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I have an old but good Trianco EuroStar 50-60 (S) oil fired boiler with a Riello RBL G5 BF burner which has been well maintained and regularly serviced by me. I am not a professional but have a reasonably good working knowledge of the boiler and acces to a Brigon test kit.

I am recently finding that when it's cold the burner is taking quite a long time to establish a flame. It will ignite for maybe 10 seconds, stop, re-ignite and so on for a period of several minutes and multiple re-ignitions before the flame is permanently established. It does not lock out. Once everything is warmed up it will establish a flame immediately.

I fitted a new Danfoss nozzle last July during the annual service. The oil pump is a little noisy but the pressure is running at the specified 70 psi. The two oil filters are clean. No water in oil tank (tested with water finding paste). I haven't used a combustion analyser or smoke pump for some time but the flame looks about right.

Before I take a closer look I will appreciate comments on possible causes of the problem. I'm considering the photoelectric cell, the oil pump solenoid coil or possibly the control box.

Any comments much appreciated. J.
 
It's none of the things you are looking at, what's the co2, co and excess air?
 
Thanks Simon. I'll check co2. Not sure what 'excess air' is? Start-up has been OK until a few weeks ago. There have been no adjustments to the air/fuel mixture. J.
 
Is the Brigon the wet kit? Not allowed to use that.

Also where did you get 70 psi from?
 
I have an old but good Trianco EuroStar 50-60 (S) oil fired boiler with a Riello RBL G5 BF burner which has been well maintained and regularly serviced by me. I am not a professional but have a reasonably good working knowledge of the boiler and acces to a Brigon test kit.

I am recently finding that when it's cold the burner is taking quite a long time to establish a flame. It will ignite for maybe 10 seconds, stop, re-ignite and so on for a period of several minutes and multiple re-ignitions before the flame is permanently established. It does not lock out. Once everything is warmed up it will establish a flame immediately.

I fitted a new Danfoss nozzle last July during the annual service. The oil pump is a little noisy but the pressure is running at the specified 70 psi. The two oil filters are clean. No water in oil tank (tested with water finding paste). I haven't used a combustion analyser or smoke pump for some time but the flame looks about right.

Before I take a closer look I will appreciate comments on possible causes of the problem. I'm considering the photoelectric cell, the oil pump solenoid coil or possibly the control box.

Any comments much appreciated. J.

I would suggest checking your manual re oil pressure, I would have thought that it should be in the region of 7.5 bar to 10 bar, 110 psi to 145 psi.
 
Thanks for your suggestions. Yes, the pump pressure should be 110psi. The 70psi I quoted was down to my faulty memory. It IS set at 110psi. The Brigon rest kit is old and wet. For both those reasons I won't use it to check co2. If necessary I shall have to get someone in to do that. I've just checked the photoelectric cell, the electrode settings, and fitted a new nozzle, just in case. To early to tell if there has been any improvement . J.
 
70psi is not enough to properly atomize the fuel for reliable ignition, mix that with the colder temperatures we've been seeing and thicker fuel as a result and that could be the cause.

Edit. Do you have a tigerloop by any chance?
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Thanks for your suggestions. Yes, the pump pressure should be 110psi. The 70psi I quoted was down to my faulty memory. It IS set at 110psi. The Brigon rest kit is old and wet. For both those reasons I won't use it to check co2. If necessary I shall have to get someone in to do that. I've just checked the photoelectric cell, the electrode settings, and fitted a new nozzle, just in case. To early to tell if there has been any improvement . J.

For some reason it doesn't update me on all notifications.
I must add everytime the oil pressure and/or air damper are adjusted then you need to do a smoke test and FGA reading, this is to set up correctly, efficiently and most importantly safely, if you don't have access to them then don't fiddle and get someone out who does and knows what they're doing please.
You say it ignites then shuts down, short cycling if you will but without going to lockout. This could of been fuel but I've seen your recent posts and all sounds ok, however what is oil pressure doing at point of loss of flame? You could have a dodgy drive key on pump or a slipping pump coupling.
The symptoms you suggest could also be caused by a weak secondary coil, weak holding voltage for said coil from control box, the control box again, too much or too little air or the balanced flue circulating flue gases. However if the flame stabilizes after some time you could potentially rule out some of them. The photocell could well be weak as well.
 
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Thanks again for all the helpful comments. Point taken about getting someone in to do a smoke test and FGA reading.

Yes, I do have a Tiger Loop. Regarding good suggestions about oil pressure at point of loss of flame (I will test this), dodgy drive key, slipping pump coupling, weak secondary coil, etc, wouldn't these things continue to cause a problem once the boiler has warmed up?

I don't think it's the balanced flue circulating the flue gases. The original flue started to cause this problem some years ago and I replaced it. As a test, removing the air intake hose to the burner does not improve the problem.

I am wondering if the prolonged wet weather could be behind the problem. The boiler is located in a garage with a single skin brick wall. It has a low-level rear discharge balanced flue with a total distance of only around 60 cm from the airbox to the outer end of the flue. Is it possible that driving rain has been entering the apertures into the incoming air part of the flue and lying in the flue, causing there to be heavily moisturised air going into the burner at the start of ignition after a period of non-operation. After repeated stop-starts things would dry out a bit and the boiler would run correctly. This is me going out on a limb a bit, but I do wonder. It's worth noting that there is a slight fall on the flue from the airbox to the outer end. J.
 
Like I said you could potentially rule out some I mentioned as like you say you'd expect it to be a constant fault.
Removing the hose for air intake is how you would check, I would also stick a FGA in.
The reason I ask about tigerloop was when I thought you said you were running at 70psi I was thinking the loop might be helping. The tigerloop or any deaerator not only lifts fuel and removes air it also helps warm the fuel through it circulating through pump and back by friction when at pump max capacity. If you were running on too low a pressure then this pre heating might result in what's happening.
Your theory about the flue is a sound one, however if you had saturated air then I would expect it to burn inappropriately, ie sooting etc. What are the flue gases like during the initial period?
I have known pump drive keys and couplings to cause this before they completely go altogether, I'm not saying this is the cause but checking pressure at point of flame failure will give you a good idea.
 
I have seen this problem on three Riello G5x burners, on one, replacing the nozzle cured it, on the other two, replacing the photocell cured it.
 
I can see JeremyB posted 29 minutes ago looking at the thread starter but no message appears here.

See this a lot, newbies posts need to be approved before they appear but the system still let's you know there's a response even though you can't see it until it's approved.
 
I may have identified the problem. During the very wet weather while the boiler was inoperative for a number of hours, rain would have been entering the air intake in the balanced flue. It seems possible that when the boiler fired up there was heavily moisturised air being drawn in and this caused the problem of establishing a flame.

I was able to do a test yesterday having been out for 7 hours with the boiler not operating. In the past it would have had a problem establishing a flame but everything was OK. I think this is because we've had 3 days without rain. Time will tell! J.
 
Fingers crossed, would be interesting if you could come back and let us know as I have never seen that before.
 
I may have identified the problem. During the very wet weather while the boiler was inoperative for a number of hours, rain would have been entering the air intake in the balanced flue. It seems possible that when the boiler fired up there was heavily moisturised air being drawn in and this caused the problem of establishing a flame.

I was able to do a test yesterday having been out for 7 hours with the boiler not operating. In the past it would have had a problem establishing a flame but everything was OK. I think this is because we've had 3 days without rain. Time will tell! J.

Yes please let us know as I've never seen it before either
 
I will report back in due course. If you experienced guys haven't met up with this one before it seems rather unlikely that the problem is what I have described. Prior to doing the test yesterday I had also cleaned the contacts between the photoelectric cell and the control box (I have no reason to believe that good contact was not being made), and I richened the oil/air mixture by quarter of a turn. I really don't think the mixture was the reason for the problem not re-occurring because I had tried adjusting the mixture previously and had reverted to my 'datum' setting. Obviously, as has been recommended here, I need to get someone in to do a FGA. J.
 
As with any fuel burning appliance you need fuel, heat and oxygen to work as you know. If for some reason you have something or things affecting any one of those then improper combustion or even no combustion will occur. To avoid problems you need to ensure:
. Adequate combustion air.
. Correctly pressurised oil.
. Clean and dry and dirt free fan blades.
. The oil cant be too cold.
. Sufficient pull on flue, correctly sized and insulated.
. Good working order nozzle.

Do you ever check fan intake and impeller when servicing for any dirt/defects?

I highly doubt the contact between cell leads and control box were bad, if they were I'd be expecting lockout. The cell wont send a signal back to control box detecting false light during pre purge, burner would ignite, again no signal telling control box flame is established and would lockout, it usually wouldn't cycle on and off if the cell was dirty, faulty, obstructed, dodgy cable or poor connection, that's how these work.
You say you've adjusted the fuel to air ratio slightly, this needs to be done in conjunction with a FGA, theres no way of saying what you've now adjusted the CO2, CO and excess air too, mix that with randomly adjusting oil pressures and your boiler is most likely burning incorrectly, inefficiently and perhaps at a dangerous CO level.
Just so you know when you adjust the air, there is science behind this, not just fiddle. In temperatures we're experiencing now you would set the burner up with slightly more air and a lower CO2, doing that means when temperatures rise and ambient air becomes less dense then there is still sufficient air for combustion and it maintains a happy medium and continues to burn correctly.

I'm happy to help you out and guide you but it is important for you to know your limits and when it's time to get an engineer out. This is a fuel burning appliance after all and get it wrong and lives are at stake.
 
Thank you again SJB060685.

I routinely check the fan intake and impeller during the annual service. I have never found anything other than minimal dirt on the fan blades. The oil pressure is 110 psi and always has been when checked in the past. Earlier in this thread I mistakenly said that it was 70 psi, but that was my memory at fault :)

I do appreciate your helpful comments and I freely acknowledge that I am an amateur at this. As the quote says - "I know enough to be dangerous" :) Having said that I installed the boiler in the first place and have managed to keep it serviced and running successfully for over 20 years. I completely agree with you that I need to know my limits and obviously now is the time to get an engineer out. From a safety point of view it is of course essential that the boiler is set up correctly, but it is worth noting that it is located in a garage and has a CO detector nearby. If it was located indoors I would definitely not be taking such a 'casual' attitude to setting up the burning correctly.

I'm still inclined to think that possibly the problem with establishing a flame is related to excessively wet conditions over the past several weeks as mentioned in my previous post, but only time will tell if that is right. Thanks again. J.
 
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The location of boiler is somewhat irrelevant to the CO, even when the boiler/burner is completely sound proof the products of combustion still exist through flue terminal and if the CO is high then this can affect anyone breathing it in, it only takes around 50/70ppm to be affected and in the region of around 150ppm can be fatal, this varies from individual as well, someone with underlying health conditions can be more susceptible than others. Also carbon monoxide testers need to be replaced from time to time.
Yes please keep us posted. If the problem is ongoing when the weather warms then we can take another look 🙂.
 

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