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Old 07-13-2011, 06:54 PM   #1
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Window AC in transom window


I've been having difficulty getting an adequate A/C solution for my 800 square foot apartment. The unit has three 8' high plate glass windows that face the afternoon sun. The only windows I can vent out are transom windows at the top of the plate glass. I had been using a portable 16000 btu unit, but it really doesn't cut it. I'm wondering whether or not it might be worth trying to rig up one of those 220volt monster window A/C's in my transom window. I can't have the unit extend out the window at all though. I'm wondering if I put the unit right up to the window frame and support it on a stand, then build an enclosure so that outside air would be taken in for the condenser cooling if I would have something that might function nearly as well as if it were properly situated. Anyone rig something like this up before?

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-D

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Old 07-18-2011, 03:26 PM   #2
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Originally Posted by delgriffith View Post
...I can't have the unit extend out the window at all though. I'm wondering if I put the unit right up to the window frame and support it on a stand, then build an enclosure so that outside air would be taken in for the condenser cooling if I would have something that might function nearly as well as if it were properly situated. Anyone rig something like this up before?
So basically you're talking about building a box inside the house that the AC will sit in, and the back of the box will replace your transom window and have just a hint of the back of the a/c poking out.

My gut says that this is not going to work well, if it at all. The window a/cs I've seen have vents on their sides as well that pull in the air which is then blown over the condenser and out the back. So with your enclosing it in a box I think you would get insufficient air to the condenser.

I also do think you might run into drainage issues unless inside your box you had a pan setup to collect the water and drain out of the sides.

Basically even if it's possible I think it would be more trouble than it's worth.

What about running a second portable a/c?

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Old 07-19-2011, 03:19 PM   #3
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Window AC in transom window


Yes, you have the right idea on what I am thinking. I am aware of the vents on the side for drawing air in, but the transom window is actually much wider than the A/C, so air can be drawn in on the sides. I was also aware of the drainage issue, and I do have a drain inside that I can plumb up to. The portable unit I have really isn't cutting it at all, I doubt two of them would do it either. It's rated at 16,000 BTU but I don't think that's an accurate rating. I have seen other units rated at 8,000 btu with the same current draw. That doesn't make sense. Anyhow i hadn't heard anything here and was sweating away so I went ahead and ordered a 220v monster window unit that is rated to cool an area nearly 2-1/2 times the size of my apartment. I'm hoping for the best... I'll see what happens I guess.
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Old 07-19-2011, 03:41 PM   #4
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Window AC in transom window


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Originally Posted by delgriffith View Post
The portable unit I have really isn't cutting it at all, I doubt two of them would do it either. It's rated at 16,000 BTU but I don't think that's an accurate rating. I have seen other units rated at 8,000 btu with the same current draw. That doesn't make sense. Anyhow i hadn't heard anything here and was sweating away so I went ahead and ordered a 220v monster window unit that is rated to cool an area nearly 2-1/2 times the size of my apartment. I'm hoping for the best... I'll see what happens I guess.
I have a 10KBTU "Newair" portable (just a 'single hose' model) that I use on the 2nd floor of my Cape house. In the evening, around 6PM, it will be close to 90* in my bedroom up there (a 20x17 room, very large)... I'll turn on the portable unit... by 10PM it's a comfortable ~77* with low humidity... though that's about the limit of this unit, it can't bring the room any cooler than about 75* even at night when the temp outside is in the high 60s.

It seems like maybe you got a lousy portable unit... 16kBTU sounds like too much for a regular 110V model...

So OK, you bought this 220V monster, a few questions--

- Do you have a 220V outlet to plug it into? Or are you planning to hire an electrician to install an outlet?

- Have your built your enclosure yet? How are you planning to support it? That air conditioner is probably going to weigh close to 100lbs if not more, it's weight will be almost entirely over the box, so you'll need some studs going from the bottom of the box to the floor to act as "legs"... this is going to be seriously unsightly

I'd love to see a few pics just to check it out
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Old 07-19-2011, 05:46 PM   #5
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Window AC in transom window


The range is plugged into a 220v 40amp circuit and my plan was to make an extension cord that will plug in there. The unit weighs in at about 140lbs, and my thought was to support it on scaffolding with wheels to roll it into position. The bottom of the transom window starts at 10 ft off the floor. I have not built the enclosure yet, I'll need the A/C unit first. And no it will not likely be aesthetically pleasing.

My building is brick and in the middle of the city surrounded by concrete and asphalt on all sides. The three 8 ft plate glass windows below the transoms let in the afternoon sun something fierce. I've got them blacked out currently with reflective attic insulation material, but it's like a cave now and still sweaty hot. There is no way to just cool the bedroom as there are no windows in the bedroom and it's on the opposite end of the unit from the windows. It's probably more difficult to cool than your average 800 square ft place.

I'll try to add photos, but I'm sure it will be a couple weeks away.
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Old 07-19-2011, 06:16 PM   #6
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Window AC in transom window


you the shower curtain fella?
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Old 07-19-2011, 07:04 PM   #7
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Window AC in transom window


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Originally Posted by delgriffith View Post
The range is plugged into a 220v 40amp circuit and my plan was to make an extension cord that will plug in there. The unit weighs in at about 140lbs, and my thought was to support it on scaffolding with wheels to roll it into position. The bottom of the transom window starts at 10 ft off the floor. I have not built the enclosure yet, I'll need the A/C unit first. And no it will not likely be aesthetically pleasing.

Let me sum things up so I'm sure I understand them--

You're planning to create a wooden enclosure which will be approx. the size of the transom window opening. On the "window" side you'll have the enclosure setup such that when butted against the transom window frame it will create a reasonably tight and weatherproof seal. On the "inside" side you'll have an opening which will accept & support the front lip of your air conditioner (which will be SMALLER then the window side, so I'm imagining a piece of plywood with a rectangle cut out the size of the air conditioner). Also inside this enclosure will be sufficient support for the back half of the air conditioner and some sort of a drainage pan which will lead any dripping out the window.

This entire enclosure will be placed on a rolling scaffold which will be rolled into and out of position.

To power this you are planning to disconnect your range, which is a 220V 40A socket, and create a home-brew extension cord to mate to the 220V (probably 20A) plug on the air conditioner.

I'm HONESTLY with you, but I think this is going to be much more difficult then you think... I think you may wind up with something half assed that leaks hot air and water in your apartment at best and at worst it will be a serious hazard.

Some thoughts--

- Get your scaffolding, determine it's height, then build the enclosure in such a way that when perched up there it will be the right height to meet with the transom. What I mean is, don't just build the enclosure then find some way to either raise/lower the scaffold, or shim things... instead build the enclosure so that it's height fits what you need.

- Does the sash of the the transom window come out completely? The types I've seen in the past will pivot at either top or bottom and will pivot either in or out... I'm guessing the kind you have must pivot at the top and pivot outward (toward the outside)? If you are going to have the sash still in place keep in mind that this will decrease your contraptions ability to vent the heat from the back of the air conditioner.

- Also keep in mind the weight and center of gravity... in the end I'm guessing you'll have a 150-170lb dead load perched on top of that scaffolding. You might want to come up with some sort of a system to tie the enclosure to the wall or ceiling, just so that it's less likely to move when you don't want it to move.

- The extension cord is of course going to violate all sorts of electrical codes and what not, but from a purely theoretical point of view, I don't necessarily see a problem with running a ~20A appliance from a 40A source, this is how the floor sander guys used to do it, they'd use either the range or dryer plug to get juice for their machines. Just be sure that you properly size your extension cord wire given the amperage and length of wire, for example if 20A is all that is required, which 12# wire will handle, you may want to consider super-sizing your cord to 10# wire so ensure it will not be the weak link in this chain. Keep in mind that the range outlet isn't designed for repeated insert and removal--it's not to say that it can't be done, just that most people plug something in, then never unplug it. So are you planning to regularly plug or unplug this contraption so you can use your stove? I certainly would not advocate creating what amounts to a splitter for your range outlet so that you can plug both in, I think that's pressing your luck.

Can you take a few pics of the window setup? It might give me some more ideas...

I wouldn't want to live in an apartment that had NO windows in the bedroom... that seems odd to me... unless this is a studio apartment and the bedroom space is not near the windows, that's a bit different...

I still think that multiple portable air conditioners would be a more reasonable solution.

Last edited by bubbler; 07-19-2011 at 07:08 PM.
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Old 07-19-2011, 07:08 PM   #8
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Window AC in transom window


Can you use reflective film to help cut down on the radiant heat caused by the direct sun? I personally would not place a unit up in some rigged box, due to when it wants to come crashing down, it will, because there is no way to anchor in the structure.
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Old 07-19-2011, 07:21 PM   #9
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Window AC in transom window


BTW, I would just like to say that I feel your pain...

I once lived on the 3rd (top) floor of a 3 family building. There were ZERO trees around that were as high as my floor, and the neighboring buildings were all 2-story, meaning they were lower.

To make things worse it was a "Mansard" style building, meaning that the 3rd floor walls are tilted at about a 10* pitch and have black asphalt shingles on them (think of it like an almost vertical pitch roof, but it makes up the 4 walls of the building).

The ceilings were only about 7' tall...

The windows were lousy aluminum replacements from the 1970s, some of them didn't open...

In the summer I routinely saw temps in the 90s in my apartment even when it was only in the 70s outside... all because my place became an oven when the sun beat down on it, and then the shingles and plaster walls would absorb and radiate the heat out at night, so I couldn't even get relief then...

The wiring in the apartment was so bad that there was no way I could run an air conditioner of any kind--there were only 2 circuits feeding the entire apartment, the fridge was on one and the microwave was on the other... when the microwave was turned on the voltage on that circuit would drop to 100V... I'm not kidding... it was scary, I didn't even want to run the microwave longer then ~30 seconds at a time because I was afraid I'd start an electrical fire...

It had steam heat and each unit had it's own boiler... for me to get any heat at all my boiler had to run such that it got the water so hot that steam would rise a good 35-40' to hit my radiators (the first and second floors had 11' ceilings)... to make matters worse there was no insulation on the pipes which traveled up within the living space of the first two floors, so in effect the pipes became radiators for the downstairs tenants warming their places on my dime... we had a fairly mild winter from 05-06 which was the year I lived there, my heating bill in February that year with my thermostat set to 55* 24/7 was over $400... zero insulation above me, drafty windows, and a boiler that had to run 3-4X longer than necessary to get heat up to my floor...

Anyway, why am I telling you this? Because even though I loved the location, I liked my landlady, the apartment itself was pretty cool (I had a roof deck to myself) there was NO WAY I was going to live another summer and winter in that place... so I moved... and actually my next place turned out to be even better--it was cheaper, better location, including electric and heat, and was larger...
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Old 07-19-2011, 08:16 PM   #10
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Window AC in transom window


Here is a photo of the original setup with the portable that I rigged up years ago and posted here for the benefit of others:

http://www.diychatroom.com/members/d...size-imgp1664/

So that shows the window. I do think that the enclosure is going to be the tricky part. It would be an insulated box the size of the window frame with automotive type rubber weather stripping to schmuck it up against the window frame, back side of the box would have a cutout the size of the A/C. The frame would incorporate a slight slope and a pan beneath it to collect drippings and plumb them to my drain inside or just outside.

The scaffolding is intended to support a human weighing more than the A/C and having a higher C/G, so I don't think stability is going to be a big issue. The wheels have brakes, so I don't imagine it would move much once rolled into position. I guess it might leak air if it isn't pressed firmly though...

The cord I had in mind is 10 gauge. I might wire it directly into the range junction box. It's easy enough to shut off the A/C while cooking - or using the oven anyhow. Stove burners might be OK considering it's 40 amp and the A/C is 15ish.
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Old 07-19-2011, 08:35 PM   #11
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Window AC in transom window


Measure out the frame, and either use Outdoor or Marine grade plywood. Place on the frame. If you know the depth to the outside edge, you can also use pine material, or the wood cut out from the opening, to allow you to create a lip, that will hold the ply at the bottom. Cut the plywood larger than the opening to allow for that bottom piece. To hold on the edges, you can use wood, or metal, with 3" machine screws that have the head on the outside with a washer, which when placed against the outside of the window frame, it will help hold the plywood against the inside frame, and on the inside, you would use wing nuts. To secure, you have the opening on the bottom, that you can stick your hand through to help turn the clamps and hold them, while you turn the wingnuts to secure.
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Old 07-19-2011, 08:53 PM   #12
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Quote:
Originally Posted by delgriffith View Post
Here is a photo of the original setup with the portable that I rigged up years ago and posted here for the benefit of others:

http://www.diychatroom.com/members/d...size-imgp1664/
...so you left the window open like that? You do realize that most of the hot air being pushed out of that hose probably blew right back in... that would be one big reason you felt like it never worked.

You should have created a cover for the entire window--either 1/4" plywood or cardboard... if you haven't tried that yet, PLEASE try that first... you might find it's a BIG improvement...

Quote:
Originally Posted by delgriffith View Post
So that shows the window. I do think that the enclosure is going to be the tricky part. It would be an insulated box the size of the window frame with automotive type rubber weather stripping to schmuck it up against the window frame, back side of the box would have a cutout the size of the A/C. The frame would incorporate a slight slope and a pan beneath it to collect drippings and plumb them to my drain inside or just outside.

The scaffolding is intended to support a human weighing more than the A/C and having a higher C/G, so I don't think stability is going to be a big issue. The wheels have brakes, so I don't imagine it would move much once rolled into position. I guess it might leak air if it isn't pressed firmly though...

The cord I had in mind is 10 gauge. I might wire it directly into the range junction box. It's easy enough to shut off the A/C while cooking - or using the oven anyhow. Stove burners might be OK considering it's 40 amp and the A/C is 15ish.
- Plumb the pan to drain outside... unless there is a sink directly below that spot (as in, that's right above the kitchen), I'd say forget snaking a drain hose around...

- Although I agree that from a weight rating point of view the scaffolding is appropriate, what is different here is that you are proposing dead weight at the top and rolling with that weight on top, that creates a different dynamic then stationary scaffolding being used to hold up a load.

- I would suggest rigging some bungie cord or something similar to keep pressure holding the enclosure against the wall. Maybe you can unobtrusively screw some eye hooks into the wall?

- I'd use some nice thick 1" weatherstripping for the window part

- I would NOT wire it into the junction box for the range. Creating a makeshift cord is one thing, opening up the wiring is another. As is if there were ever a fire you are probably liable because of the make shift cord, but opening the junction box will just make matters worse, you might even get evicted if your landlord discovered your modifications

Good luck with this, as I said, I feel for you...

Right now I'm sitting in the first floor of my Cape, it's 74* outside and feels cool... but inside it's a toasty 81*... open windows do ziltch... I have a chair setup next to a window with a box fan blowing on me. The portable AC is on upstairs, it's cooled off a bit, but still stifling...
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Old 07-19-2011, 09:11 PM   #13
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Window AC in transom window


Bubbler, wish it was 74 here. It is 90, with a feels like of 105 at 9 pm Illinois time. I would personally rather be on the coast where you are, than here.
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Old 07-20-2011, 12:55 AM   #14
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...so you left the window open like that? You do realize that most of the hot air being pushed out of that hose probably blew right back in... that would be one big reason you felt like it never worked.

You should have created a cover for the entire window--either 1/4" plywood or cardboard... if you haven't tried that yet, PLEASE try that first... you might find it's a BIG improvement...
No, it looks like it's open, but there is plexiglass - notice there is duct tape stuck to something in the photo - it's not just stuck up in the air. It is sealed, there is plexiglass there and the white vent piece is sealed with duct tape against the plexiglass.

The plexiglass broke recently and I currently have the unit venting out a peice of 1/2" plywood covering the entire transome window, and then all other windows are covered with reflective bubble insulation (like the kind for car windshields) Still sweaty hot after 3 days of non-stop full blast A/C running.

There is an A/C drain specially installed right below the transom windows, so it's awfully tempting to drain there rather than outside and risking complaints from people walking by on the sidewalk and getting dripped on.

I am thinking that perhaps a latch mechanism to pull the weatherstrip/box tight against the window frame would be a good thing. Some way to keep tension on it. Anyhow I'm optimistic that this unit, which is rated at 28500 BTU, 4.5 horsepower, will be capable of throwing the heat out.

Thanks for response - appreciate being able to bounce ideas around
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Old 07-20-2011, 01:02 AM   #15
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Window AC in transom window


Reduce the heat load first. I would work to reduce the heat coming in through the window - heavy tint, reflective covering, drapes, etc. - or a combination.

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