Cold climate field evaluation of high performance air to air heat pump systems developed through the cold climate heat pump challenge program
CanmetENERGY-Ottawa (CE-O) evaluated the field performance of three (3) innovative cold climate air source heat pumps developed through the US Department of Energy / Natural Resources Canada’s Cold Climate Heat Pump (CCHP) Challenge program. The program challenged participating manufacturers to develop, test and bring to market air to air heat pumps that would meet specific performance criteria. Several manufacturers participating in the program partnered with Natural Resources Canada’s CanmetENERGY research laboratory to undertake field performance evaluation of their candidate systems. Some of the participating manufacturers have recently announced their intention to bring their systems to the market for purchase. This paper presents coefficient of performance (COP) by outdoor temperature for three CCHP challenge systems evaluated, including two systems evaluated at the Canadian Centre for Housing Technology. A climate-specific bin model is then used to compute seasonal heating performance of the field collected test results. Results are compared to two (2) other cold climate air source heat pumps previously monitored. By evaluating performance according to operating mode, the study also analyzes low-temperature performance, part-load cycling behavior, and the effects of defrost cycles, standby modes, and crankcase/drain pan heaters on overall efficiency. Results indicated that the three CCHP Challenge systems evaluated (units 1-3) outperformed the commercially available CCHPs, having greater than 20% higher seasonal heating COPs. When considering performance across all cycles / operating modes, units 1 and 3 were the higher performing CCHP Challenge systems in the coldest outdoor temperatures, achieving COPs of 1.8 at -26°C, while unit 2 was the highest performing CCHP Challenge system in the most moderate outdoor temperatures, achieving a COP of 4.0 at 6°C.