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Rayburn 480k MX - Boiler will not ignite

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Gone-on-John

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My Rayburn has been working well for ages and although old it is regularly serviced. Now it has decided not to fire up on the boiler side, cooker works fine. I have had my usual engineer look at it but he has not been able to find the problem and says it is beyond him. The thing that I think should narrow down the cause is that the lock out light on the control box does not come on when the boiler fails to ignite. We have changed the control box but this has made no difference. Any ideas?

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SimonG said:
Oh and i don't rate your usual engineer if something like this is 'beyond' him.
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Thanks for replying Simon, Yes, my engineer probably has not done enough courses on these models but at least he told me it was beyond him before he messed up too badly and still gave me a call out.
If you can see my response to SJB. the fan seems to kick in but I do not think the pump does.
 
If the fan is running the pump IS spinning but might not be providing pressure. This is basic fault finding to be honest. Pressure needs to be proved, as does solenoid and stem function, electrode sparking and nozzle atomisation. Fair enough your guy said it’s out of his depth but I would get another engineer in to find and rectify, a decent engineer will find and fix on first visit as they should have most parts as van stock. Replacing anything in the hope to fix is a sign of a bad engineer.
 
I don't know if its just me, but if the cooker is working fine then the burner is operational, IMO your fault is in the Rayburn not the burner, could be a faulty boiler thermostat, my own Rayburn (solid fuel) has a mechanical flap that operates between the boiler and cooking zones that cuts off the heat path, I assume yours may be electronically operated and may be faulty.
 
Hi Mike. My knowledge of the PJ burner is good but I’m not to familiar with these twin PJ cookers. Do these burners have a separate pump for each burner or a shared pump?
 
I’m looking at Rayburn 480k manuals online and I’m seeing what appears to be a single pump with one pressure setting feeding two supply pipes (cooker and boiler) although there are various burners used over the years. I’m just seeing if our collective minds can help the OP narrow down his search. Now if it’s a single pump and the cooker is working fine we can rule out a fuel flow problem, drive key, pump coupling or gear set worn. Now I would check voltage to solenoid and solenoid function at the 12-14 seconds mark (whichever the control box used time sequence is) . If ok I would consider a blocked nozzle or possibly pressure pipe to nozzle (although I’ve not seen the latter personally) . Some burners have a NRV before nozzle and I have known them to block (again unsure if there is one). If ok then it’s down to ignition or air. Could be a faulty ebi, dirty electrodes, broken down HT leads etc. What would help and I’m not sure if possible is for the OP to post a video so the trained eyes and ears can get a better understanding.

Edited: One thing I didn’t mention was the possibility of the cell detecting stray light during pre purge or faulty cell signaling the box of stray light, which would prevent burner from even trying to ignite.
 
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Yes 2 burners one pump, pump which has only recently been replaced as was noisey however suspect it was fan between that and motor which was making noise as greatly improved with spray of silicone lubricant. I have swapped the solenoids between sides and all seem to be working. Would the control box light not come on if it was something as simple as a blocked nozzle. I could swop those over to check if both burners take the same nozzles. I tried firing it up this morning as I recall there was a problem that both burners would not run at the same time, if you tried the second would cut out the first. Anyway when I tried the boiler this morning even the purge fan did not start up. Cooker is still working fine. It has almost become a mission for me now to solve this problem. Thank you all for your help.- John
 
This sounds like maybe a couple problems. From what I’ve studied online the nozzle outputs are different and should not be changed, just the pressure is the same. If the burner fails to ignite and photocell doesn’t sense light within safety time (usually 5seconds) then it will lock out. Looking at those photos I can see what look like 2 coils on each feed and 1 on return, I’m unfamiliar with these units but do know they have a soft start return (which is probably 5th coil) and I honestly don’t know what that purpose is. @Best can you shed some light?
 
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I’ve studied the wiring for your model and it’s probably more than you are capable of (forgive me if I’m wrong). You say boiler burner didn’t even attempt pre purge this morning, this tells me there is probably a fault with feed to burner, possible other faults after as well. I have attached a photo of wiring diagram. Relatively easy to follow but will require a multimeter and maybe a volt stick. If you know the timing of these Control boxes it should be easy to determine what feeds are where and at what times. Again @Best can you aid?
 
SJB060685 said:
View attachment 37035 I’ve studied the wiring for your model and it’s probably more than you are capable of (forgive me if I’m wrong). You say boiler burner didn’t even attempt pre purge this morning, this tells me there is probably a fault with feed to burner, possible other faults after as well. I have attached a photo of wiring diagram. Relatively easy to follow but will require a multimeter and maybe a volt stick. If you know the timing of these Control boxes it should be easy to determine what feeds are where and at what times. Again @Best can you aid?
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I avoid those Rayburns tbh. Awful design.
Seems strange control box no lockout.
 
My last post was not quite correct when I said that the purge fan had failed as well. when I tried it last night I did not have the boiler turned on at the thermostat control. It is in fact working. but no ignition. - John
 
I have asked on another forum with regards to this unit and had a couple of responses. Although the guy has explained to the best of his knowledge how the start sequence on these work and I understand what he said I could still do with a bit more further input (might not get it). I even contacted Rayburn technical to see if they could give me a detailed breakdown of the start sequence and despite my engineering background they wouldn’t release any detailed information. As with any pressure jet burner the principal is the same, just in this case more solenoids and a soft start function. Like I said before fan runs, ignition is on at same time, cell looks for strenuous light, if ok solenoids open and you should have ignition. Anything in this sequence could be the problem as could the boiler flue way as I’m told these can easily block on these units. I can’t really advise anymore because I’m not 100% sure at the moment on this model, all I will say is what Rayburn advised me was to contact them direct and get one of their registered technicians to rectify, obviously this will come at a cost though.
 
That would mean the cell works in the opposite way to a normal burner, as far as I know the cell looks for the flame after ignition and shuts the solenoid if the flame is not present, perhaps the multiple solenoid's work differently on these units? At a guess I would say the solenoid is not opening during the ignition sequence or the feed line is blocked to that side.
 
I have attached the start up sequence from the servicing manual if it helps. The main clue for me is that the lockout light does not come on. Which seems most odd. I do have a multimeter and an oil pressure gauge but unfortunately I have very poor eyesight and find it hard to see where to stick them. - John
 
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