For a system with 6 boilers, how many expansion tanks are needed?

In a system with multiple boilers, the need for expansion tanks primarily depends on the overall design and operational characteristics of the heating system. It is typically sufficient to have one expansion tank if the boilers are designed to work together and are connected to a common piping system.

The purpose of an expansion tank is to absorb the increase in pressure caused by the thermal expansion of water when it is heated. In a well-balanced system with adequate design, a single expansion tank can accommodate the expansion for multiple boilers, as long as it is sized appropriately to handle the total system volume and pressure changes.

Having just one expansion tank simplifies the system design and maintenance, ensuring that pressure fluctuations are managed efficiently without the need for multiple tanks, which could complicate the system and introduce potential points of failure. However, it's important to ensure that the chosen expansion tank meets the requirements of the system, such as volume and pressure ratings.

In cases where there's a unique circumstance, such as significantly different pressure conditions, or if the boilers operate independently from one another, additional tanks might be considered. But in a standard operation with six boilers sharing a common system, one expansion tank is generally adequate.