Boiler Not Firing for Heating - Works for Hot Water

[Yan Pugh-Jones]

Hi looking for advice in where to start with fixing our boiler.

The boiler doesn’t turn on when central heating only is on, but seems to work fine when hot water is on.

Three way valve seems to be fine, in that radiators warm up when hot water and central heating are on, and cool when only hot water is on, so I’m guessing it’s an electric issue with either the heating thermostat, or connection between the controller and boiler.

Any ideas? Thanks

 

[terryplumb]

The mid position valve is probably your issue. Testing the voltages present at the wiring centre would establish this.

 

[ianmcd]

some pics of what controls , boiler etc that you have would help, is this a new problem or has it always been like this ?