When do you need an Expansion Tank?

In this video my son and I replace a water heater and install a new expansion tank. I explain that there are two main instances that trigger the need for an expansion tank.

Trigger #1- When the supply pressure coming from street exceeds the pressure relief pressure rating on the water heater. (regardless if you have a pressure regulator)

Trigger #2- When you have a back flow prevention device such as a check valve. (commonly found when hot water circulation pumps are installed)

Видео When do you need an Expansion Tank? канала Wroolie Mechanical