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Remodeling Basement.. Have Heat vent/return air questions.

4K views 7 replies 4 participants last post by  concretemasonry 
#1 ·
I found this site a while back when I googled something about cold air returns in basements. I have read quite a few threads about it but have some questions specific to my project.

I have a house that was built in 2005 with an unfinished basement(all below grade). It has a total of 510 square feet. Of that, 28 square feet will be a utility room that will contain the Heater, water heater, water softener, sump and drain. It will be one big room that is 365 square feet(23 x 17 minus the utility room) and the balance of the square footage is hallway to the stairs and to a small storage space. Right now it has two ceiling vents, one in the middle of the big room just back from the wall and the other one back in the storage space so nothing too much. I am thinking about running two more heat vents in the big room and then adding a cold air return. I thought I had it figured out and then I read some of the threads here. I would say I am more concerned about heating it during the winter then cooling in the summer but want both. I have had heard I need the cold air return up on the ceiling and that I should have it off the floor. Reading this forumn, I take it I definitely want it closer to the floor but then I read stuff about making sure I am pulling as much air as I am forcing into the space so how do I take that into account?

I am just starting to frame the walls so i can still run the heat vents from the ceiling or I can run them down to just above the floor so which is best for me to locate them?

The best place for me to tap into the cold air return duct is right near where it goes down the furnace and then running it over to the wall for the utility room. Will I draw too much if I am closer to the furnace?

I am running the heat ducts off the end of the square duct work in the basement for the one and then right near the furnace for the other one. Do I need a flu(or whatever you call them) to slow down/speed up the flow without drawing away from the rest of the house.

Is there anything else I am not taking into account when I do this prior to sheetrocking?

Thanks again. I look forward to learning all I can in this forum.:thumbsup:
 
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#2 ·
Where will the furnace and water heater get their combustion air from?

I believe the term your looking for is damper.

A damper can also be installed in the return that you run for the basement. To control how much air you return.
 
#3 ·
Yes, I did mean damper. Sorry for the confusion. I could damper the new additions so I don't mess how it affects the rest of the house.

As far as the combustion air...... I want to run the square duct work that fits inside a 2x4 framed wall inside the wall studs. If I run it down to the floor then it will not be centered so I am thinking of making a second cold air return vent and then running the duct work up enough so it doesn't show inside the room but then leave it open so air comes into the room that way. That is fine isn't it?
 
#4 ·
Combustion air should not be taken from a room that has a return in it. That also has dampers in the supplies that could be shut off/closed.

It could draw combusted gasses into the house if the supplies were closed.
 
#5 ·
The proper way is to have a fresh air intake into the furnace/water heater room. This way you will be using fresh air and not burning and exhausted conditioned air. The basement returnsshould be low and close to the floor and preferably on an external wall.

Many codes require a fresh air return direct from the outside (roof or wall).

Dick
 
#8 ·
Brian -

You do not want to use indoor air for combustion because you draw in cold air when heating or running a water heater through the infiltration leaks if the house is closed up.

The purpose of the fresh air supply is to eliminate the use of conditioned air and then exhausting it. There are very simple ways for preventing an excess of outdoor from siphoning into your basement from a fresh air supply. If you have an extremely tight house with no leaks, a air to air exchanger is possible, but they are rarely needed with frame construction. I had a all masonry home and finally had to buy an exchanger because it was too tight and efficient.

Dick
 
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