... a copper coil inside water tank.2.Pre-heated pressure system Working principle is more advanced than thermosyphon solar water heater ... exchanger can be used as part of a closed or open loop system, providing heating to a main hot water tank 5 ... , 10L, 20L, 30L, 60L, 100L, 150L etc.Pre-heated pressure system, Pre-heated, solar hot waterBrand nameSUNTASKProduct nameThermosyphon Unpressurized Solar Water ...