1, What is a Compressor Crankcase Heater?
In our refrigeration systems, the compressor is very important. The cold room compressor condensing unit usually consists of a compressor, condenser coil, outdoor condenser fan, liquid reservoir, contactor, starting relay etc. Within the condensing unit, the compressor will often have a heater connected in some way to its bottom section or crankcase. This heater is often referred to as a crankcase heater. A crankcase heater is an electrical device that’s designed to warm up the crankcase of a compressor.
A compressor crankcase heater is a device used in refrigeration and air conditioning systems to prevent the compressor oil from becoming too cold, which can lead to issues like oil thickening or inadequate lubrication.
Compressor crankcase heaters work by generating heat when the compressor isn’t running. They feature a heating element that’s powered by electricity. Electricity allows crankcase heaters to produce heat.
Most crankcase heaters will only turn on at the end of a cooling cycle. They won’t produce heat while your condensing unit is running. Instead, the crankcase heater will wait until your condensing unit has stopped running. The crankcase heater will automatically turn on at the end of a cooling cycle, and it will automatically turn off at the beginning of a cooling cycle.
3, The Purpose of a Compressor crankcase Heater
Pre-Startup Heating: By keeping the oil warm, the heater helps prevent issues like oil thickening, inadequate lubrication, or compressor damage during startup, particularly in low-temperature conditions.
We are always confused that why the compressor condensing units factory asks us to keep the power more than 4 hours when the unit is first started and or without electricity long time.
Because, during the shut-off periods, there are some refrigerant can mix with the oil. It will be liquid slugging and reduce lubricity in the next start. So, we add a heater in the crankcase. Then, we can warm up the oil to separate the refrigerant and oil by keeping the power for more than 4 hours.
The heater is important under the following conditions:
1. The compressor is during longer shut-off periods.
2.The compressor surrounding temperature less than 10C.
3. The way of supply oil is the oil pump.
In cold environments, for instance, a crankcase heater can protect compressors from various problems. It will prevent refrigerant from mixing with the compressor oil.
Refrigerant has a tendency to migrate to the crankcase – the part of a compressor that contains the oil – in cold temperatures, refrigerant may migrate to the crankcase where it mixes with the compressor oil. A crankcase heater will prevent this from happening by keeping the crankcase warm.
Crankcase heaters promote proper viscosity of the compressor oil. The temperature of the compressor oil will affect its viscosity. At low temperatures, it will be less viscous. At high temperatures, the compressor oil will be more viscous, meaning it will flow more easily.
With a crankcase heater, the compressor oil will maintain proper viscosity. It won’t become too cold. Rather, the compressor oil will stay warm enough so that it easily flows through the crankcase.
