Boiler fires up when programmer is off

[Connor Williams]

Hello guys, I have an S Plan heating system with hot water cylinder and wall mounted boiler.
The boiler will fire up and run for a short period even when the programmer is on timer and no heat or hot water is being demanded by the programmer or stats.

I have done some electrical checks at the wiring centre and discover that both the hot water and heating zone valves were live on the 'Switched Live' (orange wire) even when the system was switched off.

Shouldn't it be the grey wire that is the permanent live and not the switched live going to the boiler?

If I was to switch the wires at the wiring centre would this cure the boiler firing on its own as surely the orange wire is connected to the permanent live terminal at the wiring centre?

Hope all that makes sense! Any advice would be greatly appreciated and don't worry I have done electrical work before and am well aware of all safety procedures.

Many thanks Connor

 

[billybob150811]

the greys are the perm lives you really need a picture or better still a drawing for someone to comfortably say start changing the wires

 

[lame plumber]

some boiler run the pump occassionally to stop it seizing?

 

[Bunker]

Sounds like one of the valves has a switch stuck open which will give you the symptoms you record. Drop out the oranges one at a time til the pump stops that will show you the wonky one. Boiler going on and off on on its control stat.