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Nov 11, 2009 07:08 PM

Advice Needed - CFM Minimum Requirments

Hey everyone. I need some advice (and have a pretty good idea of what type of feedback I am going to get), please...

My wife and I are in the process of building a new house. This is the 2nd house we have built together and are a little smarter so we went out and bought all our appliances prior to home design (so we are building our house around our appliances!)...

Well, we bought a 48" GE Monogram Oven/Range with four (4) burners, a griddle, and grill.

During the design process we questioned our builder if we needed to "upgrade 600 CFM" which is an upgrade. The builder (heating/ac/venting contractor) charges about $5Kmore if over 350 CFM (special duct work, etc).

Well, the house is being built, the budget/$ is gone, and we now have learned we have to buy the hood vent (a disconnect with us and the builder) for it is an appliance and it is not included. We can deal with this, however...

Here is the question; Let's say I was able to find a standard 48" range hood (we are having wood pannels on the outside of the range and my wife wants to keep the hood as small as possible) with 450 CFM max capacity would you do it? What is the downside? We are not "big cooks" but who knows, I suppose it is possible for us to have all four (4) burners in use as well as the griddle and grill but unlikely...

We live in the midwest, the house is a 2-story with about 1,600 foundation and 10-foot ceilings on the main level and a lot of space in the kitchen/great room and lots of windows/ventilation. I mention this for I have read other posts where people live in smaller dwellings and want as much CFM as possible and want to give you an idea of the space/natural ventilation.

I found this on electronic bay (it has the power of 450 CFM but is only rated at 300):

Am I crazy to buy it? GE Recommends at least 1200 CFM.



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  1. Lot of questions, but one thing bothers us: Duct work for a hood is about the same regardless of CFM--the motor and its housing (on the roof or wall) are bigger (and cost more), but that doesn't add up to an extra $5K for duct work. 1200 CFM is a lot of draft. If it's too much you can run it at a lower speed (less noise too). The only times we crank ours up all the way is when we pan fry a steak in a very hot cast iron skillet and when using the iron wok.

    1. If you aren't big cooks, you'll be fine with the 450. Those 1,000 and plus monsters can reverse air flow in your chimney or furnace if your house is insulated tightly -- likely in new construction.

      To be honest, if you're looking to save money, I'd seriously consider a cheaper 30" range. Those 48" models are far from necessary, even for extremely good and avid cooks.

      1 Reply
      1. re: dmd_kc

        Wish I had the real estate for a 48" cooktop! You will NOT be fine with the fake 450. You will need 600 CFM or more with the grill and griddle, period. The manufacturer's 1200 CFM recommendation may be high, but it should give you a clue that anything less than half that is useless. Don't confuse opening windows with the ability to clear your room of fumes, grease and smoke. And Please! Call a different heating /AC contractor; that 'upgrade' charge is ridiculous.

      2. WOW 5K more,

        Here’s my take, call a restaurant supply company or restaurant design outfit near you. Tell them you have a 48” stove and need a hood company to give you a bid. The off the shelf models fit your needs like a suit at wal-mart. And guess what, custom built will more than likely be less than the number you just said.

        They will also measure in-flow and out-flow rates and supply in-flow vents if needed. I have a custom 1400 CFM and I wish I would have gone bigger for my grilling needs, I can still get smoke that doesn’t get sucked up, even if I open my windows.

        1. Well, ducting should not cost $5k, that is outrageous. You will need a 10" duct for a range that size. I am not very familiar with the GE Monograms -- but you generally add 1 CFM per 100 BTU at the minimum. For a range that size I think you should shoot for 1000cfm if you're a serious cook. The grill also will create a lot of effluent that will need to be vented. There are lots of great hood companies out there - abbaka, prestige, modern aire, independent, but would not recommend vent-a-hood for the price.

          There is no use getting a nice high powered range with under-sized ventilation. You can generlly get a local sheet metal fabrication shop to cover your ducting if you have tall ceilings.

          Since your'e in a newly constructed house, if you approach 1000+ cfm you need to ensure your local codes are satisfied in terms of make-up air, geezer is right -- you can create so much negative pressure in your home that the hot water heater, furnac,e or fireplace can backdraft into your home and cause carbon monoxide/gas problems. That problem is pretty rare, but in modern homes that are very tight, its worth considering.