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Whenever I sear steak (or cook anything on high heat), despite having our range hood on the highest setting, the smoke alarms always go off and the entire house smells pretty bad for several hours. Aside from changing my cooking habits, I was wondering if there's anything else I can do to improve this situation. I am totally willing to replace our hood if need be, but I don't want to make an investment only to find out it doesn't actually change anything. Our hood is currently a 36" under-cabinet rated at 400 CFM. We have a standard gas stove with 4 burners. Our kitchen is an "open space" concept though meaning it's kinda merged with the living room in the same space. The exhaust is supposed to go outside.

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Would a higher CFM hood "fix" the issue? Any other recommendations to what I could check?

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    "Supposed to" as in there is an exhaust vent outside, and you can feel the air come out? How far is the hood from the exterior vent and how large is the duct? – Gary Bak Mar 6 '19 at 2:03
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    How far is the hood from the cooktop? Does it cover it well? A picture would help. – manassehkatz-Moving 2 Codidact Mar 6 '19 at 2:26
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    How big is the vent duct that carries the air outside? – ThreePhaseEel Mar 6 '19 at 3:35
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    Is the filter changed regularly? – Andrew Morton Mar 6 '19 at 14:53
  • photos: imgur.com/a/cediAOT – Dandan Mar 6 '19 at 18:30
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As many have mentioned the exhaust duct needs to be sized properly, I have seen folks spend a lot on higher cfm fans that did no better because the root problem was the home was sealed so no air could get in to efficiently allow the hood to do its job. Try opening a window and see if the hood works better. If no change the duct may be two small, if the hood works with the window open you have a cheap fix. More expensive methods involve pressure switches and make up air from outside.

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  • +1 For 'opening a window'. When I need a little more oomph from my (weak) vent fan, I crack a nearby window. And my house is old and drafty. In one of these new tight builds, I think you would want/need a heat exchanging air-intake. – JimmyJames Mar 6 '19 at 14:54
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From the comments:

I haven't replaced the charcoal filters in several years

That is very possibly the key right there. Just like a clothes dryer won't work properly if the lint trap is clogged, and just like a HVAC system won't work properly if the air filter is clogged, and just like your car engine won't work properly if the air filter is clogged, your exhaust fan will not work properly if the filter is clogged.

An exhaust fan can have two types of filters:

  • Grease filter - This is designed to catch grease and particulates to prevent them from going into the effectively uncleanable (and therefore dangerous with grease accumulation) ductwork. They should be cleaned or replaced periodically.

  • Charcoal filter - This is designed to filter odors from the air. While it is not designed as a grease/particulate filter, if the grease and particulates are not filtered out elsewhere then they can clog up the charcoal filter.

So clean or replace any/all filters you can find! Then see if things are improved.

Also as noted in the comments: Charcoal filters are only used when venting to outside is not possible. I don’t think your unit is attached to an exterior duct.

I agree that generally charcoal filters are for venting inside - the concept is that there is no point in spending money to filter out odors if you are exhausting the air containing the odors to the outside. But I have seen charcoal filters in other configurations too, so that is not an absolute guarantee that you are not exhausting to the outside.

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  • It's definitely venting outside. I can see the pipes through the cabinet and there is an opening outside right behind the kitchen wall. – Dandan Mar 6 '19 at 15:40
  • If you have two filters - metal (grease) & charcoal, just run it without the charcoal filter. If it is only one combined-function filter, run it temporarily without the filter and see what happens. I suspect you will find a BIG difference - the charcoal filters I have used really cut down airflow, even when clean. And if that's the case, see if you can get a non-charcoal filter that fits the fan. – manassehkatz-Moving 2 Codidact Mar 6 '19 at 15:41
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    omg, you're right. I just read the instruction manual as well and it states you only need to put the filters for non-vented installations. I have no idea why the builder put the charcoal filters there. Took them out, seems to be working better already. – Dandan Mar 6 '19 at 18:26
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    Here are some photos btw: imgur.com/a/cediAOT – Dandan Mar 6 '19 at 18:38
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    It's hard to tell from the photo but the pipe looks like 4" you won't significantly benefit from the 600 cfm model. Hopefully removing the charcoal filters will help enough. On the plus side it looks like the venting was done well. – Joe Fala Mar 6 '19 at 19:27
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You need to investigate further. The size of the pipe going outside is a big determining factor. If it's even connected. Occasionally the exhaust outlet is connected to the back of the exhaust hood. Most cases there should be a pipe running up through the cupboard above the hood. It may be exposed or it may be boxed in. If your stove backs on to an interior wall then the pipe must conduct the exhaust a longer way. The longer the run the larger the pipe need to be. If it is a 4"pipe with a short run out, as in up a foot or two and then outside you should be okay. Then maybe a new one (not a cheap one) will help but only up to about 300-400 cfm. Cheap hoods leak through the housing like crazy. Good ones are sealed better and use better fan designs to move the air into the pipe rather than back into your house. If your stove is on an exterior wall then you can upgrade to a much larger unit and also upgrade the size of the pipe to accommodate it. The larger the pipe the quieter it will run while moving more air.

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  • Thanks for the info! This is the model I have: whirlpool.com/kitchen/cooking/hoods/under-cabinet/… My house is fairly new (built in 2013) so the builder put in everything. I can only assume they knew what they were doing... The stove is on an exterior wall and the exhaust is right behind it. So I would assume the air doesn't need to travel too far... Why limit to 400cfm though? I was looking at this: homedepot.com/p/… – Dandan Mar 6 '19 at 4:50
  • The cfm rating is a measure of how much air the fan can exhaust from the kitchen in a minutes time. The duct size is directly proportional to the CFM rating. Using too small a duct offers too high a resistance to air flow and defeats the value of a higher CFM fan. Proper duct size ensures a hood range works as efficiently and quietly as possible. Minimum duct sizes and recommended duct sizes based on a hood fan's CFM rating are as follows 400 CFM fan, 4" minimum duct size, but a 6-inch duct is recommended. A 600 CFM fan requires a 6" minimum duct size, with an 8-inch duct recommended. – Joe Fala Mar 6 '19 at 5:06
  • I've actually installed that KitchenAid model. It's a great unit. But the pipe size is critical if you want to upgrade and have it work properly. – Joe Fala Mar 6 '19 at 5:08
  • Thanks. The question is do you think it's worth "upgrading" to from my current hood? Assuming the duct work was done properly... Also, I haven't replaced the charcoal filters in several years, but my understanding is that only impacts odors. – Dandan Mar 6 '19 at 5:20
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    When you make all that smoke, can you smell it outside? – Willk Mar 6 '19 at 19:15

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