Temperature and Pressure Relief Valve

Temperature/Pressure Relief Valve (T&P)

This valve is designed to prevent a water heater from exploding if temperature or pressure exceeds safe limits, by opening and venting. Unfortunately, residential valves are somewhat prone to failure. They should be checked once a year by pulling up on the handle. Water should flow freely out and stop when you let go of the handle. If it does nothing, runs or drips, then the valve should be replaced. Banging on the handle with something hard, like pliers, sometimes will stop drips or even runs. If not, replace the valve. Hooking up the drain line with a union or flex connector makes T&P replacement MUCH easier.

People don't like to test their T&Ps. But then, we don't think it's so much fun to wake up in the hospital, or to patch a big hole in the roof, either. When water heaters explode, it's catastrophic. People are injured or die; buildings are severely damaged.

Test your T&Ps!

And one more thing: T&P drain lines should go down and out. Never up. If the valve opens, water will pool there and corrode it shut. Or freeze in the line in colder climes. We've seen lines plumbed uphill so many times we've lost count. But there SHOULD be a drain line, usually to within about six inches of the floor, or plumbed outside. That's code around here. It's to prevent you from being scalded if the valve should open while you're standing next to it.

Finally, if water is running out of your T&P line, look for the cause. It might just be a bad T&P. But it could also signal high-pressure problems or a dangerously defective control. Don't ignore it!