Which type of oil must be used with all HFCs in HVAC-R applications?

• A. Mineral oil
• B. Polyolester
• C. Alkebenzene
• D. Petroleum oil

Answer: (B)

Polyolester oil is specifically formulated for use with HFC refrigerants in HVAC-R applications. HFCs, or hydrofluorocarbons, have chemical and physical properties that require an oil with good solubility and performance characteristics to ensure efficient operation. Polyolester oils are synthetic and provide excellent thermal stability, low volatility, and better compatibility with HFCs compared to other oil types. This compatibility is crucial for maintaining lubricity and ensuring that the refrigerant and oil circulate effectively in the system.

Mineral oils, alkebenzene oils, and petroleum oils are typically used with other types of refrigerants, such as CFCs and HCFCs, and may not provide the appropriate performance required in systems using HFCs. These oils may lead to issues like refrigerant and oil separation, reduced lubrication, and ultimately, system inefficiencies or failures. Therefore, polyolester oil is the recommended choice for systems using HFC refrigerants to ensure optimal performance and longevity of the equipment.