Very strange symptom - firebird boiler Reillo burner just blowing

[Firebirdfan]

Can you remove the flexible hose from the air box, leave the door of the heatpac or the boiler house or whatever ajar and see if it runs OK for a few cycles, if a indoor boiler take more care.

It is a indoor boiler in a room directly below our bedroom so I am being extra cautious. This is the thread that I saw on another part of this forum that seems to make sense.
"The problem you have is that a seal has failed on the balanced flue, allowing products of combustion to get sucked back into the burner causing it to constantly re-cycle taking off the front cover is allowing fresh air in to dilute the POC's present in the case you should dismantle the flue and repair the seals on the inner flue joints."

As you can see from this diagram

the air inlet is not a flexible pipe but a rigid ss one. I have a 40mm solid stone wall so I am thinking that the only solution is to get to the back of the boiler, rake out the old silicone, clean scrupulously and re-silicon with high temp silicone then see if this partially or wholly cures my woes. What do you think? Regards Michael

 

[Johntheo5]

I don't really understand what the mean by the above but the air intake is very close to the flue gas outlet, this would seem to invite flue gas to be drawn into the air intake even if it is pushed right up against the cowl, can you post a photo of yours, the one shown is for a Olypic boiler.

Was your boiler cleaned out properly allowing free passage of the flue gases out of the boiler?

 

[Firebirdfan]

Hi John,
This is the diagram of my boiler, the photo was taken from the original Installation, Commissioning, servicing and User Instructions Manual which came with the boiler when I brought it from new some 20 plus years ago. I installed it myself and until this last month have had no real problems apart from replacing a control box some 3 years ago. I will take a few photos and send them on. Thanks so much for showing an interest as it really has me foxed. Michael

 

[Johntheo5]

You said in post #9, "but now it also shuts off the flame when I close the airtight cover to the motor!!", what does this imply?, does the combustion air feed this or is it to the fan?.

 

[Firebirdfan]

I don't really understand what the mean by the above but the air intake is very close to the flue gas outlet, this would seem to invite flue gas to be drawn into the air intake even if it is pushed right up against the cowl, can you post a photo of yours, the one shown is for a Olypic boiler.

Was your boiler cleaned out properly allowing free passage of the flue gases out of the boiler?

You are quite right that the position of the air intake is painfully close to the outlet but this is exactly as perscribed by Firebird according to the manual. Shown below.


I assume that the boiler was cleaned out by the qualified engineer when he serviced the boiler and I meticulously cleaned the baffles, firebox and everything I could get to each time I gave it my version of a service every year. I am not decrying the engineer but he admitted to being flummoxed by the problems and that he did not work on this type of boiler enough to be really confident that he knew the solution and left it there! As he was the last one to touch the boiler I think that he might have exacerbated a problem that was occurring before his visit but was not actually causing the boiler to stop. He adjusted the air and if that was supplying too much then it might have compensated for a dodgy leaking flue. Here are some photos of the boiler in all its glory. M

 

[Johntheo5]

That looks almost identical to my 20 year old 90S, jetted to give a output of 70k Btu/hr, ~ 20kw, except that mine isnt room sealed, it has a RIELLO G5X Burner and has never ever tripped on combustion failure.
Can you post the damper setting which you can see at the fan air intake, I will have a look at mine in a minute but I think its around 2.0, will post back shortly.

Damper setting is 2.05ish, (my boiler is actually 19 years old), its certainly not overly sensitive to the setting, I have had it at 1.8 to around 2.3 with no problems.

Have a look at your boiler rating, it may be stated 70/90, if it is jetted to 90 max, 26.37kw, then it will have a "0.85" nozzle and a damper setting of 2.2, that's assuming you are burning kerosene??.

 

[Firebirdfan]

I have now taken out and inspected the baffles, (spotless) and there is nothing in the firebox. I have inspected both air inlet and flue outlet connections behind the boiler as best I can and the red silicone on the join between the outlet flue and boiler mounting plate has gone powdery white in one place and sulphur yellow in another (again see photos). So it is probably leaking slightly there but this is inside the boiler room and the inlet is taking in air from the outside so, does it not require a leak in the inlet inside the room to allow for this contamination of gasses? The inlet seems to be simply pushed into the mounting plate but there is a drop of silicon in one area at the join so I might have siliconed it in place and this is just the excess or it could just be a push fit! It will be really difficult to strip out and clean both pipes but if this is the solution I will give it a go. What say you? M
Flue Outlet joint at boiler showing white powdered silicon and sulphur deposits

Flue outlet from above

Flue inlet sliding into boiler connector with dollop of silicon.

 

[Firebirdfan]

That looks almost identical to my 20 year old 90S, jetted to give a output of 70k Btu/hr, ~ 20kw, except that mine isnt room sealed, it has a RIELLO G5X Burner and has never ever tripped on combustion failure.
Can you post the damper setting which you can see at the fan air intake, I will have a look at mine in a minute but I think its around 2.0, will post back shortly.

Damper setting is 2.05ish, (my boiler is actually 19 years old), its certainly not overly sensitive to the setting, I have had it at 1.8 to around 2.3 with no problems.

Have a look at your boiler rating, it may be stated 70/90, if it is jetted to 90 max, 26.37kw, then it will have a "0.85" nozzle and a damper setting of 2.2, that's assuming you are burning kerosene??.

View attachment 339939

View attachment 339938

Mine is a 50/70 I think with a G5X burner and it was the lowest output they has at the time so I am assuming 50 BTU/Hr. It has a .55 -80 deg H nozzle. Your damper setting looks to be on 2.5 (half way between the 2 and the 3) but is there a needle or marker I should be looking at. If it is just the position of the sliding cover then my damper setting has been set by the engineer at 2.7 and this is way high as the manual suggests 1!? To be honest I don't really understand what the air damper does. Does it control the amount of air coming in from the outside flue or does it supplement this air with air from inside the room hence the opening in the side of the fan getting bigger as you adjust it? Either way 2.7 seems far too high .

 

[Firebirdfan]

Oh yes, I am using kerosene with additive.

 

[Johntheo5]

Mine is a 50/70 I think with a G5X burner and it was the lowest output they has at the time so I am assuming 50 BTU/Hr. It has a .55 -80 deg H nozzle. Your damper setting looks to be on 2.5 (half way between the 2 and the 3) but is there a needle or marker I should be looking at. If it is just the position of the sliding cover then my damper setting has been set by the engineer at 2.7 and this is way high as the manual suggests 1!? To be honest I don't really understand what the air damper does. Does it control the amount of air coming in from the outside flue or does it supplement this air with air from inside the room hence the opening in the side of the fan getting bigger as you adjust it? Either way 2.7 seems far too high .

Yes, there is a raised metal index bar and mine is certainly set to just over 2.0 so have another look at yours whic should have the same index bar and recheck the setting, if indeed 2.7, way too high, I would reduce it to say 1.6 to 1.8 and see how it goes.

IMO, if there is contamination then its either coming from the air inlet sucking in flue gases on the outside, unlikely though, since its ran perfectly well for years?, the most likely culprit is possibly the mounting flange gasket on the boiler front, as you probably know, there is no gasket between the burner and the mounting flange (at least none on mine anyway), you just remove the burner by opening one nut and withdrawing it, the gasket is between the mounting flange and the boiler, I've never removed mine, I just pull out the burner (every 3 years or so) and clean the cup full of mostly rust from the combustion chamber and I remove the front cover and clean the baffles, so maybe have a look at that gasket.
The damper setting simply adjusts the vol (mass) of air that is drawn into the fan,
the air required is either supplied like mine directly through vented slots in the (outside) Heatpac door or in you case via the outside air intake or, if you leave the panel off, exactly as mine.

If problems persist after above damper adjustment, I would strongly recommend just firing the boiler when hot (this is when the problem occurs?) with that front cover removed, just open a few windows and. stand at the boiler for a few cycles

 

[Firebirdfan]

Many thanks. I will do as you say. On closer inspection the flue is 2.2 so still too high. On removing the burner there is definite carbon on the bottom half of the mating collar suggesting it is not sealing perfectly but there does not seem to be a gasket nor any mention of one in the manual. I will try 1.6 and see what happens. Cheers Michael

 

[Johntheo5]

Gasket, item 9??.

 

[Firebirdfan]

Thanks for the diagram, that is the gasket for the circular flange that is bolted permanently to the fire box. I was wondering if the was a gasket where the burner meets up with the circular flange (HERE) as it is leaking slightly from the bottom.

 

[Johntheo5]

No, there is no gasket there, I think they all leak a little from the bottom due to one securing stud, photo of my gasket below, fairly crumbly after 19 years but not your problem I think.

 

[Firebirdfan]

Thanks again. I put it all back together and adjusted the air to 1.6 and it fired to temp then stopped as per the usual cycle and then re-started but failed to fire, just blew constantly but no flame out signal. I really don't think that contamination of the air intake would cause these symptoms so will change the solenoid before I take the rear balanced flue apart which will be a major task. Will keep you informed. If you have any other ideas do let me know. M