Should main vents close if on a return?

Kjmass1 · 2:50PM

We did some re-piping (highly regarded local installer) for a basement remodel. A main was shortened by maybe 40%, and 3x takeoffs were installed at a smaller size so we could route through joist bays. The 2x #2 air eliminators were then moved to the return pipe about 10' past the main for ease of access. It doesn't seem like the main vents close any more, and don't get hot. Trying to adjust the steam timing to those radiators on that branch and didn't know if I needed to add even more venting.

Steamhead · 3:11PM

Did they maintain the proper pitch on the main and return? Did they reduce the size of the main?

Jamie Hall · 3:14PM

Not clear if this is a one pipe or two pipe system. If it's a two pipe system and those really are dry returns (see various snarky comments!) then no, the vents on the returns should never see steam and therefore should never close.

Kjmass1 · 3:34PM

Sorry 1 pipe steam. plenty of pitch.

Jamie Hall · 10:10PM

The vents on a one pipe steam main extension — like yours — should see steam (after all, there's nothing to keep steam from reaching them!) and should close. Furthermore, the steam main (what you are calling a return) should get steam hot.

If not… there's a problem somewhere, and the vents can't do their job of venting that main. You don't need to add more venting — but you do need to find out where steam is stopping and why, and fix that.

Should main vents close if on a return?

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