Downdraft Systems

• The term downdraft refers to exhaust systems that sit level with or below a cooking surface. Range manufacturers often integrate downdraft ventilation equipment into stove and oven units. Integration with appliances not only reduces installation requirements, but also visually blends the exhaust system with the range. Whether integrated with or separate from a range unit, the only exposed portion of a downdraft system is the vent grate, similar to an air conditioning register. Because warm air, smoke and odors rise, downdraft systems are generally less effective at gathering exhaust than elevated, updraft systems.
  
  

Updraft Systems

• As suggested by their name, updraft exhaust systems pull air from above. Commonly called a range or vent "hood," updraft systems rest several feet above a range's cooking surface. While many updraft systems pull air into ducting, a common variation of the updraft exhaust system, called a recirculating updraft system, removes air from the range and pushes it back into the kitchen space. Although approved by many building codes, recirculating systems do not effectively remove moisture and odors from cooking areas. However, updraft systems that vent to a building's exterior remove substantially more odors, moisture and smoke than both recirculating and downdraft exhaust systems.
  
  

Installation Requirements

• Recirculating updraft systems are the easiest type of range exhausts to install. Recirculating systems mount above range surfaces and require only electrical connections. Downdraft systems and updraft systems that vent outdoors require substantial ducting installation. Because updraft vents easily route through attic spaces and exterior walls, installing updraft ducting during remodels is generally easier than installing downdraft ducting.
  
  

Cost

• Because updraft range hoods are the most popular kitchen ventilation option, updraft equipment is typically less expensive than downdraft equipment. Home improvement stores stock inexpensive range hoods in a variety of styles and finishes, and updraft duct fittings and supplies are easy to find. However, downdraft systems that are integrated with electrical oven and range units do not require dedicated wiring; a slight advantage over stand-alone updraft equipment.