Insulating interior HVAC ducts

[Robey5]

All:

I have seen some people who have put foil-backed insulation over their HVAC ducts to do... something ... here in the midwest.

I am curious about the value of wrapping my duct-work in my basement in hopes to shut it up from the expansion/contraction sounds.

in addition to possibly shut it up a little (it has the cross-broken sides as well) - will this provide any value to the amount of running the heat or AC?

What say you in the GJ?

 

[Done That]

In a hot attic...sure. In a hot/cold crawl space....sure. In a conditioned space, I don't think it's worth the effort.

No idea on the noise thing. I might first experiment with some sound dampening squares etc like for automotive use.

 

[NUTTSGT]

My heat duct in the garage from the wood furnace goes up through the unheated attic. I wrapped it with fiberglass then added some Reflectix foil bubble wrap on top of that. It made a heck of a difference in the temps of the heat coming out of the ceiling register.

Enough in fact that I'm seriously considering doing the duct work in the basement this Winter as a small project. I do have a register in the plenum of the main trunk to add some heat in the basement and push it into the crawlspace which is unheated.

Which BTW, I need to clean the box fan down there and move it as it's now 2/3 through November and only going to get colder these next few months. Thanks for jogging my memory.

 

[tab2]

Speaking commercially, it is required here in MA when the duct is in an unconditioned space, even when it is exposed to the return air (in the plenum). I would put money on it helping they system a few degrees.

I think it will help some for noise. Lined ductwork helps more for sound attenuation but that new duct for you, which I don't think it is worth it.

 

[peter2772000]

If your complaining that much about expansion/contraction noises, makes me wonder what gauge ductwork was initially used. To be honest, the only time I've ever heard duct popping noise was when high static/pressure and very thin-gauge sheet-metal was involved. And IMHO, thermally insulating a duct in a conditioned space is a waste of $$.

An unorthodox solution, but it's worked for me in the past when no other viable/practical solutions were possible. Locate exactly where on the duct run the noise is being created, then either try to pull out the sheet-metal using sheet-metal screws, or, use a hammer and a piece of wood to bash in the offending duct where the sheet-metal is furthest from any joint. I'm not talking a crater-sized dent, just enough to tension the sheet-metal so it doesn't pop any more.

 

[PWC Repair]

The plenum right behind my cold air return grill is attached directly to my air handler. It was noisy. I used spray foam followed by cheap dollar store paintbrushes to spread the foam around into a thin layer. It worked great. You can stand right next to the return now and have a conversation.

 

[bobbyjean]

i have become a big fan of rigid foam board since i used in my my garage build-you could box around the offending ductwork with that---gotta seal it up very well i would think to avoid condensation issue's if used for ac...1 inch = r-5..no itch either