Range hood – am I looking for a unicorn?
Anders_Bostrom
| Posted in General Questions on
So elusive, impossible to find. No, I’m not talking about a unicorn. It’s about the range hood.
Scenario: new construction airtight PGH and all-electric.
We are looking for a 36″ chimney-style hood, baffle filter, low noise, below 400 CFM, and that actually extracts the smoke/fumes. Most fans make much noise but have little to show for it.
In a previous build we installed a Fantech unit with an external fan and custom-built hood but this time I would like it simple.
Has anyone had any luck finding the ultimate unit or have some suggestions on what to use?
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Replies
This may give you some ideas. My setup is automated but would work well standalone.
https://www.garagejournal.com/forum/threads/automate-kitchen-exhaust-hood-fan-using-inline-ecm-fan-turbocharge-yer-exhaust.491330/
I purchased an inexpensive IKEA hood, and removed the built in fan which was pretty useless with respect to actual evacuation. The ECM inline fan is about 3 feet above the hood, hidden in the cabinetry. It is efficient and quiet. Measured CFM at the hood is 160 at max speed, however the automation system is typically dialling in fan speed around the 100 CFM mark. Speed is proportional to power use on the induction cook top.
The problem I've seen after looking at a lot of hoods with built in fans is the flow tends to be quite turbulent, and in some cases actually sends air downwards at the blade periphery. An inline fan can provide much better evacuation if the hood capture area is just a simple inverted (squared off) cone and there is no downward air flow due to blade turbulence.
HVI and AHAM both rate kitchen hoods. Look at both as some manufacturers only report to one. You can sort but Sones to find some quieter hoods.
https://www.hvi.org/hvi-certified-products-directory/section-i-complete-product-listing/
https://www.aham.org/AHAM/What_We_Do/Kitchen_Range_Hood_Certification
I purchased a Victory Range Hoods (.com) 36-inch "Twister" model in November 2022 and was able to select the fan CFM rating from several options - but it doesn't appear they provide that ability in their online ordering system (they had a 300 CFM fan available when I ordered). Maybe give them a call and see if they still allow for different CFM configurations? It's a nice unit with non-electronic controls which works very well.
All I have to say is good luck. I've been searching for similar, though with double the CFMs you're looking for and there are only a couple of brands on the HVI website with under 60dB, all of which are $2000+. I've debated about buying a cheaper hood and putting in an aftermarket fan but I haven't had time to research if that is possible or even good. I think I remember the HVI website having a fan minus hood by a brand named Wolf, maybe, which was $800 roughly. If those things have fairly universal mounting could buy that and just stick it in a Home Depot hood and perhaps come out quieter and $1000 cheaper
Eric_U,
Or use an in-line or exterior mounted motor.
@Eric-U , the Terrabloom inline EC fans I used for my setup are HVI tested: https://www.hvi.org/hvi-certified-products-directory/section-i-complete-product-listing/
The metal case is a requirement here with respect to code. From Terrabloom's site: " ECMF series fans are ETL listed and Conform to UL standard 507, Certified to CSA standard C22.2 "
6" is 260 CFM (HVI)
8" is 530 CFM (HVI)
10" is 900 CFM (HVI)
6" is more than enough for our 30" induction cook top, generally running about 50% speed (very quiet at that speed). The hood is installed 24" above the cook top. If the fan is installed 7-8 feet away from the hood with a duct muffler, it's under 60db with no issues. Fantech's LD-6 silencer is rated for kitchen exhaust, $125 - https://www.hvacquick.com/products/residential/Kitchen-Exhaust/Silencers/Fantech-Silencers
For my setup, the fan is just 24" from the hood, inside the upper cabinets. Sound levels were measured 1 meter from the hood, with the 6" inline fan, running into about 10 feet of very restrictive ducting. The exterior hood is a 4" Broan Ecovent and my 6" duct narrows to 4" at the exterior hood...not an ideal setup. Unfortunatuely the Ecovent is only available at 4".
Speed Setting 5 - 57 db
Speed Setting 6 - 61 db
Speed Setting 7 - 63 db
Speed Setting 8 - 65 db
CFM measured at the hood with full ducting etc. connected:
Speed Setting 5 - 111 CFM (this is what the system typically runs at for near 100% evacuation)
Speed Setting 6 - 124 CFM
Speed Setting 7 - 131 CFM
Speed Setting 8 - 162 CFM
I am not using the LD-6 duct silencer, but referencing their acoustic specs, you would expect a solid 15-20 db further reduction, particularly if the fan is in your attic space. Doing this again, I would 100% have put my fan in the attic with the LD-6 as it would have made my setup effectively "silent".
The smell test is a quick evaluaton of system effectiveness. I can't tell the cooktop is in use in the next room, and PM2.5 levels do not change on the main floor during cooking. The wall oven, which does not have a dedicated exhaust vent, is a different story.
I seem to not understand. 162CFM at 65dB is abysmal. The range hood at my previous house was listed at 250CFM and if I was searing a steak on a cast iron skillet I would be lucky if it sucked up even half of the smoke. The RV I'm living in while I build my house has a range hood of unknown cfm but is 67dB on high which is way too loud while I'm standing next to it, though at least it sucks up 90% of smoke I make. Because of these two experiences, my goal is to find a range hood with the commercial style grease catchers as opposed to the screens you put in a dishwasher, looking at 500cfm+, and preferably under 60dB
@eric_U, 165 CFM is actual, measured at the hood with ducting in place. Evacuation efficiency is not about CFM, it's about how well the hood actually evacuates. Keep in mind, it never runs at full speed, the automation system dials speed relative to cooktop power use. Typically it's at 57 db. That's a lot, lot quieter than a typical fan hood, measured 1 meter away.
Your 250 CFM hood was rated at zero static pressure, so the actual measured flow (particularly if it used the typical fan) was likely a lot less, maybe half of that measured at the hood. I've looked at a lot of hoods and found that some of them at full speed were creating all kinds of edge turbulence (air blowing downward from the fans periphery). With an inline fan and a decent hood, you don't get any of this...just suction at the hood. To be honest, many of the designs I've seen (hoods with integrated fans) are just plain awful. Turbulent flow at the hood and small collection areas (take the grease screens out and take a look!) seem more the norm than the exception.
CFM ratings don't tell you much about how a kitchen exhaust fan will actually work once installed. The mixed flow EC inline fans tend to work better under static pressure, and the reputable manufacturers provide charts like the one attached so you can predict actual measured flow once installed. Ideally you'd have a cone shaped hood covering the entire cooking surface leading to a 6"-8" duct. If you do this, I'd be very confident in saying that 120-150 CFM (again, actual flow with all ducts/hoods installed) 24" over a 30" induction cooktop is plenty. In my setup the fan is just over the hood, inside the cabinets, with no duct muffler, but is still much quieter than the hood with the integrated fan. It also flows a lot better.
I monitor IAQ on all three floors, and with the current fan setup, PM2.5 levels don't change at all while using the cooktop. Turn it off, and the typical baseline of 0.5ug/m3 will spike to 50-60 very quicky on the main floor, measured about 25 feet from the kitchen!
So what exactly do I need to search for, "Under Cabinet Vent Hood no Fan" or something? Buy something like this https://hauslane.com/products/uc-ps18?variant=12409615450186 and add a Fantech blower somewhere in the pipeline?
Look for "remote blower range hoods". In my case, I just purchased a hood that had a decent collector area and removed the OEM fan. The remote inline fan is wired to the OEM hood switches. Due to the way the EC motor controller works in my system, the fan switches on the hood are just connected to dry contacts, so no concerns over power etc.
I'm using this device to run the inline EC fan: https://www.getzooz.com/zen54-0-10-v-dimmer/
Power use by the induction cook top determines the fan speed via that controller.
The Fantech inline motors and LD-6 muffler are an excellent "off the shelf" solution, particularly if you install them in the attic, well away from the hood. Their EC fans can also be controlled with the Zooz Zen54. The Zline remote blower hoods look like a decent collector design: https://zlinekitchen.com/collections/remote-blower-range-hoods
I purchased an 'empty' built-in style stainless steel hood and installed a Fantech unit on the roof. We have a direct vent gas fireplace where the flue is on the far gable, hidden from view. We built a faux chimney and had a steel cap fabricated to house the range hood and main plumbing stack.
I added a Range Relief pressure sensor from AirCycler which opens an inline damper for make-up air when the range hood exhaust fan is turned on.
That looks very nice indeed! Three questions:
1. What did you source for a hood insert?
2. With regard to the plumbing stack, did you have to do anything to prevent back flow into your ventilation system at rest?
3. What climate zone are we talking here? I'd be concerned with respect to ice build up (in our Zone 7A) in the faux chimney area. That said, I really like the concept as vent hoods etc always stand out like sore thumbs on most builds. Yours is very slick.