1. Compressor design; rotary compressors being high side shell dome meaning that the mechanical components of compression are at the bottom of the compressor where the low pressure / low temperature gas enters the compressor shell. The high pressure / high temperature gas is at the top of the compressor shell. This keeps the mechanical components down where the oil is, this also reduces the amount of oil leaving the compressor.
Oil level monitoring: Each compressor has a thermistor that monitors oil level
2. Ability to pull oil from the centrifugal oil separator
3. Ability to pull oil from a partnering compressor in a single chassis
4. Ability to pull oil from a separate chassis in a dual or triple chassis configuration
5. Oil recovery mode operates all compressors at pre-determined speed (Hz / RPS) while at the same time setting each individual indoor PMV to a pre-determined position (step). This allows the system to sweep the oil back to the ODU’s. Oil recovery mode happens every time a system comes on after physically being off as well as every 2 hours of run time in cooling and 1 hour of run time in heating.
Note: occupants never even know the system is in oil recovery mode as the entire system will continue to condition the space during this function. The only caveat is during the 10 to 15 minutes of oil recovery mode run time the system is basically a constant BTUH. Another words during the oil recovery mode the system is not modulating the PMV based on return air. The beauty is the system continues to cool / heat depending mode of operation. If a zone is satisfied the indoor fan does not come on during this mode.