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The Hartford Loop: this article gives a definition of the Hartford Loop used on steam heating systems, explains why the Hartford Loop is necessary to protect against steam boiler damage, and gives a bit of the history of the development of the Hartford loop. We include sketches and photographs of the Hartford Loop piping arrangement on steam boilers and list inspection & defect points of interest.
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Definition of the Hartford Loop - what is a Hartford Loop & Why is it Important on Steam Systems?
Invented in the U.S. in 1919 by the Hartford (CT) Insurance Company in response to an unacceptable rate of steam boiler damage, loss, and even explosions, the Hartford Loop is a piping arrangement at the steam boiler condensate return line that allows condensate to re-enter the boiler but prevents complete loss of steam boiler water should a leak develop elsewhere in the condensate return line.
[Click to enlarge any image]
As you can infer by looking at our drawing at above left Boiler Without a Hartford Loop, a leak anywhere in the wet return portion of the condensate return piping that is below the boiler water line risks siphoning out all of the water from the heating boiler.
Our illustration at above right titled Hartford Loop shows where the Hartford Loop is located on a steam boiler. Above the drawing is adapted from ITT's The Steam Book.
The 2-inch Rule and the 24-inch Rule for Hartford Loops & Steam Headers
But the boiler manufacturer may provide additional steam piping specifications - as we illustrate below. For example instead of specifying that the top of the Hartford Loop is two inches below the boiler water line the manufacturer may specify that the pipe fitters maintain at least 24 inches between the boiler water line and the bottom of the steam header.
The risk of steam condensate return water leaks was and can remain significant because of the corrosive acids that form in steam and other heating boilers and because not coincidentally, the more likely place where such leaks would develop is in the last and lowest run of the condensate return line along or close to the floor approaching the steam boiler. In our discussion of steam condensate systems we illustrate a chemical injection system intended to reduce this corrosivity.
At below right our image is adapted from the piping schematic for a Weil McLain steam boiler - Weil McLain Model 78 (2014)
Do leaks actually occur in the wet return portion of a steam heat condensate return piping system? You bet they do. Depending on what's done to manage steam boiler chemistry, the condensate may be quite corrosive. Our photo at left shows two leaks at the condensate wet return at a boiler located in in the U.S. in Poughkeepsie, NY.
Watch out: at CONDENSATE RETURN PIPES, PUMPS, STEAM we explain that a leaky condensate line such as the one shown in our photo at above left can be lead to dangerous BLEVE EXPLOSIONS. You can check the water level in your steam boiler quite easily by using the built-in STEAM BOILER SIGHT GLASS.
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