William W. Plummer wrote:
Leo wrote:

When I turn on the hot water faucet in a sink or shower it 'sputters'
as if there is air in the line. I have not done any plumbing work
that would have caused this... what is happening? I can't find any
obvious leaks anywhere???


The water line is pressurized so an leak would not admit air. Maybe
your water heater is set too high and there is boiling happening.

Not always true, flowing water can pull in air through a hole, when the
flow stops the the hole becomes a leak. Google "venturi".
A leak under a slab could cause this
Dave