Replacing a 26 year old air conditioner! (Westinghouse Mobilaire)


We have a White Westinghouse "Mobilaire" air conditioner, installed through the dining room wall, that has finally given up the ghost. It was here when we bought the house, and we've been here 20 years. I seriously doubt that it can be fixed. Besides, it isn't as energy efficient as newer models.
Using an on-line calculator, we determined that the three rooms downstairs equate to roughly 425 square feet (the entire area is open, so it seems like one room!), so we figured that we need about 10,000 BTUs. However, I was surprised to see that this particular model (AL183H2A1) is 17,500 BTUs. Was that much power necessary 20+ years ago because they weren't as energy efficient as they are today? (It says "Cooling EER DOE 6.0 / 5.9.")
While it's been installed and used through the wall, the installation sleeve from outside has vents on the sides. This would seem to indicate that this air conditioner is a regular window model. I don't know when wall units were first manufactured (and the date on this unit is 07/84), so I guess the previous owner was just trying to save money.
I guess that my questions are: (1) Should we buy a model with greater than 10,000 BTUs? (2) Has anyone out there seen air conditioners on end-of-season sale? It seems that, with the advent of online shopping, there is no incentive for retailers (with online "stores") to place air conditioners on sale at the end of the season, since they're always available in a warehouse. (At least that's how I think they see things.)
Since the previous unit appears to be a window unit and there have been no problems with leaks, I suppose that we can still buy a window unit (being frugal), since wall units seem to be more expensive. Wall units also seem to be mostly dual cooling/heating units (the reason for greater expense), which I don't want.
We're in Pennsylvania, if it matters.
Thanks, T
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Wall units can have vents on the side. Those side vents just have to be spaced far enough to allow installation without the vents being blocked by the the wall. Changing sizes will mean the hole size will have to be adjusted as well. Were you happy with the 17,500 BTU? Was it too loud or blow too much cold air? I had one in my home and replaced it with 12,000 BTU. Much quieter and does the job.
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Get a pro over there and do what he tells you. He should do a "load calc" and that will tell him MINIMUM size. You can always go over that a little. There are current government rebates if you buy the high SEER units.
Steve
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On Mon 30 Aug 2010 08:20:28p, turtlelover told us...

Thru the wall units were manufactured as early as the mid-1950s. Both window and wall units were available then that had both cooling and heating capability. York Corp. made many of these.

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At 26 years I dont think it would have been putting out 17500 btu, did you need it running on high all the time 24 hrs a day when it was hot years ago, if so then maybe you need near 17000 btu.
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BTUs are BTUs ans indicate the cooling capability. It has nothing to do with how efficient or inefficient the unit is. If it's an inefficient unit it will just use more electricity to generate the 17,700 BTUS.
I'd be skeptical that a 10K unit could cool 3 rooms. With a single wall unit in addition to how much cold air it can put out, you have the issue of how the air gets distributed to the other rooms. If the existing one didn not appear to be oversized, I would go with a new unit closer to that, not 10K. It pretty much takes 7K or so to just do one room.

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<snipped most of my post>
Thanks for all of your replies, folks. The A/C used to cool just fine, and it wasnt really necessary to keep it cranked up all day. There are three considerations: (1) the unit is in the dining room (middle of the three rooms), and it faces a wall about 10 feet away (its sort of an alcove, where it gets ungodly hot when the air isnt on as needed). The air flow louvers(?) didn't turn very well so we couldn't direct the air flow toward the middle of the room; (2) the outside wall of the A/C gets direct sun; (3) one of the rooms to be cooled is a kitchen.
Well probably look for something in the 14000 range, but we will get a pro in here for an estimate.
Many thanks, T
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A new unit is probably 3x more efficient than that unit you should have junked years ago, junked because of its cost to operate. Are you going to pay a pro a service call of maybe 100$ to tell you waht you need? Units are cheap enough, for better cooling get a few small units. New units really do save money for you every month on your utilities.
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If the unit is too small that simply means on extremely hot days the house will be a few degrees warmer than it would otherwise. To what extent would this bother you?
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