Rayburn 480K query

[SJB668566]

Hi guys. I’m wondering if some of you experienced oil men can take the time to answer my query. Before I dive into that I am familiar with PJ burners and understand them, their sequences, wiring etc etc but I have no experience with the twin PJ cookers.
My query is can someone please explain to me the start up sequence for a 480K. I know some twin burners have 3 solenoids and some have 5. What is the reason for say two solenoids on cooker feed, two on boiler and the fifth? Are some NO or are they all NC? Also what is the purpose of the soft start?
The reason I ask is I’m on another forum and a home owner has asked for advice as to why his boiler burner is failing to light. Now like I said I have no experience with these things, I’m certainly not going to attempt to advise on or even try to fix but it has got my inquisitive mind thinking and I’d really like to just get a better understanding of these units.
PS. I know many people loathe these particular cookers but I’m curious.
Many thanks.

 

[Burnerman]

Take cover......
I've had some experience with a 499K and it leaves its mark to this day......I can't recall too much about it thankfully but this one had two Nu Way burners, both fed by one Danfoss oil pump. It may give you some clues regarding the 480.
The soft start is to give the appliance some 'warm up time' so that the boiler internals are prevented from cracking. The oil pump provides pressure at around 100 psi, the unit lights (occasionally ) and runs for about a minute and then switches onto its running pressure of 140 psi or whatever its meant to be.
This is the purpose of all of those solenoids - they (I believe) allow oil to be fed back to the pump during the soft start.
The big issue with these archaic things is the flue ways - two just above the burner (boiler side). They are very prone to sooting despite the oil pressure and CO2 levels being correct and they are awful to shift. Carbon also deposits on the top of the internal oven where the gases head for the flue.....an angled scraping tool is necessary here to help cleaning.
Cleaning fully every 6 months is a must.
The 499 is so bad I rig up a test station on a bench with 240v and an oil supply. If the thing starts up (keeping the photocell dark until action) its easier to adjust the oil pressure this way - and to rule out flue issues with the appliance.
Hope this helps - at least until someone with a brain cell comes along!
John

 

[SJB668566]

Thanks Burnerman, much appreciated. Leaves a couple more questions though if you don’t mind. Is there two feeds to each burner then? A primary and a return for soft start? And return solenoid shuts after this 1 minute warm up period? Also how is this soft start pressure governed? The particular pump on this appliance is a BFP 20L3 with soft start return. As far as I know this pump only has one regulator and there for there must be another regulating spool between pump and burner to govern this start pressure?
Many thanks again

 

[Burnerman]

On the one I'm familiar with, there is only one feed to each burner, controlled by the solenoids.....during a soft start, one solenoid is open which returns some oil to the pump. When the soft start cycle is complete, this solenoid shuts and full pump pressure is fed to the nozzle. With a fuel pressure pump connected, you can see exactly when this happens.
I have no experience of solenoid failure, most faults being either a dirty photocell (which took out a control box on one occasion) and the aforementioned flue ways /baffles.
I'm afraid I have no data for these things, only my own deductions and investigations so I can't guarantee any accuracy either!
I believe there is a better Ecoflam conversion for these cookers but again, no experience. I am an engineer, just not a heating one.....
John

 

[SJB668566]

Ok thank you. If I’m ever to work on these things a course would benefit me.
Thanks again