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Buderus GB142 venturi issue

TomScTomSc Member Posts: 4
Replaced a broken venturi to help solve intermittent 6A code. With new venturi of the correct size boiler goes to a 6A lockout. The only way to get it to fire at all is to block about half of the air intake (it then fires for a minute or less and gives a 6L code. Put broken venturi back in with old gaskets and it fires and runs, so far with no error code (only a few firings so far). Any thoughts? Thanks


  • IronmanIronman Member Posts: 5,513
    Has a combustion analysis been done? If so, what are the numbers?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • HVACNUTHVACNUT Member Posts: 3,072
    By partially covering part of the air intake, you're changing the air fuel ratio. That fact that has to be done means its needs to be serviced by a pro. The repair and a combustion analysis with a print out of the report.
    Don't hurt yourself please.
  • TomScTomSc Member Posts: 4
    Thank you. I have an HVAC expert who will work on it but before he services the boiler I wanted to see what this forum would offer since the GB seems to have some Buderus specific issues that could help him diagnose the problem. Any thoughts on why a broken in half venturi works but a new one with new seals does not?
  • GWGW Member Posts: 3,607
    That’s odd for sure you may have several problems. The fan may be running haywire which could possibly compensate for the Venturi issue. I’d call Buderus tech line if it were me.
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]
  • ch4manch4man Member Posts: 213
    please be careful, i have seen this before where I had a mod/con run albeit poorly with a broken venturi or swirl plate and would not run with a new part.

    BUT, it really wasnt "running" with the broken part. it was just heating water all the while producing God awful amounts of carbon monoxide. (read-deadly)

    you have several components failing, you only see the broken venturi. without training and proper test equipment you cant "see" the other components that need attention
  • Tom_133Tom_133 Member Posts: 670
    I agree with GW, I have seen the same thing. I also called tech support that day.
    Montpelier Vt
  • TomScTomSc Member Posts: 4
    Many thanks for the responses. Before the HVAC tech comes out (I have a service call scheduled) Can I, as a nonprofessional talk with tech support and take some notes to share with the HVAC tech? PS There is an explosive gas/CO alarm in the utility room as well as a CO detector/monitor near the bedroom.
  • GWGW Member Posts: 3,607
    Tom that normally doesn’t happen. Programming a control maybe, but not combustion stuff. They want to talk to real pros. You could choose dishonesty and pretend your a tech but these factory tech guys will quickly figure this out. If they don’t recognize the person calling or the jargon sounds iffy, expect to jump a few hoops with technical (expensive) tools. I hope it all works out
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]
  • TomScTomSc Member Posts: 4
    Thanks. I was just trying to save time/$ but will have my service tech contact them directly if he has any problems diagnosing the issue.
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