Central heating not working but hot water does...

[clarksonbc]

Forgive me as I am a complete diy novice. My central heating system only works if the immersion tank is also being heated. Have a boiler in the garage which fires when the immersion is heating. Thermostats all click when they should but no heat to the central heating. One thing I notice is that when the immersion heats up the pump next to it springs into life but does not when I just call for central heating. Any ideas ?

 

[gas4you]

CH zone valve head needs replacing or 3 port had if you have one.

 

[clarksonbc]

Thanks for that. Just checked in airing cupboard. I have a black device with numbers 1,2 and 3 on it (currently set to 3) and a blue headed device with a lever sticking out of it. The lever moves very freely. The blue headed device looks like it has 3 flows into it - I take it this is what you mean? Sorry for being thick but this is one area I have never ventured into!!!

 

[MANDATE]

The black device is the pump with 3 speeds which pumps water through the device with the lever, which is the valve. It has 1 flow in and 2 flows out. ie HW and CH. In many cases the actuator head can be removed off the valve spindle and replaced.

 

[bengasman]

did you check the timer?

 

[Agile]

Or the thermostat?

 

[clarksonbc]

Checked timer and thermo - all seem OK.

With regards to the actuator head. If this can be replaced does it usually invove draing the system or can it be done without? The house is only 5 years old so would you expect it to have gone after that time ? NHBC guarantee for that just ran out typically!!