electro oil stirling 40 burner problem

24 Dec 2011
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United Kingdom
This burner is fitted to trianco eurostar wm 50 in the wall boiler

Serviced a month ago and keeps locking out at the control box, the boiler will run for a few days then lock out at any time in the day.It will restart after pressing the reset button. carried out another combustion test today c02 10.6% fgt171c ratio0.004 smoke zero and the pump pressure 110psi steady.
Replaced the control box,coil,photocell and another nozzle.

Upon inspection the blast tube had slight sooting and there was dark staining around the nozzle.

I am oftec registered and this is the first time in many years I cant nail this problem!

any help will be very welcome


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Slight sooting suggests constant re-ignition. As this is wall mounted, is there a possible problem with fuel supply?(height of tank) Are filters clean? Have you checked the air tube for contamination of combustion air with products of combustion?
Just realised, the WM50 in the wall does not have an air tube. Would still suspect fuel supply. Does it have a clear flexi oil tube? If so can you see bubbles in it?
Thanks for that.

You are correct re no air tube connected to burner and the tank is slightly higher than boiler.

Forgot to say when I changed the nozzle just a week ago the existing nozzle was only fitted two weeks prior to that and noticed the inbuilt filter was slightly discoloured!
I am suspecting contamination in the oil as the outlet valve on the tank is not shutting off so not able to clean that filter!

Could the problem be a faulty motor or capacitor as these are the only 2 parts I havnt replaced yet?

The tank is 3/4 full so not able to fit an inline filter until the level drops to maybe 1/4 full
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As the problem started following a service I would suggest you look carefully at the fibre rope seal around the clean-out door access
I have had this problem on this model boiler, which was due to recirculation of flue gasses into the air intake, once the rope seals were replaced the boiler ran perfectly ;)
Ok thanks again for your help will check that rope seal and see if that fixes the problem.
If your combustion readings are uniformly good, as you state, I'd check the resistance of the solenoid, if that is OK, i'd replace the motor capacitor. They are very good at providing nuisance lockouts, esp on a boiler built in a wall where heat builds up.

Are there any sticky deposits near the capacitor where the Dielectric has been leaking out?
Since he says the pump pressure is steady at 110 psi is the motor cap really likely to at fault?

To solidify heating oil to enable a filter to be changed or added just how cold does the pipeline need to be frozen?

Next is that possible with a gas cannister freezing kit?
Thanks once again to you guys I will replace the motor capacitor on Monday.
Btw I have already replaced the solenoid and also think I mentioned previously there were sticky deposits on the sides of the nozzle after just a week!

OK Boilerman 2 thats the next first thing I will do on monday.
will let you know.

you've answererd your own question with your comments about the filter on the nozzle. Have you taken the cover off the pump and cleaned that filter/
Havnt cleaned the oil pump filter yet but will do that tomorrow.
Thanks once again

The motor capacitor is used for starting, wouldn't normally affect the motor rpm once it is going.

Regarding the filters, normally this would give a fluctuating oil pressure once the burner had been on a few minutes?

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