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Buderus GB 142 fault-2F

I've had a recurring 2F fault code on the last 2 boilers I've installed and had no luck with tech support.The last boiler we replaced with a like unit and it has been running fine for 2 weeks. Anyone else have the 2F? Thanks


  • singhsingh Posts: 865

    2F- Temps higher than set.
    How's the piping, perhaps bottleneck some where. Ex: If using actuators without a diff by pass on the system pump ,this may occur until they are fully open.

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  • ScottScott Posts: 5,884

    Why no luck with tech support ??

    I have found Buderus to be very helpfull and available.

    I belive that F2 is not a fault code but a system that code that tells you the boiler is not getting proper flow and has gone pastits ste temp.

    Did you use the manifold station that comee with the boiler or did you modifiy it ??


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  • DonDon Posts: 11

    2F indicts that the delt t across the heat exchanger is too much or too little; too little in my cases. there is no call for heat until the accuators are open (end swith) and I have a dif. pressure by pass.
  • DonDon Posts: 11

    After waiting about 20 minutes on hold; then getting a new tech. every time (14 times on the 1st boiler) they were not able to solve the problem. We used the original pump manifold that comes with the boiler.
  • singhsingh Posts: 865
    Soft code

    Check by pass setting.
    You'll notice after the next timed interval that the code goes away. Usually after system flow is adequate. Check boiler pump speed also.

    Call again. I never had to wait more than 5 minutes, and tech support has always beem helpful. Go to their website also, they have a forum to post questions.

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  • Adjust Circ

    Have you made an attempt to switch speeds on the Grundfos 15-58FC that comes on the Pri-Sec manifold? This may help you in getting the desired Delta T across the heat exchanger.

  • DonDon Posts: 11

    Yes, tried all 3 speeds.
  • Location

    Where is the job location?
  • DonDon Posts: 11

    Truckee and Tahoe City; both in California
  • Manufacturers Rep

    Have you contacted your Man. Rep yet?

  • Mad DogMad Dog Posts: 3,155
    I have seen that only on initial start up when

    The boiler was air-bound. Mad Dog

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  • DonDon Posts: 11

    Yes, After much delay they sent the rep's guy out and he's been training on the job- nice guy but no firm answers.
  • DonDon Posts: 11

    Nope, purged multiple times and air vent at top of unit is open.Thanks
  • singhsingh Posts: 865

    Well between Darin, Mad Dog and myself we probably have several dozen of GB's installed.
    All of us have had good experiences with tech at Buderus and their rep out on the job site.
    Each of us have given good possible solutions to the 2F code. You should ohm out the sensors and make sure they are ok.
    I understand California is not a big heating state. Perhaps you should make a trip out to New Hampshire and get some training yourself.

    Good Luck.

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  • Steve MSteve M Posts: 121
    The problem may be....

    I've had this code before and the problem was the internal check valve on the primary pump was clogged. I was at the job doing the annual service, cleaning heat exchanger, etc. After finishing and watching it run I exercised the speed switch on the primary pump and left the job. A few days later got a call saying no heat but they had DHW. I had flow thru the boiler because I throttled down the ball valve and heard restriction and it would lock out before I could do a Delta T across the boiler. I removed the pump and saw the impeller rotate after powering it up. I then popped out the flow check and cleaned it up and reinstalled and it ran fine and hasn't locked out since. I bet thats your problem.

  • Typical crappy Bosch Software.
  • DonDon Posts: 11

    I have a couple of dozen installations myself (including 1 in my own house) and up to this point I've never needed tech support. All of our installations are piped and controled the same. I've always been a fan of the company and used the cast iron boilers, radiators and indirects for years. My purpose for the posting here was to see if others were having the fault code. I know of one installation 100 miles south of here with a problem and have heard of the 2F fault in Colorado; which has asimular climate to us.It may be an altitude issue but in the past we haven't had the issues. My only problem with tech support was the hold time and the inabilities to solve the issue.
  • bobjbobj Posts: 2
    KIM chip

    i thnk you need a KIM chip. the new chip installs in the UBA and it changes the logic to allow more time to see a lower delta t. we have had to install many here in colorado. low gas content and high mass systems. our rep stocks these chips. you may want to contact buderus again
  • DonDon Posts: 11

    We've dis-assembled the circulator and check valve and had no luck. The factory sent us a new "kim" chip that extends the trial time for sensing delt t; it helped one and did absolutely nothing for the second unit; the 2nd unit we changed out completely (boiler and pump module) and seems to functioning properly. On the first boiler with a problem my supplier is going to install an "AM 10" module that has a memory so we can see if it's faulting and resetting- this is a seldom used second home. We've heard that a unit was faulting,resetting but keeping the house to temperature.
  • DonDon Posts: 11

    See reply above. My questions would be: did it solve the problem 100% and if you assume that the pump module hydraulically isolates the boiler loop from the heating loop why would the system mass come into play and what about all the other systems that have been operating for years? Thanks so much for your response; this is what I was looking for.
  • bobjbobj Posts: 2

    normally its on a new system start up. last week one of our customers/contractors was servicing a GB that had been in for several years fault upon restart on a 2F, we tried a lot of what was posted above with no success, finally we threw a chip at it and it took off and has been running ever since. i have had some success by closing one of the valves on the pump manifold briefly to trick the boiler, but we always follow up with a chip. i would contact buderus i dont completely understand why it works, but everytime we have had a 2F it fixed the problem.
  • singhsingh Posts: 865
    Kim chip

    Thanks I learned something. I never heard of Kim chip replacement.
    Although I never had prolonged 2F codes either.

    Like you said must be climate/area thing.

    Don, replace the KIM chip : )

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  • DonDon Posts: 11

    It's not that simple; I've had one where I replaced the chip and it faulted the second time it fired and I had another that the chip did nothing; we changed the whole unit and that has solved the problem for now. I'm curious if the kim chip has worked 100% for others.
  • California

    has no heating season. You are correct.
  • Mindless Reply

    From a mindless person, no doubt.
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