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June 20, 2006 4:24 PM   Subscribe

AC Filter: Help me pick the best air conditioner for my giant-windowed apartment. With visual aids!

I know that this question has come up before but our apartment is a bit atypical.

So after a half-dozen summers in the NYC heat my roomates and I are ready to give in and buy an air conditioner. This coincides suspiciously with us all having jobs for the first time ever.

We live in a 1400 sq ft. loft with 15 foot ceilings. No real rooms. So we're looking at something between 20,000-25,000 BTU. Price range is $400-700. This seems to rule out a portable unit. Leaning towards this bastard at the moment. Our windows are giant. 64" wide by 8' tall. Metal. We live on the third floor, so we don't have to worry about intruders.

The "special delivery" status of this unit is scaring me a bit. Couple questions:

1. This monster weighs 170 lbs. Our windows are nearly twice as wide as suggested, and 10 inches wider than the "wide window accessory" supports. I've got a screwgun and a circuar saw and am reasonably handy but I don't want to kill anyone. Are we going to be able to make this thing safe?

2. This guy appears to be 240v, but I can't find out what sort of plug it ends in. Will it work in the socket shown in Defense Exhibit #3?

Here are my visual aids:


Any advice or unit suggestions would win you our sweaty thanks.
posted by nathancaswell to Home & Garden (10 answers total)
I live in the civilized part of the country* with central heat and air, so I know nothing of in-window units.

But in photo one, you have an overhead lamp, you should put a ceiling fan. It will help circulate the cool air around the room in the summer. In the winter it will help circulate the warm air.

* in terms of climate control only.
posted by birdherder at 4:46 PM on June 20, 2006

You don't have a proper socket for a 240V appliance. According to this site, your NEMA socket is for 120V/20A (opposed to a regular one, which is 15A).

I've got just the opposite problem right now. I'm trying to find a small air conditioner (< 10,000 BTU) for a 240V outlet. Good luck.
posted by sbutler at 4:52 PM on June 20, 2006

Wait a minute... I should have checked the picture closer. You should be fine, that looks like 240V/20A.
posted by sbutler at 4:52 PM on June 20, 2006

Can you make this safe? Probably. One trick is to measure the AC unit at its widest and then cut one or two pieces of plywood to fit in the difference (depending on how much you like assymetry). Make the plywood pieces a little wider than they need to be to make up for measuring mistakes and because it's easy to make the AC "wings" narrower.

Install and attach the wings to your plywood.

You can also do another trick which is to cut a piece of plywood to fill the window space, then cut out an air conditioner sized hole in it. Install the plywood in the window and then install the AC unit in the plywood.

You probably should paint the outside of the plywood to keep it from rotting, so it will last more than one season. If you're not into decor, you can usually get deep-discounted pre-tinted paint from most paint stores from customers who weren't happy with the color.

Is it safe? Try sitting on the window sill. Can it bear your whole weight with no issues? If so, it will take the AC unit, as long as the window sash is good and solid.

Is this unit enough? Ehhh...not sure. See, AC units actually need to be rated in cubic feet not square feet, but seeing as 8 foot ceilings are standard in most homes, this is not an issue. You, however, live in what looks like an old mill building with nice high ceilings (lucky you!), giving you nearly twice the cubic feet. The unit you picked is rated for 8000-12000 ft3, whereas your place is 20250 ft3, so you're going to be working that AC pretty hard.
posted by plinth at 7:09 PM on June 20, 2006

You don't say whether you've seen Whirlpool's user manual, but it's under here (see Guides and Literature), and it includes a bit on installation and on plug shapes.

The key to safe installation is to make sure that supporting brackets, interior angles, etc., are strong enough and big enough for the particular A/C and are structurally fastened to the building envelope, not just to a wooden sill. Some apartment buildings have written guidelines and architectural drawings for this. You might do some (more) Googling and maybe see if Elgot Air Conditioning in NYC will answer your questions even if you don't buy the unit from them.

Do not just sit the unit on the sill and rely on the window sash to hold it in place. Alternatively, tell us where you live so we can avoid that sidewalk.
posted by Dave 9 at 7:31 PM on June 20, 2006

The plug is NEMA 6-20R, which mean it is a 240V, 20A plug. The unit is listed as 240V/20A. So, the plug can provided the required power, provided...

1) That it works. ;)

2) That it has copper conductors -- the specs for that model state Cu required. What this really means is that they don't trust aluminum conductors with the surge current. Surge current? Yes, this (and almost all AC units) will draw more than 20A for a very brief amount of time. Aluminum conductors, unless sized correctly, will flex a bit under the draw, eventually, this flex will cause a failure.

Properly sized Al conductors, installed correctly, are fine, but there were problems. If you have Al conductors, consult an electrician.

3) Also, because of that surge current. If you have fuses, not breakers, you'll want to make sure that there's a time delay fuse, not a fast-blow. The compressor often needs more than the rated power for a very short period of time. This is safe, but with a fast-blow fuse, it'll blow the fuse every time it starts.

If you have older breakers, they may trip as well -- breakers can get "weak" over time, and trip before they carry the rated load. This is safe, in the sense of a 20A breaker opening at 10A isn't going to cause a fire, but it is annoying as hell. The fix is replacing the breaker.

As to the plug on the unit -- the right answer here is "if it's a 240V/20A plug that doesn't fit into a NEMA 6-R20, change it." There's no danger here -- if the unit needs 240V/20A, and you install a NEMA 6-20P, you're installing a 240V/20A plug. Having said that, the NEMA 6-20 is the standard US 240V/20A plug for home use, so it is probably already installed. (The other common plug/socket is the NEMA 6-20L, which is a twist-lock connector.)

Dave 9 nails the importance of the support brackets.

Finally, on power. You're in a larger building. You should check to make sure that that socket is actually putting out 240V, and not 208. Many large buildings have three phase power feeds, and use a delta-wye transformer to get single phase loads. You get 120V by tapping from the end of a Y leg to the neutral, but you get 208V, not 240V, by tapping from one leg to another.

If this is the case, you need to make sure you unit can run on 208V. The presence of a NEMA 6 series plug doesn't tell you if you have 240V or 208V, it just tells you that it's more than 120V and less than 440V.

Some units don't care. Some units care deeply, and will not run or will fail fast on 208V. Some units care, but by moving a conductor on a terminal block, you can match the input voltage. In the case of the unit above, the specs say "207V min, 260V max", so you'd be okay both ways, but if you decide on a different unit, knowing if you have 208V or 240V on that outlet would be useful.
posted by eriko at 5:19 AM on June 21, 2006

As others have pointed out above, I doubt a single unit such as you describe is going to give you the maximum cooling capacity you need to maintain a comfortable indoor temperature during the hottest days in NYC. In such conditions, a window unit's compressor will run continuously, which is neither efficient nor good for the unit's life. You might find that couple of the newer Mitsubishi Split-Slim units meet your needs more efficiently, and safely, but the cost maybe somewhat higher than your stated budget. Still, money spent towards something good is better spent than wasted. Failing that, I'd go with a couple of slightly smaller window units with greater total capacity, for faster cool down, and better max temperature performance.
posted by paulsc at 5:58 AM on June 21, 2006

I have a window larger than my air conditioner's kit would fit and ended up building a wooden frame around it. The frame sits snug with the outside of the window frame -- basically, I can have the window wide open for a minute while putting it in or removing it and it will stay in place. I've actually screwed the air conditioner's brackets to the wooden frame. I'd imagine you could do something similar, then place some foam insulation between the wood frame and window.
posted by mikeh at 9:24 AM on June 21, 2006

What about something more like this: Portable Unit? It's only 10K BTUs but i didn't look very hard so i'm sure you could find one bigger, or worst case, use two. The nice thing about these is that you don't have to hang anything out the window bigger than a dryer hose and you can keep the unit close to where you are, potentially saving yourself some cooling costs.
posted by skatz at 11:22 AM on June 21, 2006

or i could read your post more clearly, and see you've already looked at portable units. sorry, not enough coffee today...
posted by skatz at 11:23 AM on June 21, 2006

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