Rayburn 460K won't ignite

[Williams 16]

We have a Rayburn 460k Nuway burner which is now over 20 years old which has been regularly serviced and maintained by myself and has generally been reliable. However....last week it has stopped igniting on both boiler and cooker.

Removed the burner and found the blast tube had gone on the cooker side which I replaced but of course does not resolve the firing issue. However my priority focus has been to get the boiler sorted first to get some heat back in the house!

The motor that turns the pump is starting up fine, the coupling is fine and the air fan is also starting up. I have fitted new nozzles on both burners along with electrodes and cleaned the Photo electric cells. Although I have not fitted a gauge in the oil pump yet, the solenoids are activating in the usual sequence but it's not firing which results in the box tripping out after approx 5s. Same happens for cooker side. I have measured 240 V going into the igniter but don't seem to get spark coming out is my theory? But can't prove this....is there a way to test? What baffles me though is that boiler and cooker have independent igniters so the chances of both failing at the same time is low?

I do need to check the oil pressure but it is spraying out of the nozzle which makes me think its not fuel issue. The only other thing I guess is the air pressure switch which is common to both. Could this prevent firing?

What's your thoughts?

 

[SJB060685]

What model burner is it? Do you have air switches for each burner? Do you have soft start? If the air switch is faulty or not detecting pressure then the box isn't going to bring open the coils so I doubt it's that.
It's most likely fuel or ignition problem. You should check oil pressure and whether or not theres any water in system. If neat oil at nozzle/nozzles then I'd be suspicious of the ebi transformers, they are only rated for a maximum usage time, it is possible both have failed, although pretty unlucky

 

[SimonG]

Why haven't you put a gauge on the oil pumps?

 

[SJB060685]

Why haven't you put a gauge on the oil pumps?

One pump mate fed by one motor and most likely soft start and a separate motor for fans, with air switch to prove ok. Different models of burners for these though over the years

 

[Williams 16]

One pump mate fed by one motor and most likely soft start and a separate motor for fans, with air switch to prove ok. Different models of burners for these though over the years

It is a Nu-way 460CF. It has seperate fan motor for the boiler but the cooker fan is driven by the main pump motor with a fan at the end of a drive coupling. Good point regarding the air pressure sensor, it only has one which is sensing for the boiler side only. I'm going back to it this weekend so will order ignition unit for replacement after checking the pressure output of the pump is correct. It does also have soft start fitted and there is neat oil at the nozzle. I appreciate your replies.

 

[SJB060685]

It is a Nu-way 460CF. It has seperate fan motor for the boiler but the cooker fan is driven by the main pump motor with a fan at the end of a drive coupling. Good point regarding the air pressure sensor, it only has one which is sensing for the boiler side only. I'm going back to it this weekend so will order ignition unit for replacement after checking the pressure output of the pump is correct. It does also have soft start fitted and there is neat oil at the nozzle. I appreciate your replies.

Hi. Had a similar problem with this burner not long ago, that time it was the air switch not contacting, same burner, same motor for pump and fan and separate one for boiler. If the air switch on boiler burner was faulty the control box usually stays in pre purge and doesn't go to lockout.
How have you confirmed neat oil at nozzle? Without me explaining how to.
Check pump pressure and remember soft start is around 80-100 psi initially if I remember correctly to slowly bring chamber up to temperature and not cause damage to it and baffles, soft start solenoid de energises after a set period of working time and then you have full pressure to both cooker and boiler. I suspect though that ignition is the problem, although I'd want to be sure before buying replacements.

 

[Williams 16]

Yes, a few more checks to be done to verify the pump is working correctly. Regarding the neat oil check, the tank was checked for water with water detection paste on a stick and also the hose from the pump inlet was removed and a sample taken and tested FOC which was all good. All filters are also clean. Although I can't say for sure at the nozzle but supply side is good. I'm sure you have more experience to advice on a more specific test though.

 

[SJB060685]

It involves removing the ability to spark and cell and running through sequence testing a certain way, I'm reluctant to say to be honest, plus it's two burners, not just one.

 

[WHPES]

I have the same model Rayburn here in my house. If you need me to look at anything on it, please feel free to ask

 

[Williams 16]

Thanks to everyone for all your advice. Got the Rayburn up and running over the weekend. Tested the pump delivery pressure which was all good at 5bar initial period with soft start on Boiler side and 10bar for cooker (no soft start). Checked the resistance across both ignition units at the electrodes and found no resistance on the boiler side. Removed the HT leads and re-checked across the ignition unit pins and found the same result. Fitted a new ignition unit to the boiler side which resolved the issue for the boiler. On the cooker side I found an issue with the photocell which I replaced and all working good now.

 

[SJB060685]

So ebi transformer had failed for boiler as I suspected but the photocell was at fault for cooker? If the cell detects false light or is faulty then the control box wont open coils and it goes to lockout.
You seem to have a good understanding but I'm curious do you have a flue gas analyser to set up correctly?

 

[Williams 16]

Correct, I agree that the flue gas test needs checking and possibly adjusting which will be done by friend this week who has a calibrated meter as I don't own one yet.