Originally Posted by davefleck
Why? In case of a leak between plates? Do they then have a closed circulation of distilled water and a dedicated pump?
the glycol is food-safe anyway, its only to split the heat load between two sources, instead of dumping 100% of it into the glycol and making the compressor deal with it.
regular water comes in to HEX#1 at say 60*; its chilled down to 35-40* by running 20* glycol thru it; the 40* water is then fed into HEX#2 and used to chill the 200* wort more efficiently than you could if you were using 60* water.
most of the heat load is placed into the regular water loop, instead of all getting dumped directly into the glycol system (which would both make the chiller work harder and cause a glycol temp spike/fluctuation).