Vapor System Venting

Steve_Pgh

I have the pleasure of working on a Webster "Modulation" vapor system from 1916. Many of the original rad valves and traps are still there including the "Venttrap" at the end of the dry return. I need to find a vent for the top of the Venttrap/air eliminator. From reading on this amazing site, I imagine vent selection is critical since it is the only vent for the system. Are there tables available to help size and select the vent? And of course, size is an issue... I only have 7" between the vent casting and the ceiling above. The original Webster Modulation Vent Valves looked to have a very low profile.

Jamie Hall

Didn't leave you much room, did they?

You will probably need at least two Gorton #2s on that -- you may find that more are recommended, but that would probably do it.  However... an antler with those two on it will need 12" to 14" vertical above the dry return, even with close nipples.  Which you don't seem to have.  Can you, by any chance, cut a recess into the ceiling where they could be put?  I did that, and it works fine -- but then, my basement isn't particularly finished (although it was a plaster ceiling).



There is another possibility, which I have never seen done and haven't tried myself, however -- but I can't see why it wouldn't work.  Maybe one of the real steamfitters (I'm just a building superintendent) can tell me why it won't.  Go up off the Webster fitting with a close nipple, 90 degree ell to one side, say 6" nipple, 90 degree ell down, say 10" nipple, T with leg to one side.  Take the antler off the leg of the T.  Continue down from the other side of the cross bar of the T to somewhere (there must be somewhere!) where you can tie into the wet return.

Steamhead

If that vent trap

has 1/2" plugs in the side, you can remoce the top one and add a vent there. These tappings were originally for a sight glass.