Central Heating rasiators not warning up

[Discoarc]

I have a fully pumped oil fired central heating system with a Worcester boiler, a Drayton mid-position valve, a room stat, and a Lifestyle LP522 programmer.

The system had developed a problem whereby the boiler wont fire in the heating mode, only when the hot water is selected. When this is done hot water flows through the radiators but as soon as I turn off the water, the boiler stops and heat is lost to the radiators. The mid-position valve seems to be working ok.

Can any one offer a solution?

 

[Hugh Jaleak]

Still suspect the valve. Have a read here: http://www.diynot.com/forums/viewtopic.php?t=167584

 

[flameport]

It's the 3 port valve, or more specifically, one of the switches within the valve actuator.

 

[Discoarc]

thank you for your help. i replaced the actuator and the 3 way valve is working fine