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Soft Tapping Noise- In Walls?


Apologies, because I do not know any technical terms. So I will try my best to explain
Our house was built in 1949, cape style. We have steam heat radiators; they've always made some loud noises when the heat turns on. Recently we had our boiler serviced, and a piece of pipe replaced due to a hole and leak(main steam line?) in basement, and thats made the loud clanking/banging when it first turns on much better. Whats driving me crazy is for the past few nights, I've been hearing this very soft tapping noise at about 4am/5am. Almost sounds like dripping (but have not seen any signs of water damage). I am assuming this is happening before and after the heat kicks on (we're in NY, so it's starting to get cold). This noise is enough to drive me crazy, its not loud, its not banging .... just a soft "tap, tap, tap". The walls are plaster, and floors hardwood so is this an issue if we need to look behind stuff?


  • Long Beach Ed
    Long Beach Ed Member Posts: 1,212
    edited November 2022
    Probably an expanding pipe rubbing against wood or plaster as it heats up and cools off. The problem will be worse if the new piping is copper, which should not be used for steam carrying piping. Copper expands more than iron when heated. A good mechanic plans his work to avoid this interference with structural components. It's quite common.

    The replacement of the pipe section may have repositioned other piping causing rubbing far from the repair.

    Could also be a concealed leak, though unlikely. Things were upset when the work was done and this may have caused a leak elsewhere in the system. Watch that your water usage hasn't increased.

    If you have access, you can try shaking the pipe above and below or moving the radiator slightly to reposition the pipe from its interference.

    A properly installed and maintained steam system is silent.
  • ericasoldout1
    ericasoldout1 Member Posts: 2
    The new pipe replaced in the basement was black, it did not look copper. Last week we ended up with a hole in the main line in the basement, so thats what was replaced. I don't think the pipping in the wall is copper? Thats all original to the house, built in 1949. I don't believe we have access to the pipe because our bedroom is top floor, underneath us is the living room. Should we try bleeding the radiator?
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,212
    edited November 2022
    Steam radiators can't be bled; they're not filled with water. All you can do is try to reposition the pipe away from its interference. Try to look where it passes through the basement ceiling (the bottom of the subfloor above). If it's rubbing against the wood, that is creating your noise.

    Sometimes moving the radiator slightly, if possible will reposition the pipe enough to change things. Perhaps a hanger was removed from the basement pipe and it was not replaced, or was repositioned. Look for evidence of this and lift the pipe and secure it.

    Or call back the plumber and ask him to correct the problem 𝘵𝘩𝘢𝘵 𝘸𝘢𝘴 𝘢𝘭𝘭 𝘧𝘪𝘯𝘦 𝘶𝘯𝘵𝘪𝘭𝘭 𝘩𝘦 𝘨𝘰𝘵 𝘵𝘩𝘦𝘳𝘦.

    Plumbers get those calls often.
  • KC_Jones
    KC_Jones Member Posts: 5,742
    Couple things to process. If you had banging you had water were it doesn't belong interacting with the steam in a way to cause that. Steam should be silent always, any noise is a problem.

    Second, if you had a steam main (not a wet return) rust out, you definitely had water laying were it doesn't belong. I have a house built before 1900, steam was added "later" and still using the original stem mains in the basement without issue. Keep the water moving and the steam carrying pipes will last a very long time. Your system isn't really "old" in the context of steam heat so it's surprising you had a steam main rot out. I'd be looking around for slope, and possible places that water is laying. It will add longevity to the piping and quiet things down.

    As far as the original question, I agree with the above it sounds like expansion noise and could be fixed by adjusting the pipe location in the basement. I'd speculate when the steam main was worked on they didn't get things back exactly where they came from and now you are rubbing on wood.

    I agree the plumber should be looking at this, and honestly, if they knew what they were doing, would have mentioned the water laying issue that rotted out the main.

    Again, steam should be 100% silent, anyone that doesn't agree, doesn't know steam.
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