What Is a Hartford Loop

Simply speaking, a Hartford Loop is a configuration of interconnected pipes associated with the gravity condensate return line on a steam boiler, and the point at which that condensation is re-introduced back into the boiler. It exists between the header of the boiler and the gravity return.

Do all boilers need a Hartford loop?

If the system has a dry return (as most one-pipe steam system do), you still need a Hartford Loop, even though no return piping is below the boiler’s waterline. This is because the near-boiler piping has an equalizer that keeps the water from backing out of the boiler when steam pressure builds.

How far below the water line is the Hartford loop installed?

A proper Hartford Loop is taken off the equalizing line of the boiler piping with its center 2″ below the normal water line. The shortest possible nipple and an immediate elbow turn the loop down to meet the wet return, forming a water seal.