Riello Oil Burner not starting when hot

[daveclucas]

I've had an intermittent fault with my Riello oil burner. When it turns off it won't restart. The cutout light comes on. When I press the restart it runs through the normal restart cycle but fails to relight.
The pump pressure is 8 bar and I've checked flow by bleeding it so no problem there. The solenoid is working. I've replaced the nozzle, the opto sensor, the solenoid valve and the control box, cleaned the pump filter and the line filter. All to no avail.
After it has cooled down it restarts OK but won't do it automatically. I can't think of anything else to try or test.
Has anyone any ideas?

 

[Best]

Yes, I have a few ideas what could be wrong, but your description is a bit confusing.
You really should get an experienced oil engineer to check it out & set the burner with test equipment. What is the co2 for example? It will have already cost you a fortune replacing the wrong parts. We all do tasks beyond our knowledge, but there is a safety issue here & you need the boiler set to top efficiency.
You didn't state what the boiler does exactly when it attempts to start. If it all revs up (motor & fan turning) but doesn't fire, then it's the oil pump failing IMO from what you have said, but can also be electrodes not sparking. Solenoids can & do work & fail as they heat up but rare on Riellos. If the motor fails to turn, it is faulty, or bearings tight when warm, or capacitor faulty. Don't waste your money just guessing on other parts.
Welcome to the forum also!

 

[daveclucas]

The spark is strong, the motor is fine, the fan turns freely. The pump is fine. I stripped it down and made sure the filter was clean. I'm a hydraulic engineer and am very familiar with gear pumps. Like I said in my op the pressure is 8 bar and there are no air locks.
I've had a heating engineer out to it several times and he has already changed various bits with only temporary fixes.
The only conclusion I have come to is to empty the fuel line from the tank and blow it out with an airline and then flush it through but don't know what else to try if that doesn't work.

 

[SimonG]

.....and sometimes a new part out of the box can be dodgy.

Just wondering how you know what the pump pressure is if it doesnt run?

 

[Dotty]

What does your fga say?

I should find a competent OFTEC engineer if I were you. I know a smattering about hydraulics but I wouldn't deem myself competent.

That's why I leave hydraulic problems to those with the knowledge, experience and qualifications.

 

[SimonG]

Ah, hydraulics engineer, so you shouldnt be fiddling with stuff you are not competent with. Stick to what you know and find yourself a better engineer before you kill yourself or family.

 

[Bunker]

As above, we need the FGA results, the answer is probably there (or photo being obscured?)

 

[Best]

Check oil is flowing freely to the burner & oil hoses are not folded.
Other than above, then usually a burner not starting until it cools down is caused by a faulty solenoid or control box or a slipping or jamming oil pump (which I assumed you have already ruled out?)

 

[Ermintrude]

An fga a day keeps the paramedics away!

 

[Best]

An fga a day keeps the paramedics away!

lol! And it might keep the oil delivery lorry away longer!

 

[WHPES]

've replaced the nozzle, the opto sensor, the solenoid valve and the control box, cleaned the pump filter and the line filter. All to no avail.

Gotta make me laugh!

Tried replacing the flux capacitor yet?

 

[Ermintrude]

Flux capacitor is not standard part it's the fu fu valve.

 

[SimonG]

An fga a day keeps the paramedics away!

Thought it kept the coroner away