My hot water tank has started making a odd noise, it's not the normal poppy
sound from tank deposits. The best description would be a half second drum
roil about every 10 seconds. ( almost like a animal scratching itself in the
wall) I have drained the water out of the system thinking it might be some
kind of air harmer, Drained some of the water out of tank, the only way I
have got it to stop is to shut the water to tank off and blow some water out
of PRV. The tank is about 7 years old 50Gal, GE, self cleaning. It's pretty
much non stop so any suggestion would be a help. Thanks