HRM Wallstar Oil Boiler - Advice please

[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.

 

[SJB060685]

If you have a weak spark then increasing the gap is likely to give problems, also a way of testing to see if the spark is weak. As always adjust to mi's

 

[Simonvr46]

Left heating engineer a voicemail. Burner wouldn’t start this morning took numerous attempts just kept going lockout. Gave up trying, left it for 10mins pressed reset and it started 🤬🤬🤬🤬 I just don’t get what’s causing it. It can be switched on for 6 hrs and it’ll run perfectly, it’ll stop when it gets to temp etc then restart every time. It’s just seems to be on the initial start up.

 

[SJB060685]

Hopefully the engineer will get back to you and you can mention everything we went through last night.

 

[Simonvr46]

Hopefully the engineer will get back to you and you can mention everything we went through last night.

Hope so.....
Spoke to HRM this morning, they said it could be electrode or could be to do with the air in the oil line and advised against fitting tiger loop. The way he was explaining the lockout that I’m having doesn’t appear to follow a normal pattern that you would expect for either air or electrodes.

 

[SJB060685]

I'm under the understanding that a tigerloop would void the warranty from new but your boiler is past warranty anyway. A tigerloop not only lifts fuel, it pre heats it and removes any gas bubbles in fuel supply. Having said that the danfoss pumps are more than capable of drawing fuel up to about 2.5m, even modern Riello pumps can draw fuel a certain distance. The engineer needs to thoroughly check electrode position going by the book, spark quality and whether or not its intermittently sparking elsewhere ie around porcelain protectors or HT lead. If after a number of attempts he is happy all is well then I would move onto checking atomization of fuel at nozzle, this again needs to be done safely and properly.

 

[John.g]

I assume its going through a normal pre-purge and 5 sec ignition before lockout, most burners do a 12 sec pre-purge followed by the oil solenoid energising and the ignitor/electrodes firing for another 5 secs, if no flame established after this 5 secs, 17 in all, then lockout.?
To completely rule out oil pressure problem on start up could you fit a oil pressure gauge and monitor this after failure, you can then concentrate on something else. Also after the 12 sec pre-purge you will hear a distinct "click", I don't know if this is the noise of the solenoid opening or the sound of the electrodes sparking but SJB will know this.

 

[SJB060685]

You are correct to a degree John. This is a Satronic control box so the timing sequence for ignition function and everything else is slightly different. The ignition is on from the start of pre purge and stays on till about 15 seconds after ignition. Putting a gauge on pump will tell you if you have pressure from the start. These Danfoss pumps have operating pressure from the word go, unlike Riello and some Suntecs which have a wash pressure. However the pump has been replaced so I shouldn't be the problem. If it was air in the fuel line I'd be expecting the pressure to be fluctuating up and down and not a solid 8 bar for example. Obviously if the inlet port to HP line was completely air locked then you'd have no fuel at nozzle, one of the reasons I said what I did above.
Yes solenoid have the very distinctive click when opening and closing

 

[Simonvr46]

I'm under the understanding that a tigerloop would void the warranty from new but your boiler is past warranty anyway. A tigerloop not only lifts fuel, it pre heats it and removes any gas bubbles in fuel supply. Having said that the danfoss pumps are more than capable of drawing fuel up to about 2.5m, even modern Riello pumps can draw fuel a certain distance. The engineer needs to thoroughly check electrode position going by the book, spark quality and whether or not its intermittently sparking elsewhere ie around porcelain protectors or HT lead. If after a number of attempts he is happy all is well then I would move onto checking atomization of fuel at nozzle, this again needs to be done safely and properly.

That’s basically what the guy at HRM was saying with regards to the electrode. He said to make sure that the diffuser plates in the blast tube are correct distance away from nozzle/electrodes as that can affect the nozzle pattern.
If the HT leads and electrodes are replaced then that’s everything apart from motor and blast tube.

 

[SJB060685]

That’s basically what the guy at HRM was saying with regards to the electrode. He said to make sure that the diffuser plates in the blast tube are correct distance away from nozzle/electrodes as that can affect the nozzle pattern.
If the HT leads and electrodes are replaced then that’s everything apart from motor and blast tube.

Yes the brake plate needs to be at correct position as well as like you say this will affect spray pattern, too close to nozzle outlet and it will affect its ability to ignite, or delayed ignition. MI's says 3-5mm but I'm sure I've mentioned this before?

 

[Simonvr46]

Hi john,
If you go back through these posts on here you will see a video of our burner going into lockout.
It’s just bizarre that it isn’t every time.
If it continually went to lock out and wouldn’t start i would be happier. I’d be even happier though if it started every time lol.
[automerge]1582546117[/automerge]

Yes the brake plate needs to be at correct position as well as like you say this will affect spray pattern, too close to nozzle outlet and it will affect its ability to ignite, or delayed ignition. MI's says 3-5mm but I'm sure I've mentioned this before?

Yeah I did check these when it was mentioned before and they all seemed ok to within the tolerances specified in handbook.

 

[SJB060685]

With all the parts you've had engineers randomly change you could of bought a new burner. That's another option, many decent engineers have spare burners for problem child situations like this. Maybe if they have a sound Sterling that could be fitted for a week, at least then you'll know if it's a fuel or burner problem. If that's not an option then they need to go through what I've said to rule out possibilities. If I attended and couldn't find the fault first time, after replacing the pump as you said was then I shouldn't be charging you for return visits

 

[John.g]

Any remotely operated fire valve in the oil supply that maybe throttling it?.

Oh yes, I see you had it replaced.

 

[Simonvr46]

left heating engineer a voicemail on Monday morning and tried ringing him during the week. Not heard anything. Haven’t paid anything yet so I know he’ll get back at some point.
Boiler still playing up.
Yesterday morning it wouldn’t start, tried several times ended up bleeding oil line and it started.
Yesterday afternoon wouldn’t start, again tried several times. Tried bleeding oil line again but still wouldn’t start even with 2 inch air bubble. Left it 10mins and it started.

 

[John.g]

Think you will have fit that oil pressure gauge and monitor after cut out.

 

[SJB060685]

The pump has recently been replaced and I'm assuming the coupling along with it and seeing as it's the same problem before and after I'd suspect neither are the issue. Obviously all air needs to be removed from the pump for reliable ignition, a gauge usually fluctuates with air in pump. The motor is running and assuming the coil is sound and clicks then atomization of fuel at nozzle needs to be checked along with spark. If the pump is producing operating pressure and coil opens but no fuel out of nozzle then it could be a dodgy nozzle, a blocked/partially blocked HP line or a dodgy NRV (although I'm not sure if the Sterling has one). If you have neat fuel out of nozzle next check is spark.

 

[Simonvr46]

Never did get to the bottom of this issue.

Decided rather than spend/waste money on trying to fix it.

We’ve gone down the route of having a new boiler, I purchased Worcester Greenstar heatslave II through staff discount scheme we have where I work and then paid an accredited Worcester installer to install and commission boiler.

It’s been installed 11 days and no problems at all. Starts every time and we now have constant hot water.

 

[SJB060685]

Thanks for updating us. Im sorry to hear you made that decision, although it does suggest the problem was never fuel related and was within the burner, unless the installer rectified a proper when installing.
Not a fan of combi boilers personally but if I remember correctly there's just the two of you and they are decent boilers.

Again thanks for updating us.

Many thanks, Simon

 

[Simonvr46]

Thanks for updating us. Im sorry to hear you made that decision, although it does suggest the problem was never fuel related and was within the burner, unless the installer rectified a proper when installing.
Not a fan of combi boilers personally but if I remember correctly there's just the two of you and they are decent boilers.

Again thanks for updating us.

Many thanks, Simon

Hiya, only things that have changed regarding the fueling are that the boiler is now sat on the floor rather than it being in the wall so that the pump doesn’t have to lift the oil up and the fire valve has been replaced with new one instead of the HRM version with non return valve. The installer let me take off all the parts that had been replaced, which I thought was decent of him as he could have kept them and used them.

I think we will use less oil especially during the summer as both of us are at work and we have boiler set to only come on in morning and evening to give us hot water When we need it, instead of it being on all the time and keeping the heatslave tank at constant temp.
Thanks for all your help.

 

[John.g]

Thanks for updating us. Im sorry to hear you made that decision, although it does suggest the problem was never fuel related and was within the burner, unless the installer rectified a proper when installing.
Not a fan of combi boilers personally but if I remember correctly there's just the two of you and they are decent boilers.

Again thanks for updating us.

Many thanks, Simon

SJB, you may have a few comments to make re Stored combi boilers output and flow rates, there are numerous queries on here re gas combi flow rates as well.

I am looking at a brochure for a Firebird C35 combi boiler and to quote "D.H.W. Guide Performance in litres/min (120 litre draw-off at 40C deltaT) 20". It has a primary store of 40 litres heated to 78C.
Do you know if this guide performance is typical for oil fired combis? and also how is this number of 120 litres arrived at?
My simple calc shows that if one assumes cold water at 10C, then with a deltaT of 40C the stored cylinder will give a volume of 40*(78-10)/(50-10), 68 litres at 50C (which should give 20 LPM but only for 68/20, 3.4 mins, the burner should kick in at 73C and then the 35kw boiler will give a continuous flowrate of (35*860)/(40*60), 12.54 LPM.
My main query is this 120 litre figure?, the flow rates are simple to understand IMO.

 

[SimonG]

120 litres to fill a bath. They want to give the idea that you can fill a bath before the store gives out. It doesn't last though.