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I have a natural gas range and a range hood with a fan that I find to be too loud even on the lowest setting.

The wall that the range hood is mounted to is an exterior wall, and I can see an exhaust wall cap on the other side of this exterior wall when standing outside. So, I assume the ductwork from the fan to the wall cap is a few feet long at most.

I have a few questions:

  1. To lower the noise in the kitchen, can I move or replace the range hood fan with a fan on the exterior of the home, similar to a radon mitigation fan (these are typically on the exterior of a home)? If so, what sort of fan would I use?

  2. Are there any downsides to this approach?

  3. If I have a contractor do this work, what type of contractor would I hire? It seems to be ventilation-related, so maybe HVAC?

Any other advice on how to go about this would be greatly appreciated.

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    Is the noise of the fan itself the problem or is it the sound of the air movement that's the problem? If it's the actual fan, it could be that there's a bearing going or something similar and a simple fan replacement might fix the problem. If it's the sound of air moving, then it probably doesn't matter where the actual fan is, the air moving through the hood will continue to make noise. Maybe look inside for some sort of obstruction that's causing excessive noise.
    – FreeMan
    Dec 1, 2022 at 16:47
  • @FreeMan That's a good point that it could be the air movement. I don't think most people would describe the noise as excessive, but I don't have a decibel reading. I can try to measure that later today.
    – Eric Angle
    Dec 1, 2022 at 17:03

2 Answers 2

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In theory, this could work. In reality, I am a bit dubious. Fans (kitchen exhaust, bathroom exhaust, most HVAC) are installed inside an assembly which takes a significant amount of space. With a typical bathroom exhaust fan, that space goes up into the ceiling, which is usually quite empty and several inches tall (more if there is an attic). With most HVAC equipment, the fan is part of a much larger device that is inside a room (whether that is a mini-split on the wall or a central unit in the basement). With a kitchen exhaust fan, the fan is inside an enclosure which is outside (below, normally) the cabinets.

If you move the fan to the outer wall, you need a way to fit it and mount it. That means either putting it on the outside of the wall - so a big box rather than a thin cover. Or it means putting it in the interior of the wall, which means cutting a large area to install it - either in the outside wall (not so easy, particularly if brick or block) or the inside wall (but in a kitchen this usually has cabinets over the desired location).

In addition, you would need to run power and control (on/off/speed) controls from an inside unit (which would now be little more than a control panel, light and cover for the duct) to the outside unit.

All in all, a more involved installation and more parts = higher cost.

The good news is that fans have improved a lot over the years - more power (measured in CFM in the US) with lower noise (measured in Sones). Even the lights have improved (integrated LED instead of screw-in bulbs). Look for a new unit that fits your location (length/width) and aesthetic preferences (style, white vs. stainless steel, etc.) and produces less noise than the old unit. If the old unit used to be quieter than it is now, you might be able to just replace some parts to get it back to spec., but if it is more than 5 years old I would highly recommend replacing it.

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    Aside from these points, grease extraction is also a concern. You really don't want that accumulating inside your ducts. I've recently learned about the importance of grease extraction (and regularly cleaning filters/traps) in a highly disgusting way.
    – JimmyJames
    Dec 1, 2022 at 17:25
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    The concern (which is quite a real issue) is that grease can collect in unwanted places. The filter is supposed to catch it all, and usually catches most but some will inevitably get through the filter. If the fan is immediately above the filter then you can remove the filter and inspect - and clean if necessary - the fan blades. If the fan is several feet away (attic or an outside wall) then it will be impractical to inspect and clean the fan blades and grease may actually accumulate on the first few feet of ductwork (i.e., it isn't actually so likely to blow all the way to the fan) and Dec 1, 2022 at 18:03
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    cleaning grease of the inside of ductwork beyond the first few inches is a very hard thing to do. Dec 1, 2022 at 18:04
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    Continued -- but improvising a fan location would not be advisable. You would have to replace the venting hood with a system designed for a remote fan, if there is such a thing. Dec 1, 2022 at 18:46
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    Exterior fans for hood vents are very, very common in commercial kitchens - of course, those come at commercial kitchen prices, and rarely care about being quiet. There were some common exterior wall-mount hood fans in the 1960's for household use, though. But yes, it has to be a kitchen fan to handle the grease and potential grease-fire gracefully. And they are supposed to be cleaned twice a year.
    – Ecnerwal
    Dec 1, 2022 at 19:50
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I have an installed bbq with a hood over it in a covered outdoor area (1,500 CFM) Obviously a bbq will emit a lot more greasy smoke/exhaust than an indoor oven. After a few years it got quite dirty/greasy, but it's over a bbq, not an indoor range.

OK, that said, I see nothing wrong with installing a fan / blower (etc.) where the duct from the hood vents to the outside. You'd of course have to add wiring and switching. You'll remove the existing fan. Leave the existing filters in place or even add some. I see no difference in ducts getting dirty whether you are pushing or pulling air from over your stove.

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  • "I see no difference in ducts getting dirty whether you are pushing or pulling air from over your stove." Not all hoods have filters but maybe if you have filters, keeping them would work. The only difference between pushing and pulling is how tight the ductwork is. If it's got leaks, some of the air will be pulled from void spaces instead of the hood and lower your flow. My ducts are pretty leaky and inaccessible without a major renovation. Also, when the engineer(s) designed your residential hood, they almost surely weren't considering an external fan.
    – JimmyJames
    Dec 2, 2022 at 16:04
  • @JimmyJames Actually they were. It's a custom built hood with the blower assembly in the attic and a very short run to the large vent in the roof. I realize that's not a typical setup, so you make a good point. But let's face it, most venting over an indoor stove is for cooking odors, extraction of byproducts of combustion (gas), rather than grilling or frying. I could be wrong. Dec 2, 2022 at 16:59
  • I'm not sure what you mean. The OP has custom unit? I missed that in the question. I recently removed an over-the-range microwave because it was literally falling apart. The amount of grease that came out of it (a lot onto my arms as I wrestled it out) was unbelievable and really nasty. It was then I decided I needed a real hood. In researching this, grease extraction is one of the most important functions of a hood. If that grease accumulates in your ducts, you could end up with a fire and/or critters feasting on it.
    – JimmyJames
    Dec 2, 2022 at 18:18
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    Yes, sorry, not trying to be a pain. I just want to give people a chance to learn from my mistake: i.e. not replacing the filters on my hood. I'm pretty sure the excess grease caused it to fall apart by dissolving plastic and/or adhesive. I did not understand the importance of grease extraction until I was scrubbing my arms down with dish detergent and simple green and trying not to vomit. And then there was a puddle on my patio where I left it for a few hours. My vent has a tray so it's a lot easier to see how fast the grease accumulates.
    – JimmyJames
    Dec 2, 2022 at 19:40
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    @JimmyJames WOW! that's a nasty job, probably one I'll be facing shortly. I'm thinking a "spinner" on a pressure washer with garbage bags or visquiene leading to a garbage can. in either case, YUCK big time!. Dec 2, 2022 at 21:13

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