Although air conditioner coils might seem daunting to the layperson, the technology behind them is actually quite simple. Cooling coils work by pumping a liquid or gas with useful thermal properties through highly conductive copper tubing. Heat exchange occurs as hot air passes over the coils full of cold fluid. Highly effective refrigeration units use refrigerants such as fluorocarbons, ammonia or carbon dioxide. In central air conditioning systems, the refrigerant absorbs heat as it passes through the evaporator coil in the attic or mechanical room.
The refrigerant is then pumped outside of the building to the condenser coil, where it releases heat. These systems cost thousands of dollars because of the extensive plumbing and ductwork. Also, the handling of some refrigerant chemicals is highly regulated because these refrigerants can deplete the ozone and act as a greenhouse gas. However, using ice water as a refrigerant, you can build a portable air conditioning coil in a matter of hours.
Step 1 - Determine Material Needs
Measure the perimeter of your fan. To build an air conditioning coil, you will wrap the copper tubing in a spiral pattern. Determine the length of tubing you will need to make several loops and still reach the cooler. Alternatively, if you have an old, empty radiator handy, you can use this instead of the copper tubing. Larger fans have greater airflow and will be able to cool larger spaces. Larger coolers will allow longer intervals between changing the ice water reservoir.
Alternatively, you could design a geothermal heat pump by digging a hole in the ground and running the coil into it. The power of the pump used determines how rapidly the ice water will circulate through the coils. Depending on your needs, the fountain pump could plug into the wall, run on batteries, or operate off of solar panels.
Step 2 - Wrap Fan in Tubing
Starting at the base of the fan, run tubing around the perimeter. Secure it with a zip tie or piece of wire every several inches. After going all the way around the outside, start wrapping the copper tubing in a spiral pattern across the faces of the fan.
Step 3 - Prepare Cooler
Measure the distance between pipes at the base of the fan. Punch holes in the cooler lid this far apart. Cut a notch in the cooler lid to run the pump’s power cord through.
Step 4 - Connect Coil to Pump
Use 1/4-inch plastic tubing or a ¼-inch pump adapter to connect the copper tubing to the water pump. Use plumbers’ glue to secure the connection. Trim away excess refrigerant line with the copper cutters.
Step 5 - Fill Cooler with Ice Water
Fill the cooler with cold water and turn on both the pump and fan. You should notice the cooling effects almost immediately. For the best results, replace the water in the cooler on a regular basis when it starts to warm up.