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Buderus GB142 doesn't power on

friolatorfriolator Member Posts: 3
We've got a Buderus GB142 that was installed in 2007 or so. It was chilly yesterday so I turned the heat on for the first time this season, and after 15 minutes, no heat. So I went down to the basement and see that there doesn't appear to be any power on the GB142's control panel, nor to the AM10 Outdoor reset.

I flipped the main power switch next to the boiler off and then on, no change. I checked the outlet that's in the same junction box (same power source) and there's power to the outlet. Yes, the main power switch on the control panel is On.

In the past, we had some issues with the outdoor reset shutting off, but this was due to a loose control wire from the GB142. Tightening that fixed the intermittent problem.

So, Questions:

- If the AM10 is dead, will that cause the GB142 to not power on at all? Nothing is lighting up on the GB142 control panel.
- If there's power to the boiler from the main shutoff switch, what might cause it to not power on at all? Faulty control panel? An internal fuse or breaker somewhere?

I'm handy with electrical and electronic stuff so I have no problem swapping parts out, but I don't want to buy stuff I don't need. Any guidance on where to start troubleshooting this would be appreciated.



  • ZmanZman Member Posts: 5,736
    It's been a while but I recall some fuses on the AM-10 that should be checked.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • IronmanIronman Member Posts: 5,566
    The fuses are in the boiler control panel. Could also be a bad low voltage transformer.

    You can go to Bosch HVAC and download the service manual for that boiler to see how to trouble shoot it.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • friolatorfriolator Member Posts: 3
    Thanks. The fuse on the UBA3 module was blown. But when I replaced it and the boiler powered on, I got a fault code 3L, indicating a fan issue. Went through all the troubleshooting steps in the service manual, and it looks like the fan is toast. Seems that others have had the fan blow, which in turn blew the fuse (I think I read that on an old post here actually). That's looking like the culprit right there. I've got a new fan unit on the way, and should be replacing that tomorrow or Sunday. Hopefully that's all.
  • friolatorfriolator Member Posts: 3
    New fan arrived on Friday and it took about 15 minutes to install. The heat is back on, and the fault codes are gone.


  • IronmanIronman Member Posts: 5,566
    Thanks for following up.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
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