Over the past couple of weeks we’ve been hearing this humming sound in
our home’s plumbing system. Today I isolated the problem down to a humming
toilet tank fill valve in our downstairs bathroom.
When I first started hearing this humming noise I thought it had to do with
a plumbing supply line, but I was not totally convinced of this due to the
frequency of the particular hum. It was a very low frequency hum that
crescendoed in volume from a low whisper to a loud reverberating sound,
before fading away again.
The sound was very audible on
both floors of the home. After a week of trying to figure out what was
causing the sound I discovered our downstairs toilet was the culprit.
After thinking about this situation a bit more, I began to contemplate
that there was something caught in the vent stack that was causing the
sound when the toilet was flushed. Again, the sound was so deep and
hollow sounding I concluded it could not have been the cold water supply
Photo by Mark Donovan
On the other hand, I was
baffled on why only the toilet would cause this humming sound since all of
the plumbing fixtures are in effect tied to the plumbing vent stack.
Today, however, I discovered I was partially wrong. When I flushed the
toilet I lifted the lid on the toilet tank and watched and listened as the
toilet tank filled. When the water reached the appropriate height to shut
off, the toilet began to resonate with the crescendoing hum.
What I observed was that as the toilet tank fill valve began to shut off,
caused by the height of the float ball, the arm and float ball assembly
began to vibrate.
As it increased in vibration the toilet tank began to hum in a low frequency
growl. The hum increased in volume until the toilet tank fill valve began to
finally close off the flow of water to the tank. As the tank fill valve
finally closed off the hum faded away.
So in the end the hum was associated with the supply line, and more
specifically the toilet tank fill valve shutting off. As the fill valve shut
off, the float ball and arm began to vibrate and resonate within the toilet
tank, and thus caused the low pitched hum.
To resolve this problem I adjusted the small screw setting on top of the
toilet tank fill valve. The hum seems to have now disappeared. If it
reoccurs I plan to replace the toilet tank fill valve assembly altogether.
So if you ever hear a loud low moaning sound in your plumbing system check
the toilets. You may have a toilet fill valve that is in need of repair or
Plumbing - Toilet Repair / Toilet
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Toilet Tank Fill Valves and other Toilet Parts from Amazon.com