explosion

How To Incorrectly Install the Temperature Pressure Relief Valve - Or Boom Waiting to Happen

With any luck, when I do a home inspection, I get to stay nice and bored. That doesn’t happen as often as I would like unfortunately. Part of the boredom should come from verifying mundane details that nobody would ever get wrong.

Ha. Just kidding.

In this case, the mundane detail is the temperature pressure relief valve. These devices have been required equipment since the 1960s. Their purpose is to act as the last fail-safe on the water heater tank. The tank is a welded steel enclosure which means that it doesn’t structurally fail easily. It takes a considerable amount of energy to force it into failure. Or time, but that is more for leaks. Here I am concerned with a sudden catastrophic failure.

Most people would pay more attention to their water heater if they knew they were living with a bomb. Think I’m joking? Go check out this video from Mythbusters. Don’t worry, I’ll wait.

Welcome back! Impressive, wasn’t it.

Please note that they deliberately disabled the TPR safety to get the tank to go boom. In my job, I don’t need to assume intentional action or malice. Ascribing mistakes to simple silliness or ineptitude works just as well.

In the video below, a TPR vale is installed. Sadly, it is not installed correctly and has created the potential to turn the water heater into a house killer. Maybe a people killer, too. Bad news, that. It is, however, easily fixable.

The hottest water temperature I’ve ever check was 189 degrees on an old National Steel water heater from the fifties with no TPR valve. I practically begged the client to replace it.