HRM Wallstar Oil Boiler - Advice please

[Simonvr46]

When it doesn't start at all do you hear the solenoid click?

Yeah solenoid clicks and pump draws fuel, then few seconds later boiler goes lockout.

 

[SJB060685]

So when it doesn't start at all the motor runs, you hear solenoid click and see fuel flow but it doesn't ignite at all? If that's the case I'd suspect its ignition related. Electrode gap wrong, dirty electrodes, weak HT leads, weak spark from ebi transformer or arching elsewhere, porcelain electrode covers need to be checked. Control box possibility as well

 

[Simonvr46]

So when it doesn't start at all the motor runs, you hear solenoid click and see fuel flow but it doesn't ignite at all? If that's the case I'd suspect its ignition related. Electrode gap wrong, dirty electrodes, weak HT leads, weak spark from ebi transformer or arching elsewhere, porcelain electrode covers need to be checked. Control box possibility as well

Yeah motor runs.
Sometimes it runs perfectly other times it fails to ignite.
Electrode gap is ok, transformer replaced recently due to weak spark. Control box replaced 7 years ago.

 

[SJB060685]

It's one of those where theres only so much I can do through a phone for you. If I was the engineer attending and based on what you've said (assuming I haven't misread you) is I'd be looking at ignition first. I say that because motor is clearly running, you say you hear solenoid click and see good neat fuel flow, so saying that it's either an over aired problem (which by now we think not) blowing spark away from nozzle, a problem with the ignition, be it arching elsewhere etc, or a problem delivery the fuel. I've never experienced it but those that have taught me always consider a blocked HP line from pump to nozzle outlet as well.
I can tell you how to safely check spark function and quality but its probably best left to the engineer, I do not want to be responsible for something you got wrong.

 

[Simonvr46]

It's one of those where theres only so much I can do through a phone for you. If I was the engineer attending and based on what you've said (assuming I haven't misread you) is I'd be looking at ignition first. I say that because motor is clearly running, you say you hear solenoid click and see good neat fuel flow, so saying that it's either an over aired problem (which by now we think not) blowing spark away from nozzle, a problem with the ignition, be it arching elsewhere etc, or a problem delivery the fuel. I've never experienced it but those that have taught me always consider a blocked HP line from pump to nozzle outlet as well.
I can tell you how to safely check spark function and quality but its probably best left to the engineer, I do not want to be responsible for something you got wrong.

It’s very frustrating with it being intermittent. The other half is getting annoyed and stressed with it.
Yeah that would be great if you could tell me how to check spark function and quality.
I work in engineering so have a good practical skills background but know my limit and when to get In professionals.

 

[SJB060685]

Ok. First and foremost isolate electrics and fuel near the burner, remove the coil and to make sure theres no accident due to a faulty stem (I'm not saying there is) remove the flexi going into pump and let any fuel drip into a container (pump will need to be bled afterwards). Now remove the burner from centre long bolt to expose nozzle assembly and electrodes. Now when sure no fuel can be delivered bring the power to burner on and with burner pointing into combustion chamber you are looking for good quality spark between electrodes, if it looks weak or sparking elsewhere or no spark at all then we're in the right area, I would bring the boiler off and on again a dozen times checking the spark each time, if its intermittent then a dozen times should catch it (do not run the pump without oil for too long because you risk damaging it. The boiler then needs to be reassembled and bleed the pump. DO NOT adjust oil pressure or air intake as the burner will need to be set up again using smoke pump and FGA.
The DKO does things differently in lockout. When you interrupt the burner feed and reinstate it the motor runs for 2-3 seconds and then locks out, pressing reset button will then go through sequence to lockout on last fault.

 

[John.g]

Yeah not much left to replace, the coupling was replaced with new pump.
New engineer says that the excess air amount that’s registering on FGA is ok.
He looked at electrodes when he had burner apart and said they look ok, couldn’t see any sign of arcing other than where should be.

Your screen shot shows a electrode gap of 2.5/4.5mm, I would suggest ensuring this is nearer the higher end, say 4.0mm, also it shows the electrodes positioning as -3/-1mm back from the nozzle tip, I would suggest making this as near the nozzle tip as possible, say -1mm or even 0mm., my burner (a riello, has a 4mm gap with electrodes extending 2.5/4.5mm beyond the tip). Also ensure the nozzle fitted has the correct spray angle, mine is 80 deg.

 

[Simonvr46]

Your screen shot shows a electrode gap of 2.5/4.5mm, I would suggest ensuring this is nearer the higher end, say 4.0mm, also it shows the electrodes positioning as -3/-1mm back from the nozzle tip, I would suggest making this as near the nozzle tip as possible, say -1mm or even 0mm., my burner (a riello, has a 4mm gap with electrodes extending 2.5/4.5mm beyond the tip). Also ensure the nozzle fitted has the correct spray angle, mine is 80 deg.

My heating engineer was telling me the gap between electrodes should be about the thickness of £1 coin.

If I change electrode myself will it need to be set up with FGA again?

 

[SJB060685]

The gap between electrodes and overall position is dependent on each burner, you cant compare a Sterling to a Riello. Adjusting this will not affect the combustion process but will affect ignition or delayed ignition if wrong.

 

[John.g]

Different burners yes but the gap can still be 4/4.5mm rather than 2.8/3mm.