... your choice.4) For the system with double coils in tank,it can operate with traditional heating energy equipment,such as electric ... ,gas,boiler,and so on,during raining.snowing,or cloudy.5) Adopts the closed loop, operating ... pressure: 1.2Mpa)Working principle:Installation Case: Solar hot water heating system,SRCC,Solarkeymark,ISO9001,100L~500L