Overflow pipe puzzle All aspects of plumbing questions and answers, help, tips and information

[RoyG]

Can anyone explain to me why the overflow pipe on a cold water tank (the main cold water tank, not the CH expansion tank) comes in through the wall of the tank and then has a 90 degree downward bend for a couple of inches?

It seems to me that this would potentially create a syphon effect if the water level rises too far. Once water starts to run out of the overflow it could continue flowing until the level gets below the bottom of the pipe.

And if the ball valve is still letting water in, that will not happen.

It puzzles me.

[stoneyboy]

RoyG,
It was probably intended as a water seal with the pipe dipped into the water. Unless the overflow pipe fills completely with water it is unlikely to form a siphon.
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