Working Principle:This type is same as CT-NP01,Website:http://www.chinatide-solar.com, using all-glasses evacuated tubes as the solar collector for absorbing sun energy and transferring it into heat energy. As the different densities of hot water and cold water, the hot water flows automatically upwards while the cold water flows down. The water flowing cycle is created in the tube. And the water in the storage tank is heated from this natural circulation. The hot water pressure of this non-pressure system is from the gravity, so it should be installed on the roof or at least 3-4 meters higher than hot water tap. Or you can install a booster pump to get stronger outlet hot water.The only difference is that CT-NP01 is with an assistant tank and CT-NP02 is without.TypeVacuum tubeCapacity(L)GrossWeight (KG)20GP/40HQ Loading Qty(sets)Φ(mm)Length(mm)Qty(pcs)CT-NP01-10581800101005382/197CT-NP01-15581800151507356/134CT-NP01-20581800202009041/96CT-NP01-255818002525011835/81CT-NP01-305818003030013628/67Technical data:Inner tank: SUS 304-2B/0.41mm, Φ360mmOuter tank: Galvanized steel/0.41mm, Φ460mmInsulation Layer: high density polyurethane foam 50mmVacuum tube: 58*1800mm/SS-CU-AIN/ALN or AL-N-AL coatingBracket: Galvanized steel 1.5mm with 20/25/38/45/50 degree installing angle.Electrical heating connection(inch): ¾ or 1¼Water connection(inch):½ or ¾NOTE: All the systems are available for the customization.Optional Accessories1.Booster Pump (adding the hot water out pressure)2.Temperature Monitor (showing hot water temperature inside the main tank)3.Electrical Heater (as back-up for cloudy or rainy day)