My 1999 A.O.Smith gas hot water tank (part# FSGL-40J00N010S24, serial# MC99-041697-S24) has been working fine until last 2 days. It comes on and heats the water, and turns off OK, but the water is only luke-warm (tank is not leaking). I drained it but only got tiny amount of sediment. It does gurgle and bang during the heating cycle. It used to get hotter the more you used it but now it does not. Could it be an anode rod or dip tube problem?
thanks for any advice you have