VRF Crankcase Heater Operation
A bug report
EnergyPlus I/O Reference states as follows:
Crankcase Heater Power per Compressor: Crankcase heater electrical consumption is applied only when the compressor is off or is applied during the off cycle when the compressor is cycling below the Minimum Heat Pump Part-Load Ratio.
Maximum Outdoor Dry-bulb Temperature for Crankcase Heater: This numeric field defines the maximum outdoor temperature, in degrees Celsius, below which the crankcase heater will operate.
However, what I observed is the opposite. Crankcase heater electrical consmption is applied when both of the following conditions are met;
- The compressor is ON (regardless of cooling or heating mode).
- The outdoor temperature is below the maximum outdoor dry-bulb temperature setpoint.
It would be nice to see more crankcase heater operation options in the future, but for now, I think the I/O Reference is more relevant. Crankcase heater electric consumption should be applied when the compressor is OFF.
The bug can be easily reproduced with ExampleFiles e.g., VariableRefrigerantFlow_5Zone.idf (V25-2-0).
A similar report is found on Github, but it has not been addressed enough.
https://github.com/NatLabRockies/EnergyPlus/issues/11020