One pipe steam rhythmic tapping

Dave_61

We have one pipe steam. On one or two radiators (large tall cast iron), we get this rhythmic tapping for several minutes until the radiator heats up. It’s about one tap a second. Never a bang. Then it slows down and stops after a couple minutes. It sounds like it’s coming from the first third of the radiator closest to the shutoff valve. I put a level on it, and it is tipped toward the valve. New vent on it too. Any other ideas? Thanks

Jamie Hall

That's almost surely an expansion noise. While it can be in the radiator itself -- check that the tie rods are not loose (they mustn't be more than barely over finger tight -- they break really easily! -- but they shouldn't rattle) -- but it's just as likely to be the radiator as a whole trying to expand and being resisted by the floor. Try putting some heavy plastic -- I like sections cut from milk jugs -- under all four feet.

the_donut

Could also be the riser rubbing against the floor. Check clearance and cut around floor if necessary.

Dave_61

Thanks guys. I’ll check it out