I am using glycol with my chiller but slightly different, I have 2 thermonator chillers, one I run glycol through and pre chill my ground water. The water then goes to my second chiller to chil the wort. I do a single pass with the wort and typically can chil 20 gallons from boil to about 70* in 15-20 minutes. I just recently picked up a counter flow similar to yours to try in place of one thermonator mainly for ease of cleaning.. we'll see if it changes anything.. nice system!
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