Kitchen vent fans horizontal and vertical sones different?

[Bill Dufour]

looking to buy a new over the range vent hood. I see some Broan units that are sound rated 0 sones horizontal and 6 sones vertical? I don't think any vent fan is really 0 sound and why the difference. Maybe they mean vented vertical or horizontal back into the room?
I just might buy one to return it for making any noise at all. See what they say about that!
Bill D

[Lee Schierer]

looking to buy a new over the range vent hood. I see some Broan units that are sound rated 0 sones horizontal and 6 sones vertical? I don't think any vent fan is really 0 sound and why the difference. Maybe they mean vented vertical or horizontal back into the room?
I just might buy one to return it for making any noise at all. See what they say about that!
Bill D

One sone is equivalent to the sound of a quiet refrigerator in a quiet kitchen. The advertising probably means that the sound level is than one full sone in the horizontal position. Probably written be someone that was a non-technical person.

[Stephen Tashiro]

. I see some Broan units that are sound rated 0 sones horizontal and 6 sones vertical?

Do you have a link to that specification? Is it on the Broan website?

[Jim Becker]

I know that my 48" Broan vent hood over our range pretty much is the in-home equivalent of a jet engine, especially if it's turned up to the full 1200 CFM side of the dial. LOL My vent duct is horizontal to the left for about 7'. If I do this again someday, I'd investigate a remote fan/blower option...it would be more compatible with my hearing aids. :) :D

[Brian Elfert]

I would think that any vent that is 1200 CFM is going to be noisy. My parents have a Broan that is a decade or two old and you can't hardly tell it is running on low speed. It makes a little noise on high, but it is only about 300 CFM or so.

If I put my over the range microwave hood on high I think visitors would start to look for the 747 that is getting ready to take off.

[Jim Becker]

Yes, the 1200 CFM level will be noisy, but getting the fan remote can help with that since the blower is by itself quite noisy and it's "direct" noise. Remote blower helps mitigate that direct mechanical noise a bit, depending on the distance, and what's left is the noise that air makes transiting the filters and "into the beyond".

[Mike Henderson]

I know that my 48" Broan vent hood over our range pretty much is the in-home equivalent of a jet engine, especially if it's turned up to the full 1200 CFM side of the dial. LOL My vent duct is horizontal to the left for about 7'. If I do this again someday, I'd investigate a remote fan/blower option...it would be more compatible with my hearing aids. :) :D

I have a remote fan hood on my stove and it's still fairly noisy, especially at high speed. I guess just air movement noise.

Mike

[Bill Dufour]

The zero sones was on the Lowes site. I am sure it was a misprint. The broan site does vary horizontal vent and vertical vent sones by 0.1 or 0.2. I looked up sones and zero does not mean no sound it means it is so quiet that the human ear can not hear it. Did some research and found one rated under 2 sones instead of the standard 6 to 6.5 sones. I agree a roof mount fan would be better.
Bil lD

[Rob Luter]

I was in the home ventilating industry for many years and Sone level is a contrived measurement. Broan (now Broan/Nutone) basically ran the Home Ventilating Institute (HVI), the trade group that invented the Sone as a measure of sound. They also invented the test protocol for determining Sone level, which consisted of acoustic testing under operating conditions that a fan would never see in the real world followed by a mathematical averaging of db levels at various frequencies to give favor to a particular design. The resulting score was the sone level. It's not linear. It's hocum. It's right up there with the "Air Watts" rating on vacuum cleaners. It was developed as a marketing ploy and used an "average refrigerator" as a benchmark because everyone had one of those and could relate.

No matter what the rating, perceived sound has as much to do with installation and ducting as anything. More restrictive ductwork creates more static pressure and that can cause turbulence around the tips of the fan blades that causes noise. This is reflected in the different sone levels for Horizontal (out the back) and vertical (out the top) ducting.

Fans that use backwardly inclined paddle wheels and shaded pole motors are real screamers. These are the $15 "fart fans" and cheap range hoods they sell at the home centers. Fans with FC wheels and wound motors are much quieter, as are the few axial bath products on the market. Panasonic used to make one that you couldn't tell was on. They actually added an LED indicator light to let you know it was running.

[Bob Grier]

If you can do a rooftop fan with 10" or 12" duct from range hood to nearly straight up (minimal or no bends) to the roof, then noise will not be so bad. You can actually cook and talk at the same time. However, roof top fans usually are higher cfm and make up air could become a safety issue if you have combustion sources in the house like fireplace, gas clothes dryer, water heater or furnace.

If you have forced air heating and the makeup air is tied into the furnace return plenum (common method), then if the furnace fan is not running when exhaust hood is running, some of the return air bypasses the furnace filtering system and enters the house through the furnace return air duct(s). This can be annoying. It is best to have the return air automatically turn on the furnace fan so return air will be filtered and disbursed throughout the house to avoid cold drafts near the house return air duct. Cold air in winter may trigger the house thermostat to turn on the furnace which will take care of the filtering and cold spots but it is good to have the furnace fan turn on anyways when the kitchen exhaust turns on.

I have been told that some jurisdictions require capture of the heat from the range hood exhaust.

Makeup air is triggered by a low pressure switch that opens a baffle in the exhaust duct. The makeup air duct needs to be large unless it also incorporates some sort of fan system to deliver air in the range of 1200cfm. If return air does not deliver enough air then air pressure can go negative inside the house. Alternative to not having enough makeup air while safely operating the exhaust hood is to open window or door to the outdoors but then you are bringing in unfiltered air and in the winter it may be cold.

If the house is large like 4,000 sf or leaky then there will be less makeup air required and it will be easier to supply. A really leaky house may not require makeup air.

[Jim Becker]

If the house is large like 4,000 sf or leaky then there will be less makeup air required and it will be easier to supply. A really leaky house may not require makeup air.

I can vouch for this from personal experience. The 48", 1200 CFM hood I mentioned above I installed in 2003 when I renovated our kitchen. At that time, our home was only 1950 sq ft. Running that fan full blast noticeably was pulling air from the basement area which leaked like a sieve for outside air. Our 2200 sq fit addition went on in 2007/2008. Running the fan at full tilt, while noisy as mentioned, doesn't have the feeling of air movement "coming through the cracks" like it did previous to that home expansion. It's still spilling the same amount of air outside, but that volume is a smaller percentage of the air contained in the house at any given time.

[Bob Grier]

I made mistake in my post the other day. This is wrong: "Makeup air is triggered by a low pressure switch that opens a baffle in the exhaust duct."

It should read: The low pressure switch opens a baffle in the makeup air. (otherwise the air handler would be pulling air from outside the house as well as from return air and pressurize the house. Maybe that wouldn't be so bad. I don't know. Might help control dust seeping in or coming in doors and windows when opened.