solar/ solar water heater vacuum tubes solar Vacuum tube specialties: 1. High heat effectivness: higher than normal all glass tube by 10% 2. Heat pipe conduction, no water inside, thus it is successfully prevented from the defects of tube blockage and low power output caused by water fouling and deposits or dust and sand 3. With small thermal capability, it can output power in 2 minutes, the highest temperature of cooling end can reaches 250 degrees, the average heat efficiency can still be 50% even under -50 degrees 4. High efficient selective absorptive coating and vacuum heat insulation technology ensure the tube to get higher heat output in cloudy weather and in moist area,especially in winter 5. Solar collecting plate is installed and sealed inside the tube of the high-quality borosilicate glass with 5 x 10-2 Pa of vacuum, so it can not be corroded evenin moist area 6. Hot water system can endure 0.6Pa so that it can be connected to tap water tub