Buderus GB142 venturi issue

TomSc

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

Ironman

Has a combustion analysis been done? If so, what are the numbers?

HVACNUT

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.

TomSc

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?

GW

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.

ch4man

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_133

I agree with GW, I have seen the same thing. I also called tech support that day.

TomSc

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.

GW

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

TomSc

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.

robh

Hello Tom, did you find out what caused this issue? I have the same thing and my engineer is stumped.

WMno57

Hi robh. Welcome to HeatingHelp. @TomSc has not been active for 4 years. Your best chance for getting help here is to start a new thread with some pictures.