Gas and Oil Home Heating Furnaces - REpalced REturn pipes. Now they are very noisy

I have steam heat. This year the water started to leak out of the return pipe so I had to refill the boiler every day. Most of the return was under the floor. The plumber decided to replace them with copper and keep them above the floor. Now the are noisy. Youu caan hear the water in them also you can hear knocking.
Firstly I want to wrap the exposed pipes. What material is best to wrap your heating pipes.

Secondly, any suggestions as to how to cut down the noise. I suspect it is because the pipes are mostly above the floor now and the copper is lighter than the priginal pipes that were there.

Copper is not a good choice of material to handle steam. It is a marginal material for condensate. My guess is that your near-boiler piping has been altered and that is creating the noise. The banging will occur where steam meets a thin layer of water. It would be enormously helpful if you could post photos of the return piping near the boiler and what was changed. If that isn't possible, just look at the new pipes and make sure thay all pitch toward the boiler. Some of your noise could come from contamination in the boiler water from draining, disturbing, and refilling. How long has the system been operating since the repairs?

Question? Could the fact that the pipes are no longer below the floor cause this noise also. I will check on all the othe questions and reply. The system went through the last half of last heating season.

Did youhave any answer to the question on what materials to use in wrapping steam pipes.

The best material to use is fiberglass. You can buy pre-formed pipe insulation in all sizes. It is a hard fiberglass with a white covering. It is easy to use and does not leave fiberglass exposed to the room. HD may not have it but a good plumbing supply house will.

You would have heard the noise from the other pipes even though they were under the floor.