WB 28si boiler fault

[richardd]

I was at a customer house tonite . The above boiler was givng a slow single light fault code on ch.
When I reset it and turn on the heating or hot water the boiler tries to light and actaully does light for 4-5 seconds then goes thru the same procedure 4 times then goes back to lockout.
I went thru the fault finding in the manual and this indicates a gas valve fault.
The same scenario as above happens with the combustion chamber off.
I am going to change he gas valve tomorrow. Any other suggestions.
have checked electrode they are correct and the inlet pressure is 19 mb

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[Dannypipe]

Forget that. I am dum!

[Dannypipe]

You've checked the flame rectification?

You've checked the thermistors?

[dancinplumba]

this is open forum ????

[Dannypipe]

I don't know anymore. I'm just confused. Part of the gas section is open and part isn't (apparently).

I'm not sure if we're in the locked out part or not. It should all be blanket locked out to joe public. We had this a couple of days ago!

[Dannypipe]

No we have the Gas Safe forum and the Gas Safe Registered forum.

Latter one is for registered engineers only. Confusing.

[dancinplumba]

this part is open danny, its the gas safety registered plumbers section that isnt :-)

[Dannypipe]

Yeah, I've been told that before but thanks mate. I'm a bit slow off the mark tonight.

[dancinplumba]

soz danny :-)

[Dannypipe]

I'm just not going to answer gas questions until it's all registered people only as I'll keep doing this accidently.

[Dannypipe]

soz danny :-)

My bad mate, thanks for the heads up.

[arran197]

Check your gas valve resistance and if they're right (the one should be double the other, about 180/360 ohms IIRC) then give Worcester a call and get them to give you the factory setting adjust for the gas valve. Could be that on minimum fan speed there isn't enough gas passing through to keep alight. You'll obviously need your FGA and the correct CO2 figures as well.

You might also want to check the negative fan pressure to see if it needs servicing, then check the flame probe, which if the boiler is older may be the problem. You might need to get a new seal before doing this though.