Mr_Sheesh wrote:techmonkey wrote:The other night, some dumb ass hit a branch valve for the water main in my area with his car.
Reminds me of a question I wanted to ask you folks; I've heard stories telling how a water heater "could" explode if the water mains are shut off and it stays powered up, in past I've figured "Just to be safe is wise" and flipped the breaker for my water heater off; Is that rumor true or just a neat story these folks told to tell a good story, in the tradition of Popcorn Sutton (Who had a bumper sticker "Never let the truth get in the way of a good story")
There is a pressure relief valve on the side of the heater that will pop if the pressure gets too high. It has a little lever valve on it, push on it to test it while keeping out of the way of the hot water that comes out. When they go, you have a LOT of water everywhere. The valve should be guaranteed for at least 10 years IIRC. IF the heater is empty, or you are about to empty it, you need to turn off the power to it to keep from destroying the heater elements. Also, there are sacrificial anodes inside the tank to keep galvanic corrosion from rusting away the tank, they should be checked every 5 years.