Jaguar 28kw combi boiler

[RoyLeslie47]

Jaguar boiler again 28kw combi everything checks out but the fan and pressure switch have no voltage to them. There is no voltage from the pcb to the gas control module which feeds the fan ps. I can only assume that it is the pcb. Is there anything I am missing as I can not get a board sale and return if its not the problem. Would really appreciate your views,

Regards Roy L

 

[Agile]

I expect its just the o/h stat has tripped!

But that needs a competent CORGI as its inside the combustion chamber.

Tony

 

[ghplumb]

Fuses on the board OK

 

[RoyLeslie47]

This is wife replying under instruction from hubby. Hope you understand!
Fuses are ok.
Pump is running.
Book does not say that any stats are inside the chamber but are on the outside of the chamber on the pipework.
There is no electric supply from the PCB to the gas control module which I take is mains voltage??
Appreciate your replies.
Thanks
Roy

 

[Agile]

Book does not say that any stats are inside the chamber but are on the outside of the chamber on the pipework.

Thanks
Roy

Well I would describe the location of the o/h stat as inside the air sealed combustion chamber and thats a location where only a CORGI would be advised to access.

You can check to confirm that it has tripped from its connection onto the PCB.

Tony Glazier

 

[RoyLeslie47]

Tony,
Thanks for that, no the high limit is not tripped, as I see it the fan and pressure switch circuits are fed from the gas valve module on the side of the valve, there is no power going to that so no power to the fan or ps. The book says the o/h stat is mains voltage this must come from the right hand relay on the pcb which it does not, as that relay is not operating when power is applied to the boiler, i am certain it must be the board as without mains the start cycle cant begin.

Roy

 

[RoyLeslie47]

Agile, Gasgeezer, Tony
Now, my boiler really needs some educated ideas before I commit and go and get a pc board! I have tested everything that controls the boiler but I need to understand the power distribution as the book is pretty poor on voltages at the various locations, we will be experts if we sort this one, I will gladly rewrite the book explaining how to fault find as this is crap also!

RoyL47

 

[Agile]

Ignoring how you think the boiler works, have you done a simple continuity test on the wires from the o/h stat at the PCB ?

Tony

 

[RoyLeslie47]

Tony,

I have continuity on all the wiring in the boiler, the o/h circuit does not go to the pcb, it goes to the gas valve module (on the side of the gas valve), this is the unit that is fed from the pcb. There is no supply (mains I think) to the gas valve module which comes from the pcb, that is why I think it is still the 240v section on the pcb which is missing, what do you think? We could talk if you want. Its a good one this as the pcb's are quite reliable. Its annoying that the dealers will not supply the parts to determine the the fault and then charge a bit more for the privelage.

Roy.

 

[Agile]

Again have you checked the continuity of the o/h stat to wherever the connections go ???

I am sorry to labour this point but if you had my experience of these boilers you would understand why!

Tony

 

[RoyLeslie47]

Tony,

Yes checked the o/h circuit and it was ok, fitted a new board this afternoon and it burst in to life immediately, I thought I was right as the o/h circuit has to have a supply to it and that comes from the gas valve module which is fed from the main pc board, very efficient when it is going but a ridiculously over complicated control system.

Roy

 

[Agile]

Its a very simple control system as boilers go.

The reason I was so much wanting you to fully check the o/h stat is because I have seen about 10 with tripped o/h stats, three with sticking gas valves and one with a failed fan. So far NONE with a failed pCB !!!

Glad to hear its going now.

Tony