Two Pipe System

Terry_10

I have a two pipe (early 20's) system with Mouat return traps. Recently in refinishing some floors I removed one radiator. I thought that by shutting the inlet valve I could temporarily do this with the system still up. To my suprise (or ignorance) when the system fired and steam began to flow, it was now also coming from the return side of the piping. Is this the norm on a second floor run?
Also when the system shuts down I'm getting water hammer in the return line close to the main air vent where both supply and return lines come together, before they drop towards the boiler. The return at this point also becomes to hot to touch. I have also found another area of the return that is also quite hot! All of the lines have proper slope, so could it be possible that when the boiler was replaced the water line has now changed and is backing into the return line? I must also say that I'm heavily into the "Lost Art of Steam Heat" and really appreciate this sight and all of your help!

Unknown

Check this out

http://hvac-talk.com/vbb/showthread.php?threadid=49460

Noel