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Manual Reset High Limit Aquastat always tripping

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by SIERRADMAX, Nov 20, 2013.

  1. SIERRADMAX

    SIERRADMAX Feeling the Heat

    Joined:
    Jan 13, 2011
    Messages:
    296
    Loc:
    RI
    New wood boiler user online and I know I have a learning curve with the operation. I've been lighting small fires in the Econoburn 100. It's operation alone has been pretty good so far. But, it's interface with the existing oil boiler has left us waking up to a cold house in the morning.

    For some reason, the manual reset high limit aquastat on the oil boiler keeps going off. I have a thermal switch strapped to the supply line of the wood boiler to cut power to the oil boiler. The aquastat seems to trip just before the thermal switch is satisfied, whenever the oil boiler is still providing heat. I manually reset and it must have tripped overnight (assuming the same temperature range just as the wood boiler cools down and the thermal switch restores power to the oil boiler).

    I have the HL aquastat set to 230degF. Is it possible that it sees these temps during the time period described above?

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  2. heaterman

    heaterman Minister of Fire

    Joined:
    Oct 16, 2007
    Messages:
    3,292
    Loc:
    Falmouth, Michigan
    What is the operating aquastat temperature on the EBW set at?
    How are the two boilers connected?
    Are you pumping directly from the EBW to the oil boiler or is there storage in the system somewhere?
  3. SIERRADMAX

    SIERRADMAX Feeling the Heat

    Joined:
    Jan 13, 2011
    Messages:
    296
    Loc:
    RI
    No Storage. I've been setting the water temperature to 185 degF. The two boilers are connected like the attached pdf schematic. However, I'm using a thermal switch instead of a L4006A aquastat (system note C on schematic). I don't know how reliable the thermal switch is but I have a temperature gauge right adjacent to the switch and it seems to interrupt oil boiler power around 160degF.

    Attached Files:

  4. SIERRADMAX

    SIERRADMAX Feeling the Heat

    Joined:
    Jan 13, 2011
    Messages:
    296
    Loc:
    RI
    I removed the thermal switch and replaced it with an aquastat. Fully operational now.

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