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  1. #1
    Join Date
    Dec 2018
    Posts
    1
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    Buderus 142-24 hot water too hot

    Unit is about 7 years old. Always had aquastat set to about 135* f so no scalding issues in past. Have DHW as an indirect using a Bradford-White SW250rl unit. Recently noticed DHW was unusually hot while showering and checked temp at faucet-170* f . Changed Aquastat to new Buderus unit and used copper shims to transmit tank temp back into sensor as directed.
    Water temp is now down to about 150*f BUT dial on Buderus controls HAVE NEVER been accurate. Used to have it set to about 100, which gave my water about 135ish. Now have it set to 90*, which gives my about 150ish. Can't really go any lower.
    Is there a way to recalibrate controls so the dial is closer to what actual temp in tank is?
    I am planning on installing an anti scald valve ASAP but not really sure what has changed in the last few weeks to give me such issues.
    Any insight is greatly appreciated.
    Eric

  2. #2
    Join Date
    Jan 2012
    Location
    Broomall, PA
    Posts
    1,986
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    You should have a mixing valve on your domestic tank, by code.
    Uh...Google it yourself!

  3. #3
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    17,750
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    Quote Originally Posted by lukewarm54 View Post
    Unit is about 7 years old. Always had aquastat set to about 135* f so no scalding issues in past. Have DHW as an indirect using a Bradford-White SW250rl unit. Recently noticed DHW was unusually hot while showering and checked temp at faucet-170* f . Changed Aquastat to new Buderus unit and used copper shims to transmit tank temp back into sensor as directed.
    Water temp is now down to about 150*f BUT dial on Buderus controls HAVE NEVER been accurate. Used to have it set to about 100, which gave my water about 135ish. Now have it set to 90*, which gives my about 150ish. Can't really go any lower.
    Is there a way to recalibrate controls so the dial is closer to what actual temp in tank is?
    I am planning on installing an anti scald valve ASAP but not really sure what has changed in the last few weeks to give me such issues.
    Any insight is greatly appreciated.
    Eric
    Your control may be defective please have a tech diagnosis the issue.
    Be advised domestic water tanks should be operated at a minimum of140* F to prevent legionnaires desiese from forming with a mixing valve set at 110-120*F to prevent scolding

  4. #4
    Join Date
    Oct 2009
    Location
    God's country - Shenandoah Valley, VA
    Posts
    731
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    In addition to what's been stated: are you using a Buderus tank sensor? There's no provision on a GB142 for an aquastat, only the Buderus sensor. Another brand may have a different resistance value which would give the control a false reading.

    Also be aware that the logic in the control is based upon the placement of the sensor in a Bosch/Buderus indirect tank. A different brand of indirect may have different response characteristics which could also effect the temperature.
    Bob Boan


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

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