more questions on range hoods -- hopelessly confused about MUA

tickyboxApril 16, 2013

Hi All,

I have posted here with questions about range hoods before, but I find I am still at sea on some issues -- and the more I read about cfms and make up air, the more worrying I find the subject.

I have read the article over here:

And also many of the threads on this forum, including the one set in Massachusetts where the builder ran into trouble with the inspectors for having a 1,200 cfm unit with no mua plan.

This has me fairly paralyzed with indecision. Previously, I had thought the best way to go was the most powerful range hood you could buy. Now, I'm veering in the opposite direction, towards weaker range hoods.

But, it occurs to me that I might be asking the wrong questions of myself. I suspect a lot of the posts in this forum are for kitchens with very powerful ovens. The Green Building Advisor page says to stick to 400 cfms or less, and even suggests 150 to 200 for a normal residence (seems very low!)

Our oven is not commercial grade. It's a 30" GE Profile, 5 or 6 burner (depending on how you count it, griddle/grill down the middle), dual fuel convection oven, double oven (gas top, gas convection, small bottom electric second oven). The house is not a big one -- maybe 1400 square feet, but also an unfinished basement, and unfinished attic. It has an oil burning furnace, and an upstairs ceiling fan to take stuff straight up in the bathroom, but no central air, and no plans for central air. Maybe someday, in the future, I will be able to afford a new range, in which case, it would go up a step (GE Monogram, Viking maybe), but still just be a 30 inch range.

I had been looking at various models, Kobe, and the Zephyr Savona, but both of these are 600 cfm and up, and it looks like code now requires measures to be taken for over 400 cfms? Once I took that into account, I started looking at the 30 inch Best K313930SS, which is 400 cfm. And yes, it's only as wide as the oven, not wider -- we have very little room to spare. This part also makes me nervous, but it seems again like I might be judging my requirements against some hard core chefs in here. We like to cook, and we like to experiment, but we're not actually all that good at it yet!

We are not interested in the type of hood that is built into cabinets, as the cabinets have already been ordered, and the plans leave the space for a chimney style hood.

So -- what is sufficient for this setup? What is overkill? What will keep the inspectors happy? Am I over thinking this after reading too much about MUA and how tricky it can be?


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Holly- Kay

I am in the same boat. What seems so easy to some seems a major hurtle for me. What I will say is that the width isn't as important as the depth. So thirty inches wide as long as it covers the cook top front to back and I believe that is 24 inches, should be enough. How do I know this? Someone on the forum told me because I am clueless to air flow etc. Hubby is still pushing for mw over the range and i am about to cave because I can't get answers from my kd. At this point I am so sick of this kitchen renovation that I am ready to drop the whole dang thing.

    Bookmark   April 16, 2013 at 3:09PM
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First, you should consult your local code inspectors, preferably talking to a real person who can tell you what is required in your jurisdiction. If you decide you must have MUA, it is probably best to hire an HVAC company, who has experience in these kinds of installations. There have been a lot of home-brew DIY type systems discussed, especially over on the Appliance Forum, but whatever you do must be acceptable to the code guys. Don't expect the appliance manufacturer or sales person to give you adequate advice - they will never risk killing a sale by admitting that a MUA system is required which may be more expensive than the range and vent hood combined.

The capacity of your vent hood is generally determined by the type of cooking you do, and what you can afford. In my jurisdiction, the code guy looked at what my range's manufacturer recommended for venting. If all you do is simmer, poach, roast, or reheat take-out, the 100-200 cfm recommended by that GreenBuildingAdvisor may be enough. But if you want to stir-fry, sear, or grill indoors, you will need every single cfm you can afford to clear out the smoke and grease from your living space. I really don't think you can grill indoors unless you have a hood that extracts much more than 400 cfm - probably requires 1000 cfm or greater.

As for the size of the vent hood relative to your range, the 6" wider recommendation is for optimum performance. But in the real world, many of us have to compromise due to space or budget issues. My particular work-around is to do my high heat searing or stir-frying on a burner that is centred under my hood - at least my cook top affords me that choice, with several burners of the same output.

Hope this helps.

    Bookmark   April 16, 2013 at 3:41PM
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