"daniel peterman" wrote in message
...
Possibly unrelated to water hammering I have always been curious why hot
water "sounds" different as it comes out of the tap.
The pitch changes slightly and you can hear it coming.
Is it because it is less dense?

It's because the valve's geometry changes as it gets hotter. Hotter water
is also slightly 'wetter' than cool water. The change in surface tension
affects the noises it makes going by sharp profiles in the valve.


LLoyd