How 2 properly vent windo unit whose outside is 2B enclosed area?

swampwizMarch 18, 2010

Here is the situation. I have an old house with window units. The unit in question is actually in a dedicated window (i.e., it is not regular window, but simply a rectangular cut in the wall in which the window unit takes up all the area.) The outside of this unit is currently the carport, which will be enclosed into a garage. I also plan to put a window unit for the garage itself to use during summer nights (with its metal only roof, the garage is going to be far too hot to keep cool during the day, and I can easily do what I want to do there at night.)

Anyway, obviously I need to somehow have the current window unit in question vent to the outside. The top of this unit is only about 1-1/2' from the carport/garage roof, and it is in a corner, so there are 2 walls already there. It seems that I should be able to build a small enclosure of OSB or metal duct (or maybe flexible duct?) for the base and the 2 walls up to the roof, and then cut a rectangle in the roof, and then put some type of duct out to keep the rain from coming in. I suppose that it could be a good idea to put some type of fan there to get enough ventilation as well. Then there is the question of how much headroom there should be in front of the outside of that unit.

I probably should take a picture or make a drawing, but I hope I have explained it properly. Of course, there is another window for that room that I could move the unit, but I would like to keep it open for aestethics (it is a front window) and to allow full ventilation of the room when the A/C would not be on (there is only one other easily operable window which is on the other side of that room.)

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Frame a hole in the garage wall and install it semi-permanent like I did for my daughters art studio in the corner of the garage.

    Bookmark   March 18, 2010 at 11:28AM
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The garage will be a real inferno during the day with a metal roof and a unit dumping even more heat into the garage (remember it is moving all the heat taken from the cooled area plus the power of the unit itself).

If the house is frame it is not hard to open under a window to put a sleeve in to hold a unit.

Many window units have sleeve instructions.

    Bookmark   March 18, 2010 at 1:00PM
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I'm going to have someone build a tight enclosure to fit on the outside of the unit, which will funnel into a pipe, which then will run along the rafter to the outside. Since a window unit puts out a slight pressure, the pipe would basically be like an exhaust pipe. There will also be a line for the condensate to a jug. An easy and elegant $100-150 job.

And I've decided to get a 1 ton portable unit for the garage - that way I can take it with me for my next house, and at least have a an emergency backup (for both hurricane power loss or if the central unit would go down), or even for my current house if the little window units strain under the load of a super hot day.

    Bookmark   March 20, 2010 at 8:16PM
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Trying to duct a window unit that has a fan to basically overcome the resistance of the condenser coil will have problems hitting proper subcooling temps, which will result in minimal air conditioning, high energy consumption & premature fan and compressor failure.

    Bookmark   March 20, 2010 at 9:05PM
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It's not going to work. That fan is not an exhaust fan.

Put the thing in a different window.

    Bookmark   March 21, 2010 at 3:10PM
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The unit will self destruct in short order if it is not in free air.

    Bookmark   March 21, 2010 at 7:45PM
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