clog in a one pipe steam system???

Steamhead (in transit)

water standing in a pipe somewhere. This might be caused by improper pitch, or a plugged drip or bad trap (if used) at the bottom of the riser ("stack"). Or maybe a valve in the steam line is not fully open.

Listen closely for a boiling sound within the pipe when the steam is up. This will pinpoint the location of the standing water.

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tom_82

clog in a one pipe steam system????

Ok,
We have a fairly large one pipe system.
At the beginning of the season we turned our system pressure down to ½ pound cut in 2 pound cut out. We got pretty nice quiet heat throughout the thirty units except for one stack of units.
We do have some piping problems and were terribly under-vented.
We have begun to put in more vents and replace some bad vents, yet one stack of apartments will not get heat.
If we turn the pressure back up they get heat and the rest of us swelter.
The steam is still weak under their units. For example if you open the y strainer pipe over the trap the steam looks more like the smoke at the end of a cigarette. When you do this in other parts of the building the steam comes busting out.

Can this be a clog in a pipe somewhere. What would be a sign of a clogged pipe?
Any suggestions or comments are appreciated.
Thanks
TOm

tom_82

Thanks Steamhead!
This stack(three apartments) is at the end of a weird run. THe main stops, splits and double backs to these units. Tonight, my neighbor approached me just as I was going to the basement. She had no heat in her apartment.
I went downstairs and could see the pipes below the risers were only 100 degrees ( i have an infared heat gun). I opened up the y strainer, about a half gallon of h2o came out then I checked the pipes above the trap. They were getting warmer. I ran upstairs and removed the vents from her radiators and sure enough they SLOWLY got hot.
There are two hoffman 75s above this trap.
Thanks again for all your help.
Tomorow I am going to listen for water boiling. WHen I open that y strainer pipe the steam comes out in puffs.??

Steamhead (in transit)

Puffing steam

means there's some wave action in the pipe, almost certainly a water pocket or maybe the strainer is blocked where you can't see it. Pull the strainer element completely out and see what you find.

If all the risers were doing this I'd suspect wet steam from the boiler, but that's not happening here.

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tom_82

When steam encounters a pocket of water does it DIE on the spot? Or does part of it condense and some of it get beyond the water?
I am not sure I understand how this works.
Also, when the pressure was way up those units did get "some" heat. does this mean that raising the pressure allows (at a cost, finacially, not to mention the overheating in other units) the steam to keep pushing beyond the water and maybe dry out the pocket?

we are going to check around some more this evening to see if we can detect a water pocket.

ALso, if when I open the y strainer above the trap, which is located just below the two vents and the heat comes through, would that be an indicator that the vents are bad or insufficient?

Thanks again Steamhead
HAPPY THANKSGIVING!
TOm

Steamhead (in transit)

It depends

on a lot of things. Check everything. You'll find the trouble.

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