Gloworm 120FF Turns on randomly

[splinkies]

Please can some one help with my Glowworm boiler. It works fine both with heating and central heating when on the timer. Once the set time periods are off, the gas burner keeps turning on for a few seconds up to around 10 minutes. Any ideas on what to check.

Many thanks

 

[stardanny]

Do you have a 2 or 3 port motorised valves? It may be sticking and slowly closing.

Daniel.