Steam: Two Pipe, vent broken?

Charlie_5

Help: I have a 2 pipe 1935 steam system. No pumps for condensate whatever. Wet returns go under the basement floor (just replaced!).

Question: There is a vent on the pipes near the boiler that has a screw cap which and I think parts are missing. [The vent is about 8" high, round and is near a 2 foot high cylynder.] Under the cap there is a nipple that the air goes in and out. Is there a missing part such as a spring and washer???
With this vent open the bolier creates no pressure, but with it closed it creates pressure until the pressure control cuts off (~4lbs).

Thank you!!!

Thad English

sounds like your main vent is missing

Charlie,
Is this screw-cap at the end of one of your mains? If it is, it sounds like you are missing a main vent. You need one (or more) for the system to run efficiently. Do your radiators have vents on them?
I would recommend lowering the setting on your pressurtol to less than a pound. Anything above that and you are wasting a lot of fuel (be it natural gas or oil).

Fred Harwood

vent

Sounds like the air vent on your dry return receiver/air separator. Do not block this hole. Blocking it will trap air in the system. Building pressure is not important. If air can get out of the mains and radiators, steam will condense in the rads. If the rate of condensation almost equals the rate of steam production, you get beautiful heating with no pressure buildup.

Steamhead

Is this a Trane Vapor system?

It sounds like the 2-foot-high cylinder might be a Trane Direct Return Trap, and the screw-cap on top of the vent might have held a tiny vacuum check disc (but no spring). Does your vent look like this one, without being clamped in a vise to hold it steady for the photo?

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