Thread: combustion air vents

The question that I have is "Are there any particular blueprints on where to add the combustion air vents in a clost style furnace enclosure. The closet where my furnace is located in is 4' x 5' with the furnace in the center. From the code inspectors, they stated that I needed a 6" diameter tube on close to the top and one close to the air blower. What I neeed os how far away should the vents be placed away from the furnace or can the vents be added against opposite walls up to the attic?

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Look up the manufacturer online and download a copy of the installation manual. The info should be there, with diagrams. In general, if you meet the manufacturer's specs, you will satisfy the code as well.

Originally Posted by Leonel Vela

The question that I have is "Are there any particular blueprints on where to add the combustion air vents in a clost style furnace enclosure. The closet where my furnace is located in is 4' x 5' with the furnace in the center. From the code inspectors, they stated that I needed a 6" diameter tube on close to the top and one close to the air blower. What I neeed os how far away should the vents be placed away from the furnace or can the vents be added against opposite walls up to the attic?

All depends on many things, starting with the Btu input rating of the appliance.

How high is the ceiling - 8 feet? If so, that room has 4x5x8=160 cubic feet of space, and if there are no openings, such as a louvered door or louvered opening, to other areas, than that 160 cf of space is going to require additional combustion air.

Also, I'm not sure that a 6" diameter vent would meet minimum size requirements.

There are a couple of methods available to provide combustion air, and how much air and what size openings - we do not have sufficient information to determine that. If this is new construction, you need to do what the code inspector says you need to do ... whether it is right or wrong ... because they will likely not pass it until you do what they want.

Yeah, it is not supposed to work that way, they are supposed to be inspecting to code, not to 'what they want', but I know several code inspectors who inspect to 'what they want'. Contractors here know that I inspect to what the code says, and that I give them a code section with the violation explained briefly, and when they disagree we go look it up and see *exactly* what the code says - usually I am right, but not always ... can't remember everything.

I explain that "code" is the "minimum standard", therefore 'code is the crappiest one is legally allowed to do it', some people take offense at the word 'crappiest' and say that implies 'workmanship' and 'workmanship' is not addressed by code ('workmanship' is not addressed by code), so I offer to change my wording to 'code is the most unsafe one is legally allowed to do it' ... all of a sudden the word 'crappiest' is not so bad ... they do not want to think of it as the 'most unsafe' ... works for me.

I then ask that, with code being the minimum, "What does passing a code inspection mean?" The answer is 'Not much.'

I then ask "What does NOT passing a code inspection mean?" The answer is 'A lot.'

Originally Posted by Leonel Vela

The question that I have is "Are there any particular blueprints on where to add the combustion air vents in a clost style furnace enclosure. The closet where my furnace is located in is 4' x 5' with the furnace in the center. From the code inspectors, they stated that I needed a 6" diameter tube on close to the top and one close to the air blower. What I neeed os how far away should the vents be placed away from the furnace or can the vents be added against opposite walls up to the attic?

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That is called a High-Low combustion air system. You need to compute the square footage of the room. Then look at the BTU's of the unit and compute the amount of air that is required. You need 50 cubic feet of air per 1000 BTU's.

THe information that you all provided greatly helped, now does anyone know where I might find the installation information for the combustion air vent for my Goodman GMP075-3 furnace. This is the furnace that I have in my closet

Originally Posted by Leonel Vela

The question that I have is "Are there any particular blueprints on where to add the combustion air vents in a clost style furnace enclosure. The closet where my furnace is located in is 4' x 5' with the furnace in the center. From the code inspectors, they stated that I needed a 6" diameter tube on close to the top and one close to the air blower. What I neeed os how far away should the vents be placed away from the furnace or can the vents be added against opposite walls up to the attic?

Originally Posted by Leonel Vela

THe information that you all provided greatly helped, now does anyone know where I might find the installation information for the combustion air vent for my Goodman GMP075-3 furnace. This is the furnace that I have in my closet

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Leonel,

Please contact a Licensed Professional to do this kind of work ( it can be a matter of Life and Death. )
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