Please can some one help i have a Viallent 624 boiler with mega flow system with dual zone control, the central heating comes on Luke warm when the programmer is on the off postion. I have notice that it may only come on when the hotwater diplay is swithed on. Can any one help??

Jai Patel, April 2008

CH getting warm when heating for hot water would indicate a stuck diverter valve.

Boiler comming on when no demand for heat would indicate a stuck zone valve still calling for heat even though programmer if not calling

T, April 2008