The efficiency of a heat pump explained
All heat pumps work on a declining performance curve efficiency. The colder the outdoor temperature gets the less efficient the heat pump will be. Similarly at higher target design temperatures the heat pump will also loose efficiency. However Arctic Heat Pumps have some of the best performance in both lower range outdoor temperatures and higher operating design temperatures (pool setting).
The orange line in the graph shows that even at -7ºC (19ºF) ambient air temperature and a 40ºC (104ºF) hot tub target water temperature the ARCTIC 025ZA/B pool heat pump can still deliver 6.5 kW of heat into the water, while only consuming 2.19 kW itself, for a COP of 3.0.
The blue line in the graph shows the same performance at -7ºC (19ºF) ambient air temperature but using a pool water design temperature of 28 ºC (83 ºF). It is even more efficient because the design water temperature is less that a hot tub.
Note -These are examples at very cold outdoor temperatures. The warmer the air gets the better the efficiencies of an Arctic Pool Heat Pump get!