Central heating goes off even when timer is on

[samcru]

When the central heating goes on first thing in the morning by a timer it runs perfectly, however, after about an hour or so later the radiators get cold but the timer is still on. When I check the pump first thing it is very hot and vibrating and the spring loaded leaver below in the Honeywell silver box is forward as I have manually put it there but when the radiators go cold the pump is hot but not vibrating and sometimes the spring leaver is back on itself. Even if I manually put the spring loaded leaver forward again the water still does not go through to the radiators and the pump is still not vibrating but hot.

Can anyone help, please?

[marrtin]

Have you checked the room stat is working correctly?

[samcru]

Yes, with the help of my dad, they are working ok.

[samcru]

I have entered this query twice, sorry but yes the room stat is working Ok.