Which type of refrigeration system is most likely to leak refrigerant into cooled building spaces?

Direct systems are the most likely to leak refrigerant into cooled building spaces because they use the refrigerant directly in the cooling process within the occupied space. In such systems, the refrigerant circulates through evaporators that are typically situated within the area to be cooled. If there is a breach or failure in the components, such as the evaporator coil or piping, refrigerant can escape directly into the building environment, affecting air quality and potentially posing a safety hazard.

In contrast, indirect systems utilize a secondary coolant or fluid, which absorbs heat from the air or space within the building and transfers it to another medium or location where the refrigerant cycle occurs. Since the refrigerant does not come into direct contact with the air in the occupied space, any potential leaks from the refrigerant circuit release the refrigerant outside of the building rather than inside, reducing the risk of exposure.

Centrifugal systems, typically used for large applications, often manage refrigerant more effectively because they are designed with robust systems that have lower associated leak rates compared to direct systems. Similarly, absorption systems, which utilize a different method of refrigeration, rely heavily on a stable supply of refrigerants and typically do not expose the refrigerant directly to the building space.