Vokera Flowmatic 20/80 problem

[abryan]

Hi Guys,

I have a somewhat long-in-the-tooth one of the above.

Had a problem with the fan DPS which I have replaced.
The problem was that switch was stuck saying that the fan was at high-speed. I noticed it because there wasn't the usual slight pause before the main burner lit.

The problem now is that the main burner will not light now. Pilot flame
is lit and stays lit with gas valve in the 'on' position.

I am pretty familiar with the workings of this boiler and have checked all the usual problems. Flow switch is working, DPS is working, etc..

Tried it in both DHW and CH mode but no joy.

The strange this is that I am getting 240v on the gas valve but the main burner does not light.

Anyone any ideas?

And does anyone know of a good Vokera guy in Norwich?

Thanks for any help you can give.

AB

 

[compheat]

If your getting 240v at the gas valve then its got to be the valve.
Honeywell grey push button V4600c. just remove the modureg from the old one and refit to the new. Carry out all safety checks regarding burner pressure, ans away you go.

The basic V4600c is about £70 but if you buy the Vokera valve its probarbly double the price.

 

[DP]

Look again OP. Is the fan running at low speed?

In my 18 years that I have been repairing Flowmatic boilers, only changed the APS once on this boiler.

 

[abryan]

Thanks for the replies guys. I should add the following:-

The fan changes to high speed when you either request DHW or CH.
It returns to low speed with no demand. As I said, the old DPS had stuck in 'high-speed' mode (i.e., 3 and 2 connected). The replacement works fine.

I have a complete spare boiler which I keep for parts, albeit one I got from a friend that was replacing it with a condensing one. It was working before.

My first reaction was that it must be the valve so I swapped out the complete valve and the problem is exactly the same! I guess it's possible that they are both faulty but rather unlikely...

Am somewhat stumped as to how to proceed. .

Am I right in thinking that if the pilot stays lit with the gas valve knob out it means that the thermocouple and the high limit thermostat must be OK? As far as I can see this is the only other thing that could stop the gas valve operating with 240v on the valve.

AB.