... ,AW15B,AW20,AW20BLow temperature air to water heat pump :AW10/L,AW13/LNormal air to water heat pump can work at above -10 degrees ... ,Low temperature air to water heat pump can work at -20 degrees.AW09,AW09B,AW12,AW12B, ,Power ... starter 1 phase heat pumpON LINE SYSTEM is optionalDaily hot water pump: Wilo water pump is optionalElectric heater: 3KW ,6KW,9KW is optional ON ...