21K BTU VSD Marine Air Conditioner Unit - Brushless, Variable Speed, Soft Start, Reverse - Cycle HeatVelair's I-Line VSD series units feature built-in inversion technology for better efficiency, less power consumption and no more compressor start-up power spikes. VSD units offer top comfort with no temperature or humidity fluctuation and works properly even on smaller generators and weak shore power. Features:VSD eliminates start-up spikeSynchronous brushless DC inverter driven compressorLow-speed reverse fan bladePermanent magnet fan motorElectronic expansion valveWall-mounted control panelStainless-steel cabinetConstant temperature output maximizes comfortConsumption reduction enables small generatorsMinimal fan noise and vibrationFan motor requires 30% less powerReverse-cycle for heat pump function27K BTU/h unit can work with a 3.5 kW generatorR410A environmentally safe refrigerantThis product may not be returned to the original point of purchase. Please contact the manufacturer directly with any issues or concerns.