Hartford loop

Hartford loop

[′härt·fərd ‚lüp] (mechanical engineering) A condensate return arrangement for low-pressure, steam-heating systems featuring a steady water line in the boiler.

Hartford loop, Underwriters’ loop

An arrangement of the return piping connections to a steam boiler; used to balance pressures between the supply and return sides of the boiler and thus prevent boiler water from backing out of the boiler and into the return.