I have a gas hot water heater in my basement. It looks as though black water shot out of the pressure relief tube. There is a large splat mark on the floor of dried black residue. The splat is about 6 feet in diameter.
I tested the relief valve...clear water came out.
Otherwise, my hot water has been fine and the water clear.
The only factor i can think of is that i left the house vacant for a week. During that time i shut off the cold water supply from the street.
Does anyone have any thoughts on this?
Thanks Aabob