2-pipe gravity return vapor system without main traps?

Garret

(I'm reposting in its own thread... I thought the old thread might be getting a bit unwieldy.
http://forums.invision.net/Thread.cfm?CFApp=2&Thread_ID=34889
)

A bit of a follow-up to the above discussion... I ordered all of Dan's books, and have been reading through em, trying to understand my system as much as possible.

Here's one thing I'm puzzling about. I have a two-pipe, gravity return, vapor system. I have traps on every radiator, but as far as I can tell, I have no traps on the ends of the steam mains.

I have two mains, that wrap around the basement, and meet on the other side in a tricky bit of piping. Basically, each takes a turn downward, and runs to the floor, where they meet and a pipe runs over to the wet return. There are vents at the top (there's a big hoffman on one, and I noticed there's a little metal vent tapped into the other one), but nothing on the bottom except a few T and elbow fittings.

If you'd like to see it, start at this photo, and take a look at the next four or five.

http://www.worksongs.net/photos/2006-02-Boiler-Replacement/slides/IMG_7899.html

In this arrangement, do I not need "end of main" traps at all? I've looked over the system several times, and I just don't see em.

Best, -Garret

P.S. Things are going well with my little project... I've had several contractors look over the system, and I think I've found at least one who knows what he's looking at. I'll keep you all posted on the process as we get further along.

gerry gill

it appears your

mains drop to a wet return..no traps needed..better air venting on the one would be in order tho..

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Garret

Ah, okay... that's makes complete sense. Steam can't get by water. Thanks, Gerry!