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Old December 22, 2010, 06:55 PM
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Default The $50 chiller - portable AC mod guide

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.

Portables have rotaries and they tend to be louder, but with water you can stick it in another room, and run longer lines to the PC. Make sure the room or closet has some kind of airflow, it can overheat if there's no way to get fresh air in there.

They're pretty common and people tend to hate them for the noise which is also a reason you can get them cheap :D Usually have a Rotary but very rarely you'll see a quieter reciprocation compressor, 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, making it ideal. It's also an overload, so if the unit overheats or anything it'll shut it down.

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. Doing that makes it less likely for condensation though, so it might be a good one for those wanting consistent low temps, but not looking to freeze anything.

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.

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Old December 22, 2010, 07:23 PM
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That's veerrrrry interesting. This could be a bad thing.....
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Old December 22, 2010, 07:28 PM
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thanks very much would really love a full guide to window ac's have found many but there all so hack and slash that i really didn't want to mess around with it. thanks will consider
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Old December 23, 2010, 10:48 AM
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What about refrigerator parts? They work?
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Old December 23, 2010, 11:02 AM
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From what I've heard, refrigerator parts are not meant to be used with a heat load and 100% usage. They burn out, fast. But I'm sure the HVAC techs will weigh in and confirm that.
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Old December 23, 2010, 11:06 AM
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Quote:
Originally Posted by Perineum View Post
What about refrigerator parts? They work?
Well yes and no...

Just modding in this way on a fridge isn't going to work. The capacity of a fridge is way too low the way they tune it. Maybe an old cpu or gpu but anything dual or quad the temp just rises.

The compressors from they are great though, really the best for a single stage cooler. Need to chop and change everything else, but really the 1/5 to 3/8hp compressors you'll usually see in a fridge or freezer are ideal for a quiet cooler.

Only problem with 'fridge salvaging' is the fridge :D you get a couple things, but then have to get rid of the fridge.

But one of the latest compressors I got was a fridge salvage. 1/4hp and quiet as it gets really.

If you do a lot of salvaging, you get some great parts for this stuff. Part of why I do coolers as cheap as I do really. I mean, you can spend 100 bucks getting a condensor for instance (the 'rad' part of it) but if you buy an old AC unit, you get 2 condensors, a compressor, and a bunch of other useful stuff with it and it's 100 bucks for the whole thing.

Couple fridges, couple water coolers, an AC unit and you have 90% of what you need for a nice SS cooler, and it costs very little if you can do the gassing and brazing. mainly the time it takes to make it.

So yeah, a fridge works but you can't just 'stick your PC in it' like you can with the Portable AC mod to water chiller idea.

I make and usually (hopefully) sell coolers, but if there's anyone here that wants to have a go at it I'm happy to talk them through. Toughest part is buying all the junk that goes with that. Gauges, vac pump, etc etc gets a bit costly if you're just making one cooler. Kind of ends up being something you do at least a few times to make it worth it.

Lucky I guess, I'm a fridge guy at work too, so I have everything a person needs. Been doing it since I started as a Car mechanic (AC was always an apprentice job where I started) and eventually became an AC/refrigeration tech.

PC cooling is a lot more fun though :D



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Old December 23, 2010, 11:09 AM
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Quote:
Originally Posted by SugarJ View Post
From what I've heard, refrigerator parts are not meant to be used with a heat load and 100% usage. They burn out, fast. But I'm sure the HVAC techs will weigh in and confirm that.
Funny enough, that's not really true except if you try to use it as the fridge.

If you do the 'stick your PC in the fridge' thing, it WILL burn out the compressor because the temp goes up so high. Not enough refrigerant or flow of refrigerant to keep the compressor cool.

Take the compressor out, and build it into a cooler properly and those compressors are fine, more than fine really, but often ideal because they're so quiet :)

So yeah, what you're saying is completely right if you try it without it being made right for what we do.


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