Bob wrote:
Bob F wrote:

The only reason the water heater would get higher [pressure] than the
supply is if you have a check valve before it or on the supply water
input. (Which could be a regulator)

Water expands as it heats. That's why the T&P valve is there! If that
valve doesn't open and the heat control malfunctions, your water heater
could turn into a missile. Mythbusters proved that.


Only if you have a check valve in your system, otherwise the water just
expands into the city main.

nate

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