A: Most residentual expansion tanks screw in (like a light bulb). Just make sure the heater is turned off along with the water. Relieve the pressure by opening a hot side of any faucet. Follow the intructions for checking the air pressure of the bladder before screwing the new tank in. -- EJ

Q1: Thank you for your comments. Do I need to empty the water heater any (e.g., below the level of the relief valve) before I unscrew the expansion tank? Or is turning off the water enough?

A1: This depends where your tank is located. If the pipe that the tank screws into is located above the heater and you have plumbing above that then you might want to drain some water off so nothing gets wet. It really depends on how fast you are and where the tank is located. Good luck! -- EJ (10/22/06)