Vokera 24 intermittent ignition

[Andy Doku]

I have a Vokera 24 Linea, hot water no issues, but intermittent CH.

If turning heating on, it will eventually fire up, (maybe after 1-2hrs), and will stay on with no issue until CH off for a period of time.

Then, when starting from cold, back to a 1 hr delay.

All the basics like pressure etc ok.

Had the diverter valve out and cleaned, no result.

When CH is switched on, I can hear the gas valve opening, but it never fires up.

Possible ignition PCB?

Also, maybe unrelated, getting intermittent and random CO error message, and boiler fires up of it's own accord into Combustion mode, even when set to HW only.

Have checked the combustion button which is not damaged nor pressed in. Has been reset but this issue still occurring.

Any help appreciated, thanks

 

[ianmcd]

has the display pcb been removed or replaced for any reason ?

 

[Andy Doku]

Re display pcb - Not as far as I know, no

 

[ianmcd]

have seen this once and it was the display pcb had been refitted wrongly, the selector knob can be fitted 180 degrees out, try wiggling the control knob the one that selects between ch off and HW and if when doing that you get CO on the display then if it is actually installed correctly then that is the culprit and you need a new display board

 

[Andy Doku]

Will do, thx Ian, appreciate it.

Any thoughts on the intermittent CH issues? Thanks

 

[ianmcd]

yes the display PCB if showing co is the culprit it is all the same problem, definately not the ign pcb as you suggest or you would have a 01 code on the display

 

[Andy Doku]

Ah, thanks Ian, appreciated, I will take a look.

 

[Andy Doku]

Replaced the display PCB today but no result sadly. Made sure the selector knobs were all fitted in correct orientation.

No repeat of CO mode yet so maybe was needing changed anyway.


I have however now been able to replicate the problem, (and temporary solution):

- Boiler starting from cold to CH ---> No CH
- Boiler starting from cold, run HW for (e.g.) 10 minutes *then* switch to CH ---> CH works
- Boiler cycles down and cools, following thermostat down signal, then tries to fire up again ---> No CH

This made me think of diverter valve again, but it's clean as a whistle, and no issues when deliberately activating CO mode, even from cold.


HW is fine, no issues at all.


It's not the thermostat as this was recently replaced, and I've replicated the problem as above, with the thermostat removed from circuit entirely.


Any thoughts on the above greatly appreciated.


Thanks,

Andy

 

[ianmcd]

it is definately not the diverter valve there is nothing there that asks the boiler to fire, stop pressing the CO function that is there for engineers only, sounds like the timer delay for central heating is coming in when not needed , this is a function of the main PCB to disable this add a jumper to JP9 and see if it stops your problem, you should also remove all external controls and put a link in to rule everything else out

 

[Andy Doku]

Great, thanks Ian, will do.