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which way should main steam pipe from boiler pitch?
I realize this is probably a really dumb question, but I can't find a clear answer either on this site or in "We've Got Steam Heat."
We just had a new boiler installed for our 2-pipe system and we are experiencing major hammering shortly after the boiler fires up. It's pretty clear that the hammering is happening where the horizontal supply pipes in the basement meet the risers: you can see and feel them moving, and see paint and plaster flaking off from the vibration. We rarely had any hammering with the old boiler, just sometimes on really cold days. The installer says it can't be anything they did, as they put in exactly the same model boiler as before and nothing changed.
However, I see that they raised the supply main above the header in relation to where it was before: they had to cut away to insulation to install an new strap and they cut the original pipe straps. Could that be the problem? If steam condenses into water in the supply main, is it supposed to flow backward to the boiler, against the direction that the steam is moving, or should it flow in the same direction as the steam and eventually make its way into the return pipes?