Ok crap. I had to add more antifreeze today, and when I did so I detected some air bubbles in the lines. I tapped out the air from chiller, bled it out to res over a few minutes, and started over. I was able to get 3 tests done tonight: Same voltage but range of MHz as since87 suggested. However these numbers don't seem to be matching up too well to last night's results. Some air in lines last night? Perhaps. My instinct is to just repeat expts over again and see. Anyway here are the numbers collected after purging air:
Very slight change in C/W with coolant temp this time, and consistently lower than before. I tested out chiller after finishing up and was able to get the water quite cold this time:
http://www.procooling.com/users/phae...chill/-10C.jpg
More numbers tomorrow as always.