I'd like to confirm something that I already suspect. I recently
finished my basement where my furnace is located. I've got the furnace
and A/C condensor in a small room. There are currently no air returns
in the basement to the furnace. I think I need to put a cold air return
in because when the A/C is running, all the cold air is congregating in
the basement making it almost too cold and the upper floors are almost
Am I correct in what I'm thinking?
I just finished my basement and had the same issue, only removing and
insulating the supplys helped. I cut in closeable supplys and returns in
the basement , I keep the supplys closed in summer open in winter and
return open in summer and a bit open in winter. I found a dehumidifier
is needed in summer just to keep it dry and not to cold from the cool
air that does filter down through the system. Many basements if fully
underground only need dehumifification in summer.
You really don't have the a/c condenser inside, do you? That's the unit
that gets hot when the a/c is running. It's supposed to be outdoors so
it can dump its heat into the atmosphere. If the room it shares with the
furnace has its door closed, that room will get hot when the a/c is
running. So if you opened the door a bit, the heat from the room would
spill into the basement and warm it. But this is a terrible "solution"
and wouldn't add cooling to the upper floors. Move the condenser outside.
I assume that the heating system is hot air and uses the ducts as the
a/c uses. What's the basement temperature like when the furnace is
running? Where does the furnace get its combusion air?
How does cold air get into the basement? If through registers, why not
simply close them? That would also make more cooling available to the
Depending on the placement of a new cold return relative to the supply
register, you might end up making the basement even cooler. If the two
were side-by-side, the basement would get warmer (without doing anything
for the upper floors), same as shutting the supply register. Putting a
new return on the opposite side would make the basement still cooler.
How old is the system, both heat and a/c?
The returns should be in the same areas as the supplies. Otherwise you
will have pressure imbalances in your house. This will increase
infiltration in your house and increase your heating and cooling
costs. If you put a return in the same room as the furnace without
having a supply there also, and the room is closed off from the rest of
the house, the room will get a negative pressure. This MAY backdraft
the furnace or water heater flues. You could be seriously killed! Be
careful what you do, guessing without measurements could be hazardous
to your health and electric and gas bills. It may also violate code.
agreed you don't want ope returns in the basement
you may want ot open some warm air supplies in the basment and blow
some warm air into the basment but not returns
returns in the basment will lower the air pressure in the basement
which along with the bad things stretch mentioned can also suck radon
into your house.
So what are you supposed to about all the cold air that is pooling in
the basement? I've got a return on each of the other two floors - warm
air returns as they are in and near the ceiling. Shouldn't the basement
have some kind of return?
I think I see your error. You think that you would like to have
that cold air that is pooled in the basement distributed to the top
floors of your house. But I ask you where is it coming from? If it
is coming from upstairs, then adding returns to the basement will just
increase the flow and make your basement even colder.
Well, you can't change the laws of physics! (cold air naturally
pooling in the lowest part of your house).
What you can do is control the access to your basement (shut the
door or shut the vents to the basement). That should increase the
conditioned air going to the rest of the house. If you have already
done that, then bigger vents and returns on the upper floors and
improving the insulation on the upper floors will help keep those
parts of the house cooler.
Condensor, evaporator - I can never keep them straight. I thought
the piece outside was the compressor? Whatever it is, the big noisy
thing with the fan that gets warm when the a/c is running is still
outside. The furnace, with the blower motor is inside.
The house, along with the heat and a/c are 8 years old. I actually
have no registers in the basement. The only one that was down there I
"covered up" when I finished the basement as the register would have
been in the ceiling of the linen closet. With no registers in the
baement, the cold air is getting in the basement my "settling" down
there from the upper floors. In the winter time is not that bad down
there. I assume that's because I'm pumping hot air upstairs not cold so
there is nothing to settle into the basement.
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