Design and Evalution of a Primary / Secondary Pumping System for a Heat Pump Assisted Solar Thermal Loop


A heat pump assisted solar thermal system was designed, commissioned, tested and analyzed over a period of two years. The unique system uses solar energy whenever it is available, but switches to heat pump mode at night or whenever there is a lack of solar energy. The solar thermal energy is added by a variety of flat plat solar collectors and an evacuated tube heat pipe solar collector. The working medium in the entire system is a 50% mixture of propylene glycol and water for freeze protection. During the design and evaluation the primary / secondary pumping system was the focus of the evaluation. Testing within this research focused on the operation modes, pump stability, and system efficiency. It was found that the system was in full operation, the pumps were stable and that the efficiency factor of the system was 1.95.


Solar Thermal, Heat Pump, hybrid solar thermal, Efficient heating, Hydronic heating, heating loop, primary secondary system

Date of this Version



Engineering Technology

Month of Graduation



Masters of Science

Advisor 1 or Chair of Committee

William Hutzel

Advisor 2

Mark Shaurette

Advisor 3

Chris Foreman

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