# Fresh air intake vent



## gena (Jan 6, 2008)

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


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## Topher23 (Feb 23, 2008)

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 askthebuilder.com 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?


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## gena (Jan 6, 2008)

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


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## hvac122 (Dec 10, 2007)

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.


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## jogr (Jul 24, 2007)

gena said:


> 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?


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## gena (Jan 6, 2008)

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.


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## Redparis (Feb 27, 2008)

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


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