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Topher23 02-23-2008 05:04 PM

Fresh air intake vent
I'm finishing my basement and I have a fresh air intake just hanging in the middle of my utility room. It's a full-size HVAC vent pipe and it lets in a LOT of cold air. Can I redirect it so that it runs directly to my furnace's cold air return and maybe set up another, smaller pipe to let air in for the clothes dryer?

gena 02-23-2008 05:12 PM

No, you need it for a water heater and for your furnace if it 80% efficiency.

Topher23 02-23-2008 06:23 PM

Okay, I understand that all of those appliances require combustion air - but does it need to be an 8 inch vent? I was reading on that you can use a 4 inch vent in most cases. I was also reading in Home Depot's DIY book that US building code doesn't require a fresh air intake, although Canada's does. Has that changed in the past year or 2?

gena 02-23-2008 11:25 PM

Well, 8 combustion air intake definitely is too big, unless they figured out it for the kitchen hood also.

hvac122 02-26-2008 04:09 PM

Don't get fresh air and combustion air mixed up. Fresh air is for the living area and usually goes into the return air. Combustion air is the air that the furnace and water heater need to burn properly. Combustion air would be needed with any kind of furnace and water heater in any country. The combustion air is sized by how many BTU's your appliances are rated at. We would not know if 8" is right or not unless you give us this information. It should NOT be tied into your return air. It should be dumped into the furnace room or if the house has enough air it can be drawn from the inside. I would assume that you have a sealed mechanical room which is why they brought the air in from the outside.

jogr 02-26-2008 04:31 PM


Originally Posted by gena (Post 100917)
No, you need it for a water heater and for your furnace if it 80% efficiency.

Why would you state this based on the little info provided in Tophers first post?

gena 02-26-2008 06:14 PM

I just admitted that he has a water heater. I thought that this kind of equipment exists in any American house, so I’m deeply sorry if you don’t have one.

Redparis 02-26-2008 08:12 PM

Do you have a fireplace in the home?
If so, that would be the make-up air for the firplace.

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