Increasing the R-value of duct board

My forced air heaing/cooling system's ducts are located in an unconditioned, well-ventilated attic, right above the floor insulation. They are made of 1" duct board. Anyone know of any product to boost the insulation of the duct board? What I have in mind is another piece of duct board, 1 or 2" thick, shaped into a U, so I can lower it over the existing ducts and increase their insulation on the two sides and top.
Thanks. If replying more than two days from now, please also email me; fix the address by removing the xxx.
Ray
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Why not just lay batts of regular insulation across the duct?

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Replace it with REAL duct???

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Other than the cross posting, with the several posts and concerns about your heating and cooling system should be assessed and addressed by your local *competent*, licensed, insured, professionally trained, HVAC technican.
--
Steve @ Noon-Air Heating and A/C
snipped-for-privacy@comcast.net
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If you insulate ductwork in an attic you will need to make a new vapor barrier outside the new insulation. If you don't, you will reduce the existing vapor barrier temperature below the dewpoint of the air in the attic and make it sweat. Don't put batts over existing ductwork and if you put 3 sided duct over existing you have to seal the bottom. In other words leave it alone or replace it.

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Peter,
Excellent point if you are considering cooling. Although last summer was unusually hot, and I used my a/c a lot, that's very unusual. My major expense here in central New Jersey is winter heating. (Put the heat on the first time on Sep 30.)
The idea of replacing the ducts excellent. Even though I've sealed the obvious leaks, I'm not really happy with the condition of any of the duct work. I especially don't like the low R-value of 1" of insulation. In the winter I might have 120F air in a duct passing through a 20 degree attic; in the summer, 60F air passing through a 100F attic. Horrors!
I also don't like the flex pickoffs to the ceiling outlets (their condition due to age, or the quality of the connections to the supply duct) or the way they are sized. (Same 6" pickoffs to a 45 sq ft. bathroom as to a 192 sq ft bedroom.) But with the doors open, the temperatures are fairly constant throughout the house.
Ray
Peter Swinson wrote:

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sounds likt time to bite the bullet and get it done right

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