What is a dry return?

A dry return is defined as a piping arrangement designed to carry air, condensate, and steam above the normal operating water line (NOWL). This configuration is essential in steam heating systems where the removal of condensate and return of steam are critical for efficient operation.

In a dry return, the presence of both steam and air is necessary for proper functionality. The steam needs to travel through the piping system in a manner that prevents water accumulation, which is why it operates above the NOWL. This allows for effective heating and minimizes the risk of water hammer, which can occur if condensate builds up in the system. The inclusion of air is also important because it helps maintain the system’s pressure and efficiency.

The other options do not accurately describe the function or characteristics of a dry return. A system that can contain only water would not allow for the required steam and air flow. A pipe used exclusively for draining water does not meet the conditions of a dry return. Lastly, a line exclusively for steam vapor doesn’t allow for the presence of air and condensate, which are crucial in a dry return system. Thus, the correct understanding of a dry return encompasses its role in managing steam, air, and condensate effectively within the system.