Help!! Steam expert in Allentown/Reading PA area?

though it should be secured to something.

This will have to be fixed regardless of what other problems there may be. The normal way to do it is to run both pipes separately in to a wet return on the floor and back to the boiler.

There are other options if that isn't practical.

It might have worked a little better with the firing rate of your old boiler or the near boiler piping or if the vents were poor on the other main but this is why that main is "slow".