I don't know about NY, but most places now require the furnace closet
to be a solid door.
The closet must be vented to a non habituated area, usually the attic,
or the outside.
The idea seems to be; to keep the unit from consuming all the air in a
tight building, & leaving the occupants dead.
Our code here allows the return to be just a grille under the furnace,
no actual return "duct".
Caution, if the furnace is a fuel burning furnace, having the return air
outlet at the furnace or even in the same room could cause it to create
negative pressure in the fire chamber resulting in the flames drawn
improperly outward towards the outside of the furnace or at minimum allowing
the byproduct of combustion to be sucked from the furnace and circulated
throughout the house. This would include carbon monoxide.
It depends on the type of furnace and combustion air source. A key
factor is whether a risk of negative air pressure exists which would
often be the case with a forced air system. The furnace needs
combustion air from somewhere; in many cases it comes from the attic.
Mobile homes have a closed combustion chamber with air coming in from
the outside. A clue is the sealed opening for the pilot burner.
In short, there is no definite yes or no answer. Your local building
inspector may have a more definitive answer.
A condensing furnace generally requires the vent and intake to be in the
same general area to equalize the pressures. Otherwise wind, fans,
combustion, and other conditions can cause pressure differences which will
cause the pressure sensors to shut down the furnace. Check the installation
manual for specifics.
Not sure, but I think you guys are answering the wrong question. I
THOUGHT he was asking about the cold air return. Combustion air is a
totally different question, and if it is a HE condensing furnace with
the 2 through the wall pipes, it is totally irrelevent to the
My impression also. Of course, the air has to move somehow, duct or not. My
old house had a gravity system and while not ducted to the furnace, it did
drop into the basement. You can't blow air into a room and not let an equal
amount of air out.
Whether or not the code requires or prohibits a louvered door, there are
a few other potential considerations. A louvered door:
- allows waste heat from the furnace to help warm the room
- doesn't muffle furnace noise
- provides another place for dust to settle
In reply, the waste heat warming the room is a bad thing?
My furnace, which DOES have a return duct, is out in the open for all
The louvred door will hold a LOT less dust than a cold air return
duct, and is a far sight easier to clean.
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