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Boiler over heating

Boier is 1983 Thermo flo 140 BTU unit. have owned since 1998, replaced B&G pump 9 years age with Taco and replaced valve seats in drain valve for all 3 zones. Boiler over heated - found soot blocking flu gas. Cleaned soot form cast iron sections( messy job) flame roll out no longer an issue. Boiler still over heated. Checked L8148E 1265 aqua-stat would not open circuit to gas valve and shut off flame. Aqua stat seemed original, never services since 1998. Replaced with new L8148E 1265 added thermo grease to well wasn't used previously. Boiler burners still not shutting down. measured temps with infrared thermometer sensor well only seeing temps of 160 degrees F measured temps on back side of each cast iron boiler section (5 of them) ranged from 136 to to 168 cool to hot side. Pressure running 4 to 5 pounds over cold set pint of 16 LBS. Are internal cast iron sections restricted air is purged form system out of ideas. any help would be appreciated.

Comments

  • Jamie HallJamie Hall Posts: 10,014Member
    I'm confused. First off, what is the aquastat set to shut off at? Second, I would not regard even 168 as "overheating"... can you explain what you mean a bit further?
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • dsanders9070dsanders9070 Posts: 2Member
    The aquastat is set at 210 The 168 degrees is the temperate read on the back of the cast iron sections. Could not get reading on exterior of aquastat well. The temperature increased enough to melt the pressure temp gauge. New gauge reading over 260 before I manually stopped burner. Could interior of the cast iron heat exchanger sections be restricted?
  • Jamie HallJamie Hall Posts: 10,014Member
    Difficult to troubleshoot from a distance -- but I will say this:

    Turn off that boiler with the emergency switch -- and the circuit breaker -- and tag it off. Then get a competent technician out there with the appropriate experience and test instruments and get it checked and fixed.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • SuperTechSuperTech Posts: 935Member
    Wow. Whenever something starts melting down it's a good indication that it's time to shut it down and call for help. This is far too dangerous a situation for anyone to safely offer advice without physically being there. Please let us know what the problem is and what solutions were offered.
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