Preparation
Step 1
Turn the valve on your water heater’s water-supply line clockwise to shut the water supply off to the tank.
Step 2
Turn off the breaker in the main panel to shut down an electric water heater.
Step 3
Turn off the gas to a gas water heater by turning the gas control valve to the off position on the water heater.
Replace Thread Seal Tape
Step 1
Remove the existing expansion tank using an adjustable pipe wrench and turning the tank counterclockwise at the top where it attaches to the pipe fitting. Have a partner support the tank to keep it from falling to the floor.
Step 2
Clean the threads on the expansion tank. Remove any dirt, grim or old thread seal tape from the threads with an old cloth.
Step 3
Wrap the threads in two or three layers of new thread seal tape. Reattach the tank to the fitting and tighten it with the pipe wrench
Step 4
Turn the water supply back on to the water heater. Turn on the water or gas, and light the pilot on the gas water heater.
Step 5
Watch for additional leaks from the tank. If your expansion tank continues to leak, you must replace the tank.
Replace the Expansion Tank
Step 1
Turn off all the water faucets inside your residence. Attach a water-pressure test gauge to an outside faucet. Turn on the outside faucet to get the pressure reading. Note the pressure reading on the gauge.
Step 2
Attach a bicycle pump or air compressor to the changing valve at the bottom of a replacement expansion tank if you need to increase the pressure in the tank above 40 pounds-per-square-inch.
Step 3
Check the pressure in the tank with a with a tire-pressure gauge. Add or release air from the expansion tank until the pressure in the tank equals the water pressure in your home.
Step 4
Turn off the water supply to the water heater. Turn off the water gas or electric water heater. Remove the current expansion tank with the adjustable pipe wrench.
Step 5
Wrap the threads of the replacement tank with about three layers of thread seal tape. Screw the tank into the fitting and tighten it with the wrench.
Step 6
Turn on the water supply and the gas or electricity to the water heater.