Mills System Riser Vents

BRader

Hi All. Working on an old Mills system in our local community center. This system has been heavily modified in the basement area, to the point that the basement functions kind of like a trapped two-pipe system, but the rest of the original system is one pipe. We're trying to get the venting, or lack thereof, corrected. Adding main vents in the attic is no big deal. I would like to vent the bottoms of the risers. The only catch is that they end in the restrooms on the basement level. They are worried about having main vents above the kids using the restroom in case they would spit out hot condensate. I really don't think this will be a big problem, but I'm looking for other solutions and/or ideas. Do you know of any vents that are less prone to spitting than others? I know in a properly working system it's not an issue, but it's hard to convince people who haven't had a properly working system in decades.

EBEBRATT-Ed

In a Mills the main supply goes to the attic and circles the attic with branches off the main dropping down. I would put the vent in the attic at the end of the main. The only problem with this is if the vent leaks it could ruin a ceiling before it is noticed.

If the end of the main drops down to a visible location I would vent it their if possible. But I would go in the attic and look for failed vents first.

Steamhead

You could always pipe the vents out of the critical area. We've done this- go here and look at the fourth pic in the gallery:

https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc/

BRader

Steamhead said:

You could always pipe the vents out of the critical area. We've done this- go here and look at the fourth pic in the gallery:

https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc/

That's a really good idea and would be possible to do and even hide since it's above a dropped ceiling. Thanks for the tip!

BRader

EBEBRATT-Ed said:

In a Mills the main supply goes to the attic and circles the attic with branches off the main dropping down. I would put the vent in the attic at the end of the main. The only problem with this is if the vent leaks it could ruin a ceiling before it is noticed.

If the end of the main drops down to a visible location I would vent it their if possible. But I would go in the attic and look for failed vents first.

We do plan to add vents to the main in the attic. There's currently only one tiny vent for the entire 6" main and it's not at the end. Unfortunately the far end of the main was cut off and capped years ago. We suspect that it was probably vented out there somewhere, but it's no longer there, so hard to tell. We're going to add vents at the top of the main riser to the attic and at the end where it's capped. The one at the top of the main riser will be above a ceiling, but I think we can get it setup so leaking isn't an issue. We also wanted to vent all the drops at the bottoms so that the steam gets distributed faster instead of just relying on the radiator vents. Most of the areas aren't a big deal but these restrooms could be an issue. We'll probably try Steamhead's method of remote venting.

Mad Dog_2

Use Big Mouths and pipe out like a relief valve in copper to an area of safe disposal.
OR, Use Gorton #2s and make a Small copper drip pan and pipe out the same way. Mad Dog 🐕 

BRader

@Mad Dog_2 That's a good idea as well. I like Big Mouths, but they do tend to spit. They wouldn't be hard to pipe out since they're threaded on the outlet already.