... ,ISO9001:2000 4:Produce as customer's requirment Low pressurized solar water heaterSpecifications1.Solar Keymark,SGS,CE,CCC,ISO9001 2.manufacturer, independent ... be installed on the roof to get enough water flow pressure, because the compact system is non-pressurized, water flow ... with vacuum tube solar collector. Water flow inside and complete a circulation on it own without given pressure, that is how ...