SANCO Heat Pump Water Heater provides efficiency and performance using a natural refrigerant, carbon dioxide. The SANCO Heat Pump Hot Water Heater is a split-type heat pump water heater (HPWH) system comprising an outdoor heat pump unit, with a R744 (CO2) refrigerant-to-water heat exchanger producing hot water at approximately 150 F, which is then stored in a separate indoor tank, and mixed with cold water for domestic hot water use in the home. Features high energy factor (EF) and first hour rating for HPWHs, and can operate in ambient temperatures below freezing. The SANCO unit can also be used for heating via a separate hydronic heating system. Sanden Water Heaters.