two pipe steam system with water hammer

Arnold NYC

Hi there for everyone!

I am working on a two pipe steam system in the past couple of weeks and now I need some help.

Basically I started installing steam traps on radiators that were missing them and at the same time I removed the little radiator release vents also correcting back pitched returned lines. Everything went well until I got into an apt on the 3rd floor (9th floor building) where you can hear the water entering the supply line probably from the boiler. (after turning off the boiler the main line was empty and clog free ). There is new vent on the top of the main riser but I think the system need a vent on the top of the return line plus some sort of air release piping or vent on the condensate pump. There are still apt without steam trap. One more thing I am dealing with the building engineer who said this is a very special system and the main main steam line just above the boiler need no vent (it is plugged, I don't know about that one) anyway I pasted his e-mails so you can read what he thinks. I will check the PH tomorrow. Water level pretty low and pressure is about 2PSI.
Please give me a hand to eliminate the water hammer and make this system working perfect.

Thank you very much!!!
Arnold

here is the e-mail let me know what do you think:

////////////////A main line air vent on the condensate return would be found in the boiler room of a building with a 2-pipe system with dry return, which is a configuration typical in many buildings today. Your building however has a 100+ year old pipe configuration that is best described (by me at least) as a "one-pipe, two-pipe" system. The system looks like a two-pipe steam system because there are separate steam and condensate risers, but functions in the manner of a one-pipe system, with air vents on eqach radiator and an absence of steam traps on radiators or in the basement.

We recommended (and continue to recommend) that radiators be reduced in size (except on the top floor) and be installed with steam traps during renovations. Radiators should also have air vents. The purpose of the added steam trap is to replace the oriface restrictors that were cleverely installed in the original steam valves that limited how much steam could enter the radiator to less than what could be completely condensed. This only works with large radiators.

There is no master air vent in the boiler room because air venting occurs at the individual radiators and through large vents at the top of the risers. As I recall, there are air vents on the top of the return risers also./////////