What is the function of a crankcase heater in a compressor?

The function of a crankcase heater in a compressor is to prevent refrigerant from migrating and condensing in the compressor's crankcase during the off-cycle. When the compressor is not running, the refrigerant pressure in the system equalizes. If the crankcase is colder than other parts of the system, refrigerant will migrate to the crankcase and condense in the lubricating oil. This dilution of the oil with refrigerant can significantly reduce its lubricating properties, leading to increased friction and wear when the compressor starts up. Additionally, when the compressor starts, the liquid refrigerant in the crankcase can suddenly boil, causing a rapid increase in pressure that can damage the compressor. The crankcase heater is a small electric heater that is typically mounted on the exterior of the compressor crankcase. It provides a small amount of heat to keep the crankcase slightly warmer than the rest of the system, preventing refrigerant from condensing in the oil. This ensures that the oil retains its lubricating properties and prevents liquid refrigerant from accumulating in the crankcase, protecting the compressor from damage during start-up. For example, in a cold climate, a crankcase heater is essential to prevent refrigerant migration and ensure reliable compressor operation.