old T&P valve

Found this old T&P valve on a comertial electric hot water heater on a home inspection the other day. I called out the recommendation for an annual testing of the valve and replacement every five years. Has anyone seen one of these valves?


This is not only an old relief valve but it is totaly unacceptable because you can not test it plus the set pressure can be set above the manufacturers maximum allowable working pressure for the tank. The knurled part on the top of the valve is where it can be screwed down and adjusted to a higher pressure setting. Owner generally do this when the valve starts to leak and they thing they are just stopping the leak in stead of replacing the valve.