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Water Hammer or Expanding Pipe

FJL Member Posts: 354
I have a one pipe steam system in a four unit apt building. I get a certain kind of noise in the risers at the start of a cycle, and at no other time. It is louder than a knock or a ping, which I usually attribute to the expansion of the pipes. This sound is more like a click or sometimes a clank, and I get a series of these clicks/clanks as the steam is approaching in the riser, and then nothing after the steam passes in the riser.

I've had a water hammer problem before due to a back-pitched pipe (but the pipe has been replaced and repitched), and what I hear is not as loud as the water hammers I used to get. The clicking/clanking sound is in the riser connected to the just repaired, repitched pipe. The only other thing of note is that I had some ceiling work done over the summer, and the worker replastered the ceiling to fill in the void that usually exists around the riser as it enters the ceiling. Over the course of the winter, the plaster around the riser has cracked and fallen away as the pipe has expanded.

I also get some of these clanking sounds in at least one other riser as well.

P.S. The clanking sounds are more numerous at the start of a cycle coming off a setback, as opposed to the second cycle or more after a setback.


  • Fred Harwood_2
    Fred Harwood_2 Member Posts: 195

    Sounds like common pipe elongation as it warms. The sounds a small creep can produce are varied, and can be loud, depending upon the product being rubbed by the pipe. Locating and fixing the noise can be problematical, especially when pipes are in walls, floors, etc.
  • FJL
    FJL Member Posts: 354
    Finding The Cause

    So can one of these situations be the cause?

    First, can the simple fact of replacing a stretch of pipe, in my case a seven foot length of pipe, create expansion type noises that did not exist with the old pipe? I'll never know for sure if this is the case because the old pipe created water hammers. But I'm just curious.

    Second, can the fact that my worker plastered in the space that usually exists around the pipe as it enters the ceiling cause this kind of noise? Is it worth a try to dig out some of the plaster around the pipe so it can expand more easily without rubbing into plaster?
  • Jamie Hall
    Jamie Hall Member Posts: 23,675
    yes and yes

    it takes very little change in contact for a pipe to start making expansion noises where none were before! Sometimes just a change in the hangers will do it. And yes, anything touching the pipe can make clicks, groans, squeaks, and other fun-house type noises.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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