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Weird Temperature Profile

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nonobar
nonobar Member Posts: 27
One of the peculiarities of my quirky Buderus GB 142 is demonstrated in this temperature profile.


Anyone know why the room temperature takes these crazy jumps? No one touches the thermostats, and the jumps do not appear to occur at the same time of day.

Do you believe that my water temperature sensor may be failing, thus allowing the boiler water to go above its intended limit?

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  • pecmsg
    pecmsg Member Posts: 4,952
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    cold/cool draft hitting the t-stat?
  • hot_rod
    hot_rod Member Posts: 22,472
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    What temperature is the thermostat set to? What is the differential setting?
    What type of heat emitters? High mass radiant, CI radiators can overshoot a little bit.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nonobar
    nonobar Member Posts: 27
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    pecmsg said:

    cold/cool draft hitting the t-stat?

    Don't think so!
  • nonobar
    nonobar Member Posts: 27
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    hot_rod said:

    What temperature is the thermostat set to? What is the differential setting?
    What type of heat emitters? High mass radiant, CI radiators can overshoot a little bit.

    The thermostat is set to 70. The system has cast iron baseboard FHW. I think the differential setting is less than a degree.
  • hot_rod
    hot_rod Member Posts: 22,472
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    Might check the thermostat to confirm, could be 1.5 even a 2 degree differential. That could explain some of the temperature swing.

    The boiler is just responding to a call for heat

    What’s the accuracy if the thermistors you are using for the data logging, there could be some error there also
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nonobar
    nonobar Member Posts: 27
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    hot_rod said:

    Might check the thermostat to confirm, could be 1.5 even a 2 degree differential. That could explain some of the temperature swing.

    The boiler is just responding to a call for heat

    What’s the accuracy if the thermistors you are using for the data logging, there could be some error there also

    I am using a computerized weather station to measure the indoor temperature. The chart shows 7 days of data. Only a few hours of two different days show the crazy behavior. Otherwise, the system remains between 70 and 71. This has to be something weird.
  • hot_rod
    hot_rod Member Posts: 22,472
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    Solar gain? What time of day are the peaks?
    Is there a comfort concern, or just a data obsession🤭
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nonobar
    nonobar Member Posts: 27
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    hot_rod said:

    Solar gain? What time of day are the peaks?
    Is there a comfort concern, or just a data obsession🤭

    The data indicates that the peaks occur at different times of the day, so I have ruled out solar gain. My concern is neither comfort or data. My concern is that the Buderus, infrequently decides to quit. I have a suspicion that these random "quits" may be connected to these random temp blips in the data.

    When the Buderus quits, I go into the basement. I hear one or more of the circulators running. There will be no flame. I turn off the power for a minute, turn it back on, and the Buderus fires.

    I have two other posts which describe this problem further.