Loop seal?

Paul S_3

Is this a loop seal? It looks a little different....i saw this pic on instagram they say theres about 10 of them in the system....maybe at the ends mains....its a one pipe steam system and the bottom pipe is all wet .... I dont see a point for this

Danny Scully

Hmm, false waterline more likely. Or, as always, could have just been a knucklehead!

EzzyT

That is a Loop Seal

Paul S_3

@EzzyT you are correct but @Danny Scully brought up a good point about the false water line with the inverted u seal

EBEBRATT-Ed

Don't see a need for it unless the return line was above the boiler water line. Seems like they must have had a reason.................??

In the old days they counted every fitting, hard to believe they did this by accident.

nicholas bonham-carter

A false waterline is a little more complicated and would handle all the wet returns next to the boiler.
Maybe those dry returns are pretty low at that point, and with too high a pressure, the wet return waterline would obscure the main vent, without that configuration.--NBC

DanHolohan

Loop seal

MilanD

Did this allow dimension "A" be less than 14", (18" being preferred)?

Steamhead

Is there a condensate or boiler-feed pump at the end of that return line?

DanHolohan

I would think there would be a condensate pump. Otherwise, why trap that main?

Mad Dog_2

Love those return bend fittings...mad dog

Paul S_3

there is a condensate reciever

Steamhead

That explains it.

The advantage of a loop seal over a trap is that it does not have any moving parts. The disadvantage is that it will not vent air, so you need a main vent to do that. But if a vent fails, it won't let steam into the return and cause banging.