HRM Wallstar Oil Boiler - Advice please

[Best]

That was July 2019 that it was serviced.
How is excess air reduced?

Adjusting the air is for your oil service person to do using an analyser.
I would say excess air is fine. The CO2 reading is good and reducing the air will begin to increase the CO2.
You tried putting your hand partly over air intake and it didn’t help, so leave air settings untouched.

 

[SJB060685]

This needs to be done in conjunction with a FGA (flue gas analyser) and I shouldn’t tell you because randomly adjusting can through all other readings out. Ideally you want maximum combustion and CO2 with no excess air, this however is not practical in the modern world and you will always have a lower CO2 and certain amount of excess air, this is down to the fact increasing CO2 also increases smoke and soot emissions. Again CO2 is set depending on ambient air temperature and density. If excess air was too high it can force heat up through the flue and reduce efficiency, it can also cool the combustion process and increase CO ppm as well as extinguish flame, the data sheet suggests your efficiency and CO are good, certainly for a non condensing boiler.

 

[Simonvr46]

This needs to be done in conjunction with a FGA (flue gas analyser) and I shouldn’t tell you because randomly adjusting can through all other readings out. Ideally you want maximum combustion and CO2 with no excess air, this however is not practical in the modern world and you will always have a lower CO2 and certain amount of excess air, this is down to the fact increasing CO2 also increases smoke and soot emissions. Again CO2 is set depending on ambient air temperature and density. If excess air was too high it can force heat up through the flue and reduce efficiency, it can also cool the combustion process and increase CO ppm as well as extinguish flame, the data sheet suggests your efficiency and CO are good, certainly for a non condensing boiler.

Thanks for that, I’ve no intention of adjusting settings I’ll leave that to experts with correct equipment.
2 Questions

1 - Would the excess air cause the burner to lockout?
2 - Could excess be caused if that gasket hasn’t been replaced?

 

[SJB060685]

Like I said I have known flames to extinguish due to faulty gaskets/seals, however I would expect it to happen constantly if these were a problem.
If there was a problem with gaskets/seals causing an excess of air but not enough to extinguish flame then I would expect to see other readings on my FGA out and the sheet you showed me looked like very good figures (providing they are similar now). I did say the excess air was a bit high yes but only a little to what one usually would see.

 

[Simonvr46]

Like I said I have known flames to extinguish due to faulty gaskets/seals, however I would expect it to happen constantly if these were a problem.
If there was a problem with gaskets/seals causing an excess of air but not enough to extinguish flame then I would expect to see other readings on my FGA out and the sheet you showed me looked like very good figures (providing they are similar now). I did say the excess air was a bit high yes but only a little to what one usually would see.

Figures have been very similar on last few service record sheets, although the 1 from 2016 doesn’t show excess air.
Think I’ll give the electrode gap a check sometime this week.

 

[SJB060685]

Above is a screen shot of what the electrode dimensions should be. Also note the burner head dimensions of 3-5mm. Like I said I haven’t touched a sterling burner in some time so would have to re familiarise myself. The Alan key you were turning under black cover might be the adjuster for nozzle assembly position, again I can’t remember off the top of my head so apologise if it’s not. Both are extremely important to ensure safe and non delayed ignition.
Check those out if you feel compelled but the rest leave to the engineer, I know you have a background in engineering and more importantly that you know your limits. The attending engineer should take the time to check everything.

 

[Simonvr46]

View attachment 42437

Above is a screen shot of what the electrode dimensions should be. Also note the burner head dimensions of 3-5mm. Like I said I haven’t touched a sterling burner in some time so would have to re familiarise myself. The Alan key you were turning under black cover might be the adjuster for nozzle assembly position, again I can’t remember off the top of my head so apologise if it’s not. Both are extremely important to ensure safe and non delayed ignition.
Check those out if you feel compelled but the rest leave to the engineer, I know you have a background in engineering and more importantly that you know your limits. The attending engineer should take the time to check everything.

Cheers mate, much appreciated with your help and guidance. Best hunt out my feelers to check gap. Must remember to disconnect boiler from power supply, don’t want boiler starting up while I’m checking electrodes lol.

 

[SJB060685]

Cheers mate, much appreciated with your help and guidance. Best hunt out my feelers to check gap. Must remember to disconnect boiler from power supply, don’t want boiler starting up while I’m checking electrodes lol.

Yes isolate power to system at switched fused spur and shut oil off, take solenoid off as well if really worried. Didn’t say this because it’s obvious lol.
Like I said whoever attends needs to check everything from start to finish, explain to the engineer that sometimes it starts and you lose flame during safety time then lock out and other times it won’t even start, tell them what parts have already been replaced randomly (which is not a sign of a good engineer) and hopefully they’ll get to the bottom of it. From the video I took pre purge, ignition, then loss of flame, cell senses that, I heard the solenoid close and then thermomechanical switch cause lockout. However that doesn’t explain why sometimes it won’t even start, so couple issues might be found.

 

[Simonvr46]

Yes isolate power to system at switched fused spur and shut oil off, take solenoid off as well if really worried. Didn’t say this because it’s obvious lol.
Like I said whoever attends needs to check everything from start to finish, explain to the engineer that sometimes it starts and you lose flame during safety time then lock out and other times it won’t even start, tell them what parts have already been replaced randomly (which is not a sign of a good engineer) and hopefully they’ll get to the bottom of it. From the video I took pre purge, ignition, then loss of flame, cell senses that, I heard the solenoid close and then thermomechanical switch cause lockout. However that doesn’t explain why sometimes it won’t even start, so couple issues might be found.

Who ever I get to come look at boiler I’ll be keeping closer eye on, I think after chatting to you guys on here with the advice you have all given me I think I have a decent understanding on how it all works and what to look for.
I’ll have look at electrodes 1st then get someone to look at it.

 

[Simonvr46]

Adjusting the air is for your oil service person to do using an analyser.
I would say excess air is fine. The CO2 reading is good and reducing the air will begin to increase the CO2.
You tried putting your hand partly over air intake and it didn’t help, so leave air settings untouched.

Hiya,
Ive no intention of adjusting any settings as although the burner is pain in backside sometimes, the majority of time it’s ok so I’d rather it be like that until it’s sorted out properly.
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View attachment 42437

Above is a screen shot of what the electrode dimensions should be. Also note the burner head dimensions of 3-5mm. Like I said I haven’t touched a sterling burner in some time so would have to re familiarise myself. The Alan key you were turning under black cover might be the adjuster for nozzle assembly position, again I can’t remember off the top of my head so apologise if it’s not. Both are extremely important to ensure safe and non delayed ignition.
Check those out if you feel compelled but the rest leave to the engineer, I know you have a background in engineering and more importantly that you know your limits. The attending engineer should take the time to check everything.

I had chance today when I got home from work to check electrodes. I unhooked burner unit like I had the other day and got my trusty set of feelers out. The electrodes appear to be within the specified tolerance of the the screenshot page.
I did take blast tube off and give the fins at the nozzle end a good clean, I’m assuming the fin that has corner bent over is for the photocell to detect flame? I made sure it was clean.
Also had quick look at the pump, took cover off and then undid the 3 Allen head screws, pump gears looked clean, couldn’t see anything obvious. Without fully stripping pump down and measuring components it’s hard to tell if parts are worn. Once bled air out of pump it started up 1st time.
I’ve been quoted about £125 + vat to have new pump fitted.

 

[SJB060685]

Yes there should be no obstruction so the cell can detect light, if there was the burner would ignite then go to lock out due to no flame sensing.
I mentioned the pump gear set, drive key and coupling but did not say have a look yourself lol. I know you have a back ground in engineering but I only ever opened up a pump if I had spare seals and pump at hand and after I was confident there was a problem with it. What was the drive key and pump coupling like? These pumps should all be put back together with a certain torque as we discussed above.

 

[Simonvr46]

Combustion is most likely then poor if flame isn’t partly being obscured from photocell view.
But can have one of many causes.
Nozzle could be faulty, or air setting wrong or burner drawing in flue gases, or oil pump pressure is set wrong, are some possibilities.

Current heating engineer has replaced nozzle at every service.

Pump pressure recored at the last service in 2019 was same as service in 2016 by different company and is correct to what the specification of burner

How would the burner draw in flue gases? Wouldn’t that be picked up on flue gas analysis?

If air setting was wrong wouldn’t that affect co and flue temp etc?
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Yes there should be no obstruction so the cell can detect light, if there was the burner would ignite then go to lock out due to no flame sensing.
I mentioned the pump gear set, drive key and coupling but did not say have a look yourself lol. I know you have a back ground in engineering but I only ever opened up a pump if I had spare seals and pump at hand and after I was confident there was a problem with it. What was the drive key and pump coupling like? These pumps should all be put back together with a certain torque as we discussed above.

From what I could see and feel, there was a bit of play in the gear wheel against the drive key but without knowing what is acceptable it’s hard to judge.

Had the seal on the external case needed replacing I have numerous o rings and could have temp fixed. The main body of pump is metal on metal so gave it a clean prior to reassembly.

I found data sheet for the Danfoss BFP11 pump and no torque settings shown on it, so a gentle nip or as we call it a British Standard Nip.

 

[SJB060685]

I cant remember the correct torque setting, I'm sure I saw it on a danfoss bfp pump YouTube video.
The drive key should be solid in its groove with no play, if there was it could cause your issue and eventually shear completely and you would have no pressure or ignition. A photo would of been nice but I'm not suggesting open up again. A dodgy pump coupling could also cause the same.

The burner could draw in flue gases if the flue seals had failed or burner flange gasket was faulty, or anywhere else that could allow products of combustion to escape inside the casing. You could detect these products with a FGA yes.

Just out of curiosity have you ever dipped the tank for traces of water with detection paste? I'm sure this isn't the problem due to what I've seen but thought I'd ask.

With regards to the quote for changing the pump I'm not so sure if that will help now based on what you've said today but without seeing the gear set, drive key or coupling I cant say for sure.

 

[Simonvr46]

I cant remember the correct torque setting, I'm sure I saw it on a danfoss bfp pump YouTube video.
The drive key should be solid in its groove with no play, if there was it could cause your issue and eventually shear completely and you would have no pressure or ignition. A photo would of been nice but I'm not suggesting open up again. A dodgy pump coupling could also cause the same.

The burner could draw in flue gases if the flue seals had failed or burner flange gasket was faulty, or anywhere else that could allow products of combustion to escape inside the casing. You could detect these products with a FGA yes.

Just out of curiosity have you ever dipped the tank for traces of water with detection paste? I'm sure this isn't the problem due to what I've seen but thought I'd ask.

With regards to the quote for changing the pump I'm not so sure if that will help now based on what you've said today but without seeing the gear set, drive key or coupling I cant say for sure.

I would have hoped current heating engineering would recognise fault if flue gases was being drawn back in.

I’ll have another look at the pump sometime this week and take photo. Im not sure if it was the shaft rotating of if it was the gear wheel on the drive key/ drive key in shaft.
I know when we had new oil tank in 2017 there was no mention of water in the oil when the existing oil was pumped out, also the pump showed no signs of water being sucked through.

 

[SJB060685]

If there was emulsified oil you would have seen a white gooey paste like substance. I was almost certain this wasnt the case but thought I'd ask.

 

[Simonvr46]

I cant remember the correct torque setting, I'm sure I saw it on a danfoss bfp pump YouTube video.
The drive key should be solid in its groove with no play, if there was it could cause your issue and eventually shear completely and you would have no pressure or ignition. A photo would of been nice but I'm not suggesting open up again. A dodgy pump coupling could also cause the same.

The burner could draw in flue gases if the flue seals had failed or burner flange gasket was faulty, or anywhere else that could allow products of combustion to escape inside the casing. You could detect these products with a FGA yes.

Just out of curiosity have you ever dipped the tank for traces of water with detection paste? I'm sure this isn't the problem due to what I've seen but thought I'd ask.

With regards to the quote for changing the pump I'm not so sure if that will help now based on what you've said today but without seeing the gear set, drive key or coupling I cant say for sure.

Your correct about the YouTube video, 5Nm for external Allen screws and 3Nm for the 3 internal screws.

 

[SJB060685]

Your correct about the YouTube video, 5Nm for external Allen screws and 3Nm for the 3 internal screws.

There you go, I knew I had seen it somewhere

 

[Simonvr46]

New heating engineer came and replaced the pump, after speaking to Danfoss they recommended fitting BFP21L3 instead of the BFP11L3, heating engineer set pump pressure at 120psi and used FGA to set burner up. All running spot on.
Next morning burner locked out.
Heating engineer been back and resealed all the joints in pipe work with oil seal.
Burner still locking out, but starting after reset.

This evening boiler won’t start.....

Could it be electrodes??

 

[SJB060685]

Remind me again what parts have been replaced?

 

[Simonvr46]

Remind me again what parts have been replaced?

Transformer, pump, capacitor, nrv/firevalve, photocell, solenoid and the control box (7years ago its now a dko).

 

[SJB060685]

Christ that's virtually everything. Yes if the electrode gap is wrong or dirty electrodes it could fail to ignite. If it was arching elsewhere other than at electrode ends then the photocell will usually detect false light and not even open the solenoid for ignition and go straight to lockout. Has this been checked? When the pump was replaced was the coupling checked and/or replaced? You could still be experiencing an excess of air at times if seals were perished as we've discussed before. I have a feeling you might have more than one issue still but of course I could be wrong.

 

[Simonvr46]

Christ that's virtually everything. Yes if the electrode gap is wrong or dirty electrodes it could fail to ignite. If it was arching elsewhere other than at electrode ends then the photocell will usually detect false light and not even open the solenoid for ignition and go straight to lockout. Has this been checked? When the pump was replaced was the coupling checked and/or replaced? You could still be experiencing an excess of air at times if seals were perished as we've discussed before. I have a feeling you might have more than one issue still but of course I could be wrong.

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.

 

[SJB060685]

Has he checked thoroughly though rather than just saying it looks ok? Someone I know had this recently where it was only intermittently arching elsewhere. You got fuel, you got new pump and coupling I know what I'd be looking at next.

 

[Simonvr46]

Im going to speak to him tomorrow, see what he suggests and I’ll enquire about the electrodes.

 

[SJB060685]

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

 

[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.