Just completed an inspection on a 1947 1000 Sq Ft home. The water heater appeared old but I am unable to date it using the serial number as demonstrated on www.building-center.org. I did not see a TPR valve. Were they always required or was there a year when they started requiring TPR valves?
I got curious, so I did a bit of digging. Apparently, TPR valves came about as a result of research by DIERS … “The Design Institute for Emergency Relief Systems (DIERS) was formed in 1976 as consortium of 29 companies to develop methods for the design of emergency relief systems to handle runaway reactions.”
While there is nothing specific on the introduction of the TPR, I think it’s safe to say that a boiler manufactured in 1962 probably predates the invention of the valve as we know it, although I’m willing to bet that “other methods” have been tried over the years!
Interesting topic, and I learned something else I didn’t know, so a good day all round!