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Advice on Range ventilation problem/possible solution

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We're considering a new house with an over-the-range microwave that doubles as the range hood. Problem is that the microwave is not vented outside. That's not going to work for me. It is not possible to ventilate up and to the outside, the only option is down.

We would replace the appliances, however, we must replace a range with a range - a cooktop and wall oven is not possible due to space limitations.

One obvious solution would be a down-draft range, but I had a Jenn-Air down-draft about 20 years ago; the down-draft was totally ineffective. There used to be a number of manufacturers of down-draft ranges, but my research has found only one now: Jenn-Air. And they cost about $2500. That's a lot of money to spend on an appliance that I know at the outset I will detest

Another solution we're considering, and this is where your advice is needed, is to install a traditional range hood, but select one that can be vented out the back (wall) side, and put an exhaust vent/ductwork through the drywall and down through the subfloor and out the space under the house. We would be creating a 90-degree bend in the ductwork inside the wall from the hood, and another 90-degree bend just below the subfloor to send the exhaust under the house and outside.

Is our down-ward exhaust solution feasible? Will it work and be more effective than a down-draft range? Or should I just accept the jenn-air solution? For what it's worth, the hoods we're looking at are all at 440cfm or higher.

Any advice you can offer will be greatly appreciated.

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  1. I would repost this on THS (http://ths.gardenweb.com/forums/kitch...).

    We also have a 10-yr old JennAir with downdraft...and it's also useless.

    FYI, this is a prime example of why I would never (or at least really reconsider) buying a house with no overhead exterior kitchen ventilation. Everyone always says the kitchen with granite countertops will sell the house, but for me, if the infrastructure is bad, it's endgame, as the cost of tearing out the kitchen to put in a vent is too high and/or structurally impossible.

    2 Replies
    1. re: E_M

      Thanks, I'll check out the gardenweb forums. If our ducting solution ends up being feasible, tearing out and replacing the drywall behind the range to add ductwork is a small price that I'm more than willing to pay, if it will work.

      1. re: janniecooks

        Yes, if it will work it is feasible. But so often, even on those forums, you see over-the-range microwaves/hoods with expensive and intricate marble and tile backsplashes. So if all you have to do is rip through drywall, great; but too often it involves removing the entire tiled wall, which, of course, continues on all the walls, and how in the world could you ever put them back?

    2. Is there a reason why you can't go up? A 90 degree bend will essentially leave you with a hobbled exhaust system.

      3 Replies
      1. re: wattacetti

        Yes; we can't go up because there's a second floor, and the wall where the range is located is shared with the next-door neighbors, which prevents us from venting directly thru the wall.

        How hobbled?

        1. re: janniecooks

          I suggest you review the technical information at fantech.net, as well as the Wolf ventilation guide, to understand vent runs and needs. I'm having a hard time visualizing your range/hood layout, and up and out through the ceiling joists isn't possible. Is it on an outside wall? If so, pretty easy direct out. If its an inside wall, which way do the second floor beams/joists run? You might be able to run ducts out between the joists to the outside wall, and vent there, from above the existing microwave. Our last house had an unvented microwave, inside wall, but low and behold, above it was access to a 6" horizontal vent to an outside wall. An easy replacement. Our current house [4 yrs for us, built in 1989] had a 'downdraft' only under the cooktop, and I took the easy way and installed a GE Profile downdraft gas cooktop. Big waste of money. Its loud and actually interferes with cooking, sucking the gas flame to the side from the pots. I'm investigating an Island hood, which I'll run out between the joists in the kitchen ceiling to an outside wall. Research carefully: make sure your hood generates enough cfms at the range to do the job, and watch the loudness! With a 50k btu Wolf cooktop, a 15' run of 6-8" pipe and one 90 degree elbow, I'm looking at units that do 500-700 cfm and generate 3.9 to 4.6 or so somes at the hood. I'm considering a Kobe, a Broan Rangemaster 63000, an Imperial, and a Sirius because of the cfm/sones goals.

          1. re: janniecooks

            Reading your posts again, and assuming you are in a townhouse and the range backs on the shared fireproof wall, I have to think the joists run parallel to that wall, meaning you could possibly run the vent out between your ceiling/second floor joists. And you might get lucky - did you look to be sure there wasn't a vent outlet suggesting that there is already a duct hidden up there? That was the situation in our last house. Look in the cabinet above the overrange microwave for a 'patch' covering a vent, and look to the outside walls, ceiling high, front and back of the house even with the range/microwave.

        2. I don't think your downward exhaust will work because it requires two 90 degree bends. I believe that ductwork like that will only work with one 90 degree bend, but check your local codes and the installation manual of the hood to be certain.

          I'm looking at the specs for the hood we had installed a few years ago and it shows only one 90 degree bend in all of the possible installation scenarios. So one bend will not leave you hobbled (as another post here suggests). In fact, our installation has one bend and it works fine.

          1. Thanks all for the fine advice and warnings. We're going to go for it. Here's our plan. We will be installing a smooth-top electric range (alas, gas is not an option) with a range hood. Haven't selected the range or the hood yet. For the venting, we cannot run the ductwork up to the roof because the run would be way too long, but more importantly would be more destructive to install. And the range is on an inside, firewall party wall. We're planning on purchasing a hood that has the vent opening out the back, removing the drywall from the hood down to the subfloor and installing a duct (no other ducts are present). So far, one elbow at the hood to direct the vent down. Run the duct down through the subfloor - a run of about six feet or so - then install as wide a bend possible to angle down towards grade (we have a vertical distance of about 5 feet from the floor joists to grade) to run the exhaust to the outside. We think this will work, it will certainly no less effective than installing a downraft range, and if worse comes to worse we'll install a booster fan just below the subfloor to increase air flow if necessary.

            The info on fantech and wolf was helpful, and along with hours of research on other sites we've concluded that we're not going to let the current ventilation (or rather lack of it) scotch this purchase.

            Thanks again!

            2 Replies
            1. re: janniecooks

              Jannie, can you post a follow up? Are you happy with your range hood one year later? We are considering a similar solution (regular hood vented down) for a similarly difficult kitchen space so I am eager to know if it is possible.
              I hope venting down has worked for you!
              Thanks

              1. re: Kuchtik

                We had to go with a downdraft vented through the floor under the house. When we broke through the drywall behind the range, the hoped-for 6-inch space turned out to be two inches or less, just enough for insulation but not enough for a proper duct. Had there been enough wall space we'd have tried a hood, but there was just not enough room. With our options being a recirculating OTR microwave hood or downdraft, I chose downdraft, and I don't hate it but I would have preferred a real range hood.