How Do Downdraft Cooktops Work?

Mechanics

• Downdraft cooktops use powerful fans to suck cooking odors, steam and smoke into ducts that exhaust the air outside or through a series of filters that clean the air before redepositing it into the room. Either system requires space beneath the cooktop to run the required ductwork. Because these systems use one or more fans, they may be noisy to operate, though baffles and insulation can minimize the sound.

Efficacy

• Because downdraft systems draw fumes across the cooking area and down, instead of straight up as with a traditional exhaust system, they may not clean the air of heavy smoke or humidity as well as a traditional system. Hot air naturally rises, so overhead exhaust systems don't have to work as hard to draw steam and smoke into the system. With filter systems that redeposit the air into the room, dirty filters can inhibit the ability of the system to clean the air.

Drawbacks

• If you have a gas stove, the fans on a downdraft system will pull the flame toward the downdraft, which can lead to uneven heating or longer cooking times. You won't have this problem with electric stoves. People who cook a lot of steamy or smoky dishes may find the downdraft system not effective enough at removing odors and humidity from the kitchen.

Pluses

• Many people like the sleek look of downdraft cooktops. In many, the fans stay hidden until you're ready to use them, at which time they rise from the back of the cooktop, retreating again once you switch them off. You even can purchase downdraft systems to add to existing cooktops. These systems may be less expensive than some overhead venting hoods.