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Buderus GB142 - not circulating to baseboards/indirect HW fine

DanS Member Posts: 5
Sorry in advance if this is an annoying amateur question ( I am one!)  I have Buderus GB142 with 3 zones + indirect HW.  Indirect HW works fine.  Turned on heat and no circulation to baseboard heat zones.

Tried the following: 

1. Code H 7: First shows low water pressure so I added water via the regulator - brought it 15#.  No change.

2. Assumed air in system and bled each zone. Little sign of "major air" some small bubbles. Still no change but it brought up code "OA 81" which went away.  That apparently is a message for - "you've messed with me so I'm taking a break for a few minutes."

3. Question #1 might be - I am bleeding correctly?  I'm shutting off the supply and return valves to all the zones except the supply  valve to the zone I'm bleeding.  I then hooked up a hose to the drain valve and let it run.  Thermostat is on so it should be calling for the circulator pump to run.

Anyway, I'm going to call my plumber/installer for a regular service check...but it's Sunday now, and it's cold and I figured if I can DIY it, my family would be pleased.

Thanks for your help and any ideas.

Dan S.


  • Jim Pompetti
    Jim Pompetti Member Posts: 552

    Needs 20 PSI to run . Can you post a picture?
  • DanS
    DanS Member Posts: 5

    Thanks for the reply.  Picture attached to show the set up.  Just a thought that it may also be the relay (Traco) since all three zones are down?  DS 
  • Slimpickins
    Slimpickins Member Posts: 331
    Hot water?

    Do you have hot water?
  • DanS
    DanS Member Posts: 5

    Yes I do have hot water.  It's run through a separate "zone" and the boiler is definitely running.
  • Ironman
    Ironman Member Posts: 7,119
    edited October 2011
    Boiler Pump

    I'd check your boiler circulator; it doesn't run for domestic, just space heating. It's the black one on the boiler manifold.

    Also, don't run any circulators when bleeding air. Close the valve below the hose, as well as all other loop isolation valves when bleeding air. Leave the valves open on the supply (above and below he circulator) only on the zone you're bleeding. Repeat for each zone.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • bill nye_3
    bill nye_3 Member Posts: 307
    Not all

    Not all that familiar with the GB142, but could you have some sort of weather responsive control that is not permitting the heat to run? I have seen situations with Buderus Logomatic or Viessman trimatic where a hot water only - or a night setback- or WWSD setting was selected on the control not allowing heat ?
  • Ironman
    Ironman Member Posts: 7,119
    edited October 2011


    GB142's made in the last 3-4 years have come with the AM10 reset control. It's a very simple device and WWSD is set based on outdoor temp, but there's no set back, boost or WWSD selection switch. Earlier models came with the BC10 room controller which worked off of indoor reset.


    Just spotted the AM10 on the wall under the Taco panel (white plastic).
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • DanS
    DanS Member Posts: 5

    So, finally getting a chance to follow up.  Thanks to those who posted suggestions as they are much appreciated.

    Turns out the circulating pumps weren't getting the signal to kick on due to low batteries in the thermostats.  Plumber was able to come over to take a look and immediately suspected the Traco control panel or relays.  It all checked out OK so he happened to look at the thermostat for one of the zones..put in new batteries and ...well, it's almost like saying "is it plugged in?"  but it worked and pumps kicked on.

    I'm a little confused why all three zones weren't working because the other two  thermostats still had live displays. Still put in new batteries all around and now have heat.

    (Figured I'd fess up to the conclusion on this - as embarrassing as it is - so others who check the archives can at least have one more thing to check before they spend hours trying to figure it out!)

  • MrDucks
    MrDucks Member Posts: 27
    GB 142

    Check your taco zone panel for priority. There is a jumper/switch set wrong on panel causing zones 2&3 not to work when #1 is calling.
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