One Pipe System - Boiler Removed, possible solutions using plant steam

APM

I have a pretty good understanding of both one pipe and modern two pipe systems. I am at a facility built in the late 1800's in NYC. The system was originally a two pipe system with no traps - 1-1/2" in, 1-1/4" out to direct the flow of steam. There have been TRV's, TD traps, Thermostatic traps installed and air vents removed, etc randomly throughout the building which is running at 10psi and not to my surprise having a lot of issues. I can remove all the traps and TRV's and replace the air vents and drop the pressure to 2PSI, but the biggest concern is they have removed the boiler and are using plant steam.

I've attached a picture (very rough) of my thoughts on how to remedy the system without doing a major project of turning it into a modern 2-pipe system.

Steps (after returning radiators to original design):
Drop pressure to 2PSI
Add Temperature control valve to allow system to 'breathe'
Install high capacity trap at the original water level of the boiler - hopefully this would keep a level of condensate in the system that would simulate the original design. Condensate would exit thru the trap as the t-stat called and more plant steam was introduced.
Condensate tank could still be used and condensate returned to the plant.

Thoughts?

nicholas bonham-carter

You are right about the pressure being too high., so throttle it down to ounces.
What is the need for the system to breathe?
As we all know here, "air is the enemy, to be chased out, like the raccoon from the garbage cans".
I would make the traps, and return main venting work as originally installed, and go from there. Probably a false waterline could handle any problems from the returns going dry.----NBC

APM

Correct me if I'm wrong, but in a system like this you would have the steam turn on, push the air out of the system thru the air vents. Then the steam turns off, steam condenses, and the air vents allows air to fill the radiators. That's what I mean by "letting it breath".

I only bring that part up because I have run into boilers that have been upgraded and are now running at constant pressure instead of cycling like the one-pipe system needs to do.

nicholas bonham-carter

You only need cycling when you are using TRV's, which in this case are probably band aids against overheating in an unbalanced system.
I think you could run this system in a vacuum, and get variable temperature steam into the radiators.--NBC

JUGHNE

What happened with coal fired boilers on one pipe systems?
Maybe over night only cycling.

AMservices

https://drive.google.com/open?id=0B-5hKw5FhaA4RndtYjcxOWFSYWM

https://drive.google.com/open?id=0B-5hKw5FhaA4am1Eb2VyaUNwR3c

You want to make a better steam system?
This is how it's done.