Building a glycol chiller from an 8000 BTU window air conditioner involves several stages. Please note that this project involves working with potentially dangerous elements such as electricity and refrigerants. If you're not entirely comfortable with this, it would be safer to hire a professional to perform these steps.

You'll need the following materials:

  1. 8000 BTU Window Air Conditioner.
  2. Insulated container – You can use a cooler, or build your own insulated box.
  3. 1/2" Copper tubing.
  4. Glycol – Food grade propylene glycol is typically used in these applications.
  5. Water – To mix with the glycol.
  6. Thermowell.
  7. Submersible water pump.
  8. Vinyl tubing.
  9. Teflon tape.
  10. Insulation (spray foam insulation or insulating wrap).
  11. Tools (like a drill, screwdrivers, pliers, pipe cutter).

Steps to build the chiller:

  1. Disassemble the AC Unit: Unplug the AC unit and carefully remove the outer casing, exposing the interior components. Do this cautiously as you don't want to accidentally puncture the refrigerant lines.

  2. Identify the Evaporator Coils: In an air conditioner, the evaporator coil is the part of the system where the refrigerant absorbs heat. This will be the part you're most interested in for your chiller. It looks like a series of tubes with fins attached to them.

  3. Prepare the Insulated Container: You will be placing the evaporator coil in the insulated container. Make sure the container is large enough to house the coil, the thermowell and the submersible pump. Drill the necessary holes for the input and output tubing of the glycol solution, as well as for the thermowell.

  4. Place the Evaporator Coils: Carefully move the evaporator coil into the insulated container. Try to do this without altering the existing refrigerant lines, as this can result in loss of refrigerant.

  5. Install the Thermowell and Pump: Place the thermowell and submersible pump in the insulated container. Make sure the pump is rated for the type and temperature of the fluid it will be pumping.

  6. Connect the Tubing: Connect the output of the pump to the input of your system (like a brewing fermenter, for example) using the vinyl tubing. The glycol solution will come out of this tube, flow through your system, and return via the return tube back to the insulated container.

  7. Prepare Glycol Mixture: Mix the propylene glycol with water. A common ratio is 1 part glycol to 2 parts water, but this may vary based on the specific requirements of your system and the ambient temperature. The glycol helps to lower the freezing point of the solution, so it can get colder than just plain water without freezing.

  8. Fill the Container: Fill the insulated container with your glycol mixture. Make sure the evaporator coil, pump, and thermowell are all submerged in the mixture. The mixture should also cover the intake of the pump, but be careful not to overfill.

  9. Insulate: Use insulation to further insulate the container and any exposed parts of the evaporator coil. This will help to keep the cold in and the heat out, making your system more efficient.

  10. Test: Now that everything is set up, you can plug in the AC unit and turn it on. The evaporator coil will cool down, cooling the glycol mixture in the process. The pump should then circulate this chilled mixture through your system.

  11. Monitor: Keep an eye on the system to ensure everything is working