Rayburn 480KB MXE Cooker lockout problem

[IAC]

Good morning all, Its been a while since I posted but another B of a problem has reared its head. I'm now 4 weeks into problem solving a lock out issue on the cooker burner only. The boiler side works fine. I have currently replaced all the service parts twice!! once by switching with boiler side and then new item. Cooker fires up ok and will burn to whatever temp set on thermostat (I have even replaced O'heat stat and Thermostat, why I'm not sure probably desperation) when at temp if the selected temp is over halfway the next cycle will lock out every time until oven temp reduced to lower values then burner will light. First question: is the firing sequence air purge with oil pressure building followed by ignition spark then if pec detects light oil supply on? the reason I ask is that it would then be probable that ignition spark is not happening, or pec not detecting spark. Second question , Anyone got any ideas?

 

[Best]

Is it being serviced and tested using an analyser?

 

[IAC]

Thanks for quick reply. Yes, following problems balancing readings found split on air inlet hose. repaired and now OK. CO2 - 11.1, O2- 5.9, CO-42. that all happened after lockout problem started.

 

[IAC]

Made no progress checked everyhing (but I guess I must have missed something somewhere!!!) could find no faults anywhere replaced wiring, sensors, solenoids, controller, 3 times each. Cooker still locking out 0n start when cooker at over half heat. Must be a light problem to pec but !!!! no solution. Replaced complete twin burner yesterday all back to normal looking forward to very merry cooking Christmas.

 

[SJB060685]

I know this happened a while ago but the thread has popped up for some reason. To answer your question the ignition sequence is the same for all PJ but can vary in function. During heat demand you’ll initially have pre purge, during that 12-14 seconds (depending on control box) the cell will be looking for false light, if it detects false light or resistance values are wrong then control box will lock out after pre purge and won’t attempt to light (remember a cell needs high resistance or no resistance to ignite burner, a dodgy control box could also be at fault). If that’s all good then the control box will send voltage to and energise the coil (depending on make and design of pump the pressure will already be at working pressure, just recirculating through return loop. Riello’s do things slight differently as do some suntecs). After the pre purge time coil will energise and allow fuel to nozzle (again depending on control box ignition may have already been on since pre purge). That’s basically the principle and if everything is ok you should have fuel at nozzle and ignition.

 

[Tonymus]

I had a similar fault on a 499K Rayburn, that worked on the Boiler side, but not the Cooker Burner. It would not ignite

with the cover plate removed, I turner on the Cooker thermostat and peered into the tiny window into the combustion chamber. The oil supply was obviously getting to the igniter and there was a brief flash of flame.

I pulled out the Photocell head and the end was a bit Sooty. I gave the glass lens a clean up and tried again and the photocell could then see the flame and allow the start up procedure. A quick and simple fix. If that does not work, if you can see a short burst of flame, then the Photocell has probably had it !