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Hartford loop

I have found a boiler installed several years ago and the hartford loop is above the water line of the boiler is this the problem I have during extreme cold whether the boiler will flood. I have noted to the home owner association that the a dimension may not be correct and that the end of main vents may not be working causing the condensate to hold in the system but today I noted the Hartford loop and am wondering if it also could be the cause.


  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    edited October 2011
    Yes & No

    The Hartford loop should be connected to the equalizer loop with a close nipple two inches below the minimum operating water level. (See http://www.heatinghelp.com/article/325/Piping/291/What-you-should-know-about-Hartford-Loops)

    The effect of having the Hartford loop connected above the water level would be to retain excess water in the wet return. If the boiler is filled to the water line at the start of heating season, the water level would appear lower after the first heating cycle, assuming the return was empty and the water was added directly to the boiler, because no water would be able to return to the boiler until the return filled up to the top of the Hartford loop. If makeup water is then added to the boiler, it should be able to maintain its normal level, but the level will decrease dramatically during each cycle because, since the Hartford loop is connected above the water line, the steam in the equalizer will push the water level down, impeding its return until the end of the cycle when the pressure decreases, allowing the water to rush into the boiler. This alone would not flood the boiler unless makeup water is added mid-cycle while the level is reduced.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
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