This is probably a stupid question.
I live on Lake Erie in ohio.
Does every room require a cold air return? I have a 2 story colonial
and am looking to remove a cold air return in one bedroom. The other 2
bedrooms both have cold air returns.
Thanks in advance.
Weeeelllll, yes and no about the stupid question part.
It's most likely that the design of the heating system
dictated the use of the two cold air returns. Forced air heating
works by "pushing" cold air out of a room, and pulling in warmer
air in its place. Removing a cold air return may well upset the
design balance and cause that end/side of the house, whatever, to
become cooler than the other. Certainly the bedroom would become
I'd suggest you could "test" it, but ... furnaces require a
certain amount of square footage to suck cold air from the rooms
to work efficiently, and if your design isn't over-designed, you
could fairly promptly burn out the fan motor by making it work
Now, you could probably -move- a cold air return within a room
without too much loss of comfort, but even that depends on the
layout of things.
Why do you want to remove a cold air return? Size of the return
openings and furnace btu and fan motor size might allow someone
to make a guestimate, but I sure can't. Oh, it's also related to
the square footage of the hit air supplies, too. It's more
complex than you probably think, but for the experienced it's
really pretty simple.
Personally I wouldn't do it; get someone in to size up the
situation who knows about such things first, preferable someone
good, not just a neighbor who's "heard of" things.
On 22 Feb 2006 11:26:07 -0800, firstname.lastname@example.org wrote:
If you don't have a cold air return, the room will fill up like a
balloon, and eventually burst. Most likely the windows will blow out,
and possibly the door. In extreme situations, the walls may be blown
out also. If people walk by outside, you should erect some sort of
barrier to catch the glass and other debris.
Remove NOPSAM to email me. Please let
me know if you have posted also.
A friend was told that with the high-pressure, small-i.d.-duct systems
that you don't need room returns. Because ... you don't.
Simple physical fact- if you pump gases into a chamber, you will
pressurize it until the net mass-flow-rate out equals the inflow rate.
One result of the increased pressure could be flow to places you don't
want- like through cracks to attic or past windows. Another result is
decreased inflow rate- reduced room heating.
Simply put: to heat a ft^3 in a closed room, draw that air to the heat
exchanger & then return it, heated.
Some older houses had louvered doors with served as part of the return;
fully-skinned door creates problems there. In such a situation, I
installed a "siamesed" return to 2 closed rooms. No more fungi in attic
There is only space for a certain amount of air in any room.
If you want to put hot air in, you have to provide a way to
get cold air out to make space. You can get a LITTLE bit
of space from leaks, and more if you leave the door open,
but if you're serious about heating the room, put in a cold
Do you have a return air grill in the hallway too ? For most rooms
the common air return path is the door undercut - the spece under your
door when the door is closed. I'll call an HVAC technician to check
things and advice you.
It's a design choice, One could have gone either way when designing the
system. One per room allows for the doors to seal more tightly (no gaps at
bottom) and allows for more zones (you may or may not have separate zones
for each return). One might do this to prevent bedroom zone air from mixing
with a large room or great space in a different zone etc.
You might be able to get away with sealing one return as long as they are
indeed in common and you allow venting of the room with the sealed vent
through or under the closed door (every door in the path back to the return
and cannot cross another heating zone). This will likely result in an
imbalance which may cause some rooms to be unevenly controlled. Some return
ducts are greatly oversized (being made of wall cavities) but if yours are
more carefully designed, you will starve the furnace of air making it less
efficient and increasing air noise in the remaining returns.
Try taping it closed for now and see if you detect any important
leave it there or relocate it. you will be reducing the heating
efficiency and make summer central air conditioning more difficult. see
lots of info at:
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