Over-pressurized water heater

[Mark Reinmiller]

I found this water heater at an inspection today. This is the third time I have seen this. Apparently when the pressure in the tank is somewhere above 300 PSI the convex top and concave bottom of the tank dish downward. Once you have seen this you can recognize it from a distance. The water pipes angle inward and the internal flue moves down from the top sheet metal housing. The bottom of the tank develops a reversed curvature.

At this house a pressure regulating valve and backflow preventer were present, the water heater temperature was set as high as possible, the TPV valve was probably obstructed with minerals, and the diaphragm in the expansion tank had failed. About all that is left to happen is the explosion.

BTW, Bradford White has a service bulletin on their website that explains this.

29546295472954929548

[Rick Cantrell]

BTW, Bradford White has a service bulletin on their website that explains this.

This is the link
Pressure Damaged Water Heaters (#115) | Bradford White Water Heaters. Built to be the best. (http://www.bradfordwhite.com/pressure-damaged-water-heaters-115)

[John Kogel]

Thanks, Mark.
Mythbusters found 350 psi to be the point at which the bottom lets go and the tank goes thru the roof.
But I would expect different manufactureres would have different thresholds to some extent. Bradford White made a pretty good tank, from the looks of that one. :D

[Bruce Ramsey]

Based on the color, that tank is from the 80s or 90s. 20+ year old tanks fail. Time for a new one.

[Mark Reinmiller]

Based on the color, that tank is from the 80s or 90s. 20+ year old tanks fail. Time for a new one.

It was manufactured in 1996, but that does not have anything to do with the failure. I was very strong on my wording that the water heater needed to be replaced now. The buyers agent was thinking a credit would be best. I usually prefer that but told them this was a hazard and should be replaced immediately.