Which refrigerant addition to an appliance that contains 50 or more pounds of an ozone-depleting refrigerant triggers the requirement to calculate the leak rate?

• A. During initial charging
• B. During disposal
• C. During recovery
• D. During topping off the system

Answer: (D)

Larger refrigerant systems require checking how quickly they are losing refrigerant whenever you service them and add more. If an appliance contains 50 pounds or more of ozone-depleting refrigerant, you must calculate the leak rate when you perform a topping-off—that is, when you add refrigerant to bring the system back up to charge. This helps determine whether there is a leak and if repairs are needed before continuing. The other moments—initial charging, disposal, or recovery—involve different steps and don’t require this leak-rate calculation during the act of adding refrigerant to a large system.