The refrigerant charge is the specific amount of refrigerant (measured in ounces or pounds) that a system requires to operate correctly. Every unit comes "pre-charged" from the factory for a certain length of line set, but longer runs may require adding more gas. Having too much or too little refrigerant will significantly decrease the efficiency of your heat pump systems. Technicians use scales and gauges to ensure the charge is perfect for your multi-zone configuration. Improper charging is the leading cause of poor humidity control and compressor failure. Always refer to the technical manual for your Cooper&Hunter unit for the exact charging specs.