The DVS whole house fan is the first ever to be designed specifically for use in home without attics or with sealed attics. Our engineers have taken our patent-pending 5300 fan and transformed it into a new design that exhausts directly to the outdoors. Their evolutionary approach preserves the 5300's record-breaking performance, sacrificing no efficiency while remaining powerful enough to cool even the largest homes. Designed to mount to the inside of a roof or exterior wall, DVS units allow all homeowners to finally enjoy the environmental and financial benefits of an AirScape whole house fan! Available in two mounting variants: the standard models sit within the framing to which they are mounted, the flanged version sits atop the framing. Available in ductless and ducted variants. Ductless models draw air directly into the fan. Ducted models draw air through a register and ductwork before exhausting it through the fan. 24-inch, industrial-grade fan - patent-pending design ECM motor provides outstanding power (1316 – 5064 cfm) and efficiency Automatic, R-10 insulated backdraft damper seals airtight to prevent heat loss in winter New Digital Touch Controller provide 10 speed settings and a 12-hour timer California Title 24 compliant. Outdoor openings must be protected from the elements by louvers, a wall hood, or other appropriate method, which are not included. Ordering The AirScape DVS comes in four models: DVS-NF-ND: AirScape DVS Whole House Fan. Includes fan with ECM motor, damper box, and wall mounted Digital Touch Controller. Features include: Plug-and-Play Connections (RJ-45), 12-hour Timer, 10 speeds (1316 to 5064 CFM). No duct and no flange. DVS-F-ND AirScape DVS Whole House Fan. Includes fan with ECM motor, damper box, and wall mounted Digital Touch Controller. Features include: Plug-and-Play Connections (RJ-45), 12-hour Timer, 10 speeds (1316 to 5064 CFM). OPTIONAL front mounting flange included. DVS-NF-D AirScape DVS Whole House Fan. Includes fan with ECM motor, damper box, and wall mounted Digital Touch Controller. Features include: Plug-and-Play Connections (RJ-45), 12-hour Timer, 10 speeds (1316 to 5064 CFM). OPTIONAL 7 foot duct and intake grille with box included. DVS-F-D AirScape DVS Whole House Fan. Includes fan with ECM motor, damper box, and wall mounted Digital Touch Controller. Features include: Plug-and-Play Connections (RJ-45), 12-hour Timer, 10 speeds (1316 to 5064 CFM). OPTIONAL 7 foot duct, intake grille with box and front mounting flange included. Airscape DVS Installation Manual Airscape ASM-DVS-F-D Specs AirScape ASM-DVS-F-ND Specs Airscape ASM-DVS-NF-D Specs Airscape ASM-DVS-NF-ND Specs Ships in 2-3 weeks.