Vokera Excell 80sp - Burner problem

[kenny560717]

Hi All,
I realise this has probably been covered before but all the posts I have read dont seem to be quite the same.
Problem - Vokera Excell 80sp
The burner wont come on.Although occasionally it will come on go to about 80deg then cut out.
Once I have tried and given up and the system is idle.(No demand from anywhere)The burner sparks to life.Burns for a few seconds then cuts out.

Other points
DHW and CH acting the same way.
The Flow Microswitch's are working
The fan is working when idle and then speeds up when there is demand.
The pressure differential switch seems to be working.Click when turned on.

Could it be Gas valve and if anybody has any other ideas can you please tell me prices i should expect to pay.javascript:emoticon('')
Laughing
Thanks Kenny
Hope somebody can help

I am new to this so please be kind
A little update - 240v is not present between terminal 11 and neutral on PCB - Pressure differential switch or pcb??? When it does come on it wont go of again!!

 

[Agile]

It sounds to me as if the DHW flow switch may be made when it should not be ?

Tony

 

[kier]

not bad boilers but need an expert to repair them.
contact vokera for a service agent locally to where you live,these boilers can last a long time but need a proper service [ie as per makers instructions]

 

[kenny560717]

I have disconnected the DHW microswitch completly yet it still fires up when it feels like it.
Another thing i have noticed is when you first switch the power on to the boiler the fan is on. It might just be slow speed not sure, But also there is a click from the solenoid. Should there be 240v at this or is it like you said.A switch has been made when it should not be.
The boiler is set at DHW only and as i said i had the switch completly disconnected from boiler and wires. Any other ideas?

 

[Agile]

I suspect you may have more then one fault.

Assuming its a permanent pilot model the the fan is designed to run continuously on slow speed ( slowed by the encased resistor on the RH side ).

The gas valve is powered via the relay on the little PCB. Just possibly thats faulty and making when its off!

I would recommend that you get an expert to look at it as it could be dangerous!

Its difficult in a low population area and the mileage involved means there are probably only 1-3 CORGI engineers within 25 miles and the chance of getting a competent one is perhaps quite small. The difficulty is because many CORGIs have little knowledge of the electronics involved in boilers even the relatively simple design of yours!

Tony Glazier

Stay south of Manchester!

 

[kenny560717]

Thanks for the response. I have had another look and it was the push rod for the boiler flow switch not returning to the correct position. Switch was constantly on.
With that fixed I can now concentrate on getting advice for the other problem.
Both hot water and CH cuts of when temperature reaches about 60deg. It doesn't seem to be regulating it. Any ideas?? I know how to use a multimeter!
I do want to get a corgi guy out but i would also like to have an understanding of what is going on. Plus i dont want to be hit with a big bill.
thanks again