Product Specification:Solar Water Heater Inner Tank: Food grade SUS 304 stainless steel/316 stainless steel,Website:http://www.chinasolarwaterheater.com, 0.4-0.6mm, diameter 360mm/380mmSolar Water Heater Out Tank: Galvanized steel/201 stainless steel/304 stainless steel, 0.4mm, diameter 460mm/480mmInsulation: 50mm high-density polyurethane foamedInlet&Outlet: 1/2" or 3/4", stainless steelVacuum Tube: QB-AL-N/AL-47mm/58mm-1800mmWater Tank Bracket: Galvanized steel sheet, 1.5mm/201 stainless steel, 1.2mm/aluminium alloy, stainless steel screws & nutsAccessories: Assistant tank, electric heater, magnesium anode, TK-8A/TK-7/TK-5 digital controller and so on Advantage: (1) new design side assistant tank for hard water area; (2)non-welding TechnologyModel Evacuated Tube Tank & Tube Capacity (L) Person NO. Diameter (mm) Length (mm) Quantity (pcs) BS-NP/NPS-581800-65818006601BS-NP/NPS-581800-85818008801-2BS-NP/NPS-581800-10581800101001-2BS-NP/NPS-581800-12581800121202-3BS-NP/NPS-581800-15581800151503BS-NP/NPS-581800-18581800181803-4BS-NP/NPS-581800-20581800202004BS-NP/NPS-581800-24581800242404-5BS-NP/NPS-581800-30581800303006BS-NP/NPS-581800-36581800363607BS-NP/NPS-581800-50581800505009-10Solar water heater with assistant tank model is popular in India, South America and Africa.Without assistant tank or with assistant tank on the top, the main big tank is full of water. When the water gets hot, if the hot air can't get out quickly, there is much pressure in the tank. The pressure will damage the non-pressure tank. Secondly, because the tank is full of water, the above welding of the inner tank is dipped in the hot water all the time. It may make the welding place leak. Especially in some place, the water is very hard.So according to these problems, we designed the new solar water heater with assistant tank model. Using side assistant tank, there is a little space on the top of tank, so it will decrease the pressure in the tank. Because there is no water on the top, the welding will not be dipped in the tank, so will prevent the corrosion and rust better. Besides, we use non-welding technology.Welding is damage to stainless steel. We wrap the cover on the main inner tank, there is no welding, so there is no rusty, corrosion and leaking.