Cast in BS-EN-1561-1997-ENGJL-200 iron, with a heavy fusion bonded epoxy coating impervious to chemically treated pool water, constructed in accordance with British Patent 2.092,282 Design pressure of 35psi (2.46kg/cm2) with 3/4" safety valve(s) set to operate at the maximum normal working pressure of 30psi (2.1kg/cm2) giving protection to both the heater and and the installation as a whole against over pressure. A 1/2" drain valve at the lowest point allows the heater to be left empty in winter. Flow connections consist of easily removable uPVC stub flanges into which the pipes may be fitted using suitable adhesive, as the flanges can be released easily from the heater no unions are required, nor is any form of heat sink needed. Flow direction is from left to right, but may be reversed quite simply on site following the installation instructions.