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enter image description hereI have a one story house and I think there is a negative pressure problem. If the central a/c is on and I close the hallway door the hallway heats up like an oven. This hallway leads to all the bedrooms; there is a return air vent in the ceiling and a door in the ceiling to the attic. Obviously the heat is unpleasant but is there a bigger issue with having negative pressure like this in part of your house? What can I do to fix? There is a 2nd return air in a room on the opposite side of the house - the door to this room is usually kept open.

  • I suspect you have some leaks in the ductwork or some of the conditioned air is going someplace else (like out a window?) Then the return air is being replenished by air from the hot attic. With the doors closed, can you feel hot air coming past your attic access pull down stairs? They are often not well insulated (or at all) nor well sealed. – George Anderson Aug 23 at 14:35
  • No hot air but I can strongly smell the scent of bare wood from the attic so maybe a good idea to seal the access off - what’s the best way to do so? – Coloroverkill Aug 23 at 15:09
  • I just realized the vent in the ceiling at the end of the hall is a whole house fan, not return vent. – Coloroverkill Aug 23 at 15:18
  • If you are running a whole house vent fan that would def create negative pressure if it's blowing to the outside. I think others here could weigh in with better answers and more knowledge, but from what understand about a whole house fan is you want to run those when the outdoor temps are cooler than indoor (like night and early morning) and have some windows at least cracked open. Again....not enough info on your systems (age,. design, model #'s etc.) to better help you. – George Anderson Aug 23 at 15:55
  • Thank you! Looks like I have a lot to learn about the whole house fan. It seems to just turn on automatically “when the system needs it”-whatever that means (I use a Nest). – Coloroverkill Aug 23 at 16:27
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Many homes have only one main return located at the air handler. The separate rooms have a supply but the return is the space/gap under the room door. While closing a room door might not affect cooling too much, a hallway door cutting off a number of bedrooms would have a major effect. Installing a through vent above the hallway door might be the answer.

I love whole house fans but you have to cover them up in the attic during AC season because the vent that comes with them is not insulated and any negative pressure will suck hot air out of the attic.

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  • I did not know I had to cover up the whole house fannin AC season. I’m in Texas so AC season is 3/4 of the year - is it ok to keep the whole house fan covered for this long? – Coloroverkill Aug 23 at 16:26
  • @Coloroverkill I'm in south Florida and I just throw a blanket over mine for June, July and August, the months when I know there will be no break in the heat and humidity. My whole house fan is located close to my air handler and the vent has no insulation. Your situation might be different, something to check on. – JACK Aug 23 at 16:45

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