Pete’s Homemade Air Conditioner

Credit goes out to Pete H. in sunny England for this great build. This version of the homemade air conditioner removes the need to drain water outside by using an aquarium pump, and sits on a rotating base. Check out more homemade air conditioners here.


Here’s the overall view of the unit. You can see the insulated polystyrene box containing icewater and the aquarium pump, along with the fan and attached copper tubing.


Pete did a much neater job of attaching the copper tubing to the front of the fan than I did. Using copper tubing on both the front and back of the fan is a great idea, the more copper tubing, the more heat exchange possible.


Here is a view of the unit from above, allowing us to see the copper coils on both the front and back.


Here we can see the entire system on its rotating base, allowing directional cooling (most) anywhere in the room.


This picture shows Pete’s innovation, the Internal Cooler Coil (ICC) ready to be installed. The water first runs through this coil, through the ice water, and then out to the fan. Pete and I are wondering if this actually increases performance at all, but it sure looks cool.


Here we can see the aquarium pump submerged in the ice water. Pete aims to increase the power of the pump, and replace the polystyrene container with something more permanent. A small freezer with its heat vented to the outside would be ideal.

If you liked Pete’s design, check out Spencer’s heavy duty interpretation, or my final design.

Homemade Air Conditioning Plans and Pictures
Original Design
Geoff’s Homemade Air Conditioner
Heat Exchanger Improvements
Water Supply Improvements
Technical Notes
Other Designs
Pete’s Homemade Air Conditioner
Anonymous’ Homemade Air Conditioner
Spencer’s Homemade Air Conditioner
Final Design
The Black Beauty

56 thoughts on “Pete’s Homemade Air Conditioner

    • Hi Pat – If you wanted to use a geothermal setup, it’s probably best to not try to adapt an AC unit to the purpose. Really all you’d be using is the heat exchanger and fan, neither of which will be sized properly for your application. It’s certainly possible though.

      Really you want some sort of heat exchanger/radiator that does not have too much resistance to water flow (so you can size the pump reasonably), as well as a fan to increase the rate of heat transfer.

  1. dear sir,
    i m an electrical and electronic engineering student from Bangladesh @ American International university Bangladesh….can i get your entire system/making procedure? i mean i m much interest about ur project….actually i want to make it for my room……thanks.

  2. Hey there,

    I’m basically building this same system, though on a little larger scale. I have a 20″ fan that pumps out 1800 CFM, and I’m using a little larger cooler as well.

    I have all of the tubing done, I put a straight valve in to help prime the system, and the cooler is prepared and ready to rock. The only thing I lack now is the pump.

    What kind of numbers in terms of GPH should I be looking for from the pump? Would it be better to pump the water faster? It seems like the faster you pump it the better it would do, as the heat doesn’t have as much time to heat up the water before it is recollected in the cooler, however I also think that going too fast would mean that the water doesn’t have enough to to sufficiently capture the heat, either.

    I’m no engineer, and I certainly can’t afford to buy 4 different pumps to test to try to find the right balance, so I’m basically just looking for some confirmation on this.

    • Hi Richard,

      Pumps are size for a certain flowrate at a certain resistance (or “head”). I wouldn’t worry too much about about targeting a specific flow rate – instead, I’d worry about having your pump operate within its intended range.

      Since the system is a closed circuit system, the flow rate is largely irrelevant above a certain floor. There is no “too fast” in this case. All you’re going to be doing is circulating your water faster – so it’s more important to worry about how you’re keeping the water cool in the long run.

      The major things to focus on are

      1. The quality of the heat exchanger (most important variable in terms of cooling per unit of time).
      2. The temperature over time of your cooling fluid (most important variable in terms of length of cooling). Obviously a constant source of cold water will last effectively forever, and a reservoir of cold water recirculated will eventually warm up.

  3. The heat exchanger right now is just 20 foot of soft copper tubing coiled around the fan, like you guys have all done on here. I’m thinking about doing a double coil on the front though, because I also have it spread across a larger fan. There’s on average about 1 – 1.5″ spacing between coils, which is a bigger gap then Pete’s fan here, or on your original design. If need be I may end up adding another coil on the backside or something, but I’m probably going to just run with it like it is and see what happens.

    I’m just going to use a styrofoam cooler for the fluid, but it’s a thick-walled one, that seals well at the top, so I think it should hold the cool in there just fine. It’s also a 60 qt one, so I can fit quite a bit in there as well. As long as I can get a cooler full of ice and water to last me about 8 hours to help me sleep through the night, I’ll be happy as a lark.

    Based on what you said, I’m going to go with a 92 GPH adjustable submersible pump model, then probably turn it back to about 70 GPH, so it’s operating well within it’s capabilities. $14 for the pump brings the total budget to about $52, so it’s a little higher then the original design and $2 over my budget goal, but still not bad at all. I’m sure I’ll save more then $52 in my energy bill pretty easily. Central A/C costs are ridiculous in Florida.

    Speaking of Florida, my next concern is probably going to be condensation on the coils. I figure I’ll probably just stick a towel underneath it at first, but that’s too boring, so I’ll probably have to try to think of some cool way to solve that problem. 😉

  4. Just got back from getting the pump. Actually ended up going with a 100-155 GPH pump, and after hooking it up and measuring it’s pumping at a steady 0.71 L per minute, which is just over 3 cups per minute, or 11.25 GPH.

    Now, keep in mind that it is running through 20 foot of copper tube, and currently has another 14 foot of vinyl tube, so the pump is pushing through a total of 34 foot of tubing. Plus the cooler is on the ground and the fan is about 4 foot off of it. I’ll likely move the cooler up at least 2-3 feet so that the pump doesn’t have to work up quite as much. However, even without these improvements, it’s good to know that I can get at least moderate performance with the pump.

    Finally instead of always having to get ice, I bought a 24 pack of spring water that we’re going to drink then reuse the bottles. I figure we could do 12 frozen at a time in the cooler (with 12 in the process of freezing) and keep an easy rotation. I’ll probably end up going to a 24/24 rotation eventually though, the cooler is pretty big.

    Sorry that I’m kinda turning this into my own builder’s log, but I figure people that come across this wouldn’t mind seeing the thought process.

  5. I’ve been reading through all of the different experiments and I think I am going to try and locate an old transmission cooler or small automobile radiator. I was wondering if someone could tell me how cool were they able to get the temperature down using this cooling idea? Thanks.

  6. Would it be possible to run your line through the sides of a small refrigerator to keep the water cool or would this allow freon to escape into the atmosphere?

    • Hi Steve – You could certainly do that, just make sure that the fridge isn’t venting heat into the room you’re trying to cool – closed system and all that. Instead of drilling a hole through the side, I suspect you could run it through the door seal which would be a bit easier. You might run into issues with how much electricity you use however – depends on the size of the fridge, your loading, and whether your landlord or you pays the bills.

  7. Another Idea for a cooler system could be;
    At your kitchen/bathroom sink, connect a pvc tube to the water tap, and turn on the cold water. This should at any given day yield water at about 10ºC or lower. The kitchen cold water tap will normally produce condensed water droplets on its metal parts when left on for a while. These droplets are actually the air conditioner principle at work! The cold water cools off the air, or more correctly, the air heats up the water in the tap, which means the air loses heat energy, this energy produces water droplets. Air/gas is higher on the energy scale than fluids, meaning you make energy (heating up the tap water) by turning gas(air) into fluids(water dew) and lose energy turning fluids into gas, for example in a steam engine, where the coal is burned to make water boil into steam, which is mainly air and water droplets. (I’m an engineer, sorry). Now, run the pvc tube to your copper heatsink (use bigger copper pipes or it will burst) and then back to your sink, letting the water back out. If you feel bad about wasting water, you can lead it back to your hot tub and use that as a reservoir (with a pump), in the end you could have a hot bath in your now freezing cold apartment! I live in Norway where water is free. I don’t know if that’s the case in the rest of the world.

  8. Hi there Geoff.

    Not an engineer or anything of the sort, but in light of the immense heat and lack of ability to install an a/c in a room where i need to work, i’ve tried to adapt the design i’ve seen here to a bigger sized fan;
    It’s a closed system, with water being pushed on one end from an aquarium pump in an old cooler box filled with icewater into the copper tubing set in the back of the fan, and heading back to the box on the other end.

    However, while the copper tubing attached to the back does get really really cold, it doesn’t seem to be transferring the cold to the fan for some reason. The end result is that the air coming from the fan remains the same. Any ideas what i may be doing wrong or how to improve so this will actually work right?
    Many thanks in advance!

    • Hi Mike – First thing I’d try is putting the copper tubing on the front of the fan which should help things a bit. There’s more turbulence and mixing there which in my experience tends to transfer more heat. Otherwise you’re running into the inconvenient limits of physics – there is only so much surface area on copper tubing to transfer heat. A radiator or heater core can significantly increase performace.

      • OK, I switched to a stronger pump and moved the tubing to the front of the fan, but still not seeing or feeling any noticeable change, even though the pipes are nearly freezing at start and effectively cover the entire front part of the fan..
        Not sure what you meant by using a radiator to increase the performance – isn’t the copper tubing essentially emulating what the radiator would do (next to impossible to get my hands on a radiator or heat core in these parts, and even if I could it’d cost me WAY too much)?

        Thanks again.

        • Hi Mike – The copper tubing is emulating what a radiator would do, but it only has a fraction of the surface area a radiator would. As such, it will only have a fraction of the performance.

          A radiator or heater core can be purchased for 10-20 bucks used – just check out your local pick-a-part or similar.

          • Hehe, I wish… I’m abroad right now and 250$+ would be a more accurate cost for a used one, let alone new… :/
            What kind of temp difference did you get with the output on the Original Homemade Air Conditioner you built (which is somewhat similar to what I’ve got at this point)?

  9. Hi Mike – I think you might be surprised, any old car will have a heater core you can pull out. If there’s a junked car where you are, there’s a heater core. Dig around at flea markets for old fridges, etc. Never say never!

    I’d say the original model dropped it by 5C or so, but that was with an open water supply system. A closed system won’t be nearly as effective and should really use a radiator or similar.

  10. Hey, so instead of sticking the copper tubes to the front of my fan I’m building a separate cooling coil out of copper tubing. I’m going to be bending it into shape and adding fins made of soda can skins. I’ll then blow my fan through this external coil, using ducttape and cardboard to make a small duct between the two. The big hurdle hear is air pressure drop. I’ll let you guys know if this works.

  11. I was wondering, why not fill up the bathtub and use that instead of an ice chest. Then move the fan with tubing into the hall (for instance) and drain the waste water into the sink (usually near the tub) if necessary.

    I’m not completely understanding how to make this in the first place though. It’s fascinating. It’s 103 here in Seattle and no one’s equipped for this heat, so I’m going to try SOMETHING!

  12. You could save a lot of effort by just placing a pan of ice in front of the fan and get a better cooling effect. Remember that there is a very limited quantity of cooling available in a block of ice.

    2 things: one, if you are in a dry climate, remember your high school science: evaporating water absorbs massive quantities of heat. So a fine mist will cool better than this silly contraption. Higher pressure, clean water and fine nozzles are needed (the essence of outdoor air conditioning), or just wet towels with a fan directed at them. Too bad our houses are not built water proof as misting systems could be installed indoors in dry climates.

    On a personal level, get a spritzer bottle from a cleaning company as they allow the finest mist and will last the longest, and mist the air around yourself. Mist your curtains, your hair and your cloths. Or buy a commercial evaporator or humidifier.

    Remember that as the air becomes saturated with moisture that you will need to vent it (open window) and allow dry air to enter. Hot dry air is like a cooling vacuum. Just add water.

    Second: If the climate is humid (above will not work as air is already saturated) and your water supply is cold (eg: from a deep water lake intake), set up an old car radiator (much better at heat transfer than a couple coils of copper tubbing) with a fan and run the water tap into the top. Allow the water to drain out the bottom and regulate the flow according the amount of cooling achieved. Direct drained water outside to water your garden if you have one and are concerned about waste.

    If you lived in an adobe house, adding moisture to the air and walls would make your summers very comfortable in dry climates, and you would be able to keep some windows open to listen to the crickets and birds also. Please take time to think about these things instead of buying into such a silly little recycled junior-high school science project.

    • This rocks! I just made one of these at home and it saves me having to run around misting my 1 and a half year old child. I had a blast making this, my wife thought I was crazy (until she felt that sweet cool breeze), my friends think I’m a genius and my 1.5 yr old son is no longer a little sweat monkey. Life is good.

      P.S. Coyote, live a little you silly little high-school prick.

    • Erm, Coyote … if you’ve seen the full site, some people have actually done the radiator thingy. Unfortunately, not everybody has access to one, so these contraptions are the second-best solution. 😉

  13. Without trying to get out of context or budget, the cooling process you are utilizing is based primarily on the ability to exchange heat from one medium to another. There are many resources for “junk” items that have a much higher thermal transfer coefficient than the coils of copper tubing currently utilized. In short a trip to the local wrecking yard could supercharge the volume of cold air being produced. As there is no worry or real concern of potable water within the system itself, contamination is not a major concern. Locating an old car radiator that doesn’t leak (this is a low pressure system so if it leaked in the car it may not in this application) and mounting your fan to it should increase the thermal transfer rate much better than wrapping copper tube around a fan. Keep in mind that a lot of engineering went into the design of the radiator to maximize its efficiency for just this purpose. The same is true for cooling the water in the lines. For this use a small transmission cooler submerged in the water and ice mixture. Both the radiator and transmission cooler are designed to exchange more heat than what will ever be present in the system. The flow direction should be from the bottom of the radiator as the cold water inlet and out the top for the return line. The real problem comes from maintaining a fresh supply of ice and with this in mind evaporative cooling might present simpler resolutions

  14. Pingback: Hack your cooler: Air chillers | Diy all the Way
  15. As a matter of interest in getting the water or box of ice as chilled as possible, I believe that, for a box of ice cubes or whatever at least, not sure about a water solution, that adding a good quantity of salt will take the temps down even more, super chilled! Anyone clarify if that is possible with a water solution filled with ice, or ice packs, or does it just work with ice only?
    What is the physics behind that btw?

  16. Ah, an addition, I was just too curious, Lol anyway, seems that for this experiment a good salt option is known as Light salt, as it has good amounts of Potassium Chloride, and an endothermic reaction takes place. Commonly used to chill beer cans/bottles quickly. The thing is, I can see that this will drop the temps quicker and lower, but then again, the ice might not last as long?

  17. I have a small cabin 80 miles out of town. The property has a spring coming out from a bed rock formation. I am considering running copper tubing to the spring and using a solar pump to pump the very cold water up to the cabin(bout 150 feet)to a solar powered fan. Any ideas?

    • Hey Rob,

      This should work well, however if I can I’d suggest a few changes which would make it more efficient.

      The solar powered pump is a good idea, although I’d make sure it has sufficient capacity to pump 150′. Instead of running copper tubing, I’d use normal garden hose. It’s cheaper, easier to lay a route down, and the water will absorb less heat as it’s transported from the stream to your house. The colder the water stays, the more cooling capacity you’ll have. Keep the garden hose in the shade so the water stays cool, and you can use normal foam pipe insulation if it has to cross any sunny areas.

      Once you’ve got the cold water source up to the cabin, I’d purchase an old radiator from a pick-a-part place or similar. This will ensure the best heat transfer between the warm air of your cabin, and the cold water of the stream. Use the solar powered fan to blow the warm air of the cabin across the radiator, and you should see a nice cooling effect.

      The only thing left to do is release the now warm water from the radiator outside in an area where it won’t affect the cabin or erode anything away. If you’re confident in your cabin roof, you could always release the water onto the roof – your eavestroughs will collect any excess and it’ll create an evaporative cooling effect on your roof on those very hot days.

  18. Ok. I ran across this as I was trying to make my own. All of our basic ideas about the copper tubing and the pump in an ice chest where the same. I was looking for some better ideas as all I get is a lot of condensation on the copper tubing that does not evaporate. I saw the improvements here using a heat exchanger. If I used an ac heat ex. from an old car. Do you think that would work. I really want to get this thing to work. The garage is VERY HOT this summer, and my previous design is just not cutting it. Maybe that’s because it is so hot and so humid. The heat exchanger is going to cost me about $30.00 which is about 3/4 of the cost of everything else combined(not including the fan). Should i buy it? and if i do. should there be space between it and the fan. On the front, the back… please help if you can 🙂

    • Hi Jamal –

      The heat exchanger will definitely increase your performance drastically. The only possible problem is if your cooling capacity (ie cold water) can’t keep up. Unless you have a large source of cold water to draw from, it is likely that a heat exchager will just heat up your fluid much quicker and reach a steady state of no cooling. If you have sufficient fluid capacity then it should perform quite well however – I am aware of someone who is pulling cold water from a nearby creek to cool their cabin with great results.

      The fan spacing is not critical – just play with it a bit to see what works best for you.

  19. I have a very large water supply, and am using 30 ft of copper tubing. I think one of the biggest problems I’m having is that I live in Texas, and the humidity is so high here. Thanks for the input. I’ll try a few different things and let you know what happens.

  20. hey I live in alberta canada. I built the fan and I am not feeling a difference at all. The copper will condense but I still dont feel any difference in the temp of the air coming through the fan. Any suggestions? I cant afford to buy anything else. This was my cheap idea. My wife is gonna kill me because I spent close to 75 dollars on this contraption and it doesnt work. Please help

    • Hi Matt –

      I’m sorry if I wasn’t clear, but the copper tubing was the first prototype of the air conditioner. Any new builds should take an approach similar to the “Black Beauty“. There is a significant improvement in performance using a radiator, heater core, or similar, and the cost is identical to copper tubing.

  21. Hi Geoff,
    I recently built a homemade AC unit using your directions and I was wondering if you could refer me to a site where I could buy an aquarium pump to cycle the water through a single cooler. I went to a few pet stores, but wasn’t able to find anything with a nozzle that would fit the 1/4″ inside diameter vinyl tubing I am using. Any suggestions would be greatly appreciated.

    • Hi Jonathan – You best approach would likely to be consider some adapters or connectors that will allow you to fit the tubing to the pump, or to size up your tubing to an appropriate level for the pump itself.

  22. Hey you all!

    I am not a DIYer, but I would gladly pay for a contraption like this. Who of you would proudly sell one to me?

    If I am not notified of comment answers here, email me at gidon.ariel

  23. I live in Pakistan and the temp is about112f——115f and the cost of running an air conditioner for 10 hr is unimaginable. we use desert cooler for about two months and then switch to air conditioner I will definitely go for the tube in front and back of the fan but the problem is the water must be super cooled to get the max out of the fan. I am searching for the super cooled water or use of frozen ice to keep the water temp down. The desert cooler add to the humidity so we give it up Any help will be welcomed

  24. While I have been using the fan,copper tubing, pump,styrofoam cooler. contraption for at least 30+ years in our one room Hunting, fishing cabin,Which works great in the summer in central pennsylvania, I have taken it a step further since our fridge runs anyway, I have placed the cooler in it,the tubeing is thin so there is no interference from the door seal, no need for more ice

  25. I have created all things but I have one issue I have connected one copper tube pipe into the water pump and the second end into the thermopole ice box but it can’t gives up the cold air please help me ASAP.

    Thanks & Best Regards
    Sikander Ahmed

  26. Its a nice one……. also
    “This picture shows Pete’s innovation, the Internal Cooler Coil (ICC) ready to be installed. The water first runs through this coil, through the ice water, and then out to the fan. Pete and I are wondering if this actually increases performance at all, but it sure looks cool.”
    instead of this….hope it wud be better if we tpump the ice water directly into the copper tubes and i am thinking of mixing the ice water with a coolant or heavy water…… it wud be better ryt?

  27. i have tried with ice water rotating in the copper coil with the help of water pump so the question is that can i put the exit water pipe in to the same water so it will save the waste of water and have same quantity of water in the tub

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