LOUD noises in water pipes
Posted by Charlie Bain on January 09, 19100 at 15:15:44:
My pipes have developed a VERY loud noise. Much like water hammer; but it happens most often at
night, when no water is in use (this morning at 4 AM!). It sounds like a mad-man is in the basement,
trying to yank the pipes out by hand. The noise starts moderately (perhaps 5 - 10 thumps, then builds
quickly to a house-shaking series of another 5 - 10 thumps, and ends with a giant final thump. It lasts
less then 5 seconds. Usually, there is a second, less violent series within 2 minutes of the first. It
typically happens once a day, late evening or night; been going on for about 3 weeks. Only 1 time has
any water been in use when the noise starts; absolutely no hammer from faucets, washer, or toilets
during normal use.

Some history: several months ago, the PRV on the water heater starting leaking, so I replaced it. The
new PRV leaked also: after a month, I replaced the water heater (it was 20 years old). The new water
heater "burped" water all over the basement the very first night, and several days after that.
Plumber said the line pressure was 90 PSI, and the house pressure regulator was bad. Had the
pressure regulator replaced and an expansion tank added in front of the water heater. No more "burps",
but the loud noise started. Water pressure (measured at water heater) is now 60 PSI. Installed foam
pipe insulation and metal pipe straps every other floor joist in basement. Put a hammer arrestor on
the cold water line at the washing machine, just to spend money. But still have the noise. Once time,
the noise started and I turned on the water: hot water was steady, cold water pulsed somewhat with the
noise. Opening the faucet didn't cause the noise "cycle" to stop.

Could this be coming into the pipes from outside? Is there "recording" water pressure guage that would
capture what the water pressure is? Could it come from a defective pressure regulator?

Any suggestions would be greatly appreciated.


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