reasons for a sooty exhaust

Discussion in 'Plumbing and Central Heating' started by sootylenior, 2 Dec 2011.

  1. sootylenior

    Joined:
    2 Dec 2011
    Messages:
    3
    Thanks Received:
    0
    Location:
    Wiltshire
    Country:
    United Kingdom
    Evening all, I'm new on here and a keen diy'er .I have a question about a grant oil fired condensing boiler fitted to a sealed system( i think that's the right term?) To start with the whole system (hw, ch ,boiler ,oil tank the lot) is one year old and was brand new at that point. It is still under warranty. It is a grant boiler and i think i saw the brand riello on the actual burner part of it?.It is one of their models which fits outside of the house in its own insulated housing. It has had one problem in that it failed to get the pipes hot once recently and this turned out to be a sheared drive shaft in the circulation pump itself. The engineer said that he had in his twenty odd years never seen a shaft snap like it before and that he suspected debris in the system? Anyway the pump was replaced and its been working fine.
    I noticed today that the radiators were cold and went outside to inspect the boiler and use the test switch to see what was occurring. The reset button on the burner itself had tripped and i reset it and pushed the test switch. the burner attempted to fire and a brief ignition and combustion take place(.5-1 second) then it tries to ignite again every 5-8 seconds or so until presumably the trip would pop again, I turned it off at this point as it was clear something was not right. I checked the oil level in the tank and its well above the level of the burner (gravity feed ) ,I haven't yet had a chance to check the filters out (it was dark) but i did notice that the wire mesh surrounding the boiler exhaust was very sooty and also the inside surface of the stainless exhaust outlet.I am sure that this is not right and i don't remember it looking like that for the best part of the whole year to date. What are the causes of a sooty exhaust and is it something that i can fix, like cleaning the combustion chamber and components/ blocked air intake or is their another likely reason? It is not quite a calender year yet so the boiler hasn't been serviced? is this a factor?
    I am a car mechanic, so am used to taking things apart. I do have the operating instructions for the boiler, but i thought i would ask the experts first.
    Thanks all for your expertise Cj
     
  2. Agile

    Joined:
    26 Jun 2004
    Messages:
    55,788
    Thanks Received:
    3,676
    Location:
    London
    Country:
    United Kingdom
    Wrong time of year but are you near fields where plant bits fly around in the air at harvest time?

    Or anyhthing else to block the air intake?

    All this soot may have covered the photocell window?

    It definately needs a service/repair to set it up correctly and much of the soot may need cleaning out. That can be a dirty job.

    Tony
     
    • Thanks Thanks x 1
  3. numpty1

    Joined:
    30 Nov 2007
    Messages:
    2,151
    Thanks Received:
    392
    Country:
    United Kingdom
    pe cell is dirty hence on/off operation,get it looked at by a competent person,the boiler may need attention as well[cleaning out]the burner may require setting up correctly.
     
    • Thanks Thanks x 1
  4. cozzmic

    Joined:
    20 Jan 2005
    Messages:
    791
    Thanks Received:
    63
    Location:
    Nairnshire
    Country:
    United Kingdom
    Year old? it needs a service and set up with pressure gauge and flue gas analyser plus a nozzle. Could be a fault on the boiler electrics as there was a fault with these a while back where the fan would run slow so would soot up caused by faulty PCB.
     
    • Thanks Thanks x 1
  5. simond

    Joined:
    26 Oct 2004
    Messages:
    4,311
    Thanks Received:
    320
    Location:
    Surrey
    Country:
    United Kingdom
    Thats interesting.

    Do you refer to the Grant PCB or the Riello burner controls?
     
  6. cozzmic

    Joined:
    20 Jan 2005
    Messages:
    791
    Thanks Received:
    63
    Location:
    Nairnshire
    Country:
    United Kingdom
    Grant pcb causes motor to run slower than normal therefore not enough air so it soots up. But that would be the last thing to look at, get a service done and that should sort it.
     
  7. sootylenior

    Joined:
    2 Dec 2011
    Messages:
    3
    Thanks Received:
    0
    Location:
    Wiltshire
    Country:
    United Kingdom
    Well after work today, i thought i would attack the problem in the daylight!
    Armed with the grant boiler book, it describes with illustrations how to clean the combustion chamber out. First i removed the top and side cover, then i removed the complete (short )flue pipework, i noticed that the entire vicinity of the exhaust was covered in soot ,that was the ground, the cover of the boiler, the side of the house.I wasn't prepared for the amount of soot in the pipe. Anyway i cleaned it out in hot soapy water. Next i removed the riello burner assembly and looked at the end of it ,sooty but not excessively so. so i brushed and wiped it off and looking down to the photo electric cell i could not see the end of it for soot. So i removed it from the burner and cleaned the end of it so that the cell was visible. then i remove the burner cowl (not sure what the technical term is) and cleaned the back of it and wiped over the ignitor contacts and jet assy.
    Next i removed the side plate from the boiler housing. Holy cow !!!!!!!!!!, Is that a normal level of soot for all those chambers and those turbulators after a year , literally clogged full of soot. I am not used to seeing that level of substrate after a combustion process .I work on car engines and have never seen an exhaust like that!
    I got a bin bag and attached it to the two upper cover studs and then began to remove the turbulators and tap them clean followed by a clean in the bucket of water,making sure to refit them with the edge vertical at the end,then i removed all sections inside that can be removed and hoovered up everything i could get to. i also put the nozzle through the burner hole to remove all that i could from their.Is .25-.5 of an inch over the entire surface of the inside of it a normal amount? plus extra on the bottom of the combustion area. It would seem that this model will not make a year between services unless you can suggest what makes it produce an abnormal amount of soot. Or is it the case that the soot only comes out of the flue when it's saturated inside the chamber? I have the oftec commissioning certificate dated 9/12/2010
    Model in question is grant vortex pro 15/26 .
    figures at install were pump pressure 8.5...............co2 .11.2 flue gas temp 54.1 i think ,writing a bit scruffy!
    I know they don't prove anything 12 months down the line, but do these things wear jets out like a 100,00 mile carburetor. otherwise why the change?
    Awaiting informed opinions.
    I now have a working boiler with no apparent exhaust soot at the moment (but it was dark by the time i fired it up!)
    I plan to have it serviced professionally anyway ,What does that typically cost?
    Thanks all Cj
     
  8. Boilerman2

    Joined:
    10 Jun 2009
    Messages:
    5,207
    Thanks Received:
    1,005
    Location:
    Suffolk
    Country:
    United Kingdom
    The original commissioning figures look GOOD however something has gone very wrong which is beyond DIY repair the boiler should have been registered with Garnt UK warranty for 2 years, however the Service is due you must get the boiler Serviced by an OFTEC registered engineer to enjoy the 2nd year of warranty.
    It is moste likely that the soot issue is due to adjustment of a disposible part (nozzle or filter etc) however if the fault is due to component failure, the engineer can inform Grant who will arrange for a Service Agent to repair - HOWEVER get the Service done first and keep the invoice as proof of service.

    P.S. The Grant range of boilers is aone of the cleanest burning appliances made it is NOT NORMAL for them to soot up!! ;)
     
    • Thanks Thanks x 1
  9. sootylenior

    Joined:
    2 Dec 2011
    Messages:
    3
    Thanks Received:
    0
    Location:
    Wiltshire
    Country:
    United Kingdom
    Well All, I took on board all of your advice,and booked a service with my local oftec registered company. I explained what had happened over the last few days or so and they suggested a service and a return visit in a few weeks after the smoke has cleared to test the flue gas emissions. But strongly advised me to call grant and log the fault as clearly something is amiss and see if they want to come and look at it themselves, Fat chance! They were not really interested. It's been suggested by a few pros that the nozzle/jet has become clogged/blocked and that the fine spray is more like a jet and this is not being atomized correctly and burnt efficiently? But from the level of soot in my boiler this has been occurring for some time and comfortably under a year, so it seems odd to a layman like me that such a thing could happen, after all these years of development and refinement of the oil fired system, do the fuel filters work ,or was the grit floating about from installation? As i said before the entire system is one year old? I must say a quick call to grant to log the fault and also suggesting that it's been going on for a while failed to raise any concerns from them except comments like "it needs a good service" I thought ," are you taking the p?)& ? That level of soot doesn't occur in a weeks operation!
    Anyway they suggested that i leave the appointment with the independent company and let them call grant if they find anything wrong.
    I certainly trust them more to tell me the truth rather than blame it on something that is outside of the warranty scope. I will let you all know the outcome.
    Thanks for all your advice Cj
    P.s i wonder how much fuel i have wasted and what the cost has been.
     
  10. leakydave

    Joined:
    2 Nov 2005
    Messages:
    788
    Thanks Received:
    72
    Location:
    Gloucestershire
    Country:
    United Kingdom
    At Commission stage, I thought the CO2 level should be 12.0%.
     
  11. Boilerman2

    Joined:
    10 Jun 2009
    Messages:
    5,207
    Thanks Received:
    1,005
    Location:
    Suffolk
    Country:
    United Kingdom
    Hi LeakyD Grant ask for 11-12% I NEVER set an outdoor module above 11.5% CO2 due to the design of the flue (it's not a Balanced Flue - it's a Low level Discharge type) the air inlet and flue outlet are on opposite ends of the boiler so it cannot be described as Balanced!

    To the OP - a boiler can go form spotless to completely choked with soot in less than 24 Hrs ! - seen it many times - if the problem had been building up for a long period - you should have noticed sooty smuts and smoke from the flue and responded by getting it sorted long before it got so bad that the boiler failed!

    My guess is that the boiler simply needs a GOOD SERVICE and new nozzle - which should be replaced annualy anyway! ;)
     
  12. ferdinand2000

    Joined:
    1 Mar 2011
    Messages:
    60
    Thanks Received:
    2
    Country:
    United Kingdom
    Sooty exhaust?

    Get someone to Sweep the flue.

    I'll get my coat...

    Ferdinand
     

Share This Page