We recently bought a house with an older Amana downdraft gas range. After cooking on electric coil then electric glass top for the last 11 years I was excited to have gas... until I cooked on it. For an old piece of junk range, the downdraft was remarkably strong. Therein was the problem: the downdraft sucks the flames inward so cooking was horribly uneven. I really wanted to go induction but there wasn't room to do an induction range plus pop up downdraft and the cost of relocating an oven to a wall and doing an induction cooktop and pop up vent was cost prohibitive, so instead we bought a new gas range and are installing (in the coming weeks!) an overhead island vent, since our range is on a peninsula. Sorry this got so long, but I have strong feelings about the darn gas downdraft after being stuck with it for the last 6 months. Funny PS - we got our new range Thursday, ahead of doing our countertops early next month. It can't be installed right away due to an issue with the location of the gas outlet thingy and also the existing counters are in the way by about 1/4 inch. I'm happy cooking with a two burner hot plate, a toaster oven and a 12 year old convection oven combo microwave. That's how much I loathe the gas downdraft.

Here are two pictures to illustrate what we did. I'm not suggesting that this is the only -- or even best -- approach. It's just what worked for us. To make room for the cooktop and downdraft vent in the 24" deep cabinet, the contractor removed the cabinet back and then built a 2x4-width wall behind the cooktop cabinet and the 18" cabinets on either side of it. Removing the back provided the extra needed room. He also had to shave the sides of the cabinet just a bit to fit the cooktop in, since the cabinet itself was 36". The picture below shows the cabinet with the narrow back wall. We then installed a laminate countertop over the cabinets. Adding the narrow wall behind meant that we had a 30" deep counter in that area (24" deep cabinet + 3.5" wall + counter overhang). Those extra inches were nice to have for landing space on either side of the cooktop. From GardenWeb Photos Fast forward 14 years to this fall's kitchen update. I wanted to maximize space and decided to reclaim those 3.5" (thereby giving us almost 36" between island and cooktop peninsula instead of the 32" we had). So, after removing the countertop, we removed the wall behind the cabinets and pushed the cabinets back those extra inches. Then we nailed a section of 3/4" maple-faced plywood to the back of the cabinets, added tile in front of the cabinets, reinstalled a countertop (granite this time) and the induction cooktop (also 36") and the new pop-up vent. You can see the cabinets with the plywood behind them in this picture. From GardenWeb Photos Since you are putting yours in an island, if you will have other cabinets behind the cooktop cabinet, the back of one of them might provide the stability for the cooktop cabinet and you might not need something like either our initial wall or current 3/4" plywood backing. Hope this all makes sense. Please ask questions and if you want more pix, let me know.

If you can't repair/replace your vent motor(?), the next cheapest solution may be to get a new model Jenn Air cooktop, including a downdraft vent. I believe Jenn Air still makes these. One difficulty with other downdraft vents is that they are placed just outside the perimeter of the cooktop, rather than within the cooktop (as in your photo). A vent's efficiency deteriorates sharply the farther away suction is from the effluent source, so vents set beside a cooktop tend to work best for the one or two hobs closest to them. The best solution may be a vent that sits directly above the cooktop, but obviously this is more expensive. Moving the cooktop to an exterior wall adds other expenses, but may simplify exhausting the vapors. In general, venting from a corner (or a wall) works better than from the middle of a room, as you have things now. Of course, what and how you cook, and your local ordinance regulation, may also influence your decisions here.

I currently have a Jenn-Air 4-burner electric downdraft cooktop in my island, and I hate it. It is old, came with the house, don't have model number. One large burner heats to cherry red on high and burns the pot and contents. One small burner does not get hot on low. I have to turn it to med high and then down. And remember to turn it to low and wait. Grrr. Since I am finally getting a gas line, but have limited wall and counter space, I was considering a range or a cooktop and double wall oven. Thought I would look at gas downdraft units, only found a KA Architect with an integrated downdraft and 4 burners. I want 5 or 6, 4 is inadequate for my needs. I was surprised to find that several downdraft cooktops were quite cheap, then discovered that you have to buy the pop-up downdraft hood separately, and they are $1000 and up! So you are still looking at $2000+. I don't want a hood over the island as I have a huge custom pot rack there, and don't want the expense of venting to the outside. UGH. Good luck to the OP--how did your choice turn out?