Heat Exchanger Improvements

The major factor affecting the efficiency of the air conditioner is the heat exchanger. A radiator or evaporator coil would be ideal, but cost and availability are a concern. This page details my attempts to improve performance of my homemade air conditioner with minimal cost.


Strips of tinfoil were first used. You can see some of the copper coiled along the front, from an earlier attempt to improve the heat exchanger. This wins in the cost department, but ultimately the choice was made to discontinue the use of foil as it had the annoying habit of coming undone and buzzing like mad during the night.


The decision was made to completely revamp the copper coils, and install the entire length of tubing on the front of the fan. You can see the recoiling in progress, I did a bit neater job this time (but not by much).


Here’s the completed copper coil on the front of the fan. Cold water is fed from the centre to the outside. Again, I’m unclear as to what configuration if any (cold from the inside, cold from the outside) would lead to superior performance.


I decided to use wire to create a mesh on the front of the coils. (18 gauge wire, Radio Shack, ~$5 – I’m up to 30 bucks now!) This would increase surface area, intercoil heat transfer, and turbulence near the coils, hopefully increasing performance.

I first attempted to solder the wire to the tubing, a stupid attempt as the entire system is designed to efficiently transfer away heat. After several minutes of terrible cold joints, another approach was required.


I ended up weaving the wire from the centre to the edges, and back in. Approximately 10-12 passes were used per quarter section of fan.


Here’s a shot of the completed upper left quarter.


Weaving the wire is an unbelievably frustrating experience at times. The copper tubing usually has a slight gap between the white wire mesh on the front of the fan that the wire can pass through, but at other spots the wire will catch and start to unravel. It helps to have the proper tools (needle nose pliers, beer) to stay relatively stress-free. In this shot I’m halfway through weaving the lower right quarter.

Just be patient and you’ll be fine.


Here’s the fan as it stands right now. Saturday went from evening to night, and that means I need to go somewhere with cold pints and hot women. I’ll complete the remaining quarters tomorrow when I have a bit more time and patience.

Preliminary tests are very satisfactory. The cooling rate has increased, and the room will get a bit colder as well. This will help in extremely hot situations, where heat would leak into the room as fast or faster than the system could remove it.

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

16 thoughts on “Heat Exchanger Improvements

  1. im having troubole understanding how your getting the water to run threw the copper piping from a cooler of cold ice water, how does that work?

  2. Canada boasts some very fine engineering schools. You appear to be a prime candidate! How are your math skills? Computer skills? You seem to have the ingenuity and creativity to qualify!

  3. Hi Geoff,

    I just stated reading about homemade air conditioners 30 mins ago so bear with me. What about the option of using the main plumbing of your house to send the water through the radiator or coils and then run it right back to your plumbing so you are not using any water during the process, besides the fact about this being safe, would could water be enough to make a difference or is ice requires?

    • Hi Sean,

      The performance would likely be great if your incoming water supply is cold (ie groundwater sources are ideal). The only concern would be contamination as a radiator and tubing are not ideal ways to transport drinking water. It would be best to treat it as “grey water” and use it for gardening or similar.

  4. Thank You for this information. I wanted to do something like this for my dogs (and me) as inside house temperatures are now reaching 105 degrees F. It is unbearable to say the least. My Dad had made a tiny swamp cooler from a bird cage but that was so long ago I just can’t remember how he did it. You have saved us!

  5. Dear Geoff, I am so excited about your invention! I was hoping you could help me.? I want to make these for elderly ppl living in LA and part of the desert that don’t have AC. When it gets to be 110 degrees, I worry about these ppl. I need to make the best fan air conditioner and try and keep the fan and other items at a reasonable cost. I am helping the elderly and poor through a foundation I am just starting up. I love your idea, your very smart. Your mom and dad must be so proud of you!
    Thank you
    Cindy Sprinkle

  6. Hi Joe,

    Does this increase the humidity in the room? I live in the Philippines and it’s hot and muggy here. I was wondering if this’ll work in such an environment. Thank you for sharing this!

  7. I found your page as i was looking for find a cooling solution while staying at my summer house in Andalucia where temperature can reach 35-40 degrees celsius regularly during summer.
    the knitting of the wire through the copper coil seems daunting to me, so i was wondering if fitting some spoons and forks between the coil and the cooler mesh could do a similar job with less effort 🙂

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