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Main Venting w/ diagram

Polycarp Member Posts: 135
Thanks to Rod for the great responses to my last post (<a href=""></a>). If anyone else wants to weigh in, I'd appreciate it. In that post, I promised diagrams of what I was thinking for the main vents, so here they are.

The short of it is that I have cold rooms on my furthest riser, most likely because I have no main vents. I'd rather avoid tapping my main (the last operation on the main resulted in the need to replace a section), or cutting it apart to add fittings. But I do have a run-out for the kitchen radiator just about 24" from the end of the main. Is there any reason that I couldn't also pipe the vents in here?

As you can see in the first diagram, the run-out branches vertically from the main .. a definite no-no. (Incidentally, I imagine this is making my steam (more) wet and contributing to my cold radiator problem.) So, my thought is that I can fix both problems at once: rotate my connection to leave the main at 45 degrees and then pipe the new main vents (either in an antler like I've drawn or a menorah) into the newly configured run-out. I'd include a union and a y-strainer to the vents.

So, my questions are:

- Is this approach kosher?

- If it is, do I need more than the 1 1/4" pipe before the split between vents and radiator? I figure it is either venting or supplying steam to the radiator, never both, so it should be fine.

- Did I miss anything?

Thanks in advance guys.


  • Main Vent Location

    Looking at your drawings I'd say it would probably work okay though if it were me I 'd put the vents between the radiator lateral tee and the elbow at the end of the main. Just cut the pipe and attach a short nipple and a separate tee for the vents and then use a union and nipples to connect back to the original "Main end" elbow.  You're probably going to have to cut the pipe anyway to be able to turn the lateral tee to the 45 degree.

    Make sure to use at least 1/2 per foot of slope on the radiator lateral. 

    I'm not too fond of mixing things together on the same pipe if it isn't necessary and giving the vents their own tee would get them farther away from the condensate. There is the chance that the having returning condensate in the same pipe would cause the vents to "spit"

    I think you'll be amazed at how much having the main vents will benefit your system.

    - Rod
  • Polycarp
    Polycarp Member Posts: 135
    Upstream vents

    I've been thinking more about my approach...

    The configuration and condition of the pipe beyond the kitchen run-out lateral T may not allow me to put the vents there.  However, I know I can put the vents upstream of the kitchen runout.  It would put the vents farther from the end of the main, but it would separate them from the radiator run-out.  So while neither is ideal, which do you think would be better?

    Thanks again for all your input.
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