Fan facing into room or out?
 

I have a good sized master bedroom that is over my garage and gets pretty warm during the day. At night I open windows on opposite sides of the room and have a box fan in one window.

Curious, is it better to face the fan blowing into the room and trying to push the hot air out the other window, or face the fan out to pull air into the room from the other window...or does it matter?

I have the same. I do both. Sometimes I'll put a fan facing in on one side and a fan facing out on the other to generate a cross breeze. You have to pay attention to the wind though, as sometimes it will do it for me and I don't have to run a fan.

Facing the fan into the room will create more turbulence (better mixing) and discourage warmer air from pocketing up high.

Of course, if you have the fan up high, then pulling it out may be more efficient.

Unfortunately they are vaulted ceilings and the windows are normal height and open on the lower end.

Going to play around with the fan a bit and see what works. I do know getting an exhaust fan for the garage is a must soon, all that hot air right below the room can't help even though the ceiling of the garage is insulated.

That's exactly what we did in college. Fortunately we had a corner dorm room, so we had two windows with which to work the cross-breeze concept. (My roommates were engineers. 🙂)

I've always thought of them as "extractor" fans. I always have them pulling air out of a room.

Whole house fan is the droid you seek. That requires some work though.

With fans, you can set them blowing in at one end of the house, and out at the other, so the air flows through the house. In the morning, there is often a bit of a breeze that I take advantage of to cool off the house.

I read somewhere and a long time ago it is more efficient to use the fan to exhaust the air out of a window. Don't know how true it is though.

I get the extraction theory, but in reality a tiny box fan isn’t going to do any significant extraction in a large bedroom. It’s not going to lower the temp of the entire room noticeably.

Your best bet is to have it blowing inwards, close to you so the breeze it creates cools you.

You need to open 2 windows and figure out what direction your flow is with no fan.
Use a match, paper, or candle at each window. Once you figure out your general flow (breeze)
direction. Put your box fan blowing out on the downwind window.

The old style whole house "attic fans" in the ceiling....turn them on....sucks the air into the attic. Open a window or two...nuthin' better for putting fresh cool air in a living space. Depends upon layout....YMMV

Get the warm/stale out...replace with cool/fresh....in minutes...close up house for the day when done :)

I push the warm air out.
I feel less air movement that way.
Many feel less comfortable if they sense or feel air movement.

point both out. open entrance from downstairs to let cool air in.

edit- nevermind-always point one fan in so you can put your face / talk into it like peter frampton.

Try to work with the flow.

If there are hotter parts of the room than the rest of the room and you can put a fan there, exhaust in those parts.

I actually have a whole house fan but it was installed in a downstairs hallway for some reason and is under powered to boot.

I plan on installing a second one in the winter (no way I'm getting up in the attic now). It is a home made quiet cool setup and is the 3000cfm version. Even if I have it on with the window in our room as the only opening, the air flow is still minimal and barely cools anything down. I use it over night to cool downstairs but need something for our room in addition, hence the box fan.

Figure out the air flow...go with the flow ;)!

It depends.

If you are running it at night, blowing out of the room may be less annoying to the occupants, but you are drawing warm air from within the house thorough the room, so the bedroom would be the last to cool down.

If you blow cool air in from outside, you will get the quickest temperature delta, but the focused breeze may be annoying.

Good point. I dont usually like any air blowing on me at night, dries me out and gives me neck aches for some reason...but at some point air blowing on me is better than sweating in bed wide awake!

Window AC...

There is the box fan swamp cooler, or for a bit more dough, you can throw one of these together. Break a few ice trays into it, or freeze plastic jugs of water to make it easier to swap out the ice. I might even make one, would be great to have at the track in the summer.

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Oh yeah, I don't know how much insulation you have in the ceiling of garage/floor of the room, but more would maybe be better.

It was hot as a MFer today