... for use in water heating. Evacuated tubes have already been used for years in USA,Germany, Australia, France, Japan, Canada, ... collectors use the most common "twin-glass tube". This type of tube is chosen for its reliability, performance and low manufacturing cost.Part ... with Diameter 25mm, resisting pressure 1MPa.4. Reducing the fouling on the tube wall, keeping water clean.5. Evacuated tubes are ...