glennjanie

Hey Cibula:
You had said the temperature in the attic is not much different than the main level. That being said, one run and a register in the middle of the floor should be sufficient. A 6" metal pipe duct will carry 100 cfm which should do a bang-up job for you. No need for a return.
Glenn

cibula11

Thanks. I am having someone come out today and tell me what it would cost him. Any ideas on a reasonable figure? The furnace is pretty much directly below the attic area, so it would be pretty much a straight shot from the furnace. I will probably have the holes in the floor cut to cut down on labor. Just wondering if it is something that I could tackle on my own or not??

glennjanie

Yes, you could do it yourself. With the right material and some basic tools, you could whiz right through it.
Glenn

cibula11

I don't have a lot of room on my furnace to attach the supply ductwork to. I was wondering if I could start with a flexible duct to start and then run the metal ductwork to the area. Do I need to know anything specific when attaching the duct to the furnace? Or is it pretty much cut a hole and attach?

glennjanie

Yes you could start off with flex-pipe; it should be limited to 3'. OR you could start with 2 or 3 adjustable ells; they will make any angle for you from straight, to 90 degrees. I really prefer the adjustable ells.
To attach the duct to the furnace plenum (the sheet metal box, usually on top of the furnace) you cut a precise 6"round hole and insert an "A-collar" then pipe or fittings can be attached to the a-collar. Turn upward with an ell and terminate with a 6" 4 x 10 universal boot in the attic floor. Lay a 4 X 10 floor register in the boot and you're done.
Caution: Working with sheet metal presents a lot of sharp edges, when you get cut on it the zinc (galvanizing) gets into the skin and causes a burning sensation, wear lether gloves.
Glenn

cibula11

Do I need to shut the furnace off first?

glennjanie

Sorry, I often miss the first step in instalations. Yes, it should be turned off while you are connecting to the furnace. It is possible to start in the attic and work down so the furnace will be off for a mimimum time.
Glenn