This job was an interesting one to encounter. It was in a house that a contractor had built an addition on and ''rearranged'' the steam system for the radiators of the addition. So for the next couple of years the homeowners got the pleasure of listening to their steam radiators gurgle. It was truely musical. I told the homeowner that it was ''impressive''. She didn't have a sense of humor about it tho. What the contractors did was to install under sized pipes. The pipes were all ''valve sized'', which is not how its done. The pitch of the pipes was also not correct. And they used all copper pipe which will just shorten the life of the boiler. They used whatever insulation they apparently had on hand, which didn't fit well. So we got the job to redo basically everything they touched. We repiped with cast iron fittings, steel pipe. Installed 1'' fiberglass insulation and covered the fittings in old school fashion. We redirected the steam main and return main to stay on the same side of the girder and staircase as it had always been on. The builder notched a main girder (which is not allowed) and moved the steam mains to the other side. They had sags which held water pockets. So we just took it all out and redid it. Now they have a quiet house.