Hi 3Monsters, for what it's worth off the top i don't have a solution for you. Some advice though. We too have miele wall ovens and experience lots of smoke when using rotisserie. We install the screen in the back wall of the oven cavity when cooking with rotisserie which helps a bit. From my research i found most wall ovens (if not all) vent out the front of the unit. Either above or below the door. This makes it difficult to adapt these vent ports to an externally vented exhaust pipe. When we remodeled our kitchen a couple years ago I could not find any residential wall ovens that incorporate ability to vent outside the house. Or vent anywhere else other than the front of the unit for that matter. You might want to look into commercial ovens (specifically 'deck' style) that offer exhaust vent connections. We have a large hood over our rangetop that i turn on low when the ovens produce smoke. I also crack a window open outside the kitchen area to create a draft of 'makeup' air. Since our remodel involved making our home more energy efficient, i was told high cfm / pro-style range hoods without proper 'makeup' air can create backdraft of dangerous combustion gases (CO) from gas-fired appliances in the home; furnace without sealed combustion chamber, hot water heaters, nat-gas fireplace etc.
greenbuildingadvisor dot com has some good material on the importance of makeup air in residential exhaust systems.
Hope this helps

or get an oven with a catalytic converter.

Gaggenau

Search craigslist and ebay for older Thermador CT series ovens from about 10+ years ago, the ones with small windows, blue flecked interiors, and no gasket on the door or frame. These had built-in external venting through a 4" diameter vent out the top, though your cabinet and up out the roof or wall of your house, so you could use it without heating up your kitchen or infusing your home with cooking odors. I'm not aware of any externally vented ovens still sold today, but the older Thermadors in good condition are still easy to find, and they were made in 24, 27, and 30" widths, single and double, in white, black, and stainless. After they were bought out by Bosch, the Thermador ovens were replaced with Bosch designs that weren't outdoor vented.

What lee says, we had a Thermador for 27 years, wonderful oven with 4" vent, and internal fan.
Was still working perfectly, but I went to a range and hood.
Someone got a great oven last year when I donated it!

Interesting, xedos. A catalytic converter doesn't seem like a bad idea, so long as the oven is sized appropriately to contain it. It should get quite hot, starting at oven temp and then breaking down the grease and oils into gases. I would imagine it is not inexpensive, given the need for platinum and/or palladium to initiate the catalysis.

Considering the high price of the constructive destruction that is involved in a kitchen reno, oven manufacturers shouldn't worry about the added cost of another vent stack keeping their high-end ovens from being sold. It could be an option, albeit one that might require a more powerful broiler element. I'm unclear about what flow rate would be sufficient over the period of broiling to minimize spilled effluent when the door is opened. Maybe not a lot given Lee's historical four-inch Thermador example.

kas

Just for reference, a Thermador CT227 (pic). That's a 27" double oven; a CT230 would be a 30"w double, a CT127 a 27"w single. There were also CMT variants, which were a built taller and had a microwave booster built into the top oven like the current GE Trivection ovens. Note the 4" vent in the top back corner.

I deeply dislike this lack of external venting option. I have a Miele pyrolytic oven, purchased last year. It cooks beautifully as expected. it also heats up my kitchen, adds cooking smells, & when I open it I have to literally stand right back to avoid being hit with a blast of volcanic hot air! I think front venting ovens are dangerous!

With respect to my double Wolf wall ovens. They don't vent until the door is opened. They do flow air in under the control section over the top oven, and between ovens, and push it out under the bottom oven. This air movement is purely to cool the external skins of the ovens and does not contain any cooking effluent.

The Thermador venting scheme shown above is what I would want to have available. It could be passive to the roof blower. It would still have only partial effect, as opening the oven door on a broiling steak is surely going to emit greasy moist air into the room for any exhaust air flow rate one would want to pull through the broiling process. This is a case where searing under the cooktop hood and baking in the oven will result in somewhat less escaped effluent.

A salamander (electric for use where gas isn't supplied) and a wider cooktop hood would be another approach to allocating ovens to less smokey functions.

We installed a new wall combo convection oven & microwave last December. The circa 1985 Kenmore double oven that was installed in the same space had a posterior vent to the outside. I researched all the major modern brands and found that venting ovens to the outside are no longer a thing. I'm over 65 and remember all my parents' home ovens had a vent to the outside as well as the range hood vent.

I know this question isnt the same thing you guys are talking about...but i bought a Bosch duel fuel and they said to do a 'burnout" so we did but we did it 10 times and it still smelled toxic. They took i=t back but now im afraid to get another NEW oven because it made feel so sick. ugh i love to cook...wish i hadnt goetten rid of my old oven...but now i dont know what to do