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Buder GB142 - heating water temp only hitting 153

Mplsavant
Mplsavant Member Posts: 20
in THE MAIN WALL
Hey guys.  I have a 5 year old GB142, cleaned annually, works well.  I had a pump changed 4 months ago for DHW due to an 0Y error of flow temp higher than set.   This winter now, my heating side water temp only reaches 153 degress max.  I don't have an AM10 and if I have it set to 170, it only reaches 153, if I move it to AUX, it only reaches 153.  This is only when it calls for heat....DHW is not calling for heat during this.

I checked the heating capacity via chimney sweep and it is showing "L--" which is 100%.  Any ideas on why it is only reaching 153?

Thanks

Comments

  • Ironman
    Ironman Member Posts: 7,550
    Controls ?

    Are you using the BC10 room controller or a standard thermostat(s)?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Mplsavant
    Mplsavant Member Posts: 20
    edited December 2011
    BC10 Controller

    On the BC10 controller on the boiler I set the dial on the right to the 170 temp and try it, goes to only 153 while still heating....Next test I try it at AUX and also only gets to 153.  For both tests, I turn my standard room themostat on main level up a couple degrees to call for heat.....both the 170 test and AUX only reaches the water temp to 153
  • pipe4zen
    pipe4zen Member Posts: 108
    GB

    What size GB is it?

    Does the temperature go higher on DHW call?

    What speed is the boiler pump set to? GB142-24 , Buderus recommends speed 1,

    30kw speed 2.

    Did you check if in low fire mode/high fire mode?
  • Mplsavant
    Mplsavant Member Posts: 20
    edited December 2011
    Budeus tech said.....

    The unit is a 142/24, it's been installed since 05', annual cleanings, a ignitor replacement, trap, etc but otherwise the only change is below, so setting on heating pump, etc have not changed:



    (BTW, the DHW pump was moved up to a slightly bigger one about 4 months ago due to "OY" message.  Today it hits 190 degrees and seems to pull through fine.) 

     

    Last night I did this, again, dealing with heating side, not DHW:

    - Flue gas test - temp hit 190 degrees

    - Checked the heat capacity via chimney/service buttons - shows "L--" which is at 100%

    - I know the dial itself works cause was heating at 153 last night and turned it down to 130 and flame,etc went out

    Buderus tech said:

    - Delta T between supply and return should be at least 20 degree difference, ideally 36, so I am going to check this.  He thought that the unit could reach 190 while set in AUX (again, unit does not have AM10) but it is not requiring it to.  He thinks it could be:

    - Coil clog with exchange over air handler

    - possible pump going bad

    - water flush and fill
This discussion has been closed.

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