What is this pipe near the water heater

[Joe Sullivan]

Hello,

Great forum. A pipe that is attached to my water heater was leaking this morning. It was an easy fix because the screw at the red arrow in the picture was very loose. But there was a light stream of hot water coming from the pipe in the red box in the picture. It lasted for a good few hours. Any idea where that water was coming from or what that pipe is? That light stream of water has stopped.
https://www.screencast.com/t/Fc7Y4EGcifg

Thanks a lot for any insight.

 

[Reach4]

I think that is your temperature&pressure relief valve, and it is not installed properly due to the way the pipe is run.

When does this water come out? After a shower when you are not using water, but stops after the WH has the water heated and turns off? If so, you need a working thermal expansion tank. If the thing dribbles for an hour or more, as you report, probably the T&P valve is bad. They are replaceable.

 

[Sponsor]

 

[Terry]

The T&P may need replacing. They are designed to release if pressure gets above 150 PSI or the temperature above 210. They don't last forever though.
It should drain downward the entire time, and daylight above the ground at about six inches.

 

[Jadnashua]

Not running the T&P drain line properly is a safety hazard...the way yours is plumbed, the loop will likely always have some water in it after the first time the valve opens. That could mean it could get plugged, and not be able to release when necessary. That can become dangerous. Catastrophically failing water heaters have been known to literally launch themselves out the roof, causing a lot of damage in the process when the discharge line can't open properly. Since yours is discharging, that's not an immediate threat, but it could lead to that at some time.