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Soot on aquastat

duh Member Posts: 17
What could cause soot to appear on the inside of the closed cover of an aquastat mounted on top of a Buderus oil-fired boiler, model GS115WS4?


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,840
    Convection currents would bring airborne carbon particles from incomplete combustion into the tiny openings of the control.

    There could be an electrical restriction causing resistance in a wire. the insulation on the wire would overheat and start to burn and leave soot marks.

    Look at the location of the soot and the wires around it.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    HVACNUT Member Posts: 5,841
    Clean it and see if it returns. 
    The aquastat sits on top, near the rear of the boiler. Where is the draft regulator in relation?