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Heating & Air Conditioning

Window A/C Unit Size?

15 years ago

I plan to get a window A/C unit to use when I don't need to run my central unit. The area to be cooled with the window unit is approximately 351 sq feet. An 8,000 BTU unit is rated for cooling up to 350 sq feet and a 10,000 BTU unit is rated for up to 500 sq feet of cooling.

I would hate to get the 8,000 BTU unit and have it running all the time trying to cool down the intended area, yet I would not want to get to big a unit and have excessive moisture and too much unit for the area.

I live in the HOT and HUMID south, New Orleans, LA. The unit will go on the sunny side of the house. Which unit could I safely go with?

P.S. The house is insulated.

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Comments (5)

udarrell_2007
15 years ago
I have been an HVAC licensed Tech since the mid-1970's.

That Rating doesn't mean much!
I cool +850-SF with a 6,000-BTUH half-ton 9.7-EER window unit. Even on 104-F Heat Index days it cools the entire first floor to 76-F & 50% RH.

You should use a small fan to circulate the air throughout the 351-SF room.

I use two fans to circulate the air through all the rooms & back to the A/C.

View my 1937 home & the info on the cooling process.- udarrell

Here is a link that might be useful: Optimizing Window Air Conditioning Performance
maryland_irisman
15 years ago
Darrell,

I checked out your web site...quite impressive....good stuff!!!
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It sounds great in theory, but probably wouldn't work very well, especially in some type of automatic system. Several problems come to mind. First of all is the material, itself. Calcium Chloride is a fine dessicant. Removes a lot of water, but in doing so, turns into a slurry. It would have to be heated quite heavily to be returned to a usable state. Silica Gel (those annoying little packets in packages of medicines) aDsorbs moisture, but needs a large surface area, as opposed to depth, to be effective. Since this 'unit' would have to be installed inside, in a domestic system, it would have to be installed upstream of the air handler; not a very good source of heat. The discharge air would already have its dew point lowered, so not much benefit in having it there. Also, whereas an a/c depends on heat exchange to remove humidity, a dessicant depends on prolonged contact to remove water. The velocity of airflow in a typical system would preclude that. There is also the potential for static pressure issues. Just my opinion. Do you have a link to your information? V
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You're not likely to find a new 8k BTU unit for $150. Maybe $250. Still, like most mass market appliances these days, window air conditioners aren't really meant or designed to be repaired. They're effectively disposable, kind of like diapers. :( That's a shame, not just because of the waste, but also because a lot of trash haulers will leave it on the curb. They don't want to deal with the refrigerant, no matter what type it is. If you're lucky, you may have a recycling center nearby that will reclaim and recycle the refrigerant If you're really lucky, you won't have to pay them to dispose of it for you. BTW, I suggest that you check out online reviews for the brands before you buy this one's replacement.
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aceh
Original Author
15 years ago
udarrell,

Your website does indeed have some resourceful info.

P.S. Forgot to mention that my ceilings are slightly higher than normal...9 1/2 ft high.
udarrell_2007
15 years ago
With 9 1/2 ft ceilings, I wouldn't do anything that would mix the warmer ceiling air with the rest.

With 9 1/2 ft ceilings; don't use a ceiling fan. Direct the airflow from A/C straight out never up.Keep any other fans low & blowing level at a low speed.

The warm air at the ceiling acts as an insulator that slows down heat transfer, due to less temp differential between air & ceiling surface.

Just my advice.

Hey, thanks for liking the info on my HVAC Web pages. Make hard copies & put the info to use.

I made an important change on one point on the "Trouble Shooting" page, so refresh & print the revision. - udarrell
aceh
Original Author
15 years ago
Thanks again udarrell.

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