DHW Sensor Error

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gcdchico
gcdchico Posts: 3
in Radiant Heating

We recently purchase a home that has a 20 year old Buderus system.

The Buderus Logmatic R 2107 displays DHW PROD Err. However we still have lots of hot water in the home. I have not yet tried to activate the floor radiant heating system. Does this error suggest the Buderus (80-100 Gal) holding tank has issues? Where would I search for the sensor?

Any suggestions please —- I live in Chico Ca with little to no radiant tech resources available.

Comments

  • hot_rod
    hot_rod Posts: 28,631

    Does the manual tell you what to check when you see that error code? Download a manual if there is not one on the site.

    Usually it means a bad or disconnected or shorted sensor. You would need an ohm meter to check the esnsor when it 9s unhooked from the control

    The manual would also show the ohm reading at various temperatures.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Posts: 4,877

    It seems as though you have the error message without the symptom (no DHW). Here is the boiler manual with troubleshooting beginning on page 55. I received your voicemail and will call you back later today.

    Screenshot 2026-10-31 at 2.05.27 PM.png
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    HVACNUT
  • HVACNUT
    HVACNUT Posts: 7,766

    In the meantime you can put the 2107 in manual mode ✋️ and turn the boiler temperature dial from auto to 140°. If the sensor is bad, the DHW temperature will be now 140°. Since you still have hot water, it might already be set up that way.

  • hot_rod
    hot_rod Posts: 28,631

    I have seen indirects that were not piped with check protection, or a failed check and the tank gets heated on any heat call to the boiler.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

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