Help identifying, replacing main air vent

KenF

Hi,

We have a single pipe steam heating system with an oil boiler in a 100 year old three-story Victorian home in Philadelphia. It has had an assortment of ailments, including serious water hammer at morning start-up, leaking air vents, and excessive hissing. I got a copy of Dan's book "We Got Steam Heat" and have been trying to address what issues I can before calling an expert.



Increasing the pitch of the largest radiator on the second floor has greatly improved the water hammer and leaking issues, but we still get excessive hissing, and my guess is that it's a malfunctioning main air vent in our basement. When the system is at full blast, I can't hear or see any evidence that air is venting, and the pipe is very hot just before and cold after the vent. It's about 5" tall from the base to the top, and around 3/4" where it screws in. (I've attached a couple of pictures) How can I identify which exact model and size to replace it?

Thanks!

Rod

Need Pictures

Hi- Your pictures didn't post . The only files the board software accepts are jpg and pdf

- Rod