Basement heat ducts

[phil mcc]

I am finishing my basement and am considering running the heat ducts to the wall, making one 90 deg. bend running it down the wall to the floor. I know efficiency is lost everytime a heat duct makes a bend, but how much? Having the heat at the floor makes sense but is the loss greater than just leaving the duct in the ceiling? Thanks for your time.

[Jay11J]

Phil

You are best to have the vent in the ceiling in the basement. use the kind that is found on floor vent.. That way the heat can be blown down towards the floor. Place it along the outside wall/window.. That way the heat can "wash" the cool walls.

Then use floor return to pull the cool air off the floor.

[Ed Imeduc]

Dont try and run a heat run down to the floor in the basement. Run them out to about 12" off outside wall in the ceiling. Use a 2 1/4X12 floor register. This will give you the throw and spread of the heat that you need there. Like said have the cold air return down on the floornear the center of the home.

ED ;)

[phil mcc]

Thanks to both of you for the advice. I'll do what you recommended.
I'm just curious why running the duct to the floor is not a good idea. Could you please explain? Thanks.

[Ed Imeduc]

If the run was at the outside wall first then how do you insulate it to go down to the floor? Then thats another 90o L in the pipe thats 5 ft of drag then the pipe to the floor is say 8ft so now you added 13 more ft of drag to this run. so it blowes where right back across the floor to the cold air????. When it in the ceiling there near the outside wall you blow down over the whole outside wall then it goes back to the return air.

ED :D

[phil mcc]

OK I get it. I'll leave the heat duct in the ceiling about 12" from the wall.
Now, as far as the cold air returns, I have to tap into the ducts available. Are the rules the same for cold air returns regarding bends and efficiency? One location is better but requires 2 bends to get to the floor. Another location is not as ideal but would require only one bend. What is better to do?

[Ed Imeduc]

Most of the time so its like center in the room. On an inside wall and the air can get out and back to the furnace for a cold air return.

ED ;)

[Bsalh]

Ok, now we're at odds. I completely disagree. I live in a real cold place called Ottawa, Canada. So I know about cold. I have a relatively big place and put my cold air returns (3) and heat vents (6) to the floor. They are inset between the frames (2"x6") in the basement with 3" 'Cladmate' (Dow) glued to the cement walls. This gives me an R value of 15 (other than these areas, the basement is insulated with R 20). The heat runs are this insulated 10" x 3" rectangular flexible (silver) stuff - name fails me now. This is great stuff with no heat loss at all.

Having your heat and cold runs at floor level is what exactly happens on the first floor of 2 storey house (cold air runs are usually near the ceiling on 2nd floor) and my basement is pretty warm. When you think of it..hot air rises and cold air falls. The hot air that comes from the vents does not sit along the floor. It immediately rises warming the air on its way to the ceiling. In my view and experience, this is the way to go.

[phil mcc]

Your view is just how I had originally thought about it...warm air rises and cold air sinks. But efficiency lose must be significant when adding a 90° elbow and running the additional 8ft to the floor. This must be why Ed and Jay say to leave it in the ceiling.

[Ed Imeduc]

Why add 8 ft of duct and a 90o L for more drag to get the air to the floor to blow out across the floor. When in the ceiling by the outside wall.You blow it down to the floor and with the spread of the register it like wipes the cold wall for you. yes the cold air down there should be at the floor line

Bsalh For where you live I would have put the heat runs for the basement under the slab for sure. You would have had a warm floor all the time. Infact we put the heat runs in the basement floors lots of time . Thats in Missouri.

ED :D

[Bsalh]

Of course, if your furnace has only the capacity to handle your home's 1st and 2nd floors, and there is not enough power to handle the basement, then you make do with what you got. I have a high efficiency furnace and my kid's room has a 60' run from the main trunk and it's the last to be attached. It still gets enough satifactory air supply. I realize the lenght and number of runs make a difference with regard to how hard your furnace will works, but I'd prefer to have a warm head and feet. I know lots of people who finished their basements and never visit them because it's too cold down there. Really what we're talking about is air circulation. It reminds me of a fellow who put speakers in the walls of his house - all over the place (he loves music). You'd walk all around the house and you could hear the music and still talk to each other. He didn't have to put it very loud because of the distribution factor. This is very similar although not exactly the same. Air flow and the second law of thermal dynamics. That's why I have fans in my house, too. Anyway, I talk too much...gotta go do the lawn. :blah: :eek:

[Ed Imeduc]

Thats why like the music, if you put the heat duct in the floor in the basement the slab works as one big heat sink. :D

ED :coffee: