Haphazard heating

[locsuna]

Hi all, first post so I hope I don't appear too stupid.
Heating problem is that the flow and return pipes have heat in them and the rads turn on, but don't stay on for the full timed period. Pressing the advance or turning up the thermostat gets nothing. Hot water works fine. Thermostat clicks as it should and the programmer appears alright. I'm guessing a motorised valve fault. Any ideas gratfully received.

 

[WHPES]

Have you checked the boiler thermostat as well as the room one? If it is set too low it may cause what you describe.

Sounds more like a control issue or programming as if the radiators heat up for a while it indicates the motorised valve is working.

 

[locsuna]

Thanks for the reply, I've turned the room stat and boiler one up and been in the loft to try the zone valve. The valve opens manually and can be locked open but still no firing of the boiler. The advance button fires the boiler as does turning the underfloor heating on. Could it be one side of the programmer being defunct.