Keeping upstairs cool

[shiellb]

Good evening. My wife and I are having a discussion about fans in the 4 bedrooms upstairs. We have a 2 story foyer and an open hall to the bedrooms. I say having the fans in each room blowing air out of the room and into the foyer will create a slightly negative pressure in the room and draw more cool air into the room from the vents. My wife states the fan should be oscillating in each separate room to keep the air moving in the room. Comments please.

[Egon]

Lets follow some scientific reasoning on this shall we!

Your wife is right of course!

[jaywood1207]

I have a window air conditioner for sale that would cool all 4 rooms.

[Bob_Macgregor]

I have a single, 20" fan that I put in a bedroom window upstairs blowing out. By adjusting which other windows are open in the house, I can get pretty-good air exchange where I need it. The biggest drawback to my system now is that I have to leave the window screen in place (because of our overly-generous bug supply), so the fan's effectiveness is somewhat diminished relative to what it would be without the screen.
In PEI's climate, I only need the fan for a handfull of nights in a year, anyway.
BOB

[Gene45]

Once upon a time I put a 20" fan in the door (hatch) to the attic to blow up. This way it blows the really hot air out of the attic, and it has to be replaced from fresh air in the windows. Worked pretty good.

Today I have windows on all sides, and just let the wind blow thu.

[billh]

You said you are drawing cool air from the vents. Does this mean you have central A/C but the upstairs is still too warm?

If you have central A/C there will be a tendency for the cool air to remain down at floor level and then fall down the stairwell opening to the lower level. House ducting is really designed for heating, not cooling.

IMO, a ceiling fan might be a solution but you could simulate one with your small fans. Try closing the doors too even though it doesn't seem like a good thing to do.

billh

[Bob_Macgregor]

Blowing air past your body helps cool it by dissipating body heat faster and by accelerating evaporative cooling. This does nothing for lowering the actual temperature of the room's air, though (in fact it slightly raises it because of the heat from the fan motor).
A whole-house fan (or cobbled-together substitute) will either force air out of (or into) the house and create air exchange. If the air outside is cooler than the air inside, you get the cooling effect of a bit of air movement plus actually lowering the inside air temp.
I wonder if it would work to get an old furnace squirrel cage fan and hook it up to an attic or basement window to create a negative pressure in the whole house? Then you could just open a window in the room you wanted to cool/ventilate, and outside air would flow right in.
As I said before, my cooling needs are too slight and temporary to need a very elaborate system, but your needs may call for more drastic action.
BOB

[ArtMulder]

...about fans in the 4 bedrooms upstairs. We have a 2 story foyer and an open hall to the bedrooms. I say having the fans in each room blowing air out of the room and into the foyer will create a slightly negative pressure in the room and draw more cool air into the room from the vents. My wife states the fan should be oscillating in each separate room to keep the air moving in the room. Comments please.

If you have central A/C there will be a tendency for the cool air to remain down at floor level and then fall down the stairwell opening to the lower level.

My experience matches Bill's comments.

We also have a two-storey vaulted foyer. The upstairs bedrooms open off of the upstairs section of the foyer.

We had a HVAC inspector in a few years ago who told us that we need to keep the upstairs bedroom doors CLOSED during the cooling season (not easy with active kids running around!) or the cold air will come out of the HVAC vents in the bedrooms, and just roll out the door and fall down the stairs.

We've done our best since then to listen to his advice. Keeping the bedroom doors closed helps "hold" the cold air upstairs in the bedrooms. We do notice the difference.

Actually, the ideal solution would be to have TWO sets of return air vents. During the summer you'd open and use the return air vents located near the ceiling to suck in the hot air. During the winter you'd ope and use the return air vents located near the floor and suck in the cold air.

Actually, an even better idea would be for house builders to design smarter houses. Most bedrooms these days only have one window. About a year after we moved into our house, my wife and I added a window to our MBR (a 24x48 casement) on the side of the house. This now gave us windows on TWO walls in the room. The ability to get a cross breeze through the room made a HUGE difference in the comfort level in that room. We wanted to do the same thing on one of our kids bedrooms -- it is located on the NW corner of the house and can cook in the hot summer. However, adding a 2nd window to that room is impossible because the (useless woodburning inefficient piece-o-junk) FamRm fireplace chimney runs up the outside wall that we would want to use.

[Gary in Waterdown]

Since you're going to be getting a lot of the cold air from upstairs rolling down to the main floor anyway, try closing vents on the main floor (and in the basement). This should force a higher volume of cool air to the open upstairs registers. Start with vents that aren't near entrances and south facing windows.

If you have wall returns, you can probably install upper grills in the same wall cavities. Make sure they have dampers you can open and close, and replace the lower ones with dampered grills, too.

[Gene45]

actually lowering the inside air temp.
I wonder if it would work to get an old furnace squirrel cage fan and hook it up to an attic or basement window to create a negative pressure in the whole house? Then you could just open a window in the room you wanted to cool/ventilate, and outside air would flow right in.

BOB

If you have a choice, blow the hot air out of the attic to create the negative pressure. The basement is already cool and you don't want to blow that cold air out.

[Rusty]

Wouldn't you think if you have an air conditioned house and the system is in fact providing cooling air how in the heck would the cold air ROLL down a staircase into an already COOL space?

As for builders designing and building better houses,,,,,,,,, We are and we do!

Putting more windows in a house may be great for ventilation in the Summer, unless of course you have A/C, but you might complain about the cold or the draft in the Winter. We solved that with better glass. We solved the Heat and A/C with thicker walls and better insulation,etc. etc. If anyone thinks today's homes aren't improved and improving all the time,,,,,,,,,,,Hmm??

[shiellb]

Thanks for the info. Our house does have central A/C. We use it only on really hot humid days, the rest of the time we have the windows open. I am intrigued about the idea of closing the main floor vents thereby forcing the cooled air to the second floor and letting it flow to the lower floors. Have a good weekend all and thanks again.

[ArtMulder]

Wouldn't you think if you have an air conditioned house and the system is in fact providing cooling air how in the heck would the cold air ROLL down a staircase into an already COOL space?

It seems that you are assuming that the ENTIRE first floor is completely filled with uniformly cool air. It isn't. Hot air that is generated on the first floor (from your PC, your Stove, Your Fridge compressor, your TV...) will rise. It will rise up the stairs, and the cold air that your HVAC unit pumped up there will in turn fall down the stairs into your main floor.

Unless you close the doors.

Try it for yourself. We did. I'm speaking from our own experience.

[Rusty]

It seems that you are assuming that the ENTIRE first floor is completely filled with uniformly cool air. It isn't. Hot air that is generated on the first floor (from your PC, your Stove, Your Fridge compressor, your TV...) will rise. It will rise up the stairs, and the cold air that your HVAC unit pumped up there will in turn fall down the stairs into your main floor.

Unless you close the doors.

Try it for yourself. We did. I'm speaking from our own experience.

Art I'm sure not saying it doesn't work for you but something isn't working right. Have you tried running the fan continuously? Sounds like you need more circulation thru the return airs.

[ArtMulder]

Art I'm sure not saying it doesn't work for you but something isn't working right. Have you tried running the fan continuously? Sounds like you need more circulation thru the return airs.

Ummm, you said "but something isn't working right."

I'm not in charge of the laws of physics, Rusty...
Hot air rises, cold air sinks, that's just the way it is. If you have a 2-storey space, the colder air will make it's way to the bottom, and the warm air to the top.

I don't have a 2-speed fan, so I have no interest in running my furnace fan 24/7 when all I need to do is close some doors. We try to keep the AC turned off as much as possible, and this simple method helps a great deal.

[Rusty]

Art don't misunderstand me. I'm not trying to be a smart ass. What I am suggesting is a possibility only. Sometimes 2 speed fans are just a question of wiring at the motor. Regardless, if you ran it 24/7 for a week it might tell you something. It might not too.

I know cold air falls but all I'm saying is; "IF" the air on the lower level was already cold then less cold air would migrate down to the lower level. Doesn't that make sense to you?

I guess in a nutshell what I'm trying to say is I have a reluctance to pay for a system that doesn't deliver as advertised. I'm sure your installer has done more than one house like yours. [Hell,, half the houses built today are similar to yours.] It just seems goofy to me to have to close doors to isolate areas when you paid to have the whole house air conditioned.

I'm just trying to offer some help. After all, you paid your hard earned money out. Maybe you should hold the installer up to some further scrutiny. That's all!

[Ed in Leaside]

My shop has a 16' ceiling. If I don't run the ceiling fan the temp difference up/down is at least 5C. Wouldn't make a difference if it was summer/winter AC/heat.

The spice shop has 13' ceiling. He's Indian (Gujarati) from South Africa and doesn't understand that he needs fans for the winter to push the heat down. Doesn't need them for the summer because all the AC air falls right down (HVAC is overhead).

[dave_k]

Actually, an even better idea would be for house builders to design smarter houses.

This former R-2000 builder tried that in the mid-1990's. The problem is the consumer wasn't willing to pay the very small extra price up front for a better designed, better built home. I lost money on the R-2000 houses I built. I got a lot of atta boys but no buyers. People were more interested in $/SF and if they liked the layout they would take my floor plans to the builder down the street and ask him to build it without the R-2000 extras.

I live in an old house so even with central air the insulation and ducting design sucks so it heats up during heat waves in the old part of the house. I am an early riser so during heat waves I open the upstairs windows in the morning, open the front and put some big fans in the doorway and at the top of the stairs pulling the hot air out to be replaced with cool outside air.

[billh]

My shop has a 16' ceiling. If I don't run the ceiling fan the temp difference up/down is at least 5C. Wouldn't make a difference if it was summer/winter AC/heat.

The spice shop has 13' ceiling. He's Indian (Gujarati) from South Africa and doesn't understand that he needs fans for the winter to push the heat down. Doesn't need them for the summer because all the AC air falls right down (HVAC is overhead).

We have cathedral type ceilings and I can say with certaintly that running ceiling fans makes a huge difference both summer and winter.

The main floor had an open stairwell to the basement when the A/C was put in. The A/C just ran and ran and the basement was like Antartica with less than satisfactory results on the main floor. The stairwell is now totally enclosed which fixed the problem.

billh

[jim in Halifax]

Our church's santuary has a high cathedral ceiling.....We installed three large fans many years ago and they run at 1/2 speed 365 days a year 24/7.....Keeps air moving down...Also has saved "some" saving in oil consumption over the year....Used to turn up the thermostats on Saturday am and way back after the service on Sunday. Now they are left mid 60* in winter. Also have an auto thermostat that is programed during winter season.