Need help for Vokera Excell 80SP

[JimmyMac78]

Hello guys,my oldish Excell 80sp suffered a main heat exchanger failure last week with water going through the main burner and over everything below.A new HE was duly fitted and the boiler worked a treat afterwards.However yesterday it went off with the pilot out and the pressure down.I thought OK it's just the water volume settling down after bleeding etc.I upped the pressure to within the normal range and relit the pilot but the main burner would not come on.It goes through the motions with all the familiar clicks as if it's going to light up but doesn't.
I've cleaned the venturi, replaced the air pressure switch,the high limit stat and even put a new PCB in as I thought the original might be water damaged from the HE leak all to no avail.
The pump runs, the fan runs at both speeds,the water pressure is holding up and the pilot lights. Where do I go from here?
Don't fancy too many nights without heating!
Thanks in advance for any ideas.

 

[nickso]

you have replaced a lot but what have you tested?

 

[JimmyMac78]

I've checked the voltages on the pump,the fan,the gas valve and the modulator.They all check out within the MI ranges.The old air pressure switch seemed to be Ok electrically but actually hit the microswitch fully when one pipe was off so I replaced it.

 

[BingoBongo]

ive seen water get into the gas valve.you may have also balls`d something when you have been working on it

technical term that

bg do a fixed price repair.and have 24 hour a day call out even on xmas

but told my mums neighbour who is on the service plan the cant come out for 3 days.

 

[nickso]

sounds like you have gone as far as you can. 240v to the gas valve but no ignition means either the gas valve or a gas issue.