How to Replace Your Water Heater Expansion Tank

water heater with attached expansion tank
  • 2-5 hours
  • Advanced
  • 50-300
What You'll Need
New Expansion Tank
Support Brackets
Tire Pressure Gauge
Teflon Tape
Bicycle Tire Pump
What You'll Need
New Expansion Tank
Support Brackets
Tire Pressure Gauge
Teflon Tape
Bicycle Tire Pump

Replacing your water heater expansion tank by yourself can save you a lot of money and time. With the right tools and this guide you will be able to replace the expansion tank on your water heater without calling a professional plumber. Just follow the steps below to safely replace your water heater expansion tank.

Step 1 - Identify Your Old Expansion Tank

The first step to replacing the water heater expansion tank is to locate it. The tank is usually located right next to your water heater and is connected to the water heater. Once identified, record the dimensions and connections to ensure when you purchase the new one it is going to fit and work properly. You can buy a new water heater expansion tank from the local hardware supply store or order online.

Step 2 - Turn Everything Off

flipping a circuit breaker in the panel box

Turn the water supply to the heater off by closing the shut off valve. The shut off valve may be near the heater or further up on the pipeline. If you don’t find it there, you can shut off the main water to the entire house.

Switch off the power supply to your water heater system by flipping the designated circuit breaker or turn off the main power to the house. Let the water heater cool down for some time. This could take an hour or so.

Step 3 - Drain the Water

Drain out the water from the water heater to reduce the water pressure. You can drain the water by opening the bleeder valve. Use the bucket to collect the water. Use caution since the water may be pressurized.

Step 4 - Disconnect the Expansion Tank

Disconnect the expansion tank carefully; watch out that the pipes and fittings are not damaged while removing the expansion tank.

Step 5 - Pressurize the Expansion Tank

With the water supply turned off make sure the pressure reading in the tank is “0”. Take a bicycle tire pump and attach it to the Schrader valve, you can find it at the bottom of the tank. Fill the tank with air to 12 psi or according to the amount indicated on the manufacturer’s instructions.

Step 6 - Check the Pressure

water pressure gauge

Check the pressure in the tank with a pressure gauge.

Step 7 - Teflon Tape

Get the Teflon tape and wind it around the ends of the connectors. Do not wrap the Teflon tape from the beginning of the connector, leave the first two or three threads bare or your tape will get into the system.

Step 8 - Install the New Tank

Install the new tank in the same position as the old one. Carefully connect the new tank to your heater system. Make sure the connectors are screwed on tight.

Step 9 - Check the System

You can now turn on the water supply. Check all the connectors to ensure there is no leakage.

Step 10 - Open a Faucet

Next, open a faucet and allow the water to run through the water heater system. Check once again if there is any leakage.

Step 11 - Switch on the Power Supply

Switch on the power supply for the water heater system and then turn on the water heater allowing it to heat up.

Step 12 - Hot Water

When the system has heated up, make one last check. Open the hot water faucet and check if the water flowing is hot.