What is the standard size of the overflow on an open type expansion tank?

The standard size of the overflow on an open type expansion tank is typically 1 inch. This standard size is designed to ensure that any excess water, which may occur during thermal expansion or other operational changes in the system, can be safely and effectively discharged.

An open type expansion tank operates at atmospheric pressure, allowing the system to manage excess water without creating a vacuum or back pressure that could lead to operational issues. The 1-inch overflow size provides sufficient capacity to handle the volume of water that could be expelled, helping to prevent overfilling and potential water hammer, which can damage piping and equipment.

While other sizes may be used in various applications, 1 inch is commonly accepted in the industry for this specific purpose, aligning with building codes and practices to ensure safety and efficiency in boiler operations.