Building subzero Glycol Chiller from 2 ton window AC unit???

[square_root_pharms]

Im looking to take a 2 ton window AC unit and build a glycol recirculating chiller. Most AC unit evaporators will not get below sub zero temps. is there a refrigerant type change or modification that can be made to a 230v 2600watt 2-ton window ac to get the evap coil temps lower? the colder the better for my needs. this sized unit is typically 40-45oz of R410a refrigerant with 450psig high side and 250psig low side pressures.

 

[postalbunny]

Are you sure you need lower evap temps? There's generally not much you can do... the size of your compressor and sizing of the evap. Generally it's the BTU you're concerned with.

If you a making a chiller look at the size/temp you want to chill down. For example, chilling 5gal of wort from 212degF to 65degF

Temp diff = 212-65 => 147
5gallons of water * 8.6(weight) * 147 = 6,321 BTU required to chill.

If you have a 6000 BTU/hr window a/c unit the best you could hope for is 1 hour if you don't knockit down some with ground water first. If you get a 12k BTU/hr a/c unit it's roughly 1/2 hour.

You can pre-pad your chilling time by filling the tank/reservoir and and chilling down to 35 or lower if you have glycol.