Do I need an expansion tank for my hot water heater. I have a back flow device that is T'd off of the main water line. I need to change my hot water heater and I am not sure if I need to have a domestic water expansion tank installed.
Yes, the water will need somewhere to expand, since the backflow device won't allow it to push back outside. If you dont, your commode fill valves may leak the pressure off, but it will wear on all of your valves.