Crawl space and duct insulation

[giannit]

Hi,

I can't access most of my long ductwork to insulate it, but I can certainly do the main supply duct and the large line supplying several other ducts. I have already sealed connections/joints with alum tape. I have 2 questions:

1) The furnace room is quite warm, is directly below our kitchen and actually provides some radiant heat to the kitchen floor above. Is insulating the main supply ducts worth doing or am I just redirecting the heat around for no real gain?

2) Similar question for crawl space. My family room is above the crawl space. Is there any point in insulating the duct in the crawl space which feeds the registers for the family room?

Thanks for your help.

[BaldLoonie]

1. I wouldn't worry about insulated the ducts, enjoy the warm floors.

2. I'd insulate the walls of the crawl. Help keep the floor warm.

[tedkidd]

spray foam the rim joist and down the walls. Cover the floors with plastic. Seal the ducts.

Want to know "Payback" on these efforts hire a comprehensive home assessment. The report will prioritize the things that benefit most to least.

[giannit]

Thanks for the comments. When you say cover the floor with plastic, would that be the case for a concrete floor or do you mean apply the plastic to the joists in the crawl space? That would certainly satisfy that rule of thumb where a vapor barrier goes next to the warm side.