When the heat pump is not in operation, refrigerant can move to the coldest point of the circuit and accumulate in the compressor.
Dissolution in the oil
The refrigerant can dissolve into the compressor oil.
Risk at startup
During startup, intense foaming and a temporary degradation of lubrication can occur.
Crankcase heater
In suitable systems, it helps to keep the compressor warmer to limit refrigerant migration.
