Working Principle:This type is with copper coiler (which is as the heat exchanger) inside the tank. The water flows into the copper coiler and absorbs the heat of the water in the tank via the copper coiler. And the copper coiler can bear high hydraulic pressure,Website:http://www.chinatide-solar.com, so it can be connected with city water directly.TypeVacuum tubeCapacity(L)GrossWeight (KG)20GP/40HQ Loading Qty(sets)Φ(mm)Length(mm)Qty(pcs)CT-P01-205818002020010834/82CT-P01-245818002424013031/76CT-P01-305818003030015326/63CT-P01-365818003636017524/56Technical 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-ALN or AL-N-AL coatingBracket: Galvanized steel 1.5mm with 27/30/45 degree installing angle.Electrical heating connection (mm): 47 Water connection (inch): ½ or ¾Assistant tank connection (inch): ½Coiler connection (inch): ½Vent connection (inch): ½NOTE: 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)