Planning to install in floor piping and boiler system with DHW included with heat exchanger tank. Boiler will handle heating glycol to temp necessary for DHW and then use control valve to cool for in floor heat temperature. I want to put in evacuated tube collectors to heat glycol prior to boiler, i am not sure however if i would need a heat sink for times when demand for heat are low, abs in summer when system is essentially turned off. In winter it is regular to have temperatures well into the (-30F) range and have periods of 60 or more days that do not get above freezing what so ever, then summer will not need heat for 2 to 3 months at all.