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From what you’ve written, I assume you’re talking about forced air – probably sheet-metal with riveted and/or taped joints.
I have seen this covered with fiberglass batting, with aluminum foil wrapping over, and the whole thing taped at seams and then strapped to supporting beams.
An easier alternative might be to use the extruded polystyrene sheets, cut to fit the outside of the ducts. You’ll lose more than the fiberglass but some leakage into the basement should be OK to keep it dry, warm, and usable.
I would also guess that there’s already insulation in the floor beams, between the first floor and basement, to prevent conduction/convection loss.
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From what you've written, I assume you're talking about forced air - probably sheet-metal with riveted and/or taped joints.
I have seen this covered with fiberglass batting, with aluminum foil wrapping over, and the whole thing taped at seams and then strapped to supporting beams.
An easier alternative might be to use the extruded polystyrene sheets, cut to fit the outside of the ducts. You'll lose more than the fiberglass but some leakage into the basement should be OK to keep it dry, warm, and usable.
I would also guess that there's already insulation in the floor beams, between the first floor and basement, to prevent conduction/convection loss.
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You are correct in assuming that $$$ is being wasted. Sealing and insulating duct in any space is worth while. Check with a quality HVAC contractor about insulating the duct. There is a new product for wraping duct that is working great. It's a thin, dense, foil wraped insulating material but the name escapes me right now.
*thanks for the feedfack - yes, it is a forced air system. Ducts were made on site, looks like only seams holding everything together. There is no insulation between basemet and 1st floor.thanks againscc
*If there's no insulation under the 1st floor, is there any around the perimeter of the basement, or at least the above-grade portion?
*Rebeccah: no insulation visable around perimeter either. Just blocking.
*Duct leaks probably account for most of the unwated heating/cooling.
*Stephen,This is a topic that has been much discussed. Here are a couple of links to the archives:http://205.181.179.43:8090/WebX?128@@.ee6e46chttp://205.181.179.43:8090/WebX?128@@.ee6f656The archives would be even more helpful here, but someone keeps deleting his posts.Rich Beckman
*I am a licensed mechanical contractor and beleive me...its worth it. Use a mop on type mastic to seal all seams in the duct work then use a 2" fiberglass duct wrap with scrim tape to tape all seams. This will pay for itself. If Im not mistaken up to 20% of your heat loss/gain is through duct leakage.
*When you are doing the sealing and insulating don't forget to also check out the plumbing routing. Would be embarrasing to reduce the heating bill but freeze the water or sewer.
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I am working on a 30 year old 4000 sf house with a full unfinished basement. The basement is hot in the winter and cold during AC-season. Feels like the owners are losing $$$ via the original duct work.
Is sealing/insulating the duct work worth anything? If so, what would you use?
thx
scc