Do You Need a Pressure Tank with a Tankless Water Heater?

In the world of water heating, tankless water heaters have become increasingly popular due to their efficiency and on-demand heating capabilities. But one question commonly arises: do you need a pressure tank when you have a tankless water heater? This article will explore the considerations and situations where a pressure tank is needed or not.

Understanding Tankless Water Heaters

Tankless water heaters are designed to provide a continuous supply of hot water. Unlike conventional tank water heaters, which store and maintain a supply of hot water, tankless units heat water as it passes through them, reducing the need for a storage tank. However, this does not mean a pressure tank is unnecessary in every scenario.

Key Considerations

Water Pressure

To ensure optimal performance, it is crucial to verify that your home's water pressure is sufficient for the tankless system. Most tankless water heaters require a minimum water pressure, typically between 30 and 40 psi (pounds per square inch). Low water pressure can lead to insufficient water flow and reduced heating efficiency.

Flow Rate

The flow rate of your tankless water heater must also meet your household's hot water demands. If you have high hot water usage, such as multiple simultaneous showers, you may need to install multiple units or select a model with a higher flow rate. A higher flow rate ensures that all hot water demands are met efficiently.

Whole House Systems

In larger homes or situations where water delivery is inconsistent, a pressure tank may help stabilize water pressure. However, this is not a common requirement for most tankless water heaters. A pressure tank can maintain a consistent water pressure, which is beneficial for a whole-house system but may not be necessary for a tankless setup with proper flow and pressure management.

Special Considerations for Well Water Systems

A pressure tank is particularly essential in well water systems due to the inherent issues of pressure and water hammer. Wells often require a pressure tank to store pressurized water and stabilize the system. Additionally, expansion tanks are used to cushion against the expansion of water when heated.

A pressure tank is different from an expansion tank. While they both contain an air bladder and a water tank, a pressure tank is typically larger (50-75 gallons) and serves as a storage and pressure management system for household use. Expansion tanks are smaller (often one or two gallons) and are designed to cushion against water hammer and accommodate the expansion of hot water.

City Water and Utility Hookups

For city water systems, a pressure tank may not be as critical due to the presence of utilities that handle pressure regulation. However, it is still important to have an expansion tank to manage the expansion of hot water. The utilities often have a backflow check valve that effectively traps downstream water, preventing it from flowing back into the system. This means that even with city water, expansion tanks are necessary to manage water expansion and pressure changes.

Conclusion

Overall, while a pressure tank is generally not required with a tankless water heater, ensuring adequate water pressure and flow is crucial for optimal performance. In well water systems, pressure tanks are essential for storage and pressure stabilization. In city water systems, expansion tanks are necessary to manage water expansion and prevent pressure issues. Each scenario requires careful consideration to ensure a reliable and efficient water heating system.

Keywords: tankless water heater, pressure tank, water hammer