Worcester 24i junior non condensing breakdown

[sammathias]

Called to a breakdown. Basically boiler locksout and flashes 4 times a second.
Fans working getting 240, pumps getting 240, working but not really strong.
Boiler lights and runs for a minute or so then I noticed the fan cuts out and burner flames come from under burner. Flues clear and cleaned fins on hex. Almost certain it's a PCB fault. Has anyone come across the flames coming from under burner and locking out?

 

[Aire]

Have you checked the gas valve setting?

 

[sammathias]

5mb but on low fire and before it gets a chance to ramp upto high flame fan cuts out and flames discharge from under burner into chamber. Looked into it abit more and it seems the PCB isn't letting the fan ramp upto high speed causing it to cut out. New PCB I've got to fit tomorrow. Hope it all goes well.

 

[Gas74]

Yeah will be Pcb but make sure it’s not stated melting the aps where the tubes attach due to flames licking up the side.

 

[sammathias]

Aps tubes are all sound. Will let you know how I get on with the new PCB tomorrow

 

[Gas74]

Remove the tubes at aps. Check holes not distorted on aps. This can be caused by the faulty Pcb.

 

[sammathias]

Changed PCB this morning and all working

 

[Harvest Fields]

Awesome news. Nice easy job for you then.