"Vox Humana" > wrote in message
...
>
> The basic problem is that steam and smoke rise. Downdraft systems are low
> and are in the center or back of the cooking surface. At best, they only
> capture some of the smoke and grease. The telescoping version is probably
> the best design. Downdrafts tend to suck the heat from burner when they are
> in the cooktop as is the case with models like JennAir. Still, if you have
> a tall pot on the font burner and the downdraft is several inches below the
> top of the pan at the back of the cooktop, you aren't going to capture much.
> Ideally an overhead hood is somewhat larger than the cooktop so it captures
> the smoke as it rises and disperses.
>
> I have a JennAir gas range. I had to install overhead ventilation because
> the downdraft didn't do an adequate job. Until the overhead ventilation was
> installed, the smoke alarm went off every time I used the grill. The range
> is install against an outside wall so there was no issue with the length or
> design of the ductwork. Downdraft is the choice of last resort. Cooking
> needs to be functional. When you don't have good ventilation, not only will
> your home be smoky, but that smoke will coat all your surfaces and fabrics
> with a film of grease.
>
> I would put the cooktop against a wall where you can install conventional
> ventilation or get a good looking hood to go over the island. Of course if
> you are just configuring a display kitchen where you won't do much cooking,
> it won't really matter.

Exactly my experience. I have an electric cook top where the vent runs down the
center. I won't try to explain the problems b/c they are exactly as you said.

My BIL just built a new house with a gas cook top and the pop up in the back.
It's worthless for the front burners but does an excellent job of sucking the
flame sideways on the back burners.

One thing I think hasn't been mentioned; they stink. All that smoke and grease
gets sucked down through a 4 - 6 " pipe running under the house to the outside.
Eventually it will build up and begin to stink. The only way to keep the smell
out of the kitchen is to run the vent constantly.


Tyler