ya, if you wanted to go much below 20f with your water temp youd have freezeup problems on the heatercore. my aim wasnt so much to reach sub-zero...(the comressor is rated 25-55f evap range) I just hate seeing those 140f system temps when its 110f in the shade here in the summer time. I would love to use A/C to cool the whole house, but my electric bill is already $300 a month
