Click here to Find a Contractor in your area.
In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Need to contact us? Visit

New steam pipe LOUD BANGING!

I just finished a gut renovation of an apt in New York with a one-pipe steam radiator. The plumber had to replace a steam pipe that was leaking that went from the 6th floor to a small mezzanine/top floor. I know the plumber put in a slightly smaller pipe (3/4" ? instead of 1 1/4"?), but said that should be fine for a small mezzanine room. Now that the building heat is turned on, there is a ton of SUPER LOUD banging coming out of the radiator on the mezzanine every time the heat turns on. Wakes me up several times a night (and the neighbors, sometimes, too!). There is also an annoying tapping (almost like dripping sound) in the downstairs wall where this pipe was installed. The plumber insists that he didn't change the pitch. The upstairs radiator is sloped (slightly) towards the valve, which is 100% open. It is the same cast iron radiator that was in the room before, though it was kept in storage for a year while the apartment was renovated and the plumber installed a new valve and air vent.

Any thoughts on what we might be able to do to control the LOUD CLANGING sounds? The building has about 20 apartments, and my (top floor) apartment seems to be the biggest problem. I can ask the manager to bleed the system. Anything else they should try (adjust pressure, switch radiator?)


  • Jamie HallJamie Hall Member Posts: 6,851
    If he really put in 3/4 inch pipe -- I hope black iron -- it's going to bang on startup. Pretty well guaranteed. In fact, it might bang all the time. The minimum pipe size in the tables I have is 1", and that handles a maximum EDR of 28 for a runout. Pretty small.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • KC_JonesKC_Jones Member Posts: 3,249
    Need to put in the larger pipe, the plumber messed up and should fix it. And honestly should fix it on his dime.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • FredFred Member Posts: 5,495
    If it had 1-1/4" run-out to that radiator, why did he decide he could reduce it to 3/4" ? That is too small to supply steam AND allow condensate to return at the same time and is likely too small to support the radiator in that Mezzanine. Additionally, did he reduce that pipe to 3/4" on the horizontal? Depending on how he reduced it, it may hold water.
  • KC_JonesKC_Jones Member Posts: 3,249
    You will find after this experience "good enough" with respect to steam heating actually isn't good enough.

    Your contractor isn't knowledgeable with steam to have done that, I would recommend you don't ever let them touch the system again at least after they fix this mistake.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • JohnNYJohnNY Member Posts: 1,852
    Wow. Any plumber working in NYC should at least know that much. Yes, the ¾" pipe has to go. I'm surprised your Super allowed that to happen.
    For private consulting services, find John "JohnNY" Cataneo here at :
    "72°F, LLC"
    Or email John at [email protected]
    Or at Gateway Plumbing & Heating
    John travels regularly to out-of-state clients for consulting work.
  • MilanDMilanD Member Posts: 965
    Aaaand, there is nothing your super can "bleed". This is not hot water with trapped air.
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!