Yikes! Is this a test question for wanna be interior designers, or a lesson in what not to do for architects? Just where does the downdraft system vent to, the infinite dirt filter below?

Given a limitation on cabinet costs setting the scope of kitchen changes, conventional solutions that meet the standard requirements of effective cooking effluent plume capture and containment (C&C) are not apparent.

Down-draft ventilation is far from optimal for C&C, although some find it adequate when the inlet is high enough to divert some of the rising and expanding plumes, given an adequate blower and duct system.

A vertical duct should not be excluded until you do some exploratory work to determine the layout of bedrooms and their closets with respect to the kitchen layout below. Perhaps the seller has blueprints.

A horizontal duct below your ceiling may not meet your sense of aesthetics.

Embedding a duct in your ceiling may be feasible, albeit messy.

Some of these approaches could make cabinet changes to get the range onto a wall space the lower cost option.

You may be in a position where you have to adopt the solution that people in controlled city condos sometimes have to adopt -- a recirculating vent system that actually works. At one time, excluding commercial systems, a recirculating hood that works was an oxymoron. Some residential systems have appeared in recent years that have received positive comments here, including one from Vent-a-Hood, and maybe from Broan. Searching this site for 'recirculating hood' should provide some leads.

I am not in a position to do cost estimating, and in any case believe that homing in on a few solutions trading effectiveness, aesthetics, and installation complexity need to be selected first.

kas

Thanks for your response. ***As far as I was able to tell***, the downdraft is piped under the kitchen and out the side of the house. It doesn't appear to just vent under the house. I am 90% sure about this, but who knows sometimes.

The sad part of this is the kitchen was remodeled in the past 5 years and they moved the range from the wall (where microwave is) to island. It is a single older woman who lives there alone, and I doubt she has done much cooking to notice the problem with her down draft.

Because the house was remodeled, to be first and foremost as aesthetically pleasing as opposed to functionally sound, I am not sure that the going through the second floor to the roof will work. A pipe would go right through the middle of the bedroom, or have to make 2 right angles to go through the roof, or 1 to go through the side wall.

The only downdraft that looks like it would it would work is the Best Cattura Downdraft. It stands up a monster 18 inches but may actually *somewhat* work.

Thanks for the tip about recirculating hoods, I'll take a look at those. If anyone else has any input I would welcome it.

The underground duct system can only work, even at the level of performance of a downdraft vent, if the pipe diameter is large enough and the exit into the air is free enough and the blower is powerful enough to flow the desired CFM through the pressure losses of the system. Going to a larger downdraft aperture in the hope of better performance may be thwarted by being gagged by the existing duct design. (There are axial fans that can push a lot of air though a lot of restriction that are used for aerospace applications. Usually these are screamers requiring ear protection to work near.)

Vent ducts are supposed to be steel due to potential grease fires, and they are rarely stainless steel, so I wonder how long one would last underground. PVC could last indefinitely, absent a fire, and maybe burn without hazard under a concrete pad, but does it meet code? And in any case, what diameter is it? Do you see an exit pipe anywhere outside?

I suppose we should consider the possibility that the existing downdraft was intended to appear to meet code and not intended to be effective.

kas

for clarification: it is a dirt floor foundation. there is a few feet clearance from below the subfloor to dirt. Nothing is buried underground. That would probably change a lot of your response.

Since we haven't moved in yet. I don't have access to the house to verify the ducts or post a photo.

My personal guess would be that if she could've put in a hood, she would have even if the house was redone solely for esthetic reasons…

I live in one of those city condos that doesn't have external venting. We got a Zephyr Europa model recirculating hood and it really works very well (for what it is - it doesn't compete with an external vent). Within its category, I'd give it a 10 for smoke, grease and moisture capture, but a lower grade for keeping the condo odor-free. Our surrounding cabinets are grease-free.

thanks for the info so far. So to throw another wrinkle, If I went induction instead of gas, would it a down draft work better (as opposed to using gas)? I am on the fence about gas vs induction. All my pans would work with either gas or induction, so that isn't a concern. Both seem to have their pros and cons. But if one or the other made the whole thing easier to do, it could help as a tipping point.

A down-draft system (really side draft over the cooktop) won't interfere with the flame behavior if there is no flame.

For a given pan temperature, the cooking plume velocity is a bit lower for induction than gas cooking (due to the gas hot combustion products joining with the cooking plume), so deviating the plume toward the downdraft aperture will be a bit easier with induction (but still partially unsuccessful due to the momentum vector of the plume being upward).

kas

I'd for sure test drive an induction before having a gas stove that isn't vented outside. I've never used an induction but people seem to really like them.

I like the idea of induction.... the wrinkle is gas is a known entity. I know exactly how gas works and performs. I am sure everyone who made the decision to switch from gas to induction knows exactly what I am saying.

The one other thing I like about induction, is we have younger kids. The idea of the cooking being done in the island, while more of a showcase, isn't as practical. Induction could be safer with everything else going on in that area.

too. many. choices.