Central heating not firing up but hot water is fine

[Kaiserchief75]

Hope someone can help. I have a Worcester greenstar 24i boiler with an unvented cylinder and the central heating has stopped working but the hot water is ok. I have 2 2port motorised valves and the only way I can get rads hot is if I run the hot taps and open the heating motorised valve to manual. I'm not sure if there's a problem with the valve, programmer or boiler?? I also have a room stat in the hallway. Some advice would be appreciated.

 

[75pete]

It sounds like the valve.

 

[MANDATE]

If you have 230 volts at the motorized valve, then you know the programmer and room stat is not the problem.
If you have to move valve manually it suggest the motor needs replacing

 

[Armo74]

The motor has gone in the 2 port heating valve. Depending on make and model a replacement syncron motor can be fitted.

 

[Kaiserchief75]

Thanks for the replies, the motorised valves are Honeywell type. I'm still puzzled though because when I've slid the hw setting to off position, manually opened the heating valve and slid the ch to on there's still nothing. The boiler only seems to fire up when there's demand for hot water at the cylinder. Am I missing something?

 

[Armo74]

It's possible that both the motor and the microswitch in the actuator that fires up the pump and boiler is faulty. Might be time for a new actuator

 

[45yearsagasman]

Am I missing something?

Yes you are missing something.
1, By manually moving the valve the microswitch will not be made. It needs to be driven fully open by the motor for the switch to be made.
2, Please follow the advice given previously and replace the synchron motor in the CH valve after testing it to prove that it has failed. Tis a very common fault.

 

[Kaiserchief75]

Ok, thanks again. How do I go about testing if the motor is goosed? I'll give it a go.

 

[Agile]

Ok, thanks again. How do I go about testing if the motor is goosed? I'll give it a go.

Call me out and I will have a gander!