indeed I do know where all of the dampers are, and they are accessible. At least I think I have access to all of them. I did play around with the dampers a bit and noted that they were all open, but Iím not certain if they are loose or not. I suppose I should look at that more closely..

Assuming I can confirm that the dampers are not loose, what is another likely cause? Iíll say that the ticking noise does kind of sound like it could be damper related, but the ďbangingĒ noise does not. Also, the ductwork is silent when I run the a/c or just the blower fan (without heat). Heat is the only thing that seems to cause the noise.
 
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Old 05-08-21, 08:45 PM
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Hmmmm...... that is strange that you only hear the noise with heat. That would indicate a duct expansion issue. Although as the duct work expands it can make noise sliding against the framing.... it's not usually that loud.
 
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Old 05-08-21, 09:50 PM
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In this case, I can confirm itís quite loud. Loud enough to wake us up and annoy us when weíre trying to fall asleep 😞
 
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Old 05-08-21, 10:35 PM
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Heat is the only thing that seems to cause the noise.
Probably not going to be happy with the answer but would say it's a pretty normal situation, heat comes on, ducts warm up, metal expands, makes noise.

We recently moved into a home
Personally I would give it some time, we have a very loud GEO thermal unit that at first was annoying, now, it's just background noise!
 
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Old 05-09-21, 03:27 AM
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This is our second house. First one made no noise. Thatís also perplexing. Whatís special about this one, and how do we fix that?
 
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Old 05-09-21, 03:30 AM
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how do we fix that?
Probably not any one single items, it's a system and unless your going to go to extreme lengths to pretty much tear it apart and start over!
 
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Old 05-09-21, 02:43 PM
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Well, let's say we did tear it apart and started over. How do we ensure this doesn't happen again? I guess what I'm getting at is: there _must_ be a known cause. I'm trying to determine what the cause might be, so we can address.
 
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Old 05-10-21, 01:55 PM
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Sheet metal expands when it heats up. If it is confined so that it can't get longer/wider, what happens? It bows up or down. Ever see how they made thunder noises for the old Dracula movies? With a sheet of thin metal, press on the edges, and wave it back and forth.

The only certain way to get rid of metal expansion would be to replace the ductwork with flexible ducts. That's impractical, I suspect.
 
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Old 05-10-21, 03:30 PM
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replace the ductwork with flexible ducts
It's not the material, metal duct work is the norm, it's how it was installed.

Too tight, no expansion joints, not enough clearance, there is no way we will ever know what you have and how it was installed. Could it be repaired, probably, does it need to be torn out, maybe not.

Just like my comment about our noisy GEO system, I had several people out to look it over, some guys said it was the size of the duct, the blower speed, etc.

Ultimately a guy steered me right, took apart the inlet and outlet fabricated trunks, insulated the inside, 90% of noise gone! Just go to find the right solution!
 
 

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