Are Expansion Tanks Necessary For Tankless Water Heaters?

Expansion tanks may or may not be required on tankless water heaters. Tankless water heaters are an energy-efficient alternative to traditional storage tank water heaters.

Expansion tanks are typically installed on storage tank water heaters to help regulate water pressure. However, it is not always necessary to install an expansion tank on a tankless water heater. It depends on the specific installation and the local plumbing codes. In some cases, the water heater may already have a built-in feature that compensates for pressure changes. It’s always best to consult with a licensed plumber to determine whether an expansion tank is required for your tankless water heater installation.

Tankless water heaters are gaining popularity among homeowners due to their many advantages. These water heaters excel in energy efficiency and provide an endless supply of hot water. However, in some cases, expansion tanks may be required. Expansion tanks help regulate the pressure caused by thermal expansion, which occurs when water heats up inside the closed system of a water heater.

The controversy surrounding the need for expansion tanks with tankless water heaters stems from the fact that some experts argue that they are not necessary. Nonetheless, it is always best to consult with a licensed plumber about the specific needs of your tankless water heater.

Understanding the importance of expansion tanks and their purpose is vital when it comes to ensuring maximum efficiency and longevity of your tankless water heating system.

How Do Tankless Water Heaters Work Without Expansion Tank?

Tankless water heaters work by heating water as it passes through the unit, which eliminates the need for a storage tank. As water heats up, it expands, which can cause pressure changes and potential damage to the unit. However, tankless water heaters are designed to handle these pressure fluctuations without requiring an expansion tank.

The debate around whether expansion tanks are necessary for tankless water heaters is ongoing, with some experts arguing that they can help regulate pressure and prolong the lifespan of the unit. Ultimately, whether or not an expansion tank is required depends on the specific installation and plumbing system being used.

It’s important to consult with a professional to determine the best course of action for your home’s water heating needs.

Importance Of Expansion Tanks On Tankless Water Heaters

An expansion tank is a vital component for any water heating system, including tankless water heaters. Even though they don’t have a tank, they still require an expansion tank to prevent pressure from building up in the pipes. Expansion tanks operate by absorbing the extra water pressure that results when the water heater heats the water, reducing the risk of damage to the pipes.

The same principle applies to other types of water heaters too. Not installing an expansion tank can cause leaks, corrosion, and eventually lead to system failure. Therefore, it’s important to install an expansion tank on your tankless water heater to ensure the safety and longevity of your system.

Factors To Consider For Expansion Tank Installation On Tankless Water Heaters

Expansion tanks are vital for managing pressure changes in tankless water heaters. The size of the water heater and water pressure it produces should be taken into consideration. An expansion tank helps alleviate pressure caused by water that expands when heated.

It’s best to install an expansion tank on the cold water supply close to the water heater’s entrance. By doing so, it ensures proper function and optimal protection from pressure fluctuations. Installing an expansion tank will increase the lifespan of the water heater, prevent leaks, and ensure safety.

It’s important to choose the correct size and locate the expansion tank correctly for it to function adequately.

An expansion tank is essential for any type of water heater system, including tankless models. Without one, pressure levels can become dangerously high, potentially causing damage to the unit or even the entire plumbing system. In this article, we’ve covered everything you need to know about expansion tanks for tankless water heaters, including how they work, why they’re necessary, and the potential consequences of not having one.

If you own a tankless water heater, it’s crucial that you have an expansion tank installed to protect your investment and ensure your safety. Don’t wait until it’s too late – contact a professional plumber today to get an expansion tank installed on your tankless water heater.


Overall, the installation of an expansion tank on a tankless water heater is not required by code, but it can offer significant benefits to your home’s plumbing system. The expansion tank helps to regulate pressure changes and reduces the risk of damage to your water heater and pipes.

It also prolongs the life of your water heater and prevents leaks and costly repairs. Whether or not to install an expansion tank on a tankless water heater depends on your home’s plumbing system and water pressure. It’s always a good idea to consult with a licensed plumber to determine if it’s necessary for your specific situation.

Investing in an expansion tank may cost a bit more upfront, but it can save you money in the long run by preventing damage, prolonging the life of your water heater, and reducing the risk of costly repairs.

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