Quick Tutorial w/pics Modified in window A/C unit. Extremley cheap!

Discussion in 'Do It Yourself' started by CDXXFiles, May 7, 2011.

  1. ****This is just a quick look at how we modified an in-window a/c unit to cool our small 4x8 Secret Jardin Darkroom 2 veg tent. I didn't provide exact measurements because everyone's a/c will be a little different but I promise the concept will work for most in window units with only a sheet of plywood, a saw, a roll of metal tape, and some ducting. Feel free to ask questions and I'll try to get back to you asap.****

    Well recently in our larger 5x10 flowering tent we are noticing the stand alone a/c has a few kinks here and there that seem to plague all in room a/c units. According to the box and the directions these were problems they had fixed but don't be swayed.

    For one, it came with an in-unit fan that is supposed to blow the hot air out the provided ducting, but because of the way we are venting both the large and small tents a/c systems out the same dryer duct, we seem to be getting a lot of blow back into our large tent and as a result, the stand alone a/c's thermostat is set at 65 to keep the tent at a balmy 77 haha. We are going to remedy this by buying another 4 inch blower fan to assist the one already in the stand alone unit, so right there you have another 80 dollar investment bringing the total to at least 230. Also the humidity drain on the stand alone a/c is placed on the very bottom corner of the unit. There is a lot of humidity in our large tent, but the box and the directions assured us it could handle it so we didn't think much of it at the time but this claim is false. We have to leave the cap unscrewed at all times now and rotate towels to keep a pool of water from forming underneath it. So not only is it going to cost us 230 dollars more in the end but its kind of another one of those routine maintenance things I'd rather not be dealing with haha.

    That being said, my friend brought over this box he made for his cabinet hydro set up with the exact same window a/c. As you can see he took measurements of the back (You need to make sure that you measure so that the intake vents on the back are uncovered by the wood or the tape) and cut pieces of plywood the top, bottom, and sides so that they would form a box around the large hot air vent at the back. He also cut a small hole out of the bottom piece so the humidity drain could just drop straight into a five gallon bucket underneath. Then he cut a piece to cap the box off and make it air tight, and he cut a 4 inch hole in the center so we could feed a length of 4 inch ducting in the back connected at the other end to a 4 inch blower which pulls all the hot air away from the unit and the tent. The box is air tight because rather than connect everything with glue, or nails/screws we just sealed it together with the same metal tape we use on the rest of our ducting. It is expensive tape but it is way stronger than duct tape and will last a long time.

    As far as I can tell from watching the temps in both tents recently it is certainly a more efficient way to cool your tent than a stand alone a/c even if it does take more work in building the stand and rigging up the vent in the back. Your going to save at least 200 dollars not to mention the hassle of having to go on yet another shopping trip.

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  2. Foil tape seals all haha.

    Nicely done it appears it will work. An additional blower (inline or squirrel cage) will help reject the heat and prevent and draft back into the rooms. If you can manage to find a 4" round takeoff with a dampener it will seal up nicely to your plywood and will also prevent some blowback when one unit is off.

    This is a takeoff:
  3. Yeah, we actually have a 4 inch blower on there right now and it's been keeping our 4 x 8 from getting any blow back. We need another one ASAP because of the blow back into our bigger tent from smaller one haha. I wish I would have taken pictures of the process of building this because we sealed off both sides of where the ducting comes into our plywood with the same metal tape and there still aren't any air leaks. I'm deffinetley now looking into this takeoff thing though, becuase that could really help us in our big tent...
  4. Home depot may sell them - I know I have seen takeoff's there before.

    If not try an HVAC or Ductwork/Sheetmetal Supply house.

    What you want is a 4"/5" Stick-on Takeoff with or without dampener. The stick on takeoff has an adhesive backing so it will seal right up to your plywood/ductwork. You should still screw it down.

    Well done.
  5. i cant wait to try this!!

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