No Hartford loop?

Luv'nsteam

Upon examining a Weil-McLain, gas-fired boiler, one-pipe steam system for a friend, there is no Hartford loop.  However, after reading TLAOSH, page 83, right column, five paragraphs down, Dan states there is no Hartford loop on a steam system with counter-flow mains.  The system indeed, has four 2" counter-flow mains (total load is slightly less than 62K Btu minus pick-up factor). 



This sort of makes sense to me, in that there are no wet returns to make into a Hartford loop, but I am having difficulty expressing the logic behind this to my friend, who, incidentally, has had three contractors come in (to certify system for a future owner of the house) and state different issues with the system, among them, no Hartford loop.



Can anyone please help me understand the logic behind this so I can correctly explain the lack of the Hartford loop in layman's terms to my friends?



Thank you,

Mike

Big-Al_2

Dry Return

It's based on the first rule of plumbing:  Sewage runs downhill.



The Hartford Loop is there to keep boiler water from draining out of a leaky wet return line . . . meaning a return line that's lower than the lowest permissable water level in a boiler.  It's basically an inverted trap. It makes the water in the boiler flow up before it can drain down into a wet return . . . and it can't . . . drains always flow downhill.  Since a counter-flow main is by definition higher than the boiler, and water can't drain upwards, there is no need for a Hartford Loop.  The same is true for a parallel flow system with a dry return, providing that the return is connected to the boiler well below the water line.   Installers and inspectors who don't understand its purpose, those who don't grasp the first rule of plumbing, will insist on a Hartford Loop on a dry return . . . but in reality it just adds a low spot in the pipe to plug up with sediment.

Luv'nsteam

Big Al,

Thank you.  That helps alot.



Mike