Steam Return Piping

Matt_28

Hello, I had been told that I should change one return pipe leading from the Main on my one pipe system. I have two returns that head toward the boiler, each has a main vent, but one connects to the other just under these vents. Then, one pipe connects to the bioler below the water line.

I have been reading alot about main venting and decided to take off my vents to make sure they were not clogged, plus I wanted to see what type they were. The vent that is leading into the other was clean inside and the other that has the straight run down to the water line was filled with rusty sediment. I could blow through both of them without a problem.

My question is, should I repipe the second return to connect below the water line or is the connection above the water line okay. I do have some beginning, middle and end hammer on the main that is connected above the water line.

Thanks for you advice
Matt