Anybody ever modded a window A/C unit?

C

cyclone3d

[H]F Junkie
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Aug 16, 2004
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Well.. right now I have, at my disposal, 5 different window A/C units... the smallest is either 5000 or 8000btu.

The one 8000btu unit I have states that 8000btu is equal to a bit over 1100w.

That got me thinking. Since the Vapochill units only do around 200w and are so expensive, wouldn't it make sense for people to start making their own phase change units from window A/C units?

If/when I get the time and money to mod one of these units... I may do so. I've never had a phase change unit... and I think it would be nice to have one to play with.

BTW... a 5000btu unit can be bought new (on sale?) for around $100.

Another thought would be to have the A/C unit ducted into the case.... I'm sure it would cool it down quite a bit and condensation shouldn't be a problem as the evaporator sucks almost all moisture out of the air by condensation.
 
So.. nobosy is responding....

Anyway.. over the last few hours I've been doing a bit of research.

From what I can find, the "best" solution for now would be to build a chill box and have the window A/C unit recirculatin the cold air in the chill box.

All I would have to do is run the drives and possibly the power supply externally... I would think the power supply would be fine inside the chill box though.

From what I could find, with a 5000btu unit, it should yield air temps somewhere in the negative teens or twenties celcius under full load.

As for an 8000btu unit, which is what I would probabyl use.. I should be able to easily get
-30c air temps under load.

Condensation won't be a problem as the A/C evaporator takes care of that.

I wasn't able to really find any pics of actual sytems done like this though.. I need to do a search over at the Extreme Overclocking forums.
 
do a search for cascade chillers.. they are what most people do for extream cooling, when they have an extra a/c unit like this
 
Maybe if you waited more than an hour plus change someone would respond. This is after all a holiday weekend and many people are doing things with families now.

Have a little more patience.
 
Wrong forum to learn about this type of cooling.

To use window ac units you have to either heavily modify them or slightly modify them . And to heavily modify them you need a 608 type 1 degree. Slightly means you just put the evaporator in a container of anti-freeze. Sounds easy to make one cool a computer doesn't it? Its actually quite hard.

Here is the area where you would heavily modify them.

http://www.xtremesystems.org/forums/forumdisplay.php?f=80

And here is the slightly modified are. It can be hard depending on how it is done.

http://www.xtremesystems.org/forums/forumdisplay.php?f=155

[H] is not the forum for extreme cooling, this is where xtreme systems comes in.

Oh and with this type of cooling you can not convert the btu's. Say you have 8,000btu's which equals 1200watts, it will not cool 1200watts maybe 800. Phase cooling is not easy at all.
Also you need to get this book.

http://www.amazon.com/Modern-Refrig...1089218?ie=UTF8&s=books&qid=1188775787&sr=8-1

Hope this helps.

Tyler
 
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Argghhh.. stupid page logged me out while I was typing a message...

Thx for the replies anyhow.... I guess I got kinda impatient. seemed longer than it was since I made the first post.

Anyway.. the 1100 watts on the one coller was how much watts the unit itself uses... it is a very inneficient unit.

I have a much better whirlpool unit that is rated 9.8 out of 9.9 for efficiency.

I will be making a chillbox to put the computer in... just going for the cold air thing right now. The evaporator should take care of the condesation.

I'll disable the thermostat by installing a switch.

Once I test out the cold air system.. I may end up going with modding an A/C unit to do the whole water cooled type system.
 
with a 5200btu unit ducted into my sidefan, i was able to cool a stock fx-51 to 12c at idle on a 90F day. condensation became a problem and my asusprobe was reading in text that looked like chinese.
 
If you put the whole system in a chillbox, you won't have issues with condensation.

And... if you have it recirculating the cold air in your chillbox it will get even colder provided that you have the temp probe disabled on the A/C unit.
 
To use the ac you would need to submerge the evaporator in anti freeze and create a watercooled system.

Note: That ac unit has a POWER CONSUMPTION of 1100w, 8000btu is actually around 2300w. Also, good luck getting air colder that 0C for longer than 10 mins as the evaporator will freeze up.
 
cyclone3d said:
If you put the whole system in a chillbox, you won't have issues with condensation.

And... if you have it recirculating the cold air in your chillbox it will get even colder provided that you have the temp probe disabled on the A/C unit.
Click to expand...

You will still get condensation if the dew point is breached. And freeze up the evap and fry some hardware :(

RoBo said:
To use the ac you would need to submerge the evaporator in anti freeze and create a watercooled system.

Note: That ac unit has a POWER CONSUMPTION of 1100w, 8000btu is actually around 2300w. Also, good luck getting air colder that 0C for longer than 10 mins as the evaporator will freeze up.
Click to expand...
Right on, Air recirculated into the a/c unit that is all ready cold will freeze the evap in short time. But as he says put the evaporator in a cooler w/ pump and If you run the right mix of water to (choose your best mixing agent here) it will be good to -50c easy.

thore said:
do a search for cascade chillers.. they are what most people do for extream cooling, when they have an extra a/c unit like this
Click to expand...

A cascade chiller is a waist of time IMO, Also a cascade in any form is advanced phase building and way over your head if this is your first or even second build. The tuning of the cap tubes alone is enough to get your head blown off not to mention proper gas pressures and so on. DO NOT BUILD CASCADE ON FIRST, SECOND, hell even 3'rd BUILDS !!!
 
cyclone3d said:
Well.. right now I have, at my disposal, 5 different window A/C units... the smallest is either 5000 or 8000btu.

The one 8000btu unit I have states that 8000btu is equal to a bit over 1100w.
Click to expand...
Depending on how bad of condition they are, you might want to hold them for a little longer... Wait till summer hits, wait a little longer, then advertise in the newspaper/radio that you have 4 or 5 beautifully working airconditioners for sale. Use gained money from these sales toward a Vapochill unit. Seriously, when people figure out stores sell out of airconditioners, and when they realize those said stores do not have 50,000 airconditioners in the back room... they want an airconditioner one way or another.

cyclone3d said:
That got me thinking. Since the Vapochill units only do around 200w and are so expensive, wouldn't it make sense for people to start making their own phase change units from window A/C units?
Click to expand...
Not quite, unless these people are bored, have lots of time to waste, and dont mind having nearly 2000W of heat being blown around in a room.

cyclone3d said:
If/when I get the time and money to mod one of these units... I may do so. I've never had a phase change unit... and I think it would be nice to have one to play with.
Click to expand...

(Correct me if Im wrong, its been a long time since ive messed with this stuff)

Well, keep in mind how these units work and are designed when playing with them. Older units (1990s and before), should be R12. Some might be R22. Units up untill the past few years, were usually R22, although the new HFC134a junk is most common in new ones. Propane is also being used, or at least ive been told its being used.... Not straight propane, but its almost the same thing.

Boiling points (at sea-level/1-bar):
R22: -40C
R12: -29C
Propane(HC-290): -42C
R134a: -26C

R12 can do -40F, and colder, if the evaporators pressure is low enough (in a vacuum).
R22 can do -40F without pulling a vacuum.
HC-290 can almost do -100F in a complete vacuum.
Water, regular ordinary water, will boil at room temperature if the pressure is low enough.

And by vacuum, I mean lower than atmospheric pressure. Sea-level is 1 bar, 14.5PSIA, or 14.7PSIA (Pounds/square inch absolute). Can a compressor in a refrigeration system draw a vacuum? Yes... Not a complete "vacuum", but systems with R12 can have a low enough pressure on the evaporation side, to have low low temperatures. I wont go into detail about how it works, since that can be found on howstuffworks.com, wikipedia, etc... and plus I cant remember much, so id rather not risk potentially giving out complete BS. But, They operate at certain pressures, use a specific size/length of orifiace to restrict the refrigerant before entering the evaporator.

The compressor itself, is a fixed-displacement pump. Each time its piston comes up and down, it is moving a certain volume... although that specific volume changes depending on the density, determined by pressure. But, that oriface which is between the condensor and evaporator, if it is restrictive enough, the compressor pump can have a low pressure on the "Low side". If the oriface is restrictive enough, like in freezers, the low-side/evaporator can have lower boiling temperatures, which allows the refrigereant to boil and remove heat, at damn cold temperatures. If the oriface is not very restricive, and allows refrigerant to pass more easiliy (Such as in airconditioning units), the evaporator's pressure should be higher (more volume of fluid), and beyond a certain point, the refrigerant entering the evaporator as a liquid, will no longer be able to evaporate, and remain a liquid as it winds through the copper and enters the compressor.

To keep things short(er)... because they are designed to do something specific, such as cooling your home, you probably cannot get them to -10F or whatever, even if you had the evaporator cased in styrofoam and had no air moving. What ive seen happen with my unit, the refrigerant no longer fully evaporates into a gas, and remains a liquid. When enough liquid reaches the compressor, it hydrauliclly locks... Then of course the motors thermal breaker opens, and you are sitting there with nothing happening as the motor cools down.

If you have any questions about this, it might be better to PM me, since these are the issues that usually result in long, rambling responses.

cyclone3d said:
BTW... a 5000btu unit can be bought new (on sale?) for around $100.
Click to expand...
At the big blue/grey coloured retailer where I am enslaved, I have seen them as low as $89. Its been awhile since ive seen the prices, because they are perpetually sold out (see above post). Asking $40-50 each, used, seems fair to me.

cyclone3d said:
Another thought would be to have the A/C unit ducted into the case.... I'm sure it would cool it down quite a bit and condensation shouldn't be a problem as the evaporator sucks almost all moisture out of the air by condensation.
Click to expand...
Thats how I had my K7 set up. I put a 12V car-radiator fan onto the condensor, and only turned it on/off when needed, along with spraying water on the condensor... helped cool it down without using the fan as much. The lowest I could get it to go, was around 30F. Much below that, and the compressor would lock up. This was mostly a "ehh, I have a whole weekend to kill... what else am I going to do?" project. It might be useful if you want to put peltiers on things, without having frost, but oil immersion might be better, although someone who has done oil-cooling would have to comment on that.

And remember, there still can be moisture in the air. It depends on what the discharge air temp is, what the temperature of the evaporator is, what you will do when the compressor cycles off, and how it deals with defrosting. Large volumes air coming in at 90F, coming out at 50F... It may still be moist. Small volumes of air coming in at 200F, can come out at 20-30F. It all depends on how much heat can be removed from the air before it has exited the evaporator. If any outside air is coming into that case, then you have potential for condensation all over everything inside, and outside, the computer. It only works, if you can be sure *dry* airconditioning air is coming in and nothing else.

But, leaving practicality and rationalization out of these types of projects, it is always interesting...and always [H]. Don't keep it real, keep it [H]. ;)

Edit:
One actual, Practical use could be:
Manually cut/pull off aluminum fins from the copper tubing on the evaporator without puncturing any of the lines, and bend copper tubing to fit alongside them, epoxied or otherwise. Pump oil/water through the new copper-tube set, and cycle the AC unit on/off when needed, much like aquarium refrigeration setups. I was interested in trying this with oil-immersion cooling, though its hard to justify doing so, while living in an apartment.
 
cre8chaos said:
Right on, Air recirculated into the a/c unit that is all ready cold will freeze the evap in short time. But as he says put the evaporator in a cooler w/ pump and If you run the right mix of water to (choose your best mixing agent here) it will be good to -50c easy.
QUOTE]

i used pure antifreeze on my first modded ac unit and it froze up and f'd up my pump. if you're going to make a chiller like this be sure you have a high enough flow rate or your liquid has a low enough freeze point.
Click to expand...
 
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