DIY Portable Air Conditioner?

[Bradley Miller]

I've got a 5000 BTU window unit and I'm wanting to build a box around it and make it a portable unit. It's a new model that doesn't have a condensation tube it just has a slinger to deal with water. I'm wanting to make it into a portable unit for another project . . . anyone else have any ideas or suggestions? (Besides buying a new portable unit . . . I couldn't beat the price.)


My plans are to build the box about 8 inches bigger on the sides and about (leaving 4 inch gap on each side) and about 8 inches at the back. At the top of the box I'm going to install a fan that will be wired to run continuously and that fan will draw air out via 4 inch pipe to window. Does this sound like a viable plan?

 

[Bradley Miller]

I'll post what I've built so far . . . this is a quick sketch below. I'm going to have a fan with a 4 inch pipe running out for ventilation. The AC unit has intake grill openings on the sides and top and then the condensor on the back. My concern thus far is air flow -- will I need a 2nd air inlet (from outside air) to go directly to the grill openings on the top/side to make this work?

 

[Uncle Buck]

What is the whole box thing about, or what is it supposed to accomplish?

 

[Bradley Miller]

That's the "portable" part, since I don't have a window to stick it in. I'm trying to make something like a portable ac unit that uses a hose to duct hot air out. Currently I have the thing surrounded on top/sides by 2x4's. So it's got about 3 1/2 inches on sides and top for air flow. I'm thinking I might have to build a divider in the box and have the front side draw air in from inside room or perhaps another hose outside. I'm afraid that with just the single hose in a sealed box, it's going to be like sucking on a soda straw in a tightly closed bottle . . .

 

[Bradley Miller]

Ok . . . since I seem to be the only guy stupid enough to do this . . . I'll continue my ongoing saga with an update on what I've done so far. I got my box built around the AC unit. Just to do a "what if" kind of test, I sealed off the box except for about 1 1/2" on the top of the lid, no fan yet (other than the internal one) and nothing else to get rid of the hot air. It was mainly seeing if the unit would shut down or cool properly. It seemed to work great after my little thermal episode. This 5K btu window unit is a newer model with the condensation "slinger" (?) that puts the water on the condensor. The other night while building the box, the water was whapping me on the face, but in my thermal test the water pretty much was evaporating off. The unit I'm building is going on a boat, incase anyone was wondering. I didn't want to front a $800+ roof hatch air conditioner, so I'm building this portable unit to vent outside my canvas camper enclosure. (This is a 26 1/2' cabin cruiser.)

I'll have to put a few pics up and take temp readings. A friend of mine has a portable AC unit but his was over $700, and he only used it a short time and still wanted about $500 for it. So far I'm into mine for . . . . hmm . . . zilch.

 

[Vetter]

I don't see why this wouldn't work, but why the box? I would think a sheet metal box(like a furnace duct) just on the exhaust side, ducted outside would work.

 

[Bradley Miller]

Asthetics . . . I'll be using the unit as a table also . . . the exhaust side will be going outside the camper enclosure on my cabin cruiser.

 

[Vetter]

Sounds cool, let us know how it works. My window unit throws out alot of heat, so that box might get pretty hot, even with an exhaust fan.

 

[Bradley Miller]

Tonight I got a dryer vent tube (90 degree) and a fan/motor from a fridge and installed it on my box. The fan was exactly 4 inches in size and blows right into the tube on the box. I also got a ?? foot foil tube for getting the air out. I'll have to come up with some spiffy looking thing to go outside the camper enclosure. I'm also working on the wiring. The fan will run continously and I'm adding an extension cord end to run other items (like maybe a fan to blow air around outside the box). I've gotta finish things up by tomorrow night.

I'm anxious to get the thing together to test it fully. I'll let everyone know how this turns out. If I can sleep in this heat (Missouri) aboard the boat I'll have succeeded.

 

[Bradley Miller]

Last night was the "let it cook" test night. I got my wiring all done for the box. I had to make one modification to the outlet cover that I was using, since it was flush against the side of the box, I trimmed it down and it fit perfectly. My father-in-law had a nice meaty cord with a GFI built in, so I wired it directly to a outlet box. The AC unit plugs into that. The outlet box also has a pigtail running out of it for my extension cord end. (The pigtail is so I can plug in auxillary air moving fans outside the unit.) When the thing is plugged in, the little 4 inch fan starts running, and runs continuously.

I put the entire contraption together and started doing another thermal test and didn't like what I was getting. I yanked the AC unit forward a couple of inches and added a pass-thru window fan to circulate the air better. My AC outlet side kept climbing (jumping to 65 degrees, up from 60) and my heat extraction side went past 120+ degrees on my 6 foot dryer vent hose. (Don't know where it went or would have went to as I ran out of range on the thermometer I was using.)

Obviously that wasn't going to work so it was back to the drawing board. I decided that the thing was going to need to have two chambers instead of one. The back chamber still lets air out via my 4 inch fan and outlet hose. The front side chamber brings air into the AC unit. After those modifications my AC side temps went back down below 56 degrees or so. In looking at portable units at the store, they do the same type of thing, bringing room air into the unit and exhausting it out the hose side. I didn't check my outlet (heat) side temps again, but at least I could put my hand on the hose and hold it without discomfort.

So there you have it, I'm going to put a few last minute touches on it before carting it down to the lake for a "real life" test. If this works then I'm going to take it back, and then carpet and pretty it up. My wife wants to use it as a little table in our camper enclosure on our 26 foot cabin cruiser.

Pics will be coming soon!

 

[TEXACMAN]

From what I can see you need to take the dryer vent off and put a duct start collar and a piece of flex duct on it as large as you can get on the back of that box. [Should have it at Home Depot] A/C works on the principle of removing the heat from your space you are tryng to cool so you need to get as much heat out of the condenser coil side as you can. Also make sure you don't cover the vents on the sides as they are there to **** air in from outside to blow across the coil to get the heat out. Hope this helps.

 

[Bradley Miller]

Thanks Texacman! Here's what ended up happening. Thursday I was still getting the heat issue so Friday when I got home I made a divider to seperate the unit. I dragged this contraption down to the boat and set it up . . . . the thing was overheating. I ended up ripping the AC unit out and sticking it in the doorway to the boat cabin with a towel drapped down over the door. That night it reached about 62 degrees by morning. The next day we went back to the drawing board and got another exhaust hose (4 inch) and installed it also, but this one didn't have the little helper fan. With everything setup the hoses were both blowing a pretty good volume of air and the AC didn't shut down (thermal overload) anymore. Unfortunately it never seemed to help enough. The cabin temp dropped maybe 2 degrees, The upper camper area (vinyl cover) seemed a bit cooler, but that cooler air couldn't quite make it to the cabin area of the boat. We left it going all night and it seemed to help at least in our rear sleeping berth area, but not enough to call it good. I'm back to the drawing board again . . . this time I'm going to put the AC unit on the top of the boat and blow into an open hatch with an enclosure. This will effectively make it back into a window unit, having plenty of cooling room around the rear. I doubt we'll be able to cool the upper camper enclosure area, so we'll just shut the door.

I think the camper enclosure cooling was the biggest flaw in this, it's not air tight, doesn't have any insulation, and the only way in is a zipper and door that is like a giant hole that would let volumes of hot moist air back into need cooled.

 

[Bradley Miller]

So I'm progressing with "PLAN B" which is making my window unit AC do a 90 degree into a boat cabin. The actual boat hatch air conditioning system is like $800 . . . a bit pricey for a bit more plastic, a vinyl baggy to seal things up. I decided to use thin board (?? name ) to basically redirect the air from the window unit down into the cabin. To make things as easy to deal with as possible, I'm using an aluminum frame as my structure. Basically the AC will set on the boat on a plywood peice (with ropes so I can just lift it up and lower it into my dock side box). The aluminum frame with the thin board covering it will slide up into the hatch and slip onto the top of the AC and hang there via a little bracket. The hatch will be made air tight via an off-season AC covering bag that will have velcro on the sides and seal the drop in unit against the boat and hatch frame. Tonight I've got most of the frame and structure for the thing done. Having a 14" chop saw with aluminum angle makes things go really quick! I'm using rivets to hold everything together.

Since the unit normally has the controls at the top of the AC unit, I toyed with moving them, but decided against it. Instead I have a board that I'm using to divert the air intake from the cooled air coming out. That board will be on a hinge with a spring, that way I can simply reach up and turn the cold controls and it will go right back in place. (I need to scan my diagrams and put them up here.)

How applicable this is to a garage project is questionable . . . but I'm learning all sorts of different kludges for my dismal tool array. I had a half baked idea to use a roto-zip knockoff as a router, but parts of it fell off (cheap plastic!!!) and I decided I might cause myself great bodily harm. I also tried my cheapie drill press with a roto-zip bit, but it doesn't turn fast enough. My dad has two Shop Smiths . . . I'd love to buy one of them, but last time I looked he was hogging them both. . . . talk about multi-tasking!

Oh well . . back to the garage!

 

[Bradley Miller]

The new AC system version 2.0 is up and going. Pics and info here: http://bradndebtoyyot.blogspot.com/

We'll see how this one works.

 

[Bradley Miller]

And to follow-up . . . the AC system version 2.0 was installed on the boat this weekend. Unfortunately temps didn't get quite so bad that the AC was totally necessary. I did look and at one time it was 86 degrees outside and 70 degrees inside. I think 70 is about the lowest the boat will go. The AC unit goes down to 64 on the thermostat, but I suspect that despite my air diverter portion, the unit is still sucking in a bit of the cooled air and cycling off a bit sooner than expected. I could probably change the air duct slightly and get things cooler, but I don't see any need to right now. Plenty chilly for sleeping!

 

[FEF]

Any new news???


I'm attempting a similar thing, for use in the shop for spot cooling. I have to be carefull, though. Many AC's of that type don't like to be opperated at any angle. Other more expensive units are good for 30deg. That's a fair amount of tilting.

 

[Bradley Miller]

So far so good. My wife used the boat a whole week on vacation and didn't have any problems with it. I checked the min/max temps on the boat and so far I've made it down to 67.5 degrees inside (at night). The AC unit I have is at a slight downward angle (to outside condenser) but seems to be happy. I haven't had any problems with condensation dripping out, unless it's a very cold/rainy day . . . then the water seems to pool a bit and not evaporate off. The spot cooler I built is in the garage floor ready to be taken apart as I don't need it in the garage. My duct work is exposed/leaky enough that I have a nice cool garage.

I was considering closing my duct work up, but I've seen a few houses so far that have had a mold problem where they weren't 100% tight, so I think I'll put up with the occasional drips when the doors are open.

 

[Bradley Miller]

And for those who enjoy a little entertainment . . . here's my AC version 1.0 pics . . . I decided I might keep it together long enough maybe to make a pass on Craigslist or something before dismantling it for the wood. Enjoy!

A 5000 BTU slips right in the opening and will cool and not overheat at least.

 

[jepps3]

Does this boat A/C still work??

 

[portableac7]

Change 5,000 BTU window unit become portable air conditioner, wow nice idea but need little bit effort......... You can do it Man....





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