worcester 28 he intermittent explosive ignition

[buckley plumb]

Hi got a worcester combi 28 he .its got the same heat cell as the new cdi . the boiler lights and runs ok .i can turn the boiler stat up and the boiler fires as normal turn stat down and then up again and lights normaly .turn the boiler off then on and boiler fires ok. but turn boiler stat down and then turn it up 5 mins later and explosive ignition. the gas valve is not passing done drop test and the boiler does 20 sec air fan air purge before lighting - to make sure i turned stat down and closed gas tap on boiler waited 5 min then turned stat up and gas tap on and still explosive ignition. the bearing plate is ok the igniter is ok and the heat cell is clear .the burner looks ok and has an even flame cover and glow.any ideas worcester say try burner and sparker and if that fails gas valve or possible pcb giving slow ignition.there is no way i can go and but these to try on the customers boiler .has anyone come accross this

thanks ant

 

[buckley plumb]

this is sorted now - called worcester in the end - they were 100% aure it would be the burner cracked common fault on these or the ignitor probe.the engineer come out and checked both then the gas valve for passing all ok . in the end it was the pcb giving a slight delayed spark.how can solo gas engineers compare with the manufacturers who carry all the parts on their van and can put parts on to try.bring back simple boilers.

ant

 

[Billy Bob Bob]

we cant but we live and learn