Yellow flames from burner

Discussion in 'Plumbing and Central Heating' started by John Brown, 1 Dec 2016.

  1. John Brown

    John Brown

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    Looking for some advice please as im not a professional.

    Got an Ideal Mexico CF 100 boiler (approx 20y old) which has 2 burners side by side. It has not been regularly serviced but when i got a gas Safe engineer to service it last week, he said there was uneven burning and one of the burners had yellow flames while the other was solid blue. He took the burners apart and cleaned out the little holes on the surface of it, then he cleaned out the lint guaze that sits just underneath it and put it all back together. However the yellow flame still persists. Theres nothing really to see any different on the surface of the 2 burners. Is it due to the little holes being blocked or worjn down so they are too big/small.

    Unfortunately these burners are now obsolete and if i cant get it fixed, i will need a new boiler...

    Any thoughts? obviously i am not using it at all at present till i have a solution. Just wanted to understand a bit more behind the reason the flames are the way they are.

    Thank you in advance for your advice...
     
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  3. Agile

    Agile

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    These old boilers should be serviced every year to keep them safe.

    It is difficult to know exactly what the problem is.

    Or how keen he is to really repair it as probably sees a nice job replacing it at an elevated price.

    We cannot give technical advice here on gas matters.

    But all I can say is that I would expect to be able to cure it.

    After they have been disturbed the dust causes yellow flames for perhaps up to 30 minutes after it is put back together.

    All I can say is that I am so confident that I could cure it, that if you were local, I would come to you on a no fix/no fee basis!

    If you must replace it then at least get three quotes!

    Tony
     
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  4. John Brown

    John Brown

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    Thank you for your honest reply.
    So it it usually the dust that causes the yellow flames or blockages to the little holes in the burners?
    Could it be a sign of damage to the actual burners themselves such as early cracking or problems like that?
     
  5. Agile

    Agile

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    Usually just dirt/rusting.

    But I have NEVER ever needed to replace any of them.

    It is easy to trick people into thinking that the boiler has to be replaced.

    Particularly if you are panicking because it is cold and suddenly he becomes the only engineer who is able to replace it at this busy time!

    Tony
     
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  6. John Brown

    John Brown

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    This is good to know thank you!
    It did look very rusted when he took it out - is there a risk that long standing rusting will have corroded through the metal completely? He wondered if there may have been a crack under the rust is what he told me. How important is the lint guaze bit inside the burner?

    Thanks again
     
  7. Agile

    Agile

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    They never look very good but after my cleaning they work fine.

    Tony
     
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  8. Terrywookfit

    Terrywookfit

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    I usually give them a wash in hot soapy water followed by a rinse under the tap.
     
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  9. steve32

    steve32

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    Not everyone thinks like you how do arrive at that conclusion
     
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  11. Jackrae

    Jackrae

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    I would suggest you get a heating tech who knows how a naturally aspirated burner is meant to work, can read page 22 of the boiler manual and can think problems out.
     
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  12. mcmoby69

    mcmoby69

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    Yellow flames indicate incomplete combustion which results in carbon monoxide production because the air supply is not correct.

    You need to get it sorted.
     
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  13. MrTherm

    MrTherm

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    @ John Brown

    re:- "Just wanted to understand a bit more behind the reason the flames are the way they are"
    ........................
    The two burners are identical at manufacture but the R/H one has a pilot bracket fixed and is therefore more expensive. This style of burner were made by 'Aeromatic' and were used in many makes and sizes of boilers.

    Gas enters the burner via an injector at the throat and entrains air for combustion at the primary air port, the air/gas mixture is fed into a cone shaped flow diffuser built inside the burner which helps to give equal flame characteristics along the length of the burner head surface, a gauze mat lies just below the flame jet holes and prevents any lighting back of the gas as flames will not flash back when diffused through a gauze.

    I have seen cases where the inner burner diffuser cone is completely split and opened which is caused by the burner lighting back (burning inside the burner) most obviously caused by ineffective/defective/damaged gauze strip.

    While the original burners are obsolete i believe they are obtainable on an OEM remanufactured basis.

    A quick Google shows the price of £160 for the R/H one. Other parts are also available.

    These Mexico boliers should last a lifetime if cleaned, adjusted and maintained correctly.

    regards
     
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  14. ianmcd

    ianmcd

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  15. John Brown

    John Brown

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    After cleaning away some of the surface rust, he has shown me a small area on the top surface of the burner (where the small gas outlet holes are) that has corroded through and now there is a 7mm sized hole through the shell of the burner. Is this why there may be yellow flames? Does this mean the burner is not usable anymore? He thinks the heat exchanger above may have been leaking for some time onto that spot causing it to corrode through.
     
  16. MrTherm

    MrTherm

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    Yes, discard and renew the defective burner.

    Many of these older boilers caused water droplets dripping from a specific point of the heat exchanger on initial first cold start up caused by condense of the flame on the cold serface but disappears after warm up.

    A visual check when boiler off/cold would confirm if there is a definite leak.
     
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  17. John Brown

    John Brown

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    Thanks agian - how would I know if there was a definate leak when the boiler is off ( as it is off now)? Will it continue to drip down into the floor of the boiler constantly? If there is a leak, how can it be traced as theres rows of fins etc in the heat exchanger - does a leak mean that part needs changed too?

    Thanks agian and sorry for all the questions.
     
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