A downdraft cooktop works about the same way as a regular range vent hood, with a few small exceptions. You can find downdraft vents in a couple of different versions. Downdraft cooktops pull the grease and smoke from cooking through an exhaust fan that is in the stove assembly as opposed to a hood that pulls from above.
Active Downdraft Exhaust System
Some of the downdraft vent systems are active. A button gets pushed when the vent is going to be used and the vent lifts from the rear of the stove between 8 and 10 inches. As soon as the vent completes its movement it automatically turns on. The smoke, grease, and fumes get pulled through the vents out through a series of ducts that go down below the cooktop and outside. Government regulations require for safety that all exhaust vents lead outside.
Central Downdraft Exhaust System
Another version of the downdraft cooktop is set up with a central venting system running vertically down the center of the cooktop between the left and right burners. This type of vent does not move, instead, the exhaust fan is under the cooktop surface and leads the exhaust outside. You can also turn on this version of the downdraft vent with a switch.
Downdraft Cooktop Ventilation Concept
The concept behind either of the downdraft options is a circulatory expulsion of the pollutants that occur with cooking. Even though heat rises, the pull of the exhaust fan in the downdraft ventilation system sucks the gas and grease back down into the vent ducting. Because the vent continues to pull the air down, those same pollutants continue down the ventilation ducts, follow the 90-degree bend and move out of the house.
Pros of a Downdraft Cooktop Exhaust System
Downdraft systems are better than no ventilation system, although if you have the option to install a vent hood over your cooktop, you will find that a hood works more efficiently. After all, heat and all things that are in the heat, like fumes and grease, will go up. An overhead vent will continue the updraft that is created naturally by heat's rising.
Another difference between the downdraft ventilation system and a hood assembly is that there is no lighting fixture available.
Cons of a Downdraft Cooktop Exhaust System
The downdraft vent has its fans and its critics. Some find absolutely no difference between the two ventilation choices. Some enjoy the aesthetically pleasing choice of a downdraft vent with nothing hanging overhead in the center of their kitchen. Still others, however, are very dissatisfied with the idea of a downdraft vent. They say a downdraft vent can blow out a gas burner if it is turned down on low, or that the back burners are the only ones that get proper ventilation. Other comments include burner settings.
A gas-powered cooktop has its fans who enjoy cooking with gas but for those who prefer electric burners or have no preference, then the countertop downdraft cooktop venting and the cooking choice is a good option.