Insulated flexible heat duct

DangerMouse · 04-14-2010, 11:30 AM

Any thoughts on using this for the entire job down in my crawl space? I already have it on three runs off the old ductwork I'm removing. The flex part is only a few years old, so I plan to keep it where it is. It'd sure make my job easier, I would think. Anyone know of any on-line tutorials? EZ-install sites or similar?

Thanks guys! I googled it, but didn't find much.
(Searched here too, of course, same thing.)

DM

**beenthere** · 04-14-2010, 04:02 PM

Flex can be used for both a trunk line, and for supply branches.
Some areas interpret the code on flexible duct connectors to include flex duct. It doesn't. but those areas won't let you use it for a trunk line.

Flex duct needs to be installed using a flew duct FR chart. Not the standard FR chart for sheet metal.

EG:

6" sheet metal pipe at .08" FR will flow 100CFM.
6" Flex duct at .08" FR will flow 75CFM.

**Gary in WA** · 04-14-2010, 04:04 PM

I know you need the next size up and the flex should be no sharp bends and stretched out to be efficient: http://rockwallcontrols.com/Resident...ag=air-ducting

http://www.mmmfg.com/pdfs/True_Cost_...x_10-27-06.pdf

http://www.thefreelibrary.com/Pressu.....-a0201591046

Be safe, Gary