How Much Glycol Is Needed

[tom@arcadia]

I'm having trouble justifying more glycol percentage in my chiller.

My chiller is located in the cellar area of the brewery and the ambient temperature in there is around 40F all year.

Do I need to run my glycol at 35% glycol 65% water if my glycol tank is not exposed to winter freezing temperatures. I know that more glycol in the system than is needed reduces the heat transfer coefficient.

I'm running at about 20% glycol now which was increased from 8% glycol earlier but I am not sure I need to go to 35%.

I am a little confused because Pro Refrigeration says that most systems run at 35% glycol and that you need your glycol freeze temperature to be about 20-25 degrees F below your system set point. We run our set point at about 24 degrees F normally but have had to lower it to 14F lately due to some issues.

Any suggestions?

[BrewinLou]

Glycol is not added to deal with ambient temp around the unit. Glycol is added to prevent the freezing of the unit itself. The glycol goes through a heat exchanger inside the chiller, on the other side of the exchanger is refrigerant. If the mix is not correct the glycol mix freezes inside the heat exchanger, which will damager your compressor and pump(s). The money is worth it, the compressors used in chillers are some of the most expensive on the market.