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Gas Conversion/ Deteriorating Smoke Pipe

Paul48 Member Posts: 4,470
I had my Smith 8 series boiler converted with a Carlin ez-gas before last heating season. This year, I notice the smoke pipe between the boiler and chimney is deteriorating rather quickly. Is it possible something is not right, and causing this?


  • Steamhead
    Steamhead Member Posts: 14,864
    Moisture in the chimney

    can do this. This can come from rain entering the flue, or a too-low stack temp which causes the flue gases to condense.

    Have a pro check it out.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Paul48
    Paul48 Member Posts: 4,470
    edited November 2013

    Thanks Steamhead,

    The chimney is capped, but there is moisture issues, and the guy that installed the burner noticed it as well when he fired it up the first time. He did down-fire the boiler, and I have a copy of the combustion analysis. I guess the question is, how much can you safely down-fire a series 8 -5 section, without causing problems?
  • j a_2
    j a_2 Member Posts: 1,796

    is this an inside or outside chimney, meaning ,except above the roof line is any chimney wall exposed to outside?
  • BobC
    BobC Member Posts: 5,232
    How low?

    i know JSTAR has downfired the Carlins on the Smith G8 to match the connected load with good results, hopefully he will find this thread.

    I suspect having an exterior chimney could be a problem. If that is the problem maybe you could use an insulated liner or surround the liner with vermiculite.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Bob Harper
    Bob Harper Member Posts: 882
    chimney issues

    If any portion of the chimney is exposed to the outdoors below the roofline, it is treated by the codes as an 'exterior' chimney. When switching fuels, you should have had a Level II chimney inspection, which undoubtedly would have called for a listed chimney liner and replace whatever connector is going bad. Combustion analysis would then tell the tech what he needs to tweak the firing. He may be able to set the burner for a 3-4 min. post-purge to correct condensation in the connector but if its doing that there, what's happening in the chimney?

    If it is unlined, it must be lined at once. If it has an old tile liner a level II will show failures most likely but you also have to consider a cold stack and being oversized in most cases. The listed liner will take care of most of these issues as long as its properly sized.
  • Paul48
    Paul48 Member Posts: 4,470

    The chimney is centered in the house, and was re-lined. The boiler operated for 12 yrs, without a barometric damper, as was stated as acceptable in the I&O manual. There was never a problem with moisture. Since the change to the ez-gas and addition of the damper, the problem seems to be the worst below the damper.The boiler was down-fired approx. 25%, and is running at 150000 btu's.
  • JStar
    JStar Member Posts: 2,752
    Smoke pipe

    That firing rate isn't TOO far under to be a big problem. What were the stack temperatures? Was the boiler completely cleaned and swept out?
  • Paul48
    Paul48 Member Posts: 4,470

    The boiler was cleaned thoroughly..... T Gas= 520.5  T Air=78  O2=4.4%  CO=5ppm  CO2=9.2%  Exc air=26%  Efficiency=80.4%  Losses=19.6%  Delta T=442.4  Ref. O2=0.0%  CO=6ppm
  • j a_2
    j a_2 Member Posts: 1,796

    Bob is on target with the liner…My reason for asking about outside wall exposed,is if it is, I recall it has to be a stainless steel liner thanks
This discussion has been closed.