Kitchen Ventilation
Choosing a kitchen ventilation system to suit your needs and your style.
Cooking produces a host of harmful by-products—heat, smoke, grease and odors—that not only accumulate on surfaces and give the kitchen a dingy appearance but also make the room uncomfortable for someone preparing a meal.
Moreover, many people use the kitchen or kitchen area as a place to gather and entertain. Proper ventilation will make the kitchen area much more pleasant. The right range hood will keep the air in your kitchen clean and comfortable.
Here’s what you need to know to choose a kitchen ventilation system that fits your cooktop and your space.
Updraft System or Downdraft System
Any kitchen ventilation system falls into one of two main categories: updraft and downdraft.
Updraft systems, the favorite among kitchen-design professionals, install directly over the cooking surface. These devices use a blower to gather vapors that rise naturally during the cooking process and then push them outside through a duct.
Updraft Systems
If you think an updraft system has to be accompanied by a boxy metal hood you’re in for a surprise. Newer models from Miele, GE Monogram and Zephyr utilize what is known as perimeter capture, a system that pulls contaminants to the edges of the hood rather than the center, allowing for slimmer, sleeker designs, such as flat or gently curved panes of glass or metal panels that project out from a wall and fold away when not in use.
Gaggenau’s AH 600 ventilator makes use of the Coanda effect, a physical principle that allows it to lift and remove vapors before they escape from the hood. The awninglike device employs two fans instead of one. The first fan, positioned at the front of the ventilator, generates a flow of air that pushes smoke and steam toward the back of the unit, where a second fan pulls them up into the duct-work and out of the house.
By comparison, a traditional ventilator uses a single fan to capture vapors and draw them up and out of the house.
Downdraft Systems
Downdraft designs pull air across the cooking surface and down through a duct that leads outside the home. Unlike hoods or canopies, which are purchased separately from a cooktop or stove, these devices are often integrated into the surface of the cooking appliance.
Since these units rise no more than 10 inches above the cooking surface, they’re too short to capture vapors rising from a tall pot, and because their methods of capture fight the natural laws of physics, most designers prefer to reserve this type of ventilation for situations where a traditional kitchen hood will not work well.
They’re best in kitchens with cathedral ceilings, where the length of the ductwork would be too great to work effectively, or in an island configuration where the homeowner doesn’t want to block the view.
Hoods or downdraft units without ducts leading outside the home are not true ventilation systems. They recirculate air, and have a limited ability to reduce grease, smoke, heat and odors.
Air Volume
Whether updraft or down, the effectiveness of any ventilation system depends on the volume of air the blower can move in one minute in relation to the heat output of your cooking surface.
This measure, CFM (cubic feet per minute), generally ranges from 100 to 1,500. To calculate the CFM your cooking surface requires, you need to know its total heat (BTU) output, which can be found in the appliance’s user guide.
For example, a range with four 10,000-BTU burners has a BTU output of 40,000. For conventional (less than 60,000 BTU) cooking products, measure the width of the cooking surface in feet and then multiply by 100. For example, a 30-inch cooktop requires a 250-CFM system.
For 60,000 BTU–plus pro-style appliances, the formula is different: Determine the BTU output and then divide by 100. So a 90,000-BTU cooktop will require a 900-CFM system. In addition to operating at a high enough CFM, the unit must also fit the width of your cooking surface. A 30-inch range requires a hood or downdraft vent that is at least 30 inches wide. If space permits, bigger is better, say manufacturers. The reason is simple physics. The larger the capture area, the less likely grease and odors will escape. For example, for a 30-inch range, a 36-inch hood is best.
A hood’s depth—the distance it projects from the wall—is also important. You want to make sure it covers the middle of the front burners. Otherwise steam and vapors will escape every time you use those burners.
Bonus Features
The newest systems do more than remove smoke and steam. Many have sensors that will switch on the fan automatically when they detect heat rising from the cooking surface. Delayed turn-off keeps the exhaust running for up to 20 minutes after the cooktop has been turned off, ensuring all vapors are removed.
Some vents can be tied in to a system that monitors ventilation throughout the home. Broan’s LinkLogic allows kitchen ventilation to work in conjunction with attic ventilation and ceiling fans throughout the home to maintain quality indoor air.
