Two pipe steam ?

Steamhead (in transit)

this could be a number of things. You will have to take a closer look at the system to see just how it's put together.

If the building is in fact 120 years old, and the system was put in when it was built, this could be a "two-pipe, air-vent" system. This system has shutoff valves on the supply AND return radiator connections, and an air vent on each radiator.

Where it differs from later systems is that the return lines handle condensate ONLY- NOT air. If this type of system has dry returns, they must NOT be vented. Of course, the steam mains must be vented as we usually do. If you want to put TRVs on this system, you must use the air-vent type as you would on a one-pipe system.

If the radiators have the usual Vapor-style connections- a steam supply at the top of one end and a trap (or other device) on the return connection at the other end, those radiator vents do not belong there. The dry returns on this system are supposed to handle the air as well as the condensate from the radiators. Somehow, the air is not being vented properly. Find the problem and fix it, and get rid of those radiator vents.

If you're not sure what it is, take some pics and post them here.

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HAROLDS

Two Pipe Steam ?

My company is starting a new project which we have to replace steam atc valves at all radiators along with the traps, while at the site today I found most radiators also have vents. Any one know why? I was always told two pipe does not need vents. The building is 120 years old.