... set value, the controller shall start the circulation pump automatically.2) The circulation pump makes heat-conducting liquid circulate automatically.3) The ... Bathing, washing, domestic heating9) Workable at anytime and enjoyableModelTubeQty. per 20 Container ( set)TH-58-1800-1658-1800mm, 16pcs115TH-58-1800 ... -1800-2558-1800mm, 25pcs74TH-58-1800-3058-1800mm, 30pcs61 20 Tubes Heat Pipe Solar Collector