Are all inline range hood fans created the same? 1000+CFM Q

auroraborelisJune 25, 2013

I am trying to make a decision on the single most confusing part of my entire new construction project - the range hood!

Our two main concerns are a quiet hood, and one that works well!

I'm looking for a chimney style contemporary stainless steel hood. There are lots in the same style, so it is more about what

We have about 25' of 10" ducting, with two 90 degree turns.

I have read a lot of great things about the fantech inline options, but I don't know what hood to pair it will. Are the expensive modernaire ones the only options?

Will the Viking, Kobe or Zepher inline option be just as quiet?

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xedos

The noise is made by the fan/motor and the ductwork.

It will be hard to tell by brand which is quieter as many co.'s don't publish sound ratings on inlines and your ductwork and where you actually mount the motor will impact the noise too.

Just get the hood that fits your budget and sense of style and don't fret about which one is quietest.

WIth a 1000+ CFM motor and 10" duct , none are going to be silent from @ 25% power on up.

    Bookmark   June 25, 2013 at 8:04AM
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kaseki

With enough length and room for it, a Fantech silencer/muffler installed in series with the fan will reduce most blade induced turbulence noise and upstream duct turbulence noise. Baffle turbulence noise, not a serious problem usually, will of course not be affected by the silencer.

Pick the fan to provide the desired flow rate at the pressure loss that the ducting, hood, and imperfect make-up air "system" will cause at that flow rate. Fantech publishes fan curves (or data) for their fans to make this analysis possible (given that the rest of the numbers you need will have to be guesses).

Or, if you want a 1000 cfm, take a WAG and use a 1500 cfm at zero static pressure motor. However, without hood dimensions, choosing a flow rate is cart before the horse..

kas

    Bookmark   June 25, 2013 at 9:16AM
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auroraborelis

I'm sorry, I'm not sure what WAG stands for.

The hood will be 36" wide and 24" deep, and it will be over a 36" induction cooktop.

I realized I need more CFM due to the run of ducting - 4' up to the ceiling, 90 degree turn, 7' straight, 90 degree turn and then approx. 14' straight up through the roof.

There are a ton of hoods that fit my budget and style, so finding a quiet one is the main concern.

I'm aware that there will still be air noise, but I want to remove as much as the fan/mechanical noise as possible. Our floorplan is very open and I don't want to be in the position (that I am in now) that I don't want to turn the fan on due to noise.

As for make-up air, it doesn't seem to be a requirement in my area (northern California) shocking because everything else here is so strict! That said, I'm not concerned as I will just open a window when I need to turn it up higher.

    Bookmark   June 25, 2013 at 11:50AM
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weedmeister

WAG = SWAG = Stupid Wild @ss Guess.

If you have two 90* turns, you might want to think about converting them to a pair of 45* turns. The reason is that they are 'gentler' on the air flow and cause less turbulence and restriction to the overall path.

    Bookmark   June 25, 2013 at 12:49PM
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auroraborelis

The 90 degree turns are into and out of the ceiling... I wonder if two 45 degree turns are an option. Interesting idea thought!

Oh... and I now love the WAG acronym!

    Bookmark   June 25, 2013 at 5:58PM
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auroraborelis

Okay, next silly question.

Is the Viking inline fan just as quiet, and work just as well, as the fantech inline fan?

    Bookmark   June 25, 2013 at 6:09PM
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kaseki

Technically, you need the same cfm at the greater pressure loss from the two 90-degree sections

The actual flow rate needed for a six square foot aperture size is probably only a nominal 540 cfm (for wokking, frying, and searing), so selecting a fan in the 800-900 cfm at zero static pressure range should be good enough for the pressure losses from ducting, hood transitions, bends, baffles, and make-up air restrictions, and typical fan curve performance. Obviously, with a list of items that long, the actual restriction pressure loss can widely vary, but I think the factor of around 1.5 should be enough to make up for several sins.

I don't have experience with the Viking inline fan, and don't recall anyone here describing it before. If it is an axial fan, then it should be similar to Fantech's offerings, but does Viking provide enough data?

kas

    Bookmark   June 25, 2013 at 9:59PM
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Stickball

Why not go external? This is a 1,500 cfm Viking unit that I did NOT want on my standing seam metal roof.

It's now painted to match the house and it's totally protected and easily serviceable. I have about a 30' run of 10" with only one 90 bend and one 45 bend. Well under the 75' maximum limit.

Still under construction so I can't speak to the noise level. But I put in spray foam insulation and that has greatly reduced external noise levels, all around.

    Bookmark   December 8, 2013 at 12:42PM
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Stickball

Internal view...

    Bookmark   December 8, 2013 at 12:44PM
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foodonastump

Hope that's not a window you're planning on using for MUA! ;)

    Bookmark   December 8, 2013 at 8:59PM
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scole250

Do you have any other gas appliances inside? Furnace, water heater, dryer, fireplace? If so, you need make up air else you'll be sucking that exhaust into your home, even with an open window.

    Bookmark   December 9, 2013 at 9:01AM
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kaseki

That housing on the side of the house looks very much like the blower housing I have on my roof sold by Wolf for their pro-island hoods. In Wolf's case the unit was made by Broan.

And with respect to "window MUA," my blower exhausts air down at least 10 ft of roof, and thence over a two-foot overhanging eve. The window below it, if open, will pull in cooking odor. Some care is needed in selecting the location for MUA intake vs. hood exhaust to avoid recycling the exhaust. In the case shown in Stickball's photo, one hopes for effective baffles, because some higher frequency window washing may be on the horizon.

kas

    Bookmark   December 9, 2013 at 10:03AM
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