Classic Heating system not working properly

[debt1203]

Hello!
I hope someone can help me, I have a classic boiler and heating system which works like a dream when its on the timer which is twice a day.

But I press the manual button, mainly in the evening, on the main control nothing happens, the separate thermostat is set at the max, 30 degrees and when you move it I can feel it click but the heating still does not come on.

The strange thing is that when I have pressed the manual button and I run the hot tap for a while, the heating will then come on! its baffling me completely!

Please help!

 

[45yearsagasman]

A "classic boiler and heating system" doesn't tell us much.

 

[debt1203]

Sorry its a Ideal Class FF250 system.

 

[ianmcd]

sounds like you have an S plan system with two zone valves and the end switch on the CH one is faulty, when you run the HW the temp in the tank will drop and the HW valve will bring the boiler on