AO Smith GPHE-50 knocking at 5 a.m.
by Deb Binderman
(Santa Fe, NM)
I have had an AO Smith GPHE-50 for a little over a year, which is located right next to my master bedroom. Every morning at about 5 a.m., the water heater begins a series of knocking noises for around half an hour--not really loud, but loud enough to wake me up. Quick little knocks, like a coffee percolator until the motor gives a little whirring that ends the episode. I just had it flushed, hoping that would help, but it hasn't. I'm thinking of putting the electrical plug on a timer, but I don't know if it will help and I'm nervous that might hurt the system. I don't know what to do short of getting rid of it and replacing it with a tankless, which shouldn't produce any noise except when it's in use.