Potterton Promax Combi HE Plus, E133 Fault

[JJ The Plumber]

Assuming that the spark is ok and fan is running am I correct that the gas valve isn't letting through to the burner.
Checked the injector is clear and chamber to the burner.
I thought the fan pulled gas from the valve and into the chamber to mix and then to burner.
Fan seems to run well so thought gas valve.

 

[dancinplumba]

yes, put your mano on outlet test point if you get negative reading gas valve is opening

 

[arran197]

The fan opens the gas valve more as the fan speed increases, but you'll still notice a drop on the inlet pressure as it opens the solenoids. Make sure the tube connecting the gas valve breather is not split, twisted, kinked or not fitted.

 

[zeebeedee]

Unscrew the solenoids from the valve. When sparking occurs they should grip a metal screwdriver, do the negative pressure test on the burner pressure test point, if theses both check out you can rule out the valve

 

[JJ The Plumber]

Guys I went back to the job today as the gas valve had arrived.
Fitted it and away she went. When trying the old one I had a drop in pressure as if it was trying to let gas through but obviously not enough for ignition.
Once I'd set the boiler up with my analyser it worked a treat.
I know the common problem is usually ignition probes, condensate blocked etc. but just to let others know it can also be a gas valve.
Thanks for all of your input it's good to bounce a few ideas around.

Cheers
JJ

 

[CES]

Thanks for getting back to us with the solution. Its always handy to share experiences with problem boilers.

 

[arran197]

Did you try adjusting the old gas valve? If someone had been out before you and cranked the throttle down, or even up too much, that may have caused the problem.

 

[JJ The Plumber]

Did you try adjusting the old gas valve? If someone had been out before you and cranked the throttle down, or even up too much, that may have caused the problem.

Yes I tried it in various positions but it just wouldn't work.
When the new valve was fitted it fired instantly and then I just needed to set it up to the correct level.