Furnace Ducts

[ToothFairySpaniel]

What is the best material to use for insulating rectangular and round furnace ducts?
Please give me a brand name that is readily available at HVAC stores or on the internet. Too what type of tape is best for adapting the insulation? Thanks for your time!

[HayZee518]

Ideally, 1/2" thick neoprene foam is the best but the price of the stuff is prohibitive for most homeowners. Next comes aluminized fiberglass which is a compressed fiberglass product that is glued to the surface of the duct. and lastly flexible aluminized fiberglass which is just wrapped around the duct. There are different grades of duct tape which should be used. Get the stuff that is the stickiest you can find.

[Hube]

fiberglass board 1" for the rectangular ducts.
flexible fibreglass for te round pipes and fittings.
Do not use duct tape.
use aluminized foil tape for all joints