A heat pump simply moves heat from the air and transfers it to the pool/spa water. A heat pump uses a refrigeration cycle exactly like your refrigerator or air conditioner uses. A proven safe, economical and very trouble-free system.  A heat pump allows you to heat your pool or spa economically. Depending on energy costs, an AquaCal heat pump can save you up to 80% over propane gas, 50% to 70% over natural gas, and over 600% against electrical resistance heaters found on most spas. This is the reason why thousands of customers choose a heat pump to heat their pool, rather than alternative types of heaters.  If you plan on heating your pool, a heat pump makes the most sense, and the most economical heat pumps feature SCROLL compressors.  AquaCal's HeatWave heat pumps were the first heat pumps to feature SCROLL compressors as their standard compressor.