Capacity range 80 100 120 150 200 300 500 750 1000 1500 2000 Energy efficiency class D B A C Number of coils 1 2 Water tank Stainless Enameled Nominal power (kW) 3 9 12 14.9 23.1 23 29 Control electronic control mechanical control Voltage [V] 0 / 230~ 230 V~ 230~ / 400 3N~ 400V 3N~ Method of water heating Electric heating element + two heat exchangers Electric heating element + one heat exchanger Pipes diameter (plumbing system / heat exchanger) 1" / 1" 1" - 1 1/2" 1" / 1 1/4" 2"/1" 3/4" / 1" 3/4" / 3/4"