Gas piping serving heating appliances is allowed to also serve what other equipment?

The correct choice highlights that gas piping intended for heating appliances can also be utilized for cooling equipment, particularly in the context of gas-fueled cooling systems, such as absorption refrigerators. These systems rely on a gas supply to generate cooling, thus allowing for flexible use of the gas piping infrastructure.

When considering the context of the question, it's crucial to understand the application of gas piping systems. The integration of gas piping for both heating and cooling can streamline installations and is permissible as long as the equipment adheres to safety codes and standards. It emphasizes the versatility of gas arrangements in providing multiple functionalities, optimizing space, and efficiency.

The other choices present equipment types that do not directly utilize gas as their primary energy source. Ventilation equipment primarily relies on electrical power, and while electrical appliances obviously require electricity, they are not designed to accommodate gas piping. Water heating units, however, typically utilize gas for heating but are generally considered a separate category that has its own dedicated gas piping requirements. Thus, the answer relates specifically to the compatibility of gas systems with cooling applications, which is a valid consideration in modern installations.