Worcester 28i Junior gas valve problems

[Rckape]

I've replaced the old gas valve on the above for the new sit valve. The boiler was firing on on the old one but the FGA reading were way out.

I've followed all the instructions on setting the high and low for the size of boiler.

It's now not firing. On call for heat I get 35v at the molex connectors for around 2-3 seconds. For the same period of time I get a pressure drop on the gas inlet test point.

I get a spark on the igniter at the pcb and at the end of the leads and still no ignition.

The only thing I can think is that I've been setting the min/max incorrectly. The solenoid only opening for a 2-3 seconds is bugging me, I don't know how long they open when all is well.

I even refitted the old gas valve to check and it did exactly the same.

Am I missing something basic?

 

[Pelsey]

Try turning the max screw anti clockwise a 1/4 of a turn until it fires, then go from there

 

[AMGasServices]

Or give worcester a call they'll tell you how to reset the gas valve.

 

[arran197]

Reset the gas valve and start again,the gas valve should come with the instructions on how to reset the settings. Check the inlet pressure is ok. Ignition electrodes can snap and the flame sensing electrodes burn away, so have a look at those, just bare in mind the red seal will need replacing regardless if you take it out.

 

[thompsonbrown]

Check the flame sence electrode is correctly fitted.

 

[Rckape]

Thanks for the replies chaps. I went back Monday morning armed with a fresh set of electrodes.

I double checked everything, i knew it wasn't the rectification electrode as there was no flame through the mirror plate. I spoke to Worcester technical, who were as stumped as me - nice to know I didn't miss anything daft.

I took the electrodes out and they looked OK, but changed them anyway as there weren't a lot of options left. Put it all back together and fired first time. Winner!