... 2 The circulation is closed loop for themal collecting and enchanging start and superior heat collecting.3 the heat pipe material ... copper header pipe, insulation layer, manifols casing,sensor port, inlet and outlet, condenser, heat pipe, heat transfer fin,tube cap ... , thickness about 1.2mm, it keeps the water clean and drinkable and temperature. automatic argon-avc welding technics ensures on leakage ...