I haven't looked at current specs or installation instructions but I did my downdraft install and duct design. First, your inline blower set off sirens in my head. Please have Dacor mail you their specs and confirm that their current spec permits the inline blower. For me it was 6 weeks from receiving specs from them until I purchased the unit and installed the ILB. They changed specs without notice (I found out accidentally) and then it took a lot of calling and arguing to get them replace the ILB with a remote blower. When I did my install, the cutout for the dd adjoined (and was narrower than) the ct cutout. The dd does not come apart. It was lowered straight down through the counter cutout and screwed to the bottom of the cabinet. Mine is in a standard depth cabinet in an island. I ducted through the back of the cabinet and down between the floor joists and then a run to outside to the remote blower. I then installed cabinets behind the island on a platform raised 9". In the 9" space is the ductwork curving into the floor, the gas shutoff valve, the junction box for the oven (undercounter next to the cooktop). All wrapped with house matching panels. So the counter must be installed first. You need to be able to access the front of the unit to anchor it to the cabinet floor. You have to plug it in to the outlet. (My outlet is installed in the far back floor of the cabinet.) You have to be able to access the side that you are going to be attaching to the ducts; I vented through the back but my unit had more than one option. You need the right tools. I had a couple of very large drill bits and what I believe was an electric coping saw to cut the cabinet backs as necessary. You need to be able to access it for servicing. My island back cabinets with house matching panels fit together like a puzzle but removing 4 screws lets you move a cabinet (with attached panels) to expose the the duct attachment. (Removing one screw from a panel for the gas shutoff, another screw from another panel for the oven junction box., I have 18" drawers (standard is 21") under the cooktop that all come out to allow access to the unit.

I am in the same boat. Replacing my second Jennair, --maybe I should just keep it? Can not help you too much. what I have been told, is that the size of the ductwork will be different. Depending on the space and the size of the ducts in the new system, you could be looking at trouble. Either that there will not be space in your cabinet or under the cabinet, for the new size of duct. Or expensive work, and frustrated installer having to go out to buy the right attachments. SO I am going to dig out my old Jennair materials and take that with me to a dealer to see what best matches it. Maybe even photograph what is under your current cooktop and downdraft. One dealer told me it washighly likely that the new downdraft would have totally different sized ducts. The point is that Jennair was pretty ineffective, and the new one might be better, but trouble to install. You may need to replace the ductwork.

When one is cooking with high heat, the uprising effluent velocity can be 3 ft/s. When this is intercepted by an overhanging hood, it is feasible to capture and contain it with modest air flow rates (90 cfm/ft^2 with baffles). However, when using a downdraft aperture at the back of the cooking surface, capture and containment would have to start with redirecting the effluent momentum from rising to horizontal motion at the aperture. This requires at least as much transverse velocity at the effluent as the effluent has (causing a curving trajectory). However, air velocity outside of a duct drops rapidly with distance, meaning that for full capture of effluent from the front burners using a downdraft aperture the size of the cooktop, the air velocity at the entrance to the downdraft system might have to approach ten times that of the effluent. 30 ft/s is 20 mph close to the mesh, and maybe 40 mph through the mesh gaps, so one can imagine that the noise level might be a tad higher than desirable. Hot greasy cooking only on back burners might reduce the ten times factor to three times, so a large exhaust blower that could handle the restrictions (pressure losses) of a downdraft system might be effective, albeit still somewhat noisy. To the extent that they are cost and aesthetically feasible, hoods approximating commercial units will be more effective than hoods that greatly diverge from this pattern. kas

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?