Boiler won't switch off when cylinder stat is satisfied

[jaw]

Hi

I visited a customer this morning. They have just bought the house and have noticed that the boiler will not switch off when the cylinder stat is satisfied. I have checked the operation and voltage outputs of the cylinder stat, 3 port valve and time clock and all are ok. What I have noticed in the wiring centre during testing is the following:

1. When power to the time switch is first put on the wire connected to the cylinder stat "call for heat" (not the orange to the 3 port valve) shows no voltage which is correct.
2. When in operation the "call for heat" side of the cylinder stat becomes live and the boiler fires.
3. When the cylinder stat is satisfied the boiler does not switch off and there is also live voltage from the wire connected to the "call for heat" wire (again, not the orange wire)
4. If you turn the power off to the timeswitch and back on again the wire connected to the "call for heat" side becomes none live again until the cylinder stat is used again.

I believe that the original wiring of the controls is wrong but before I call out an electrician I just wondered if anybody had come accross a similar problem. I can't get any other info from the customer as they have inherited the system. They were told by the old owner to use the immersion heater to warm up the water!!!! This need'nt be the case as the boiler will do both - to be honest I do smell a rat!

Your thoughts are most welcome

Thanks

 

[Roger Welton]

Any strange ones I just rewire myself it only takes half a hour or so and at least you know it is right from then on.

 

[zeebeedee]

Ill second that learned the hard way on that one

 

[mountainman]

I agree 🙂

 

[PlumbBobBob]

+1 from me