water heater expansion tank

[Jeff Zehnder]

Are expansion tanks required at water heaters?

[Garry Sorrells]

Think the answer you are looking for is between the last shutoff valve and water heater.

[Jerry Peck]

Yes, no, and maybe

If there is no backflow device (check valve) or pressure regulator - no ... unless water utility requires it.

If there is a backflow device or pressure regulator - yes ... except that the code only requires a means to control thermal expansion, so most AHJ permit expansion tanks or pressure relief valves (not the T&P relief valve).