Question about venting steam radiator?

I have a vertical steam radiator, steam inlet at the top and water drain at the bottom. See link for a picture, but rotate it. I have had 3 different plumbers give me 3 different methods to install a vent. Right now I have a "trap" at the bottom, and it started leaking after a few years. Another plumber... show more I have a vertical steam radiator, steam inlet at the top and water drain at the bottom. See link for a picture, but rotate it. I have had 3 different plumbers give me 3 different methods to install a vent. Right now I have a "trap" at the bottom, and it started leaking after a few years. Another plumber said the vent is incorrect, and it should be at the top. Yet another said a proper vent at the bottom. What to do? what kind of vent? thanks

http://steamradiators.com/orderingpages/...
http://steamradiators.com/images/custome...
Update: The radiator manufacturer says no vents are needed in a 2 pipe steam heat system. Insists that is true. I also checked with a leading manufacturer of vents, and they could not offer any opinion.

rotate first link 90ยบ. Second link is as is.

problem is leaking vent/trap.
2 answers 2