What's a Water Heater Expansion Tank, And Why Do I Need One?

A water heater expansion tank gives space for excess water and air to expand as they heat up in your water heater. As the water and air heat up, they expand and enter the expansion tank. That relieves the excess pressure on your water heater and pipes. When the water and air cool down, they contract and create a vacuum in the expansion tank. It fills up with air from the atmosphere. This helps maintain the system's pressure and helps your water heater work right.

If you don't have an expansion tank, the expanding hot water and air have nowhere to go. This can cause lots of issues, such as stress on your water heater, which can lead to damage and even failure. Without an expansion tank, your water heater may not be able to keep the temperature stable. That can lead to lower efficiency and higher energy bills. On top of that, the extra pressure can lead to noisy pipes that might even burst, resulting in costly repairs.

An expansion tank provides a place for the expanded water to go, which helps even out the pressure in the system. This can help prevent damage and extend the life of your pipes, fittings, and other components. It can also help your fixtures last longer because it eases the stress high pressure can cause. Finally, an expansion tank can help to keep your water heater working the way it should. As the water heats up, it expands and can increase in volume. An expansion tank allows for that increase. That can lower the risk of damage and increase its efficiency.

In most cases, the plumbing code requires an expansion tank for a new or replacement water heater. Depending on where you live, you may even need to add an expansion tank to your existing water heater. Some places make it a legal requirement to protect against the risk high pressure brings with it. That makes it crucial to check if your system needs an expansion tank.