Heat Pump COP with solar-warmed inlet

[Robert Scott]

The COP of a geothermal heat pump is given for inlet water temperatures in the range of 30-50F as being from near 1.5 to about 3.0. Does anyone have any data on what the COP would be if the inlet temperature were raised to about 75F by low-grade solar heat?

I currently have a "Water Furnace" brand heat pump with a closed-loop feed system. I am trying to decide if I should add solar heat using an independent system, or if I should use the solar heat just to boost the efficiency of my heat pump, One of the advantages of the second approach is that I can make use of lower temperature storage of solar heat, as opposed to the direct method. But the second approach won't do me much good unless it significant raises the COP of the heat pump.

Robert Scott Ypsilanti, Michigan

[new jersey]

Ctizian On Patrol works for me and I enjoy watching it Tony

[Stormin Mormon]

Wasn't that in one of the Police Academy movies?

[new jersey]

Yep I can hardly wait for new one to come out Tony

[geothermaljones]

Your COP will increase greatly. Contact Water Furnace, a WF dealer, or check their website & get the design/engineer specs. They should have the heat production capacities for a wide range of EWT's. COP's should be clearly stated or easily calculated.

Make sure you isolate the solar panel system from the loop field w/a heat exchanger & circ pump, as the sun isn't constant & the panels may/will have a huge heat drain on the loops system on cold nights in the dead of winter. The increased antifreeze quantity required, without panel isolation, will also (negatively) effect the systems operation. You could look at a indirect water heating tank with loop field water circulated through a tube inside a tank of solar heated water. When the sun shines you crank up the solar panel pumps & heat the tank as high as you can. When the suns down the tank will drop, but shouldn't drain the loops if properly installed. You could even have a secondary pump on your loop to tank tube that "injected" warmer water from the tank exchange simple temp controls will run the pump until tank temps & loop return temps are near equal.

goodluck geothermaljones st.paul,mn.