I recently bought a house so I can't comment on history, but our
plumbing has a water hammer that occurs when shutting off any faucet
in the house. The hammer is delayed about 0.5-1 sec after turning off
a faucet (or toilet, or appliance).
Many of the pipes are pretty loose from what I've been able to
access. I don't know if there is a pressure regulator on the main
line. I've tried 'emptying the lines' in case the house does have air
chambers, but that made no difference.
Most postings seem to focus on specific faucets or appliances causing
the hammer, where as I have an overall hammer .... doesn't matter what
is turning off. The hammer doesn't happen if we slowly close a valve
or when some other faucet is running.
What would be my next step? How do I know if the house has a pressure
regulator? Is there an easy pressure test I can do? Install a gauge
on a water line? Find, fix, install main water regulator? What would
a main regulator (installed) cost?
Find where the line enters the house and follow it. If there is a
regulator it will probably be after the main shutoff. You can get a
screw on pressure guage that will go on one of your outdoor faucets.
Knowing the pressure will not tell if it has a regulator or not but if
it is higher than 50 to 60 lbs you could try adding a regulator to see
if that helps with your hammer. Does it hammer with both hot and
cold, or just cold? A small bladder tank can be added by inserting a
T into your line and that will probably solve it. It helps if you can
figure out where it is hammering. You need a helper for that.
I was getting a bang-bang-bang every time any water valve shut off.
Turned out to be the Pressure Regulator.
Usually located very soon after the main valve, before any fixture or
junction, although outside hose spigots may have been plumbed before
it to have street pressure.
There are <$15 Pressure Gauges that screw onto hose threads to test
the pressure. Adapters are also available. Look for something in the
45 - 55 range for normal house pressure.
The first house I ever rented had that problem . Found it when I went
to turn the water off to drain the sytem. Main valve was about half
open. Opened it the rest of the way up and no problem. Suspect this
valve may have also been bad.
It you;re interested in the mechanics, theory & how to address water
hammer check out the website
Get a water pressure gauge at the hardware store like:
(Amazon.com product link shortened)
First next step, measure water pressure at house entrance.
To minimize water hammer pressure should be 65 pis or less.
Determine if house has pressure regulator.
If yes, lower pressure & test water hammer behavior.
To minimize noise, secure pipes. Securing the pipes may less or
eliminate the noise caused by the water hammer but the hammer still
The hammer can be reduced or eliminated by lowering hose pressure or
installing water hammer arrestors.
At my house, the city water pressure is ~82 psi which I lower to 65
I have one hose bib before the regulator and it really has some decent
flow & pressure.
The hose bibs beyond the regulator have much more subdued
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