Kitchen Ventilation
Clean the air -- and do it with style
Installing a kitchen without planning for proper ventilation is akin to lighting a fire in the fireplace without opening the flue. The system you choose must tackle smoke, heat, grease, moisture, and odors, while remaining as quiet as possible (8 sones or less). Vent units range from totally discreet to bold and flashy.
Your main choice is between hoods and downdraft systems.
If exterior venting is impossible, cabinet-mounted ductless hoods can draw out some smoke and grease through charcoal filters -- but they return air and heat to the room.
A hood should cover the entire cooking area and extend 3 to 6 inches over on each side. If the hood is 16 to 21 inches deep, place its bottom edge 24 inches above cooktop. Position a 24-inch-deep hood up to 30 inches away.
Are there drawbacks? Downvents don't work as well on a tall stockpot as on a skillet at cooktop level. However, recent systems are more efficient than those available just a few years ago. There have also been problems with long, twisted duct runs. Always route a downdraft system to the closest outside wall.
To find the number of CFM for your wall- or cabinet-mounted hood, the basic formula is: 50 to 70 CFM times the square footage (length times width) of the hood opening. The minimum rating is 300 CFM.
To determine the rating for a freestanding hood, the formula is: 100 CFM times the hood's square footage. The minimum rating is 600 CFM. The shorter and straighter the duct run, the more efficient your hood will be.
Commercial ranges and cooktops can really crank out the heat; you may need to make extra provisions for these. In addition, if you live in a super-insulated modern house and are planning a powerful vent system, you could require an intake fan or window to replace the air that's being sucked out. If you have questions, consult an experienced HVAC professional.
Your main choice is between hoods and downdraft systems.
Vent hoods
Unless your range is downvented, you'll need a hood above the cooktop. Ducted hoods channel air outside; roof- or wall-mounted exterior blowers are the best blend of quiet operation and efficiency. There are two basic types: freestanding and cabinet- or wall-mounted. In addition, the cabinet-mounted hood comes in a sleek, low-profile version that pulls out from under a wall-hung cabinet for use. Whichever type you prefer, look beyond style for convenient, variable speed controls and built-in lighting.If exterior venting is impossible, cabinet-mounted ductless hoods can draw out some smoke and grease through charcoal filters -- but they return air and heat to the room.
A hood should cover the entire cooking area and extend 3 to 6 inches over on each side. If the hood is 16 to 21 inches deep, place its bottom edge 24 inches above cooktop. Position a 24-inch-deep hood up to 30 inches away.
Downdraft systems
If your kitchen style is open and orderly, you may wish to put a downdraft system in the range or cooktop instead of a hood overhead -- especially if the unit is housed in an island or peninsula. Standard, convertible, and modular cooktops all come with downventing options. Some have grillwork between cooktop modules; others run along the back and may be raised electronically for use. The downdraft unit sets up air currents that draw smoke, heat, and moisture down; grease is trapped below.Are there drawbacks? Downvents don't work as well on a tall stockpot as on a skillet at cooktop level. However, recent systems are more efficient than those available just a few years ago. There have also been problems with long, twisted duct runs. Always route a downdraft system to the closest outside wall.
What size do you need?
The power of a fan or blower is rated in cubic feet per minute (CFM).To find the number of CFM for your wall- or cabinet-mounted hood, the basic formula is: 50 to 70 CFM times the square footage (length times width) of the hood opening. The minimum rating is 300 CFM.
To determine the rating for a freestanding hood, the formula is: 100 CFM times the hood's square footage. The minimum rating is 600 CFM. The shorter and straighter the duct run, the more efficient your hood will be.
Commercial ranges and cooktops can really crank out the heat; you may need to make extra provisions for these. In addition, if you live in a super-insulated modern house and are planning a powerful vent system, you could require an intake fan or window to replace the air that's being sucked out. If you have questions, consult an experienced HVAC professional.
