I have a GE 50 gallon gas water heater. It works great but when any thing like shower,washer or dishwasher stops using hot water it makes this real tinny sound that you can hear all over the house. I have been next to it when it makes this noise and it sounds like it is coming from inside. It dose it every time hot water is stopped being used. It sounds like something hitting the flu pipe. I seams to be getting louder as time passes.Any thoughts are should I consider replacing.