Carrier dedicated outdoor air unit DOAS utilizes variable capacity compressors on the lead circuit and efficient scroll compressors on the lag circuit, that have been optimally designed for use with Puron® refrigerant (R410A). Operating efficiency of the units may be increased by adding the optional energy recovery system. All 62X units include a factory installed and programmed BACnet controller, capable of standalone operation or integration into a building automation system. ideal for schools, hotels, offices and other buildings that require efficient and reliable ventilation.