Anyone modify window unit to provide portable air?

[243]

I moved into my new place in May and the attached 2-car garage is all brick with two windows that face the street. I do not want to put a window unit in the existing window due to the security risk or punch a large opening in the brick so my plan is a mini-split, but I simply don't have the funds to do the project this summer.

I was looking at portable AC's and the premium price over window units and thought a window unit may work as a portable for the summer.

Anyone modified a window unit for use as a portable?

My first thought is to build a plywood box, install the unit and run flex up through the ceiling and let the exhaust exit through the attic to the gable vent. Condensate would be easier running a line from the pan to the bottom of the garage ledge that is lower than the garage floor and let it run to the driveway.

My parents have a two year old LG 18 or 24.5 btu unit sitting in the garage, they wanted to give me the unit but I suggested they keep it on standby in case their AC failed and I needed to install it again for temporary cooling, they are in their 70's. However, they would let me use it and that would be a good opportunity to test the cooling requirement of garage.

 

[Milton Shaw]

You would have a lot of problems getting enough air flow if you have it in a plywood box. They need a lot of air flow to keep the condenser coil cool and the compressor from overheating. The outside fan is not designed to operate under the restriction that you would have running it in ductwork. This is a bad idea to try, bite the bullet and get a mini-split or a PAC hotel motel unit and do it right. You will never be happy with this cobbled up mess you are describing.

 

[Fueler]

Here is a "get by until ..." idea. When you are working lift the door enough to slide the unit under the door. Block off the rest of the space with a piece of plywood. Or some variation thereof. Not ideal by any stretch but.......

 

[Warrenator]

I did this, called it my "redneck central air". Basically i taped two rectangular to round sheetmetal vents onto the front of the ac unit, then put two of those long floppy insulated ducts onto those with clamps, tape, and sprayfoam to keep the condensation down. Put the ends of the ducts into the room i wanted cool. Works great.

 

[Brian_WK]

I did this, called it my "redneck central air". Basically i taped two rectangular to round sheetmetal vents onto the front of the ac unit, then put two of those long floppy insulated ducts onto those with clamps, tape, and sprayfoam to keep the condensation down. Put the ends of the ducts into the room i wanted cool. Works great.

This actually works great. Did the exact same thing for my brother to work on airplanes as a spot cooler when they are sitting out in the sun baking. Make sure to have the fan running on high all the time and have the front slightly higher then the back (the evaporator condensation will run to the condenser area and help cool the condenser as well as drain the water).

Good luck

 

[243]

You would have a lot of problems getting enough air flow if you have it in a plywood box. They need a lot of air flow to keep the condenser coil cool and the compressor from overheating. The outside fan is not designed to operate under the restriction that you would have running it in ductwork. This is a bad idea to try, bite the bullet and get a mini-split or a PAC hotel motel unit and do it right. You will never be happy with this cobbled up mess you are describing.

That's the Garage Journal spirit!

It looks like most manufacturers including LG are using a 4" exhaust duct for 14K btu, I noticed two manufactures are using (2) 3"-4" exhaust ducts. My plan is 12" flex from the box to the attic, 4" provides 12.5 square inches of exhaust and 12" provides 113 square inches of exhaust.

The double duct system calculates to be 560 btu/sq.in. for the 14,000 system and a 12" duct is 212 btu/sq.in. for a 24,000 system.

 

[soob]

I got the portable unit I use for my house garage off Craigslist for $100. Might check that out...

 

[GDPossehl]

Ultra cheap. Rig up a couple of these and you're in business.

http://fivegallonideas.com/air-conditioner/

 

[243]

We have moderate to high humidity in my area of Texas, evaporative cooling would be an option if I lived west of Austin a few hundred miles.

 

[Zeke]

What about the intake for condenser cooling? You don't want to be using your conditioned air for a couple of reasons, one being that it will create negative air pressure in your conditioned space. Putting the hoses on the front of the unit seems like it would work. Either way, you need a return and a supply or outside air to make up for hot exhaust.

 

[soob]

Ultra cheap. Rig up a couple of these and you're in business.

http://fivegallonideas.com/air-conditioner/

You get 144 btus of cooling from melting that ice, per pound, plus 1 btu for every degree it goes up in temperature. So if it starts at 0 F and goes up to 80 you get:

5 gallons = 40 pounds of ice * 144 + (80*40) = 5760 btu + 3200 btu = ~9000 BTU. But it's released over the course of however long it takes to melt and warm (i.e., slowly). Plus it raises the humidity of the room. That's really not all that great compared to an air conditioner.

 

[Jagmandave]

I don't think it works that way, he said they use a frozen gallon milk jug - sounds to me like you freeze it and put it in the 5 gallon bucket, so you're not blowing air over the ice itself but over the plastic frozen jug?

If that's how it works it shouldn't raise the humidity any.....if anything I'd think it would drop the humidity by trapping the condensation in the 5 gallon bucket?

 

[Falcon67]

We have moderate to high humidity in my area of Texas, evaporative cooling would be an option if I lived west of Austin a few hundred miles.

Maybe not lately we're pretty dang wet these days, got 8" this week. Used to be our RH was in the teens, this year feels like we all moved to Lufkin.

 

[coralnut]

When I look at those fan + ice coolers I wonder why nobody's worried about electrocution risk. It's not like it's possible for any contraption like that to get UL approval.

 

[bczygan]

Window unit plus security bars.

 

[Bigbandguy]

An uncle of mine did this in a two room lake house. He had the AC unit which was about an 18000 BTU and it seemed like a good idea. He placed it in the attic space and ducted the exhaust to a ventilator grate in the gable. He used regular air conditioning ducts to the two rooms. As a final touch he relocated the controls down into the main room of the cabin by just soldering on extra wire and mounting the control on the wall. He had the attic well insulated so there was not much noise and it cooled that little place like a bandit. Cost less than 100 as someone had given him the unit. You would have never known that little cottage didn't have central air except for the fact that there was no outside unit. Uncle Bud was a sharp cookie.

 

[soob]

I don't think it works that way, he said they use a frozen gallon milk jug - sounds to me like you freeze it and put it in the 5 gallon bucket, so you're not blowing air over the ice itself but over the plastic frozen jug?

If that's how it works it shouldn't raise the humidity any.....if anything I'd think it would drop the humidity by trapping the condensation in the 5 gallon bucket?

If it's just one gallon it's so undersized that it'll have no real impact on the temperature unless it's a few inches from your face.

 

[LS6 Tommy]

You get 144 btus of cooling from melting that ice, per pound, plus 1 btu for every degree it goes up in temperature. So if it starts at 0 F and goes up to 80 you get:

5 gallons = 40 pounds of ice * 144 + (80*40) = 5760 btu + 3200 btu = ~9000 BTU. But it's released over the course of however long it takes to melt and warm (i.e., slowly). Plus it raises the humidity of the room. That's really not all that great compared to an air conditioner.

Sorry, but that's not correct. 9000 Btu is 3/4 of a ton of refrigeration. 1 ton of refrigeration is the amount of Btus needed to melt 1 TON of ice in 24 hours. That's just a wee bit more than 5# of ice...

Tommy

 

[soob]

No, 1 ton is the amount of btus needed to be applied per hour FOR 24 hours to melt a ton of ice. I.e., 12k x 24 = 288,000 btus from melting that ice. 40 pounds (i.e., 5 gallons) is 2% of a ton, 2% of 288,000 is 5760. QED.