HVAC air circulation/hot bedroom

In every room of my house there is one heat register and one intake vent at floor level (except the bathroom which just has a register).

In the winter, if I close my bedroom door, the room does not get cold or hot, it’s just fine. In the summer, however, if I close my bedroom door, the room is stuffy and hot. Even an oscillating fan doesn’t provide much relief.

I have read on this board that the optimal way to use intake vents is to have one near the floor for the winter to suck in cold air and one near the ceiling for the summer to suck in hot air (hot air rises).

I was wondering if having my bedroom’s intake vent modified so it can close, and adding a second intake near the ceiling would do any good for solving this problem. Unfortunately for me I think this might be an expensive thing to do…the intake doesn’t just sit between two studs, it’s real ductwork. So the project would involve drywall and paint and stuff. And I’d want to do it in at least two rooms.

Another thing I thought would be to add vents to the bedroom doors, but this would let light in to my awesomely-dark bedroom and I’ve never seen this in anyone else’s house so it wouldn’t be good for resale.

What’s the deal, tho? Why is my room so stuffy? Don’t other people sleep with their doors closed?

First…it is much easier to heat a house than cool it.

Without more information, we can only give you the common problems. (and solutions)

You need a greater volume of air to cool the room ------both in supply registers as well as intake registers-------(vs heating), so you may have an undersized “intake” (called “return” in HVAC jargon) in the bedroom. To cool, it’s not enough to put cool air in the room; you need to “recycle” the hot air to be cooled.

Thats not an issue in heating. So you may need a larger return.

Or…you may need a larger supply. Even if the air is frosty cold if you don’t have enough of it, you’ll still be hot.

Or…they could both be problems—not enough supply or return.

If you give us:

  1. Square footage of the room
  2. The size of the supply register and the return register, and if you can;
  3. The size of the duct going to those registers
  4. What direction the windows face, and how much of that (roughly) is glass.

We’ll give you better info.
While we’re at it, you could have an A/C system that is low of Freon etc. (not as likely if it cools just fine with the doors open)

The room is 10’ x 11’.

The supply is 18" x 6" in the baseboard like this. The duct is an 8’ pipe going to a 12" opening.

The return is 30" x 6" like this. I have a cabinet about 4" in front of half of it, the other half is clear. I can’t tell about the duct going to the return. It’s either some setup where the duct is a piece of sheet metal tacked to the floor joists underneath to create a “duct” or it comes right off the main return (it’s only like 5’ away from the furnace/blower). I can’t see.

The 56" x 32" window faces north and is 90% glass. But it is covered 100% of the time by a room-darkening shade underneath permanently-closed traditional blinds.

AFAIK the A/C is fine for my house. It’s only 3 summers old. My house is only 1040sqft, with a full basement (there are two vents in the basement).

The only time I seem to feel hot in here is when I am in the master bedroom with the door closed when it’s 60+ degrees out. Otherwise, I’m never really in a room with a door closed (er aside from the john). I do live in the Cleveland area, which is quite humid.

Many HVAC systems put in by builders tend to have incorrectly designed duct system, poor cooling load.