05 11 2023
About Thermal expansion tanks |Aquasky

A thermal expansion tank is a device used to regulate water pressure in a closed system. It is typically composed of a pressure vessel, a diaphragm, and inlet and outlet connections. The tank works by absorbing the excess pressure that occurs in a closed water system due to thermal expansion.

When water is heated, it expands, and this expansion can cause an increase in pressure within the water system. Without a thermal expansion tank, this pressure would build up and eventually cause damage to the system or even lead to an explosion. The thermal expansion tank is designed to prevent this from happening by providing a space for the excess water to expand into, thus reducing the pressure within the system. This tank has a flexible diaphragm inside that separates the water from a compressed air chamber. As the water expands, the diaphragm compresses the air in the chamber, allowing the water to expand without increasing the pressure within the system.


Thermal expansion tanks are commonly used in residential and commercial plumbing systems. They are especially important in homes with closed-loop hot water heating systems or in areas where water supply systems are subject to large temperature changes.


In the United States, thermal expansion tanks are subject to legal regulations. The following are some of the legal regulations related to thermal expansion tanks:

1. Pipeline and Hazardous Materials Safety Administration: The Pipeline and Hazardous Materials Safety Administration (PHMSA) is the federal agency responsible for regulating pipeline safety. PHMSA has established regulations for thermal expansion tanks, requiring that all thermal expansion tanks installed on pipeline systems must comply with federal laws and regulations.

2. Local building codes: Each state and city has its own building codes, which include provisions for thermal expansion tanks. These regulations may require thermal expansion tanks to meet specific requirements or standards for particular applications, such as building height or usage.

3. Manufacturer standards: Many thermal expansion tanks have specific standards established by their manufacturers. These standards may require the tanks to meet specific material, design, or testing requirements to ensure their safety and performance.

4. Installation requirements: Installing a thermal expansion tank requires following specific installation requirements to ensure proper installation and operation. These requirements may include tank location, size and location of connecting pipes, and other specific requirements.


In summary, a thermal expansion tank is an important device that helps regulate water pressure in closed systems. It is especially crucial in homes with closed-loop hot water heating systems or areas where water supply systems are subject to large temperature changes. The diaphragm tank, with its flexible diaphragm, is a popular type of thermal expansion tank that is both efficient and low-maintenance.


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