HVAC duct noise

[TJG]

We built (had built) a new house last year. Going through heating last winter, cooling this summer and now back to heating with this crappy WI weather, I'm feeling that I need to do something about my HVAC ducting.

Overview: All my ducting was custom made (all rectangular in shape) to fit in a specific area of my basement. We did this so that when I finish off the basement, I won't have too many areas of drop ceiling.

The contractor used metal duct hangers where they could (similar to this: https://www.ductworks.net/wp-content/uploads/2012/09/hanger.jpg) and made customer hangers (again, out of metal) where necessary.

My problem: As the ducts heat up, the metal expands and contracts ever so slightly. At a different rate than the hangers. The result is pops and clicks between the hangers and duct as they move against each other.

I've remounted as many as I could - separating the hanger from the side of the duct so there was no rubbing, but in certain areas I just couldn't move them enough. I've tried putting various fabric in between, however the results have been inconsistent.

I'm now leaning towards replacing the remaining offending hangers with vinyl hanger strap (http://www.homedepot.com/p/Master-F...-Hanger-Strap-HS1-75WV/100396948?N=5yc1vZc5hs or similar).

Has anyone used this product before? I want to eliminate all noisy ducts before they are drywalled in and the noise becomes permanent. Any other possible suggestions are welcome! The contractor has been out and also removed some of the hangers, but really they aren't trying too hard to make it right (or, silent!).

Thanks,

 

[zmaxmotorsports]

Id just put an extra screw from the hanger into side of trunkline.

 

[The Cobbler]

what about removing the ( hangers one a time), using silicone between them & the duct & re installing then? maybe use a rubber washer behind the screws so you don't squeeze the silicone to zero .
also,as you already know the nature of the duct is that it expands & contracts with the heat/cold, so you might never get all the creaks out

 

[TJG]

I will try another screw from the side. . my issue is only one side is visible of the three lines - they are spaced about 3/4in apart, so I'd have to take entire runs down. I can slip a long extension in between to put in a screw to the joist, but its a challenge!

See pic in next post to view what I'm dealing with.

 

[TJG]

 

[GETRIDAONE]

I can't tell how long but the duct looks like it has been made in very long sections. Here in the south, duct is about 4' & max 5' sections. The long sections will tend to expand and contract more with less locks and drives for reinforcing. I don't see any duct sealer on the seams of the system either. Does it have internal sealer in the seams already. You will lose a lot of air with unsealed ductwork. I assume the duct has liner for insulation on the inside ?
The black strap could be used for metal duct but is primarily used for hanging flex duct.

 

[pseudorealityx]

Just put some neoprene wherever you've got metal to metal contact where it's squeaking. Also... what's with the lack of insulation?

 

[TJG]

There aer multiple sections, probably max 10ft long. I also do not believe there is internal insulation. That is something I've already thought about - if only to the run to my bedroom. I'm assuming its a pretty big job (read: I couldnt do it) to take the entire run down and add the insulation though.

Edit: Lack of insulation where, around the ducts?

 

[Jackfre]

Is the noise from oil canning on duct itself? I don't see any breaks in the longer pieces. You could replace your hangers with trapeze hangers. Some angle brackets, all thread and uni-strut and Bob's your uncle. The good thing about the uni-strut is you can hang other gear off it.

 

[TJG]

Nope, no oil canning, just the clicks and pops.

The lengths are about 10ft between each piece of ducting.