radiator vents strangely, not heating

Campo

I am working on an old two-pipe/air vent system in a large office building. A large, upstairs radiator which is at the end of the line (farthest from the boiler) is not heating properly. I have replaced the main line vent with a Gorton #2 and there appears to be no problem with the steam quickly reaching the end of the main in the basement. The problem is that it is not getting upstairs well from this point. I figured that the size of the radiator would require me to drill and tap more vents one it. However, when I removed the existing vent to see if less restriction would allow the steam to rise quicker, I noticed that air was actually being sucked into the radiator. My qestions are:

1) Was this just caused by the steam condensing at the end of the cycle?

2) Would a vacuum-inducing vent actually be a good idea on just this radiator becase it would help to suck any remaining steam toward it at the end of the cycle?

3) What would happen if I put a small vacuum pump on this radiator? (not permenantly but just because I am curious)


Thanks for all your help.

Campo

Steamhead (in transit)

Check the pitch

on any horizontal pipes feeding that rad. My feeling is you have a water pocket somewhere.

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