Venting the mains

Mike Parvin

We have a one-pipe steam system servicing our NYC coop.
The header feeds four serperate mains. Three of the mains are 2.5" in diameter and one is approx. 5" in diameter.
There are no vents on the mains and the system short cycles.

The initial step in addressing this issue has been to identify locations for venting the mains.

The problem I have is that only the largest main has a horizontal run that can be vented 15" after the last riser. The other mains are more like risers that have wet returns where everything is verticle and there is no place to attach a nipple and a vent.

The questions I have are:

1. Should every main be vented or is venting the largest main sufficient?

2. What's the design for venting a main without a sufficient horizontal run after the last riser?

3. What's the design for venting a main where there isn't enought room to the ceiling to run a 6"-10" nipple and air vent?

Thanks for any feedback you can provide.

Mike Parvin

Not enough room to vent the main

We have a one-pipe steam system servicing our NYC coop.
There are no vents on the main and the system short cycles.

The initial step in addressing this issue has been to identify a location for venting the main.

The questions I have is what's the design for venting a main where there isn't enough room between the ceiling and the pipe to install a 6"-10" nipple and air vent?

Thanks for any feedback you can provide.

Steamhead

What I usually do

is drill into the side of the last tee on the main and tap it for the proper size pipe thread, install a short nipple and elbow in the hole, then raise the vent as high as clearance will allow. I've never had a problem with this method, even though it's not the optimum configuration.

Next step is to determine what vents to install. To do this, measure the length and diameter of your mains and post the info here. We can tell you what's needed.

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Mike Parvin

The length and diamater of the main

The O.D. is 3.5" and the length is 366" ~ 30.5ft

Steamhead

That's 3-inch inside diameter

Start with one Gorton #2 vent. This is the biggest steam main vent available. If the main is still slow, add a second Gorton #2. Drill and tap a 1/2" hole for each of these vents.

If you have trouble finding Gortons, go to www.gorton-valves.com and get in touch with Ken Kunz. Tell him I sent you.

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Mike Parvin

Thanks

Thanks Steamhead, will do as you've suggested.

I think there's enough room to install the #2 but since it's 6 3/8" tall I don't think I'll have much of a nipple after the elbow.