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Buderus GB142 randomly refuses to answer call for heat

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nonobar
nonobar Member Posts: 27
edited February 2023 in THE MAIN WALL
My Buderus GB142 serendipitously fails to ignite; usually in the morning. I see, in this forum, much finger pointing at the AM10 module as the culprit. My question is this: if your system does not have an AM10, what does the ourdoor sensor actually do, and how? Could a failure of the outdoor sensor thermistor cause the system to not ignite when a call for heat is active?

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  • Ironman
    Ironman Member Posts: 7,399
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    Are you saying the boiler has an ignition failure and throws a code (usually a 6a) or that boiler is not responding to a heat call from the thermostat?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,831
    edited January 2023
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    The outdoor sensor tells the AM10 what temperature is it outside the home. It is a thermistor . Basically a resistor . You can check the AM10 for the ODT on the screen. See if it is in range . In the program , there is a setting at what ODT temperature to allow heat . The AM10 modulates the boiler for what is needed to heat the home at that given time ..

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  • Derheatmeister
    Derheatmeister Member Posts: 1,572
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    I would start by removing the flame sensing rod and cleaning it.
  • nonobar
    nonobar Member Posts: 27
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    Let me try to clarify. The system has no error code that I see. It does not respond to a call for heat from the thermostats. The system does not come with an AM10. To get the system to ignite, I simply have to shut off the power and turn it back on.

    Without an AM10, could the outdoor sensor be causing this problem?

    The system will run perfectly for several days and then, out of the blue, it decides to not answer the call for heat. Then I simply need to turn off the power and turn it back on again to get it to work for another few days.
  • yellowdog
    yellowdog Member Posts: 159
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    if the boiler is not showing a code, then it did not try to ignite. something else is going on. 6a seems to pop up pretty easily on my own boiler over its 16 years of service. i have had to change the gas valve twice and the inducer motor once to correct it. it has never been the igniter on my own boiler that causes it not to light. if you do not have an am10, where is your outdoor sensor wired to?
  • nonobar
    nonobar Member Posts: 27
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    According to the installation menu, the outdoor sensor goes to the blue terminal on the external connection board with no AM10.


    It makes me wonder, what does the AM10 add to the system performance?
  • Ironman
    Ironman Member Posts: 7,399
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    If you have no AM10, then the outdoor sensor has no effect on the boiler, unless you have the BC10 room controller - in which case it influences that.

    If you have a simple thermostat, it should be connected to the “WA” terminals.

    How about giving some clarification on what you have?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Ironman
    Ironman Member Posts: 7,399
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    Just to help clarify from our end: an ignition failure means the boiler attempted to ignite but failed.

    If it fails to respond to call for heat, that’s not an ignition failure.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    GGross
  • nonobar
    nonobar Member Posts: 27
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    My system has 5 zones and DHW.

    Here is my situation. The house gets cold. I go in the basement to find all the circulators running. The flame led on the display is off. I turn off the electricity and turn it back on and the flame led lights up after a few moments. The house then warms up.

    I only believe that I have no AM10 because when I lifted the cover on the right side of the display, there was nothing there.

    How can I tell if I have a BC10 room controller? What is a BC10 room controller?
  • Big Ed_4
    Big Ed_4 Member Posts: 2,831
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    the AM10 connects to the boiler on the FA plug , The AM10 mounts on control deck or wired remotely . It could be on the wall .

    You may not have one ...

    Flipping the switch will erase most error codes.

    Just flipping the switch gets it going ?..... bad connection or control ,

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  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,245
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    I put in alot of them, enthusiastically, but the longevity is...eh..Probably could have used a full maintenance 3 times a yr.  I'd doba Viessman if you can swing it...The real Mc Coy.  Mad Dog
  • yellowdog
    yellowdog Member Posts: 159
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    the next time it does it, look at what the display says before turning the power off. it should show a code if it is a boiler issue.
    nonobarIronman
  • Big Ed_4
    Big Ed_4 Member Posts: 2,831
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    Also if you get a error code , before resetting push the wrench button to get the sub code ..

    There was an error rendering this rich post.

    Ironmannonobar
  • nonobar
    nonobar Member Posts: 27
    edited February 2023
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    My wife woke me up at 5:30 this morning to tell me the heat was out again. Indeed the (cast iron) baseboards were cold. I put on some clothes and went down to the basement. There, to my surprise, I found all three led lights on the BC10 were on. Wait; What?

    I pushed the service button and got an H with two minus signs in front of it. (boiler in hot water mode)

    I felt the in and out pipes on the five zones. They were all cold.

    Then, all the leds went out. I pushed the service button and saw an OY. (something about the supply sensor). Then I saw an OC. Then I saw the normal -H, the leds were on, and the house began to warm up.

    Where is this "Supply Sensor"? Can it be changed?