My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Malcolm Hoar wrote:

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Any other theories/inputs? Anyone else even observed
this effect?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~


Would you have well water? After filling for a while, would you be
hearing more water pressure when the well pump kicks in? Do you get the
same sound with just the hot water running?...cold water off.

avid_hiker wrote:
Malcolm Hoar wrote:

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Any other theories/inputs? Anyone else even observed
this effect?


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~


Would you have well water? After filling for a while, would you be
hearing more water pressure when the well pump kicks in? Do you get the
same sound with just the hot water running?...cold water off.



Have you every noticed how the pitch changes when you stir sugar into
your coffee?

In article .com, "avid_hiker" wrote:

Malcolm Hoar wrote:

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Any other theories/inputs? Anyone else even observed
this effect?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~


Would you have well water? After filling for a while, would you be
hearing more water pressure when the well pump kicks in? Do you get the
same sound with just the hot water running?...cold water off.

No well (or pumps) here. Regular city water supply.

I've generally noticed it with the hot faucet full on and
the cold faucet off.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

In article jVvph.138931$YV4.36926@edtnps89, Pason wrote:
avid_hiker wrote:
Malcolm Hoar wrote:

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Any other theories/inputs? Anyone else even observed
this effect?

Would you have well water? After filling for a while, would you be
hearing more water pressure when the well pump kicks in? Do you get the
same sound with just the hot water running?...cold water off.


Have you every noticed how the pitch changes when you stir sugar into
your coffee?

No, I only add coffee to my coffee ;-)

But I suspect you're describing a different manifestation
of the same effect. If so, the change is likely in the
reverse direction because I presume the sugar would make
the coffee more dense.

Your data suggests the effect is indeed density related I
think.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.
- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.

QED


Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Malcolm Hoar wrote:
In article .com, "avid_hiker" wrote:
Malcolm Hoar wrote:
However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Any other theories/inputs? Anyone else even observed
this effect?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~


Would you have well water? After filling for a while, would you be
hearing more water pressure when the well pump kicks in? Do you get the
same sound with just the hot water running?...cold water off.

No well (or pumps) here. Regular city water supply.

I've generally noticed it with the hot faucet full on and
the cold faucet off.


I've always thought it was the sound of the rubber gasket in the faucet
itself. As it heats up, it gets more pliable and thus its vibration
characteristics would change. It may even pop in or out, reducing water
flow....

Pure conjecture on my part, though.

CptDondo writes:

I've always thought it was the sound of the rubber gasket in the
faucet itself. As it heats up, it gets more pliable and thus its
vibration characteristics would change. It may even pop in or out,
reducing water flow....

Pure conjecture on my part, though.

I have no more authoritative a take, but am leaning toward it being
the warmer faucet bits than the actual water modulating the sound as well.

--
Todd H.
http://www.toddh.net/

Malcolm Hoar wrote:

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

I've noticed this as well. Regular copper pipe.

Chris

Chris Friesen wrote:
- Malcolm Hoar wrote:
-
- - However, I can tell when the water is hot by *listening*
- - to the flow. The sound of the water changes quite significantly
- - and I've been trying to figure out why.
-
- I've noticed this as well. Regular copper pipe.
-
- Chris

Chris,

What were you doing at Malcolm's house?

Sounds like it's all about the diffence in bubble-density between hot
and cold water. Google "hot chocolate effect". Here are a couple of
links:

http://www.acoustics.org/press/143rd/Rossing.html

and

http://www.kilty.com/coffee.htm

"Physicist Frank Crawford noticed this same effect in hot chocolate
(American Journal of Physics, May 1982), and explained it as being due
to the dependence of the speed of sound in water on the bubble density.
What we are hearing are longitudinal oscillations of the water column.
Crawford heard pitch changes of nearly three octaves in a tall glass
cylinder. Gas bubbles reduce the speed of sound in the liquid, which
lowers the fundamental mode of the liquid column. As the foam clears,
the speed of sound rises and so does the pitch. Crawford called this
'the hot chocolate effect.' "

---------------------------------------------------------------------
Malcolm Hoar wrote:

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

It's the sealing washer of the hot water valve that gets
soft when hot and muffles the vortex area around it.

On Thu, 11 Jan 2007 18:44:28 GMT, (Malcolm Hoar)
wrote:

My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?



I think it's the expansion of the metal in whatever
constriction is causing the harmonic in the first place,
but a reaction of an anti-scald valve to the hot water
would also do it.

In article , Ermalina wrote:
Sounds like it's all about the diffence in bubble-density between hot
and cold water. Google "hot chocolate effect". Here are a couple of
links:

http://www.acoustics.org/press/143rd/Rossing.html

and

http://www.kilty.com/coffee.htm

Bingo, we have a winner, I think. Thank you very much for
the pointer.

The hot water is saturated/supersaturated with dissolved air.
The aggitation caused within the faucet and the pressure
reduction on exit cause many bubbles to form. Hence a
"softening" effect not unlike that created by an aerator.

This seems very consistent with the nature of the sound
change I've observed. Much more plausible than a simple
density change effect.

Mystery solved, to my complete satisfaction, at least!

Back now to the regular schedule of electrical code issues
and broken appliances and other problems for which the
solution is caulk, duct tape and/or WD40...

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

DerbyDad03 wrote:
Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.
- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.


And ice is the thickest water of all...

Malcolm Hoar wrote:
However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Hot water is happy water.

"Hi, ho, hi, ho, it's off to work we go..."

Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~

I have seen this with well water and with a water-main system.


Cold water can hold more air in solution than hot water-
Water under pressure holds more air than water at 'room pressure'

The cold water that comes out 1st keeps its air in solution (at least
for a longer time), the hot water has its air come out of solution as
soon as the water gets past the valve.

The noise is the air bubbles forming or bouncing around etc...

Dave

In article .com, wrote:

Cold water can hold more air in solution than hot water-
Water under pressure holds more air than water at 'room pressure'

The cold water that comes out 1st keeps its air in solution (at least
for a longer time), the hot water has its air come out of solution as
soon as the water gets past the valve.

Yup!

The noise is the air bubbles forming or bouncing around etc...

Well it's not a noise created by the bubbles per se. But I am
persuaded that it's the bubbles that soften, dampen and change
the pitch of the sound created by the running water.

I have endured this "itch" for several years. It really does
feel good to finally scratch it ;-)

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.


How water is expanding parts in the valve, usually rubber washers.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~|
Malcolm Hoar "The more I practice, the luckier I get". |
Gary Player. |
http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

--
Joseph Meehan

Dia 's Muire duit

"Malcolm Hoar" wrote in message
...
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

I had a faucet that would do thid. If you just turned the hot on
a bit, when the sound changed, the flow dropped - almost
to zero. I figured it was the expansion of parts in the valve
since the effect was so obvious.

Bob

In article ,
Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~

It's definitely an observable phenomena. The effect of heating up the
faucet valve may be more significant than you think. Certainly you
have observed some types of faucets that greatly reduce the flow when
hot water reaches them. Another thing I can think of that may account
for a sound change, is that hot water has very little dissolved air in
it compared to cold water.


--
Make it as simple as possible, but no simpler.

Larry Wasserman - Baltimore Maryland -

Malcolm Hoar wrote:

My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

Physics class was one of the most traumatic experiences of my life, and
I didn't learn much there. But ... hot water is higher pressure, moving
faster, higher frequency across the joints? Kind of like a steam whistle?

On Thu, 11 Jan 2007 18:44:28 GMT, (Malcolm Hoar)
wrote:

My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

I have definitely heard it in my shower.
--
Mark Lloyd
http://notstupid.laughingsquid.com

"Properly read, the Bible is the most potent
force for atheism ever conceived." -- Isaac Asimov

On Thu, 11 Jan 2007 16:04:43 -0600, "HeyBub"
wrote:

DerbyDad03 wrote:
Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.
- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.


And ice is the thickest water of all...


Ice should actually be less thick, considering that water expands when
freezing.
--
Mark Lloyd
http://notstupid.laughingsquid.com

"Properly read, the Bible is the most potent
force for atheism ever conceived." -- Isaac Asimov

On Thu, 11 Jan 2007 16:06:00 -0600, "HeyBub"
wrote:

Malcolm Hoar wrote:
However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Hot water is happy water.

"Hi, ho, hi, ho, it's off to work we go..."


Sounds strange, but true in a way. Hot water is more excited.
--
Mark Lloyd
http://notstupid.laughingsquid.com

"Properly read, the Bible is the most potent
force for atheism ever conceived." -- Isaac Asimov

Mark Lloyd writes:

On Thu, 11 Jan 2007 16:04:43 -0600, "HeyBub"
wrote:

DerbyDad03 wrote:
Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.
- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.


And ice is the thickest water of all...


Ice should actually be less thick, considering that water expands when
freezing.

Ah, but, (to continue this physical science mental masturbation
session), it depends on how you define "thick." :-)

Per mass of water, ice is going to be thicker dimensionally because of
its lower density. Which was probably Bub's clever point.

Best Regards,
--
Todd H.
http://www.toddh.net/

In article , Mark Lloyd wrote:
On Thu, 11 Jan 2007 18:44:28 GMT, (Malcolm Hoar)
wrote:

My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

I have definitely heard it in my shower.

Yeah, there's little doubt in my mind now -- it's the
bubbles. The hot water is supersaturated with dissolved
air. It's agitated by passing through the faucet and
then subjected to a pressure reduction. All that air
is released in the form of bubbles. So what we hear
is the difference between a stream of water and a
stream of something approaching a foam -- very
different sounds.

I must say, solving this little mystery has been MOST
satisfying ;-)

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

On 11 Jan 2007 11:34:36 -0800, "DerbyDad03"
wrote:

Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.

This already has most of the heat of hot water (the TOTALLY
ARTIFICIAL) 0-point used in both Fahrenheit and Celsius temperature
scales hides this fact.

- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.

QED


Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~
--
Mark Lloyd
http://notstupid.laughingsquid.com

"Properly read, the Bible is the most potent
force for atheism ever conceived." -- Isaac Asimov

On Thu, 11 Jan 2007 21:44:46 GMT, (Malcolm Hoar)
wrote:

In article , Ermalina wrote:
Sounds like it's all about the diffence in bubble-density between hot
and cold water. Google "hot chocolate effect". Here are a couple of
links:

http://www.acoustics.org/press/143rd/Rossing.html

and

http://www.kilty.com/coffee.htm

Bingo, we have a winner, I think. Thank you very much for
the pointer.

The hot water is saturated/supersaturated with dissolved air.
The aggitation caused within the faucet and the pressure
reduction on exit cause many bubbles to form. Hence a
"softening" effect not unlike that created by an aerator.

This seems very consistent with the nature of the sound
change I've observed. Much more plausible than a simple
density change effect.

Mystery solved, to my complete satisfaction, at least!

There is a big difference between 200 degree coffee water and 130
degree tap water. I wouldn't be to sure that the coffee effect is what
you are hearing.

In article , wrote:

Mystery solved, to my complete satisfaction, at least!

There is a big difference between 200 degree coffee water and 130
degree tap water. I wouldn't be to sure that the coffee effect is what
you are hearing.

Take a bottle or can of soda. Heat it up to 130 degrees, shake
the container (c.f. water forced through faucet) and remove
the cap (water exiting spout)...

Yes, I realize that's an extreme case but there's little
doubt in my mind that there will be significant bubble
formation with the hot water faucet that could easily
account for the change in sound.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Malcolm Hoar wrote:
In article .com, wrote:

Cold water can hold more air in solution than hot water-
Water under pressure holds more air than water at 'room pressure'

The cold water that comes out 1st keeps its air in solution (at least
for a longer time), the hot water has its air come out of solution as
soon as the water gets past the valve.

Yup!

The noise is the air bubbles forming or bouncing around etc...

Well it's not a noise created by the bubbles per se. But I am
persuaded that it's the bubbles that soften, dampen and change
the pitch of the sound created by the running water.

I have endured this "itch" for several years. It really does
feel good to finally scratch it ;-)

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

I have had times when it was relatively quiet until the hot water
arrived, so I think its supportable the bubbles themselves (during
formation, or going through a restriction) make noise.

Dave

In article om, wrote:

Well it's not a noise created by the bubbles per se. But I am
persuaded that it's the bubbles that soften, dampen and change
the pitch of the sound created by the running water.

I have had times when it was relatively quiet until the hot water
arrived, so I think its supportable the bubbles themselves (during
formation, or going through a restriction) make noise.

Hmmm, I don't think that's an effect I've observed but you
make a good point. I can see how that might happen.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Oh the pain! The heartache! My "thickness of water" theorem has been
disproved!

And I thought I would be joining Mssrs. Smoot and Mather in Stockholm
next year.

Mark Lloyd wrote:
On 11 Jan 2007 11:34:36 -0800, "DerbyDad03"
wrote:

Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.

This already has most of the heat of hot water (the TOTALLY
ARTIFICIAL) 0-point used in both Fahrenheit and Celsius temperature
scales hides this fact.

- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.

QED


Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~
--
Mark Lloyd
http://notstupid.laughingsquid.com

"Properly read, the Bible is the most potent
force for atheism ever conceived." -- Isaac Asimov

On 12 Jan 2007 13:33:58 -0600, (Todd H.) wrote:

Mark Lloyd writes:

On Thu, 11 Jan 2007 16:04:43 -0600, "HeyBub"
wrote:

DerbyDad03 wrote:
Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.
- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.


And ice is the thickest water of all...


Ice should actually be less thick, considering that water expands when
freezing.

Ah, but, (to continue this physical science mental masturbation
session), it depends on how you define "thick." :-)

Per mass of water, ice is going to be thicker dimensionally because of
its lower density. Which was probably Bub's clever point.

Best Regards,

Sorry, I noticed the ambiguity too late.
--
Mark Lloyd
http://notstupid.laughingsquid.com

"Properly read, the Bible is the most potent
force for atheism ever conceived." -- Isaac Asimov

I will follow your logic as soon as you tell me how much heat "weighs".
Heat is just the average kinetic energy of the molecules of the
substance. More heat=more energy.
More energy=larger distance between molecules.
Larger distance between molecules=Less Density.

That is the correct logic you are looking for.
Doug

DerbyDad03 wrote:
Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.
- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.

QED


Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

how much heat "weighs".

I'll get back to you as soon as I finish reading the article that the
following abstract describes:

On the Weight of Heat and Thermal Equilibrium in General Relativity

Richard C. Tolman
Norman Bridge Laboratory, California Institute of Technology, Pasadena,
California
Received 30 December 1929

In accordance with the special theory of relativity all forms of
energy, including heat, have inertia and hence in accordance with the
equivalence principle also have weight. The purpose of the present
article is to investigate the thermodynamic implications of the idea
that heat has weight. In particular an investigation is made to see if
a temperature gradient is a necessary accompaniment of thermal
equilibrium in a gravitational field, in order to prevent the flow of
heat from regions of higher to those of lower gravitational potential.

A preliminary non-rigorous treatment of this problem is first given by
attempting to modify the classical thermodynamics only to the extent of
associating with each intrinsic quantity of energy an additional amount
of potential gravitational energy. In this way an expression is
obtained for increase in equilibrium temperature with decrease in
gravitational potential which, however, could in any case only be
correct as a first approximation in a weak gravitational field. A
discussion of the uncertainties and lack of rigor of this preliminary
treatment is then given and the necessity pointed out for a rigorous
treatment based on the principles of general relativity.

A rigorous relativistic treatment is then undertaken using the
extension of thermodynamics to general relativity previously presented
by the author. The system to be treated is taken as a static spherical
distribution of perfect fluid which has come to gravitational and
thermodynamic equilibrium. The principles of relativistic mechanics are
first applied to such a system in order to obtain results needed in the
later work. And it is then shown that these mechanical principles
themselves are sufficient to determine the temperature distribution as
a function of potential in the simple case of black-body radiation. The
principles of relativistic thermodynamics are then applied to this same
case of pure black-body radiation and the same expression for
temperature as a function of potential obtained by the thermodynamic as
by the mechanical treatment. This may be regarded as giving some
measure of check on the validity of the proposed relativistic
thermodynamics.

Following this, a thermodynamic treatment is given for the temperature
distribution in the more general case of matter and radiation and a
result found which harmonizes with that for radiation alone. A
treatment is then given to the distribution of a perfect monatomic gas
in a gravitational field both on the assumption that the total number
of atoms must remain constant and on the assumption of the ready
interconvertibility of matter and radiation. In the latter case the
same dependence of concentration on temperature is obtained as was
found by Stern and by the author for the case of flat space-time.

Using a system of coordinates such that the line element for the sphere
of fluid takes the form

ds2=-eu(dr2+r2dθ2+r2sin2θdφ2)+eνdt2 the general result for the
relation between gravitational potential and equilibrium temperature T0
as measured by a local observer in proper coordinates can be given by
the equation d lnT0/dr=-1/2dν/dr

This equation reduces in the case of a weak field to that obtained by
the preliminary non-rigorous treatment, and gives a very small change
of temperature with position in fields of ordinary intensity. The
result, however, is one of great theoretical interest, since constant
temperature throughout any system which has come to thermal equilibrium
has hitherto been regarded as an inescapable thermodynamic conclusion.
It is also not out of the question that the effect might sometime be of
experimental or observational importance.


©1930 The American Physical Society

Doug wrote:
I will follow your logic as soon as you tell me how much heat "weighs".
Heat is just the average kinetic energy of the molecules of the
substance. More heat=more energy.
More energy=larger distance between molecules.
Larger distance between molecules=Less Density.

That is the correct logic you are looking for.
Doug

DerbyDad03 wrote:
Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.
- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.

QED


Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

DerbyDad03 wrote:
how much heat "weighs".

I'll get back to you as soon as I finish reading the article that the
following abstract describes:

On the Weight of Heat and Thermal Equilibrium in General Relativity

Richard C. Tolman
Norman Bridge Laboratory, California Institute of Technology, Pasadena,
California
Received 30 December 1929

In accordance with the special theory of relativity all forms of
energy, including heat, have inertia and hence in accordance with the
equivalence principle also have weight. The purpose of the present
article is to investigate the thermodynamic implications of the idea
that heat has weight. In particular an investigation is made to see if
a temperature gradient is a necessary accompaniment of thermal
equilibrium in a gravitational field, in order to prevent the flow of
heat from regions of higher to those of lower gravitational potential.

A preliminary non-rigorous treatment of this problem is first given by
attempting to modify the classical thermodynamics only to the extent of
associating with each intrinsic quantity of energy an additional amount
of potential gravitational energy. In this way an expression is
obtained for increase in equilibrium temperature with decrease in
gravitational potential which, however, could in any case only be
correct as a first approximation in a weak gravitational field. A
discussion of the uncertainties and lack of rigor of this preliminary
treatment is then given and the necessity pointed out for a rigorous
treatment based on the principles of general relativity.

A rigorous relativistic treatment is then undertaken using the
extension of thermodynamics to general relativity previously presented
by the author. The system to be treated is taken as a static spherical
distribution of perfect fluid which has come to gravitational and
thermodynamic equilibrium. The principles of relativistic mechanics are
first applied to such a system in order to obtain results needed in the
later work. And it is then shown that these mechanical principles
themselves are sufficient to determine the temperature distribution as
a function of potential in the simple case of black-body radiation. The
principles of relativistic thermodynamics are then applied to this same
case of pure black-body radiation and the same expression for
temperature as a function of potential obtained by the thermodynamic as
by the mechanical treatment. This may be regarded as giving some
measure of check on the validity of the proposed relativistic
thermodynamics.

Following this, a thermodynamic treatment is given for the temperature
distribution in the more general case of matter and radiation and a
result found which harmonizes with that for radiation alone. A
treatment is then given to the distribution of a perfect monatomic gas
in a gravitational field both on the assumption that the total number
of atoms must remain constant and on the assumption of the ready
interconvertibility of matter and radiation. In the latter case the
same dependence of concentration on temperature is obtained as was
found by Stern and by the author for the case of flat space-time.

Using a system of coordinates such that the line element for the sphere
of fluid takes the form

ds2=-eu(dr2+r2dθ2+r2sin2θdφ2)+eνdt2 the general result for the
relation between gravitational potential and equilibrium temperature T0
as measured by a local observer in proper coordinates can be given by
the equation d lnT0/dr=-1/2dν/dr

This equation reduces in the case of a weak field to that obtained by
the preliminary non-rigorous treatment, and gives a very small change
of temperature with position in fields of ordinary intensity. The
result, however, is one of great theoretical interest, since constant
temperature throughout any system which has come to thermal equilibrium
has hitherto been regarded as an inescapable thermodynamic conclusion.
It is also not out of the question that the effect might sometime be of
experimental or observational importance.


©1930 The American Physical Society

Doug wrote:
I will follow your logic as soon as you tell me how much heat "weighs".
Heat is just the average kinetic energy of the molecules of the
substance. More heat=more energy.
More energy=larger distance between molecules.
Larger distance between molecules=Less Density.

That is the correct logic you are looking for.
Doug

DerbyDad03 wrote:
Follow my logic he

- Cold is the absence of heat.
- Cold water is just water.
- Hot water is water with heat added.
- Therefore, hot water is thicker than cold and squeezing it through
the pipes makes a different sound.

QED


Malcolm Hoar wrote:
My bathtub is located some distance from the water heater.
I turn on the hot faucet only and wait. The tub starts to
fill, with cold water initially. After a while, the water
becomes hot. That's all fine and as expected.

However, I can tell when the water is hot by *listening*
to the flow. The sound of the water changes quite significantly
and I've been trying to figure out why.

Clearly, the hot water will be slightly less dense than
the cold but I have a hard time imagining this would
cause an audible change in the sound. Also the metal
faucet will expand and that might change the sound of
the water whistling through the valve. Again, it's
hard imagine the thermal expansion of fractions of a
millimeter causing such an audible effect -- think
about the size of changes between two notes on a piano,
guitar, flute or whatever.

This happens in my current home but I have a vague
feeling I've seen (heard) the effect at other homes too.

Any other theories/inputs? Anyone else even observed
this effect?

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

Reducible to each individual moving particle's mass going up a skosh
due to its velocity?

What is the actual peak (between collisions) velocity of, say, a
molecule in some given solid at some given temp?

Dave