The $50 chiller - portable AC mod guide

[Gray Mole]

I'd promised someone a thread on a cheap air conditioning mod, since I get ahold of portable AC units here and there. This is THE time of year to pick up a used one for cheap. This one was 50 bucks for a 12000btu unit. That's around 3500 watts, so way more than enough.

Oh, and I know I skipped a lot of steps, but I forgot that I was going to do a little guide at first, and I wasn't going to rebuild it, or bend the pipes back up and then down. Once is enough.

Anything from 6000 to 12000 will do a great job at low temps and high load.

I don't know what they get for portables over there in the UK, but here they're pretty common and people tend to hate them for the noise. Usually have a Rotary now, somewhere in the 10 to 15cc range, about 5/8hp to 1hp depending on the units. LG, Hitachi, Rechi, Toshiba, depending on the brand it could be any of those or others.






I like the Danby units for this. Not that Danby is a great brand, just that the way they build the portables makes it easy to strip without removing the gas. You can get all the wiring out of the way just by removing the panels and a few plates, and you get enough screws and hardware that you can easily mod it back to what you want. The Toshiba Rotaries they use are pretty good too.

The only tools I needed were a pair of cutters, and a drill. A pair of tin snips is really handy for fabricating the bit of support with all the extra plastic junk gone.

I needed about 10 cable ties and a bit of wire guard to route some wiring safely but there really wasn't much to add.



The tough and dangerous part is the bending of the copper pipes for the evap. It was upright when I started, so I had to very carefully bend it horizontal, small bends at a time, NO KINKING or it's over. Once you get it closer to where you want, bend it so that the new tray/reservior can be used.I recommend using a knife to slice the insulation off of where you'll bend and then you could reuse it with rubber cement. If you don't remove the insulation, you risk kinking it.






Keep in mind, the longer straitaways are easier to bend. The longer pipes will also 'twist' a little without danger, just not too much. Support the pipes close to the evap and condensor, real danger spots for leakage if they kink up on you.




Don't try to heat the pipes to soften them, and there will be really stiff parts that won't bend nice. Just move to another location that'll still give you what you need. If you do it just right, it'll all be within the area of the base, so you could (if you wanted) stick panels on. Even the original ones might fit back on, even if it's just to pretty it up enough so your wife or mother won't freak when she see's it



That's the only 'part' you really need to add. I used a tray out of a plastic 'standup' organiser but a tub with a lid the same size is ideal. I find most portables, and Danby especially, use an evap that perfectly sized to fit one of these plastic tubs.

After that, it's just a matter of putting styrofoam into the tub to hold the evap up a few inches, so that the water is able to travel over and under. That done, I'd be using more styrofoam (just packing material, it's waterproof) to create a 'shroud' of sorts, so the water has to go through the fins. If you do it dry, and then silicone the works so it has to travel the way you want, you're set. Just put one hose above, and one below the evaporator. Then the water has to go through, and that'll give you the best heat transfer you'll get from this mod.



Once you have the evap set and the hoses in, you just need a lid. drill holes on the lid and run your pipes. You can silicone the lid on if you want, depends if you're going to be moving the thing around a lot. When you're happy with how it's done, you can insulate the res however you can with what you have.



Kept getting colder too

Cheapest way to do it is to blag some basic house insulation (that's kind of in keeping with the whole 'cheap chiller' mentality we're going for here) and make it best you can in a wrap around. You could use duct tape as a final wrap to keep the insulation in place. Just a big 'sleeve'.

I didn't show the setup on the evap or the insulating of the res, but I'm using this condensing unit on a cascade later on, so no point in making any of it permanent.

That's is, you just fit your water loop in and plug it in.

The plugs themselves here in Canada/US have a safety switch, but the UK has switched plugs on the wall, but these can work as a switch.



Once everything was stripped and I had the wiring for compressor and fan run out, there were only 2 wires from each. Most of the time there's a small power block in the AC units and I used the one that was there, which took spade connectors. Already on the wiring so no mod there either. I just found places to drill and screw down the fan capacitor, compressor run capacitor, and power block. too easy really.

Other than that, you could get fancy and reinstall the controller for the AC unit to control the temp, but they're limited to around 10c at the lowest, usually more like 15c, but taped to the water inlet on the res, it would give a reasonably low temp.

Just full power with 50/50 coolant would work though, and not freeze up on you. Could also buy a cheapo refrigeration controller from Ebay, just a basic Eliwell or whatever for single temp control if you don't want full power, but as a benching chiller that's only on when you're working it, it's a pretty cheap way to get into phase.

Full power? I'd say the water would still run into the negative numbers even with a quad and 3 gpu's. If you had a max of 1500w (and that's a lot of cpu/gpu's) I'd guesstimate -10 at the evap. That could be off by a bit either way, but still it means you best look at insulating the lines and waterblocks just as if you had a mild phase unit on DD.

I guess if you scored a unit for 50 bucks and spent another 50 sticking a cheap/ebay controller on it and prettying it up with a couple things, then it'd be a $100 chiller, but the basic no frills one just like this for benching would work fine.

Only reason I posted another cheap ac guide is because the ones here are showing the window units, and the portable is easier to make a selfcontained/on-wheels kind of setup.

I didn't show it, but there are a lot of long L brackets you get, and you can use them to support the condensor, the reservior, etc and more than enough screws to fab it up.

So I hope that's a decent little guide on that. Window units and such are close to the same, but the portables always have the evap on top, condensor on bottom similar to this so it's not too tough to do it this way, and most of the time (and you really do have to be careful about the bending) you can do it all without taking the gas out, meaning no HVAC stuff involved. Still, gloves/goggles/common sense are required to be safe.



Gray