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Jan 5, 2007 02:06 PM

Venting your Kitchen with a high volume hood? Efficient homes vs hoods

Lets talk ventilation. Give us your thoughts on your fancy new hood your air flow related concerns.
Houses, condos etc...

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  1. I was following your discussion on this topic in the "commercial gas ranges" thread, and I agree it's a real issue. We installed a Thermador hood with outside blower that draws up to 1000 cfm and I'm always careful to slightly open a door or window in the kitchen to provide makeup air. Even at the lowest setting (300 cfm), opening a sliding door a half-inch or so makes a noticeable difference - and creates a pretty stiff breeze coming in through the door. At the highest setting, it can reverse the flow in the fireplace.

    Question for you - I recognize that opening a door is a kludge of sorts; is there some better way of solving the problem?

    1. Yes there are a many different ways to solve this issue. Really the choices depend on your climate,your particular homes setup and budget.
      Everyones situation is a little different.
      Cheapest solutions i've seen are wall dampers for fireplace makeup air that are installed in an adjacent exterior wall near your cooking area.
      These are manually operated with a little knob. They are not the best solution for a cold climate,however functional.
      The options go up to powered make up air ventilators,with variable speed interconnected to your vent device(exspensive).
      You need to strike a balance that meets your needs between all of your factors. If your home has a HRV,any make up air, type of heating system,fireplaces,air flow conditions,weather, etc....

      1. Both places I've recently lived have the kitchen exhaust vented just over the window you'd be most likely to open for make up air. Incredibly poor design.

        When I redo the kitchen I'm putting in a specific make up air intake and having it open out behind the fridge. The waste heat off the fridge coils will temper the air and the box itself will diffuse the flow. An electric damper will be tied into the blower motor. I also run an fireplace insert that I worry about backing up.

        Now if I could only find a dishwasher that vents to the outside....

        5 Replies
        1. re: Scrapironchef

          I've been watching this thread as well as the one in "commercial gas ranges" and was hoping someone might have a specific solution...

          We are doing new construction (due to my severe allergies and chemical sensitivities) and the kitchen will be as commercial as we can get away with in a residence (my wife is a retired chef). Because of my medical condition, the house will be air-tight, with all the air exchanges being handled by the HRV (heat recovery ventilator) and HVAC system with better than HEPA filtering.

          Our cooktop will be a DCS (48" wide, six 17K BTU burners and a charbroiler). The main sink will be a standalone one, 3 compartments and two 30" drainboards. 11 feet overall. (I'm just trying to paint a picture here.)

          Here's the dilemma: the cooktop is a standard 24" deep. We want a hood (1200 CFM external blower) with makeup air since the house will be so tight. The only hoods with makeup air that I have found are all 42" deep (jutting out from the wall) because they are made for commercial installations.

          Installing a manual louver is not a good option due to memory issues; i.e., we won't remember to do it. Opening a window is out of the question because of the air filtration issue. Having makeup air come in from the front of the hood and get exhausted out immediately would work, except we're back to the 42" hoods.

          Does anyone know of a hood that only comes out 24-36" from the wall but that also has makeup air built in?


          1. re: bobmac1547

            Well, code in some areas requires that any kitchen hood fan that expels more than 300CFM activate the house's vent fan to prevent backdrafts as well as replace the air that is leaving the house.

            Even with your HVAC system you'll still need a house vent fan (either built into the HVAC unit, or separately). You'll need to get wiring to the kitchen fan that will turn on the house fan when the kitchen fan is turned on.

            And I'm not sure if you already know this, but it's nigh impossible to make an airtight house unless you use spray foam for insulation, regardless of what your builder is telling you.

            1. re: Shazam

              Wehave been working with our HVAC for almost 3 years with this problem. We have a 48" GE Monogram and a wood burning fireplace.
              They installed a damper on the outside wall and between the backsplash and vent hood. Know we have trouble with the smoke going up and around the vent hood. GE says they have never heard of this problem. I wish I could find a vent hood with make up air.

            2. re: bobmac1547

              Have you found a hood with make up air? I have similar issues.

            3. re: Scrapironchef

              I am going insane trying to figure my hood configuration. I am getting a 60" Blustar, (160,000 BTU's) My house is foamed - air-tight. I live in the south. I am trying to figure out what to do with the makeup air thing.
              I am looking at a 1500-1600 CFM liner/external blower. I have talked to my HVAC guy about coping a commercial hood and putting a 6" space along the front of the hood for makeup air - Expensive. Or should a put a damper somewhere. What did you do? Did it work? Don't want to have to open a door.