[net.physics] hot water faucets

ss (05/12/83)

The reason why hot water from a faucet reduces after a while is
that the faucet uses a metal ball valve. As the ball heats up, it expands
and reduces the flow of water. It was probably meant to help keep the
temperature of the water coming out of the faucet relatively constant,
if the hot water temperature varied somewhat. ( This obviously dosen't
work if you have ONLY the hot water running.)

Sharad Singhal

smh (05/12/83)

This is a common problem (feature?) with hot water faucets.
A faucet is very much subject to thermal expansion, being
mostly metal.  When you first turn on the water, the pipes
have cold water in them.  When the hot water reaches the
faucet, its dimensions change sufficiently to alter the
washer clearance at the valve seat.  Monitor the change
in flow while feeling metal parts of the faucet sometime...