got a ravenheat csi 120 and the pressure keeps rising until pressure release kicks in. the filling loop is disconnected and when i turn the cold water supply off it stops filling. i`m assuming the divertor valve sticking. took it out and cleaned and checked it but appears ok. anyone any ideas

desperado, June 2010

Flat plate exchanger leaking cold feed into heating circuit system over pressurising to water main pressure and hence lifting safety valve, diverter valve only diverts hot boiler water either to C.H system or to D.H.W via the flat plate type exchanger.

Guytawe, June 2010