Are my ducts noisy because of heat or too much air?

[Dom]

quoted text -

They would have to be the type of earplugs you get at a firing range. Trust me, this is a BANG!

[Dom]

You're my neighbor!

[trader4]

research on filters and get ones that allow the maximum air flow, and I'll report back In a day or two to tell you if it helps or not.  I still don' t see what I can do if it is a balance problem.  Is there a away of fixin g that?  Who do I call to look into it?

I'd do the AC blower test first, just for the hell of it. It's kind of mandatory to do that before you close up the drywall again, anyway. You need to make sure there is no more banging with AC too. And it takes 5 mins to open the breaker for the outside AC unit and turn the AC on via the thermostat.

[Dom]

e research on filters and get ones that allow the maximum air flow, and I'l l report back In a day or two to tell you if it helps or not.  I still do n't see what I can do if it is a balance problem.  Is there a away of fix ing that?  Who do I call to look into it?

Hmmmm. I didn't know that, but its a good idea. Maybe I just won't close the drywall until it is possible to turn on the AC in a few months. I really don't want to fool with the breaker. I don't know what I'm doing out there.

[chaniarts]

it's totally dependent upon the guy. you really want 2 people: one to fix the ducts, and one to do the drywall repair. they won't be the same people usually, if you're using subcontractors. if it were me, i'd do the tear out, have an hvac guy repair the duct work, wait a week to make sure the problem was solved, and have a drywall guy come in to fix the holes.

if you do the tear out, you'll be able to pinpoint the problem just by looking at it, or feeling the duct, after turning on the heat. you can see and feel the duct move. you may be able to wrap insulation around it, or do something to muffle the noise, which may be all you need, without having to replace it.

[trader4]

That's what I would do too. I surely would not get a general contractor who then subs out the work for a small job like this. Now you're paying overhead for the GC to do what?

Actually, this could be within the scope of a competent handyman. I don't think you probably even need an HVAC guy. If it were me, I'd open it up, and see what's found. If it's a section of duct that's flexing, could be as simple as buying a piece of thin angle stock, like you hang garage door openers with at HD and screwing it on. Or nailing a piece of furring strip to support it.

I would focus on eliminating the movement that is causing it, not trying to muffle it. And I agree, that if he can do the tear out himself, he could save a lot of time and money. It coud take a while to find it, test it, make sure it's eliminated. Especially since it appears to be heat related. May have to wait half an hour between tests for it to cool down, etc.

[trader4]

ome research on filters and get ones that allow the maximum air flow, and I 'll report back In a day or two to tell you if it helps or not.  I still don't see what I can do if it is a balance problem.  Is there a away of f ixing that?  Who do I call to look into it?

You most likely don't have to go out there. Unless your circuit breaker panel is outdoors. If it's inside, all you have to do is find the breaker for the AC and turn it off. It should be labeled and it will be a double one, 30 to 50 amps. You just turn it off like any other breaker. The furnace and it's blower run off a seperate circuit/breaker that serves the furnace.

[Dom]

some research on filters and get ones that allow the maximum air flow, and I'll report back In a day or two to tell you if it helps or not.  I stil l don't see what I can do if it is a balance problem.  Is there a away of fixing that?  Who do I call to look into it?

Okay, I misunderstood. I thought I had to uncover a circuit breaker at the AC unit (told you I don't know what I'm doing here). So I turn it off at the circuit breaker panel -- can do. Then I turn on the thermostat to AC? Sounds like with the breaker off, nothing will happen at the thermostat, but I can always give it a shot.

[trader4]

do some research on filters and get ones that allow the maximum air flow, a nd I'll report back In a day or two to tell you if it helps or not.  I st ill don't see what I can do if it is a balance problem.  Is there a away of fixing that?  Who do I call to look into it?

The double pole breaker that goes to the AC unit only powers the outside unit, ie compressor. The furnace has two low voltage wires that go to the outside unit that switch it on. So, when you turn off the AC breaker, the furnace still has AC power via it's own totally seperate circuit. Selecting AC and lowering the thermostat will result in the furnace blower going on and it sending a signal to the AC outside to start up. With no power to the AC, all you'll get is the funace blower running at AC speed, ie highest speed.

[TomR]

If you haven't taken care of this yet, here's something you may want to try first.

You said the duct is in the ceiling and I assume there is no attic space above it where you can access the duct from above. So, if it is in the ceiling, that probably means that it runs along the ceiling above the sheetrock between two ceiling joists. Ceiling joists are usually 16 inches apart (16 inches from the center of one joist to the center of the next joist). So, if you were taking out a section of the sheetrock to completely access the duct, you would probably take out a section that is 16 inches wide and whatever length you need. Then, a replacement piece of sheetrock would get screwed back in place to the two joists and the edges taped and patched. (NOTE: If the duct is in a soffit, it may be a little different, but I am assuming your duct is in a flat ceiling).

But, here's my suggestion before taking out a big section of sheetrock. First try cutting a small hole out of the sheetrock in the area where you are hearing the sound. The hole could be just 6" x 6" or so. You just need a utility knife or something similar to cut out that section. Then you should be able to see the duct. With the hole there, watch and listen and see what happens. "Maybe" you will actually be able to see the duct move or pop when the big bang happens. That would be good news. But, even if you can't see anything happening during the big bang, maybe you will be able to hear that it is really coming from that location. And, maybe you can try wedging something in between the sheetrock and the duct and see if that changes the bang. If it were me, that's what I would do, even though I know how to take out and replace larger sections of sheetrock etc. You could even do more than one test hole if needed.

The main reason for trying this first is that is costs nothing to do it, and if you are able to solve the problem from there, re-patching the small hole will be very easy. It can be a do-it-yourself job even if you never did that before just by watching a couple of YouTube videos that show the process step by step. And, taking out a small hole or two first won't change anything in the long run if you later need to take out (or have someone else take out) a larger section of sheetrock.

[DD_BobK]

+2

OP- You've gotten a lot of great advice. Approach this "fix" is small stages, you'll be sure of getting it right & at the minimum cost. I would suggest cutting "joist to joist" center line pieces so the replacement is easy. With a reasonably sized access panel (~16" x 36 to 48") you should able to observe the behavior & do try a modification.

Good luck, let us know how it turns out