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LGB boiler venting

Smith19Smith19 Member Posts: 95
Hello all -
Does anyone know if the Weil MClain LGB gas boiler can be vented with a barometric damper? I would think not - however I have seen many atmospheric water heater installs with a barometric. Current job is incredibly tight - the LGB's large vent hood is contacting the wall behind.



  • SWEISWEI Member Posts: 7,356
    Yes, it can. Code compliance and warranty would be in question for most installers, but with proper training and a good understanding of the physics you can make the call.
  • Smith19Smith19 Member Posts: 95
    Anywhere I could find examples of a good install in that fashion?
  • SWEISWEI Member Posts: 7,356
    @captainco and @Tim McElwain both have numerous examples and may be willing to share.
  • HenryHenry Member Posts: 963
    It is completly illegal in Canada. The manufacturer will not honour the warranty as you will have modified the product and uncertified it.
  • ChrisJChrisJ Member Posts: 10,860
    @Smith19 Are you in Canada?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Smith19Smith19 Member Posts: 95
    ChrisJ said:

    @Smith19 Are you in Canada?

    No, so I should be okay for now.
  • captaincocaptainco Member Posts: 450
    I have helped contractors modify hundreds of Weil-Mclain LBG type boilers and many other brands. We have talked to Weil-Mclain engineers and they won't openly accept it because they realize too many contractors aren't smart enough to do this modification. In 1993 I did a field test with the top field engineer from AGA Labs, when they were still the certifying lab of all gas appliances. I know there were at least four of these boiler in a school with drafthoods. In this case, the boilers were poisoning school kids even though they were installed according to manufacturers specs. They were modified with barometrics, under their observation, and spill switches were added, The unsafe condition was rectified 100% and the boiler were now safer than original design. AGA wrote a report that stated barometrics are a viable replacement for the traditional drafthood. I added "When installed by a properly trained technician." I have attached a drawing of the three ways we have modified them in the field. If this doesn't help, let me know. Oh yes, on a new installation it is rare that an inspector will allow it.
    As Timmie know I teach this coast to coast and he addresses this at his classes and in Canada to keep people alive. Apparently that is not on most manufacturers agenda. I can e-mail the AGA Field Study report from 1993.
  • AbracadabraAbracadabra Member Posts: 1,948
    @captainco you don't happen to have a copy of the AGA report that you could share do you?
  • captaincocaptainco Member Posts: 450
    Gee, I forgot. I think this is readable. Some of the pictures aren't clear, but there were some LGB
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