Effect of Solar Pre-Heat on a Heat Pump

Phelps_Clarke

If I have a solar system that is primarily for domestic hot water, but I want to use as much heat as possible from the solar storage tank in the winter so I decide to use a hydronic booster coil installed in the duct work upstream from the heat pump coil what will be the effect on the efficiency of the heat pump.  In this scenario the solar will rarely if ever be close generating enough energy to actually heat the house.

For example, say I have a 110 solar tank and I pre heat for a heat pump, so maybe now the air the heat pump coil sees is 78 instead of 68, how does that affect the efficiency of the heat pump.  At what solar generated air temperature should I disable the Heat Pump completely.  Do I need to worry about diabling the heat pump or what? 

I think return air is a great target for solar because it is so cold compared to even the coldest return water in a hydronics system.  Is this true?  I know the air is not so dense but with free solar btus, what is a little extra fan energy?

EddieG

I.....

would not pre-heat return air on a heat pump. A hydro coil with 110 degree water isn't going to do much for you, if anything. I would keep the heated solar  water stickily for domestic.  JMO

meplumber

I agree with Eddie.

Water at that temperature would be better served into a flat panel radiator piped to a bathroom or bedroom.  Size the radiator for the low temp and install a Non electric Thermostatic Valve.



Good Luck.