Downdraft Components

• A downdraft cooktop has a vent component that rises from the cooktop itself when you are cooking, usually via an electrical motor. This creates a backsplash wall that is actually a screened vent, which uses a fan to draw off cooking exhaust. The vent is attached to the same ductwork system that an overhead version would be, only it flows down through the crawlspace instead of up into the wall or ceiling.
  
  

Replacing Cooktop

• You can easily replace one downdraft cooktop with another, but using existing downdraft ventilation is another question. The easy answer is yes: you can use your downdraft ventilation with a new cooktop -- you need to if it is also a downdraft. However, the component, the rising vent wall and electric motor will need to be replaced along with the cooktop.
  
  

Using Ventilation

• Just because you can't use the cooktop components for downdraft ventilation doesn't mean that you can't use the ventilation system itself. The ventilation ductwork is still there, even if you switch to a different unit. That ductwork is necessary for the new downdraft and must be used if you buy a new version. This can help save significant costs in the remodeling that would otherwise be necessary to make room for a downdraft stove.
  
  

Benefits to Stay with Downdraft

• There are benefits to sticking with a downdraft cooktop when you're buying a new version. In many cases downdraft units are located in areas where updraft versions would not fit, such as on counters and in the middle of kitchen islands. You would have to switch around where you install your stovetop, which is another increase in construction costs that's unnecessary if you simply switch to another downdraft and use the same ventilation system.