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CH set to 170 boiler doesn't reach it

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TimmyLS
TimmyLS Member Posts: 7
Hey all, I have a wmb-155c NG boiler and its acting weird lately. I've set the heating water temp to 170 but when thermostat is calling for heat the boiler will briefly fire at "medium" (flame indicator on display) until it reaches 140ish and then go down into low fire and maintain right around that temp. It will stay on like that for quite some time as house isn't heating up enough to shut the thermostat off. Any ideas??

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  • kcopp
    kcopp Member Posts: 4,448
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    If the outdoor temp sensor is installed and set to modulate based on the outdoor temp it wont get there. Is the house warm?
    TimmyLSSuperTech
  • TimmyLS
    TimmyLS Member Posts: 7
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    Kcopp thanks for the reply. There isn't an outdoor temp sensor installed on this unit. I've seen mention of it as optional in the manual. 

    Our house is fairly warm, 65, thermostat set to 68 though.
  • HVACNUT
    HVACNUT Member Posts: 5,887
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    Number 6, CH user setpoint is default to 158°. 
    TimmyLS
  • TimmyLS
    TimmyLS Member Posts: 7
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    Interesting, though by changing the CH +/- on the front panel doesn't that change that parameter? I have set it to 170 by doing that.
  • hot_rod
    hot_rod Member Posts: 22,472
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    Are you in the installers mode when you make changes? Usually there is a passcode required to change some parameters
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • TimmyLS
    TimmyLS Member Posts: 7
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    hot_rod said:
    Are you in the installers mode when you make changes? Usually there is a passcode required to change some parameters
    No. What I'm talking about is simply changing the CH temp to 170 using the front panel, no code required... I see there are vast menus of options but they require a proprietary connection to a computer to change it looks like... the DHW temp changes just fine by this same method, but the CH temp never goes over 150 or so...
  • hot_rod
    hot_rod Member Posts: 22,472
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    Check the sensors with an ohm meter, you could have one out of range.
    The troubleshooting pages explain how to get into installer mode to read any faults. The control will know why it didn’t reach the operating condition. Could be too high of a delta, high flue temperature or other issues.

    You either have to sit in front of it, catch it in the act, could be the call for heat drops off before it hits the programmed temperature?
    or pull the info from the data logging function deep in the control menu, the history mode.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    TimmyLS
  • TimmyLS
    TimmyLS Member Posts: 7
    edited February 2023
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    hot_rod said:
    Check the sensors with an ohm meter, you could have one out of range. The troubleshooting pages explain how to get into installer mode to read any faults. The control will know why it didn’t reach the operating condition. Could be too high of a delta, high flue temperature or other issues. You either have to sit in front of it, catch it in the act, could be the call for heat drops off before it hits the programmed temperature? or pull the info from the data logging function deep in the control menu, the history mode.
    Thank you for all of this. It got me checking all the actual values vs default values.... found that value p13 CH maximum output was set to 00. No idea how or why it was, as this is the first time going into these menus, but I put it on 75% and it got up to temp (165) in a few seconds afterwards. In inquiry mode, after the change sensor 1 reads 164 sensor 2 reads 165 and sensor 3 (CH return) reads 159. Exhaust sensor reads 152. 

    I think this corrected my issue. Or at least solved one problem!