On Thu, 15 Mar 2007 12:47:08 -0500, "dnoyeB" wrote:

On Thu, 15 Mar 2007 10:17:31 -0700, Ike wrote:

For the past 3-4 years, we have heard an intermittent
humming/vibration sound in our house. The sound is loudest in the
master bedroom (of course) and eminates from the wall on my side of
the bed. The sound is loud enough to hear in most parts of the house.
I have gone to great lengths to find out what is causing this sound.
This past weekend while replacing the auto-fill valve on our pool I
finally discovered how to make the sound stop.

In order to replace the valve I had to turn off the water supply. As
soon as I turned the valve, the humming stopped. After replacing the
auto-fill with a new one and turning the water supply, the humming
returned. Turning off the auto-fill every night so I can sleep is not
a solution.

There is a back flow preventer valve on the auto-fill line.
Considering the auto-fill valve itself is new, I no longer suspect it
as the cause of the humming. So now I suspect it is the back flow
preventer valve for lack of a better answer. Has anyone ever heard of
these valves making noise? What would be in their design that would
cause this?


That is a form of 'watter hammer.' Install a water hammer arrestor near
that valve. Its not a faulty valve necessarily. Its kind of like your
water pipes are out of 'tune'. What you hear is a harmonic vibration just
like a wind instrument. You can change the sound of a wind instrument
by opening and closing the path the wind can escape. A water hammer
arrestor kind of does the same thing. This can occur when you change the
structure of your piping by adding on some new pipes. Such as a pool, or
extra bathroom, etc. If it was there during initial construction, they
should have installed some arrestors already.

It can be somewhat bad for your pipes too as they are not designed to
sustain vibration like that indefinitely.

I am familiar with water hammer because we use to have a house that
had the problem. In this case the noise only happens when there is NO
water flow. When the swimming pool auto-fill kicks in, the noise
disappears.