One air conditioner or two? Advice please.

Here is a bad drawing of the layout of our upstairs (1.5 story, built in 1952):
West
10ft 9ft __________ _________ | | | | | |___| |
| ___ | North 11ft| | | |12ft | | | | | | | | | | | | |__________| | | |_________|
East
*adults are in the north bedroom, a child in the south *Area between the 2 rooms is approx. 3ft x 4ft landing with stairs going down towards the west *Open sides in each room are the windows (basically straight across from the doorway *air conditioner will be installed in wall, directly under window (air could hopefully flow directly through doorway to other room) *total square footage to cool is 230 sq ft. including the landing
Which option is better:
1. Put an 8000 btu air conditioner in north bedroom 2. Put a smaller btu (5400? 6000?) in each room 3. Something else?
We want both rooms to be cool enough to sleep, we don't want some of us to freeze and some of us to boil. Currently it is about 34-36 degrees celcius in the rooms after hot summer days. Thanks!
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On Tue, 20 Jul 2004 04:56:17 GMT, blue
IAWT !
..or is this one of those strange puzzles !:-)
..some advice. IF you really want a half constructive indication of what is best then take some shots of the layout and post them into a binaries group (alt.b.test would suffice). A picture is worth a thousand words ,,yeh? My initial reaction to your post is..IF you are thinking of installing wall-rattlers then buy the cheapest and go with your own estimation. Your call is probably closer than most :- )
Hih's
BTZ
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blue wrote:

After playing with your ASCII image (they don't work very well most of today's products) I would suggest that trying to get buy with one air supply for two rooms like that is not going to work well.
I would consider something else. I would go for some kind of central unit. A HVAC professional should be able to offer you some suggestions. Questions about where you live, if you own the home or not, and other construction factors are not known to us, so it is a bit of a problem for us to address. For example if your current heating system is old or inefficient it may be much better to replace it with a good central system and save you money in the long run, but if you are renting and plan on moving next year, that may not work, unless the owner can be convinced of the advantages to him of updating they system.

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Joseph E. Meehan

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My opinion:

My reasoning is that you can not be sure of good enough air flow using only one unit. As for the "something else" option, a ductless heat pump (split system) would probably be better (more efficient and much quieter), but more expensive.
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Thanks for the opinions so far, sorry for the crappy ascii. I believe I am using Times font, size 16 and the encoding is Western (ISO-8859-1) if that helps the drawing work out better for anyone! But heck, I am using my boyfriend's Mac so who knows with these crazy Apple products. :-)
Basically their are 2 rooms joined by a 3x4 landing. One room is 11x10 and the other 12x9.
I realize central air is the best option but I guess I should have mentioned that we have had pros from 6 companies in an all of them have said that because our furnace is older, it is larger and air conditioning will not physically fit with our furnace and basement ceiling height. Thus, we are waiting for central air until we replace our furnace. This won't be for a few years as the current furnace is still in good condition and replacing the furnace was not in our current renovation budget which already ran out and put us behind schedule on our other renos. :-) thus, we are looking for the window/wall units for the next couple of summers at which point we will replace the furnace and upstairs windows.
blue wrote:

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blue wrote:

Depending on the efficiency of the furnance you have and what you may buy, and the increased efficiency of a central unit vs. window units, you may want to rethink your economics. The cost of doing it right, may not be all that much after all. Interest rates are going up; getting it all now may not be so bad and will be a lot more comfortable.
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Joseph E. Meehan

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What is the total Btu needed for the area?
The problem with one large unit is air distribution. As you note, one room will be very cold, the other warm. Two units would be best. I do my entire upstairs in a similar manner. Bedroom has 6,000, Dining room has 12,000, a fan blows cool air from the dining room to the living room. Two bedrooms are not used and the doors are closed. If one or both are to be used, another 6,000 in one of the bedrooms does it.
My lower level is cooled with one 14,000 Btu unit. Family room is a bit cooler than the other end of the house, but it is close enough for comfort.
More costly systems are available, but cost depends on the ducts, etc that are needed. If you are in a moderate climate, it may not be cost effective for the little se it will get. Ed
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Edwin Pawlowski wrote:

According to this Maytag chart I have, 8000 btu would be good for the entire area, about 230 sq ft. this chart says 6000 will only do up to 200 sq ft. which is close, but I figured the extra air flow with the larger one might benefit the 2 rooms. I am looking at 2 units right now but it seems it is difficult to locate 2 smaller (5400 btu) units in my city without special ordering them for a pretty penny. If I go larger in each room I might not have efficient cooling/humidity control (according to the web sites I've reading, all say not to go bigger than you need).

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If it's just for temporary use until your furnace breaks, then just get two used window units and be done with it.
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On Tue, 20 Jul 2004 14:36:55 GMT, blue
snipyt

UR the expert,, go with your 'gut feeling',, it s your hard earned dollars, after all. I doubt a 'professional' could help you - other than clarifying terms for time payment. <G>
BTZ
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blue wrote:

I think two 6000's would be enough, depending on how well everything in insulated. I cool my whole house with a pair of 8000's, one upstairs and one on the main level. (the one upstairs does most of the work.)
Bob
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Put a smaller AC in each room. I think Home Depot has 5k btu units on sale for $55 right now. You will probably want to close the door to your bedroom at times, right? And you can control the temperature of each room individually.
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Larry Wasserman Baltimore, Maryland
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blue wrote:

I would say two separate units. Putting a large unit in one room and trying to cool two rooms has a few problems. 1. Both room doors need to be left open. 2. The room containing the unit is probably going to be much cooler than the second room. 3. You will probably need an auxiliary fan to blow the cool air into the second room.
You have another problem that would require the doors to be kept shut whether you have one or two units.. In your particular case, you have a down stairway between the rooms. The cold air coming out of either, or both, rooms will just pour down the stairs.
Before I got CAC, we had three AC units for three bedrooms on the second floor. The 3 bedroom doors were at the end of a 3' wide hallway which had a 90 down staircase at the other end. Because we sometimes left the doors open (to cool the hall and the bathroom), we used to hang a sheet in the hallway between the room end and the staircase end to keep the cool air upstairs. I had thought of putting a door at the staircase end of the hall, but decided against it because it was only needed in the summer and the door framing would narrow the hallway to where large items would have difficulty getting through, or worse, couldn't get through at all.
.
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On Tue, 20 Jul 2004 11:17:01 -0400, Bill Schnakenberg

snip
do not we all :- ) First rule of thermodynamics,,there is no such 'thing' as cool..or cold..or freezing.
snip.

/me deletes the rest of the dribble
yeh,, well, UR an Xpert , huh?
BTZ
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The most effective way to use a fan to aid in cooling a second room would be to have it blow the hot air *from* the second room *towards the a/c* so the a/c can more easily remove the heat from it.
JFYI
Dan O. - Appliance411.com http://ng.Appliance411.com/?ref411=air+comditioner
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On Tue, 20 Jul 2004 04:56:17 GMT, blue

Since these are attic rooms you need slightly larger units. Also how well insulated? If original 1952 construction probably vey little. You have heat gain through ceiling and three walls not just two walls like you would have on ground floor. Since this is temporary for a few years why build them into the wall? it means you need units with a sleeve and will have to patch the wall after you remove them.
I have a cape with two bedrooms, one about 12 by 9 uses a 6000 btu unit and the other about 12 by 113 used 7000 btu unit. I would not get any smaller as these are barely adequate. These were rebuilt because they previously had no insulation in the walls only in the ceiling.
As others have stated one AC will not cool two seperate rooms, plus one has south exposure and one north so one will have more heat gain during the day.
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Thanks everyone for the advice!
blue wrote:

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