... No water inside the tubes when it works, it can work as usual under -38celsuis 6)Bathing, washing, domestic heating ... 7)Pressure: 0.7Bar 8)capacity: 100L, 200L, 250L, 300L, 400L, 500L Working principle ... does not reach Tmax, electrical heating system will start to work Pressure solar energy, pressurized solar collector, pressure solar hot ...