volkera 28 cycling problem

mhat04 · 16 Apr 2005

I have a volkera linea 28 (5 years old).
Every so often (Friday night especially!!)
The boiler goes into a cycle where it ignites - lights - then switches off again over and over every 4 seconds approx.
Because of this the CH/HW never gets very hot.
I checked all the switches and sensors and they appear to be ok.
Has anybody had this problem before??

croydoncorgi · 16 Apr 2005

Sounds like the pump's stuck.

does the HW work OK?

mhat04 · 16 Apr 2005

Thanks for reply.
The same problem occurs for Hot water or heating the darn thing just goes on and off over and over again so the hot water is barely warm.

fitz1 · 16 Apr 2005

It could be prblem with flame rectification or gas valve

mhat04 · 16 Apr 2005

Cheers,
Flame detection might be a possibility.
I'll look into that
Can it just be a dirty or faulty electode ?

DP · 17 Apr 2005

Service as suggested by Vokera, should be carried out initially. Wonder if the boiler has been serviced since it was installed. If it was, what was the duration of the service. 15 minute look at the boiler is NOT a service

andy14b · 9 Jul 2005

Same thing is happening to me, in the mornings it works fine and later in the day it's a bit of a gamble, sometimes it works sometimes not. the flame lights for a few seconds and then it seems like there is a surge of gas that blows the flame out. It all started a few weeks ago after a neighbour had some plumbing for a new bathroom.

If you ever got this sorted please post how it was fixed.

Cheers

Andy

ChrisR · 10 Jul 2005

There's more than one thing which can cause this sort of problem. AS DP says, a good service would probably sort it out. Corgis only.

andy14b · 15 Jul 2005

BG fitter changed the ignition PCB which seems to have fixed the problem.

mhat04 · 2 Oct 2005

Sorry about not posting a reply earlier, but I sorted the problem.
Anyway for those who may have a similar problem..

The problem however was the ignition control board.

As an electronic engineer this was a baffling one to figure out because it did not make sense.

It is not just an ignition circuit but has an independant valve shut off relay which was kicking in closing the valve after a few seconds.
This relay circuit is probably a safety override which makes sure the gas is not on if the a flame is not detected, regardless of the main control.

Replace the unit with a new board, which is mounted on the Gas Valve.

The annoying thing is that the main PCB knows nothing about the fault so just keeps on wearing out the gas valve by opening it over and over again.

Guess the Gas valve is probably on its way out next having done thousands of operations needlessly.

DP · 2 Oct 2005

There is NO PROBABILITY in it.

The gas valve is opened by the sequence board to allow a small amount of gas to pass onto the burner and light the gas with a HV spark. The gas lights, circuit detects flame. Spark stops. Flame gets bigger.

Incidently, there are other components on the boiler that can give very similar symptoms.

As I said earlier, a service will not be out of order.

easyfozz · 8 Oct 2005

andy14b said:
BG fitter changed the ignition PCB which seems to have fix
ed the problem.

does this work

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volkera 28 cycling problem

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