Induction or electric coil will avoid gas combustion products infiltrating the household air when there is no capture and containment ventilation above the cooktop.

There may be value in testing for zinc level when finger circulation is deemed insufficient.

To even suggest a ventilation scheme, I would need a sectional view through the middle of the cooktop to show the cabinet, wall, attic, roof, basement, downdraft ducting, and apparently, screen porch deck and roof. A dimensioned plan view will also be needed.

Are the manufacturer and model number of the cooktop classified data? If so, can we have both surface and counter cut-out dimensions?

Bosch and Fridgidaire offer induction cooktops with real knobs. Sticking with (better) induction will mean that ventilation is less critical than it would be with gas.

You will need to check the specs carefully but I think a pop-up downdraft can go behind the cooktop on a standard depth cabinet.

you can do a hood, there are lots of great options if you move away from traitional

this one could go above the window, light andventilation

lots of optionsoptions here

By inside the cabinet is downdraft venting, I believe you mean the ducting is there. A Best Xattura downdraft would work with induction. Demo a Bosch and Miele induction cooktop. The control sensitivity could work for you. Downdraft doesn't go with gas as much because it distorts the flame.

"I dislike the induction cooktop. I have very cold fingertips and have a difficult time with electronics that require fingers touches."

Frigidaire Professional FPIC3677RF 36 Inch Electric Induction Cooktop

There is also a 30" model

Neither wanted to tackle a hood over the cooktop because I have a barrel tile roof.

Specialty roof so you need a tile roofer to handle the roof penetration and install of the vent pipe, not a run of the mill GC.

@James Overton: "Without extra depth to the cabinet, you will not have room in the cabinet interior for a cooktop and separate pop up downdraft"

No, the spec sheet for the Bosch HDD86051UC downdraft hood shows that it and a Bosch cooktop require a 22-5/16" or 22-11/16" deep cutout.

@James Overton: "A 22 3/4” cutout in a cabinet whose interior is only 22 3/4” leaves zero margin for error..."

Dunno. I don't know where "interior is only 22 3/4” comes from; it's not the appliance diagram. My IKEA Akrum cabinet is 24" deep. The hood/cooktop combination appears to be designed to fit within such a cabinet.

I did contact a roofing specialist

I was quoted $1700 for the roof vent alone. Does not include hvac from hood to roof. Everything is adding up quickly

Wdccruise

The bosch downdraft and cooktop is what one contractor said would fit. Reviews of the bosch downdraft are mixed at best. But I guess something is better than nothing

not understanding whats wrong with a wall mount hood that circulates not vented

hahahahahah as home are and have been since the cave days. Humanity still carries on!! SERIOUSLY James?????????

Could you go out through a wall somewhere instead of the ceiling and roof?

I considered going through the wall above the window and enclosing the duct inside a faux beam on the screened porch and out the back but several issues with this. I would have to remove my fan with light that is currently in the middle of porch. And the vent would exit above screen, I didn't think that would be good placement

There are probably ways you could still have the fan, if you used a flat oval duct of the proper size to run across that ceiling. And depending upon which way the joists run, you may be able to at least partly bury it in that ceiling. It's a bit of cobbling, but I think it could be done in a way that looks decent.

Converting round to square and then over and out is not difficult.

My 2 cents…

I suspect that I am more accepting of down drafts than most people here, but… just spend the $1,700 to go through the roof. Doing anything else is penny wise and pound foolish.

Pop-up downdrafts are rather expensive (the Bosch is around $1,700) and not half as effective. You will end up with better results using the cheapest 36” island hood you can find ($500). You are still going to have to run the ductwork with downdraft, which is going to have to get to the exterior somehow, so you are going to have some type of penetration to the exterior. The counter is going to have to be modified and possibly the cabinet. The total net savings of a downdraft is likely only a couple hundred dollars if that. I wouldn’t be surprised if it turns out to be more expensive.

When I first read your post I was assuming we were talking several thousand dollars to go through the roof. Even if it was $1,700, that is just not that much to end up with a safer (especially for gas) and more effective system.

Don’t let the tail wag the dog.

Agree with bry911.

The $1700 quote actually sounds quite reasonable, especially given that the roof is barrel tile. Quite a lot more complicated to penetrate compared to most other roofing.

Straight up and out the roof is the most efficient way to vent. And compared to the cost of downdrafts or complicated routes with corners, transitions and needing to try to hide it in faux beams, the least expensive way, IMO.

I was quoted $1700 for the roof vent alone. Does not include hvac from hood to roof.

The duct from the hood is not a big expense, if that is what you mean by HVAC. And I would not expect the roof guys to handle that part of the install anyway. That is part of actual hood install; the length of the duct will be dependent on the positioning of the hood, something the roof people cannot accurately predict.