Also, something to think about is tempering your makeup air. Work for a commercial HVAC company, so this was nothing new for me. But, depending on where you live (really hot / really cold), you might want to temper your makeup air. Otherwise, on a hot Austin day, your dumping a lot of heat into an already hot thing, so if your “slaving away” at the hot stove, drawing in 90 / 100°+ air will make that feel even more miserable. Or likewise, if your somewhere really cold, you could be dumping literal freezing temperatures into your kitchen, which could affect the temperature of what’s on your stove. And while yes, the hood should in theory capture most of this, if your HVAC system is running while the exhaust fan is running, my guess is you’ll get less capture of that makeup air from the hood then you’d like. Yes, it can be expensive to do, but in the same regard, it might be worth it.
Great idea, and actually required by IRC code if the hood is, I think, 400 cu ft or more. Otherwise the house will be under negative pressure when the hood runs, If you have built tight. I did this on the house I just built for myself. I have a cooktop on the island, and the vent is on the surface of the island, right next to the cooktop. It goes to an intake at the rim joist, that looks like a foundation vent, and the filter is there. I had put a damper on it that was supposed to open upon a draft, but the spring is a bit too strong. So it just has a filter. Next time I will probably motorize it, so it just opens when the hood fan runs.
I love this. I'm moving my make-up air from the basement to come up right under my range. The air will come up over the front of the range and pull grease and steam. I believe all high output stoves should have this built into the front of them.
Yeah, as a HVAC installer I prefer your description over what is in the video. As there flow from outside to the range hood is a direct linear line travelling over and around the range.
@@jmlcolorado in colder climates a good option is to pre heat if needed and deliver the make-up air into the pantry where it cooler air would have a chance to mix with the conditioned air. The pantry would stay cool and dry and the occupants would be shocked with cold unconditioned outdoor air.
Hi Matt, Gr8 topic. That was a major concern for me when I was building my ICF house 4 years ago which is very tight and with a balanced flow from an ERV. You might recall advising me on that. Well, We just a normal range hood with an inductive cook top, nothing so elaborate. But we also have a whole house Vacuum & Dryer which blow out air. My solution was to use my UltraAire XT105 (another item you recommended) & its very handy auxiliary fresh air intake. The cool part is i have 3 current sensing switches that sense if the hood, vacuum or dryer are on... the then activate & open the 100cfm XT105 auxiliary air intake. I love the UltraAire XT105 for some important reasons... the make up air is a big one. Thx for your years of advice!
As a operating HVAC tech, I'd definitely frown upon putting that damper in a tight space. It's not a question of if it will fail but when. That and I've already seen a few other members of the trade noting the actual ductwork. I love the channel, Matt, but I'd take a closer look at what the difference is between a good setup installed sub-par versus a good setup installed to spec.
I am not a fan of "tight envelopes" this is how we got sick building syndrome and had to start monkeying with airflow to deal with the issues cause by plugging all the air gaps/leaks.
I would like to see more about this topic specifically for retrofit applications. My wife cooks in the house just about every day and the smells linger. I also just put in some new panasonic bathroom fans and when they turn on you can tell they are causing the house to pull in air from various locations. I would like to be able to sync up a make up air system when either a kitchen or bathroom an comes on.
What you want is a chimney effect with range hood exhaust. Bringing in air right there pointed at the source of the smoke and smells is going to blow that air and smoke all throughout the room, and displace some of the air you are trying to exhaust when some of it makes a hard U-turn up the vent. Replacement air just needs to makeup for the negative pressure the exhaust is creating in the room, and should be anywhere else than near the exhaust source. It's like pointing a HVAC supply register right at a return.
Exactly. I'm thinking to cut some vent holes through the wall behind the kickboard under the cooktop, ant then putting a grille in the kickboard to tidy it back up
I'm not really sold on this setup. In a tightly-sealed modern house, you are already going to have an ERV/HRV. I would say just put a fresh air supply _somewhere_ in the kitchen (not even near the stove necessarily) and let _that_ system temper the incoming air. Granted, it would lower the ERV/HRV efficiency since the air going out through the hood wouldn't be going back through the heat exchanger, but you wouldn't be be dumping unconditioned air right on the person in front of the stove. There also wouldn't be a potential "short-circuit" problem either.
Exactly what I was thinking too. You already have "make up air" from the ERV. Why don't you just up the capacity of the ERV to supply the exhaust hood and you're done.
What if the make up air came out the back, and the exhaust fan was in the front? That way the hot makeup air doesn’t dump on the person at the stove? I think they try to avoid using the ERV as the makeup air, because that’s not fully conditioned air. So if you don’t do makeup close to the hood, it’ll suck up all your conditioned air, dump it outside, and it gets replaced with slightly humid, warmer air from the ERV all throughout the house
99% of the air will be sucked straight out with the dirty moist air from cooking, this is how it's done In commercial, with a perfectly balanced hood air conditioning is unaffected
Glad to see you trying to actually to bring make up air into the equation. When I did new hvac construction, the builders didnt care about the heating or cooling the house correctly, much less make up air for an exhaust system.
Thank you so much for posting this, I didn't consider this location, I have specified under the range, under the refrigerator, other places, but not right next to it. I love it!!
The path of return air vs suction induced by the vent is just short circuiting the cooktop. Ideally the path of fresh, return air would be under the stove or in the kick of the cabinet below the cooktop. This would create a path that pulls air past the cooking surface. I have a window near my vent hood. Opening it causes the air to go from the window to the hood, bypassing the cooktop. It tends to not help remove smoke or steam very well. This will be a similar weakness in design. Yet I understand the constraints of design and structure and as shown this is much better than no fresh air return.
I was planning to copy this idea, but there are some concerns brought up on a Green Building Advisor Q&A: "Kitchen Exhaust and Make-up Air in One Range Hood" and while it looks good, is not such a good idea. Thanks so much for all your great videos Matt. I have learned so much over the last several years and it was you who set me on this journey, and I am a bit of an evangelist telling people to look into it.
Great video Matt, I put the make up air in my kitchen in the floor near the range, it works so well and is so much better than heating or cooling all the air going up and out the hood.
It appears as though someone didn't follow the manufactures specs when they installed the hood fan. The hood will not function as designed. Usually, they require a 27" to 30" max/min distance above the cooktop (cooktops are usually at 34.5" to 36" off the floor) and unless Matt shrunk a whole bunch and is now under 5'6", the hood will not function as designed. All the air that was supposed to go up the duct will be just the makeup air and the steam and grease will find somewhere else to go. By adding the makeup ducting in the front; you have to make the hood surround huge and thus have to raise it so you can cook without smacking your head on it. The fan hood is for residential and not made for this application (unless I am mistaken- doubtful, provide model number).
yup. the hood is only 300cfm. ive seen a higher cfm fan closer to the range fail to expel enough smoky air from cooking. this would have needed a more "professional kitchen" approach. actually surprised if this will meet local code, but I guess it will otherwise matt wouldn't have installed it.
@@Foche_T._Schitt The manufactures specs of 66" off the floor apply to the actual fan unit, not the shroud. If the shroud is built lower/closer to the stove you will not be able to do any actual cooking. That shroud sticks out from the wall at least as far as the cooktop. If it is built to the specs, it has to come down to a maximum of 66" off the floor. Most people would have to contort themselves trying to get the head under shroud (your design idea) to see in a pot or do any stirring, making for a very unsafe situation. Next time you are in front of the stove, put a box at 66" off the floor and out from the wall as far as the front of the cooktop/stove and you will see what I am talking about. This design and application is a no-win situation.
It's also possible that this is a high end house getting spec'd with commercial quality hardware. If I could afford a house of this size, I wouldn't be putting in appliances I bought at the big box store.
My range hood is 3 speed, 250cfm, 500cfm, 1,000cfm, I use the first setting if using 1 or 2 burners, 2nd setting is 3 or 4 burners and oven, 3rd setting is if I burnt something or cooking something like salmon in a skillet, lol. If I have to use 3rd setting I will open a window, there is no returns in the kitchen or adjacent hallway.
I find these videos interesting, but I must say the real take-home lesson is that I am very lucky to live somewhere where you can actually open a window occasionally. Apparently, Houston is not such a place. You have to think all these people living in sealed up houses with their carpets and paint and such slowly off-gassing are going to end up with long-term lung problems or worse. I have a whole house fan, and while there are plenty of days I button up tight because it is too hot or too cold, I rarely go more than a week or two without opening up the windows, flipping on that fan and replacing all the air in the house with fresh air. Even hot summers occasionally have a cool evening or the occasional warm afternoon in winter, allowing this to happen at minimal or no cost. The idea that I should be afraid of pulling a bit of fresh air from outside when running the range hood for 20 minutes or so is just insane to me.
Houston, or Florida where I live, yeah those days are few and far between where you’d actually want to open a window. Even if the outside temp is nice, humidity, pollen, pollutants, smog, etc are likely present and just makes it all the more work on your AC to cool your house again. This is a super smart idea for what Matt cooked up to prevent depressurization and not exhaust all the air you just paid to condition.
Wouldn't a setup like this create a short-circuit where the vent will actually just be pulling only the outside air our of the house without much of the particles from the range being captured?
the path of the molecules are corelated to convection path, the molecules density in corelation with the atmosphere molecules density and the intake and outake position...if you'd want to get rid of heavy and or cold particles you'd want the air outtake to be under the intake... TL'DR' : now that mean if the particles are hotter or and lighter you'd want the outake to be above the intake
No. In order to exhaust air, you must have make up air. In a very tight house like they build today, that exhaust fan would do very little in terms of cfm exhausted without it. Kurt Zimmerman. Former hvac contractor and lead mechanical Inspector for st. Louis county Missouri.
@@teaforbastards It's more a matter of air density than a venturi effect that inhibits a "short circuit". The cooler bypass air is denser and falls onto the stove area. It's then heated and rises; picking up particle along the way. You won't see a venturi effect until the air gets closer to the exhaust inlet where the velocity of the air increases. There may be some slight circulation that bypasses the stove, but it would be negligible.
50 years ago having a makeup air vent next to your 60% gas furnace combustion chamber was a huge saving in not bringing cold air into house where you didn't want it, then it went up the chimney with flue gases. Maybe next is concentric exhaust pipes for bath fans, for make up air, fresh air blows in (static w/damper) on 1 vent and other side exhausts. With houses becoming so tight would 70 CFM's be a problem?
A D the there is not enough thermal heat generated and cooking duration is too short in residential applications. This was a thing in commercial systems 20 years ago, but the issue was that ductwork could not be sealed, cleaned or fire wrapped, and was a potential fire hazard. Plus seasonality made this a good idea in winter, but poor in summer.
This looks like it would short circuit the air path and not remove air/particulates coming off the range hood efficiently. Wouldn't it be better to have a makeup air vent somewhere else in the kitchen. Also the added filter, while nice to remove incoming particulates, is going to further hamper the hood's effectiveness. I would double or triple the filter media surface area (more filters) to get as little resistance as possible if a filter is a must.
Looked at the filter On the inlet side of the filter and the leaving side of the filter the contractor who designed, installed the system just taped into a sheet metal pan of the filter box.. What a bunch of people who really do not knot the art of suck and blow There should have been rectangle to round transitions at a minimum of 12" to capture the full area of the filter. What i see is contractors who operate out of there truck , no sheet metal shop, what a shame the homeowner is screwed again Sorry Matt
Coincidentally, I have the same honeywell filter box on my furnace - I get 4-6 months depending on seasonal air conditions (farm country - summer/fall have a higher dust load). Its probably overkill in this particular application, even when properly installed, but that's $25 a pop for the merv 11 filter. It probably translates to a $100 loss over the life of the unit, considering unused media area (and a filter replacement every couple of years). The real screw here is the foil tape job - I got a chuckle out of that. I'm surprised that passes code as a failure of the foil tape (which I've seen with hot/cold cycle applications) could result in what amounts to a chimney exhausting into the attic. Also - how many home owners are going to remember to replace that filter, in the attic, every couple of years?
In this setup 63% of the filter element is in the flow path. What does the rectangular to round transition cost in comparison to the filter element? Am I ever going to recover the difference? After running it in the intake I could take it out and run it in my furnace for a few months to use up the remaining capacity, until I get the DP alarm. Flow will take the path of lowest resistance.
@@paulchevako :) kind of my point as well... the tape failure risk, the extremely long service interval, and the fact that this filter resides in the attic are bigger concerns - IMO.
About time make up air is being added to homes! Commercial kitchens have active blowers to supply air, and some plenums in front of the hood have a separate plenum that also supplies conditioned air. So most of the makeup air going into the hood is just outdoor air, but there’s a thin stream of cool air coming straight down to keep workers cool in a hot kitchen.
Or warm(ish) on a cold winter day. Here in mn, a commercial hood will have a make up air u it with something like a 60 or 70 deg Delta t. Still chilly if you're a short order cool on a -20f day, but better than nothing, and eliminates condensation in the mua supply duct
One of the important reasons to do this is not the effectiveness of the exhaust fan -- that hood creates a powerful negative pressure on the envelope and so a would pull water through any holes. Any house built as tight at Matt makes should probably have a Z-duct for makeup air (without a damper) -- negative air pressure will be made up either by an uncontrolled and unlocatable leak, (or the ineffectiveness of the exhaust fans.)
Only point that was missed was how you are tempering your make up air. Thermolec has a pretty good modulating make up air system. Other than that good setup and design.
Filtered fresh air but not tempered. Wonder what the comfort of cooking in the winter will be. A follow up video with a theatrical fogger through the fresh air intake with the exhaust fan running would be welcomed. No doubt make up air is needed. Likely we have all been to a restaurant that lacks make up air... hard to get the door open those first few inches and then you feel like you are in a wind tunnel. With a tight house, one should also consider make up air for fireplaces, gas/oil furnaces water heaters, and bathroom exhaust fans?
As an HVAC owner/operator this is code to have make up air for anything over 400 cfm (Michigan code). I find it extremely wasteful to use anything over 400. In the winter you have extremely cold air being put into your home and in the summer, extremely hot /humid air. ERV are an option but not very effective/efficient and very costly. People need to stop trying to make their residential kitchen be a commercial kitchen! If you want a commercial kitchen, buy a restaurant or become a chef.
I've done make-up air in a few client's homes.... however, it's important to note it's only really necessary for high end hood fans pumping out 600cfm or higher.
We have a 60" hood in our new house (foamed insulation) and had makeup air installed not as close but near by in kitchen like this. I requested that it have a filter on it like you did but they (Casa Mechanical) told me the filter would prevent it from working as it would be too hard for air to come through so it would come from undesirable places. I have a passive makeup air vent like you describe that simply opens a damper when the hood is activated. I'm intrigued to learn that the passive style can be filtered as I really didn't want to be bringing pollen or bugs into the house as we took so much care every where else to prevent that with the ERV and such.
large filters like these pleated filters do not block the movement of air.. Smaller ones that much move a lot more air over a given size will require a much higher velocity and will act as its own damper cutting down the ability to supply enough make up air
Although the larger media filter has a low resistance to flow in comparison to a standard 1" filter it is still resistant. Air is lazy and will always take the path of least resistance. If the house is submarine tight then in theory it's a good idea, in reality that filter will likely cause just enough resistance to encourage the air to enter from unwanted infiltration. Essentially the filter makes the small bad holes bigger if their resistance to flow is lesser than the filter. This would only apply for passive ventilation which it appears to be in the video. If you are going to filter than you should have forced air. A better approach would be a wall stack with passive fresh air inlet located near the cooktop, put a mechanical damper with a pressure switch connecting it to the exhaust system or simply a well balanced barometric damper would do the trick. If your worried about critters just ensure your intake is screened and well positioned. I wouldn't overly concern myself with worry over pollen, etc. Its intermittent temporary source control that when set up properly should not impact IAQ no more than if you were to open the door to go inside.
@@dustincole2625 Thanks, that has been my working theory with the setup I have. The intake vent is on kitchen ceiling near the hood and has a very short run of duct work to the outside. It has the pressure sensor you mention inside the hood duct work so the damper opens when I turn on the hood. I figure and hope that the ERV and general AC cleans up the air pretty quick anyway.
@@realpdm you should be fine, just remember that it's only bringing in the untreated air during times of use. So long as the damper closes after each use the amount of untreated air is relatively small so your existing systems should handle it.
What about the bath fans and clothes dryer? They need a supply of outside air as well. Wouldn't an exchanger connected to the HVAC system be the best for all of these, including the range hood? I understand the concept of a dedicated air supply from outside not needing to be conditioned for the range hood in this application, as it's theoretically exiting the building immediately, thus not causing much of a heat/cooling issue.
Yup. Heat pump dryer. Also, looking into Lunos eGo for bathrooms. Self contained, through-wall ERV. Not sure if cfm is technically big enough for a large bathroom, but worth looking into
This set up drastically reduces the capture efficiency of the hood. I.e. Not going to suck up air from the range as well. The make up air inlet needs to be further away. This is why they are often tied to the home air ducting or coming in under the range.
it would be wise to install the make-up air into the plenum of the return air to condition AND filter the air so requiring only 1 filter to service which should be changed 2-3 times a year anyway.
Yes, this is what I was thinking. If the outside air is very different in temperature, humidity and contaminants than the inside air then why would you dump it into the living space? Seems best to condition it before letting it come into contact with inhabitants. Introduce it directly to the return supply and get it over with. Otherwise save the expense and just open a window!
Great topic thanks. Been wondering about this for a while. Though we are going to have the make up air coming through a flat duct just below the stove top.
Yo ski, I was thinking the same thing. I live in Arizona, and I was going to create a way to take hot/dry air from the attic in the summer, to put INTO the dryer, and exhaust to the outside as normal. Then in the winter, take the air from the house, run it thru the dryer, and exhaust it to the inside of house. I have electric dryer (not gas) and I could use the humidity and heat in my house in the winter, and use the hot/dry attic air to quickly dry my clothes in the summer. (The HOA prevents hanging of clothes outside to dry) It’s a closed-loop in either case. No net movement of inside and outside air. Thereby Cooled air stays inside in summer, and heated air stays inside in winter.
It does seem like a good idea to manage the air flow for an exhaust hood. I like that it has both a damper and a filter. However, I wonder how much the system, hood included, contributes to the house's total leakage. I think I might personally prefer to avoid the penetration altogether. Which is why I am leaning toward an induction range with an air handler that merely filters and recirculates the air. What do you all think? Pros and cons? I live in an extremely hot environment, so the overall goal is to keep the heat out.
I'm wondering about this myself. Matt has another video where he shows the science behind matching the makeup flow, but it was in a different scenario with the makeup being at the other end of the kitchen.
Placing the inlet air immediately adjacent to the draft inlet reduces some of the draft forces above the pots and pans on the burners. This will result in needing to use a higher fan speed than might have been necessary. Adding inlet air is a good idea, but if the inlet air can be placed somewhere other than right next to the draft inlet, the efficiency of the draft fan is not reduced.
Why would we have to use a separate filter for the kitchen range hood makeup air? Would it be a good (or bad) idea to allow for kitchen hood makeup air by using a whole house ERV system? I would think that this type of setup would also allow the homeowner to control the incoming makeup air temperature, humidity, cleanliness, only need to stock one type of filter and not disturb a normal kitchen hood exhaust airflow pattern. Hopefully someone has the knowledge and/or real workd experience to let me know if my thoughts are completely wrong here.
I've been pondering a bit on how to deal with kitchen exhaust in an airtight construction. Basically my current thinking is that makeup air defeats the entire purpose and circumvents any efficiencies and advantages gained from an ERV/HRV. You're instead going to directly put potentially freezing or sweltering outdoor temps directly indoors, at whatever humidity level. Instead it's likely better to put ERV/HRV into boost mode and put a return at or near the kitchen. Plus not using gas, or cooking very grease heavy foods.. maybe use an oudoor kitchen/grill for that. Basically, just don't use a hood. Edit: Forgot to mention the option of a recirculating hood. Not bad if you REALLY want to cook foods with lots of particulates/smoke, but keep in mind the ongoing filter costs.
You cannot successfully setup an erv unit for your whole house to supply air for a unit that runs for such a short period of time, that being said all passive design projects I work on here in nyc call for electric stoves- no gas at all- to be used in such an air tight house to eliminate having to install an exhaust that would lead to heat loss
I own Restaurants we have tempered make-up air. Which means the intake air is heated/cooled according to the season. The last thing you want is 10 degree air in the winter blasting on your cooks freezing them and getting them sick. In the summer hot humid, sticky air making your cooks miserable sweating and dripping sweat on the food. Un- tempered air over works your heating and cooling systems. I have seen restaurants with untempered air over working their kitchen's A/C roof top unit to the point where they have a sprinkler running on them so they don't over heat. Also my hood co. Has a specual device that measures the air pressure so you can balance the air flows on the intake/exhaust fans. This guy Knows nothing about a proper exhaust system with make-up air. Your system needs to be certified. Not some home made nonsense. We spend $30,000 to $50,000 on an exhaust hood system, the best one made is Captiveaire. They make small ones for above dish washing stations that might work as a home system. Your idea of using air from a whole house air exchange system is a much more sound.
All the above. Work for a commercial HVAC company. Usually the engineer specs tempered makeup air. But, on a house if done right, it probably could be done with an ERV / HRV. The ERV would be interlocked with the kitchen hood and would then provide the makeup air that way. Again, it doesn’t have to be from a duct right next to the hood, just the hood needs that extra air to come from somewhere.
Kevin Murray- in theory it “can” work but a homeowner would have to take on more expense to get an oversized erv unit which will effect the whole house for a singular unit that runs for a short amount of time, this whole makeup air system is really over engineering houses to solve an issue you can really fix by just opening up a kitchen window since this air system isn’t bring in temperature controlled air anyway
I just did one of these, ended up retrofitting and moving the make-up air in the back. Customer complained the make-up air was unconditioned and blowing hot/cold air on their hands and face when cooking. About a $2500 CHANGE ORDER.
Did you move it in the back behind the stove or ducted the same way next to the hood, just the make-up duct against the wall instead of in the front? Did it solve the customer's problem?
@@chvitaly Ended up running it into the AC supply for around 4 diffusers in the kitchen area with a flow diverting valve to make sure it never put back pressure on the air handler. No complaints so far.
What do you do to temper the air? In the north in winter that would be very very cold air coming in. A commercial unit would normal have a direct fired heater to preheat the make up.
I could be wrong, but won’t having make up air immediately next to the exhaust cause turbulence and disrupt the flow out the hood as well as scatter the air you want to exhaust? Seems like make up on opposite side of room would create smooth flow and capture more particulate from cooktop.
Make up air should come from below, it's just gonna make a quick "U-turn" with that setup and not actually pick up the fumes from below very effectively. 😉👉
Matt, love your show, I learn new stuff all the time. My two cents: Maybe a little guitar slide as you start to say your outro, might help tighten it up a bit and make it not sound as "silly" for lack of a better word. You got the right idea though, keep up the great work!!
Pretty much code everywhere with a ginormous hood. But honestly you don’t need anything greater than that in a residential house. Save yourself the money and get a 400 cfm fan. I had one in my passive-ish house and it was fine. Also had a makeup air in my restaurant and it was *really* expensive.
Without a fan pushing this "makeup air", this is still relying on negative pressure INSIDE the space to draw the air through the filter. Look at ANY commercial set of prints and you'll find when an exhaust system is used whether it be for car-mon, dust collection, restaurant kitchen hoods, lab hood, paint spray booth etc, they have a POWERED MUA, not just a hole in the structure with a powered damper. This would be classified as relief air not makeup. To be makeup air, you MUST have a fan pushing the air back into the space in equivalent volume or your depressurizing the space which is the ENTIRE point of "makeup air". So, not a killer system but a lazy workaround that will limit the efficacy of your hood and cause other issues due to the depressurization. It's kinda the whole point of an MUA system. Is there a follow up video where you test the home's pressurization before and after the exhaust fan is on? And a smoke test to make sure your hood isn't just short cycling? Builders and HVAC pros already don't think about the V in HVAC enough so I can't say I'm surprised.
Make-up air for hood fans with more than 300 cfm has been code in Canada for years now. Usually connected to the furnace and (filtered) fresh air intake. Why is this a better system? You would think the incoming air would disrupt the flow of the exhaust, and make it less efficient?
So, is he suggesting that if my house was built in the ‘50s and I’m installing a completely over powered 900 CFM fan that I probably have enough air leakage to forego an intake fan? I didn’t realize this was an issue when I bought the fan. I’ve never had good ventilation in a kitchen and I don’t ever want smoke in my house again so I bought the most powerful fan I could buy.
The more I find out about what's necessary to make a good HVAC system work, the more I'm starting to wonder if it's actually a good idea for code to require all that in the first place. They want this stuff to be as tight as a submarine, which is great for keeping pests out but terrible due to trapping mold and harmful fumes instead. I can't help but think for every 2 problems a seal house & good HVAC system solve, they create 2-3 more to replace it
We all know what you're saying, be we all know that giving up is the wrong answer. Building better buildings takes work, but it's worth it in the end when they're more efficient, more comfortable, and longer lasting.
Make up air should really be done somewhere else like the basement. Far away from the range makes it to where if your make up air is really hot or really cold like Michigan weather, that uncomfortable air gets acclimated before a human feels the discomfort while still giving the appliance what it needs.
Yo ski, i contemplated similar. I live in Arizona, and I was going to create a way to take hot/dry air from the attic in the summer, to put INTO the dryer, and exhaust back outside as normal. Then in the winter, take the air from the house, run it thru the dryer, and exhaust it to the inside of house. I have electric dryer (not gas) I could use the little bit extra humidity and heat in my house in the winter, and use the hot/dry attic air to quickly dry my clothes in the summer. (The HOA prevents hanging of clothes outside to dry) It’s a closed-loop in either case. No net movement of inside and outside air. Thereby Cooled air stays inside in summer, and heated air stays inside in winter.
This will become another filter that just doesn’t get changed because it looks like it’s buried in the attic! Next issue is another electrical component hidden away (24v damper motor) that will never get fixed if these owners or even next owners don’t know what the vent is for. Too high tech for people who just want simple!
i hate how most range hoods have a CFM rating of 400, which is a code requirement. But these range hoods are pretty useless - they dont suck up heavy smoke, grease, and pungent odors. I prefer the Chinese range hoods with 900CFM made by Sakura, Pacific, or Accela. Captures grease and its really effective. I'd just use it with the window open.
Interesting- being so close to each other I would had thought it’d short cycle. I have been thinking about reversing the flow from a down draft for make-up air but it could interfere with gas ranges. I like your idea, have you seen it in action?
it looks like a mini commercial restaurant grade hood LOL how much does something like that cost??? i find normal residential ones witht he tiny mesh filter are garbage
Sorry, Matt, but the placement of the fresh air inlet makes no sense at all. This placement of the air coming in from the outside would just lead to it going right back to the outside. You want to suck up what's below though (i.e. the smells coming from the cooking). So the fresh air should come out from below the sealing. This way you produce an airflow that would provide fresh air to the room, while all the air from the smelly cooking is sucked in and transported to the outside.
Hey Matt, love your videos. I'm a mechanical contractor in NC and I am trying to make myself into one of the high quality (instead of low cost) contractors. I was wondering what made you decide to stick with a passive make up air instead of active. Is the hood a low CFM (400-600) hood or is it higher? I'm about to install make-up air for a home where they are installing a 1,100 CFM hood, so I'm going active, and putting my outside air vents in the floor below the cabinets in several toe kicks... I watch your stuff, especially when it comes to mechanical and building envelopes. Any thoughts would be really appreciated... or if you already have a video on this that i've missed...
I’m a little concerned about the fire code safety of putting an exhaust vent, supply duct, and gas stove in such close proximity, particularly in a non sprinklered residential installation. You typically don’t want to create the opportunity for a runaway fire to constantly be fed by both oxygen and gas fuels. Is there a fire damper on the supply side unit to mitigate this risk?
@@lisao3041 IIRC, code calls for make-up air for only certain sized vents. With new houses getting tighter and tighter, even the ineffective vent hoods track homes have can create a negative house pressure. Of course, a lot of those cheap units don't actually pull the air from the house, but instead pass it through a simple filter and back into the kitchen. I'm eating dinner with a HVAC engineer tonight. I'll ask him.
Interesting setup. We're in the midst of planning renovation of a 1940s brick cape cod, and my wife wants a hood in the kitchen - but I've been resisting after listening to many of your videos and Joe Lstiburek video/articles. We're hoping to reno the house and new addition to Passive House 0.6 ACH@ 50 Pa (or better as you seem to have accomplished on some recent builds). So here's my question or maybe challenge: Why not just ramp up the home ventilation system during use of the hood to balance the airflow - instead of installing yet another mini-ventilation system? Is the overall performance better/cheaper to install the system you're showing? How does the use of that dedicated ventilation for the hood system affect the performance of the whole-house ventilation system (HRV or ERV)?
I'm so not convinced having the supply right next to the event well actually remove the particulates. Your fresh air is going to go straight to the outside missing what year really after.
My thoughts exactly. The airflow doesn't cross the particulate area at all. I'd be interested to see a smoke test to see what air mixture actually ends up happening.
It works in commercial kitchens. This is literally the same setup used in restaurants and commercial kitchens. The Makeup Air being right there, creates what is basically an “Air curtain”, the force of the air being pulled downward extends past the grill and then allows the heat and particulates from the range to be pulled out. I’ve worked on both ends of this. I spent time in the restaurant design industry doing work in New Mexico, Arizona, and Las Vegas, NV and now I’ve been working for a commercial HVAC company doing project bidding for the last 14 years.
Why not put the air intake in that wall directly behind the exhaust? Would be a tighter space and wouldn't allow for such an enormous filter (is that huge thing really necessary?) but would save a lot of flex duct.
Is there a Make-up air unit that has a dx coil to temper the air? Those 100+ temps in the south could make cooking miserable, plus tax your central air unit
Any advice for someone who wants to get into carpentry, but not have to build fast houses? I joined a union after high school, but quit a few months in because of getting tired of hearing things like "it's not a church, just put it up there" I quit a $50/hr job to make $14/hr to do shotty work. Needless to say I went back to making $50-60/hr, but the work is boring and lazy. I'd rather learn craftsmanship the proper way the first time, instead of having to relearn it later. Is it a matter of putting in the time? If so, I'll pass and keep earning a high wage, and try to learn it on my own.
In theory, at least for restaurant code, the hood should be flush to the back wall and should extend at least 6” past the cooking appliance on the other 3 directions. For an island without a back wall, the hood should extend at least 6” from all 4 sides, not including makeup air.
i am confused regarding exterior wall installation,which one is the best to the value and cost effective like STO German or BASF or rock wool or glass fiber , please help us out thanks
Something i haven't quite understood over the time i've been watching. I get the benefits of keeping the house tight...but are there any drawbacks? And if the majority of your air intake and filtration is through your a/c etc are there any negative effects from extended power lose like low air levels and co2 buildup etc. Obviously one could open a window or a door but at the same time if it is below freezing outside this could be an issue or if you are asleep or your kids are home alone and don't know what to do. Is there some sort of safety system built in to prevent these kinds of problems?
If all you did was make your house tight and not do everything else that goes along with that, yes, there are drawbacks. The house has to be managed as a system. And along with airtightness comes ventilation and other things.
Why don't you have a heat recovery system built into this system? Why wouldn't you want the make-up air come in from the bottom of the Stove with the hooded vent and come in from the top with a downdraft system? Of course the best thing is to go back to the old ways and actually have a cook house.
Also, something to think about is tempering your makeup air. Work for a commercial HVAC company, so this was nothing new for me. But, depending on where you live (really hot / really cold), you might want to temper your makeup air. Otherwise, on a hot Austin day, your dumping a lot of heat into an already hot thing, so if your “slaving away” at the hot stove, drawing in 90 / 100°+ air will make that feel even more miserable. Or likewise, if your somewhere really cold, you could be dumping literal freezing temperatures into your kitchen, which could affect the temperature of what’s on your stove. And while yes, the hood should in theory capture most of this, if your HVAC system is running while the exhaust fan is running, my guess is you’ll get less capture of that makeup air from the hood then you’d like. Yes, it can be expensive to do, but in the same regard, it might be worth it.
Great idea, and actually required by IRC code if the hood is, I think, 400 cu ft or more. Otherwise the house will be under negative pressure when the hood runs, If you have built tight.
I did this on the house I just built for myself. I have a cooktop on the island, and the vent is on the surface of the island, right next to the cooktop. It goes to an intake at the rim joist, that looks like a foundation vent, and the filter is there. I had put a damper on it that was supposed to open upon a draft, but the spring is a bit too strong. So it just has a filter. Next time I will probably motorize it, so it just opens when the hood fan runs.
Tom Tillman
This seems like the ideal setup to me
I love this. I'm moving my make-up air from the basement to come up right under my range. The air will come up over the front of the range and pull grease and steam. I believe all high output stoves should have this built into the front of them.
Yeah, as a HVAC installer I prefer your description over what is in the video. As there flow from outside to the range hood is a direct linear line travelling over and around the range.
@@mennomateo it creates an air wall, like the opposite of the air curtains some retailers have.
I like this method too!
Place grill in the toe kick.
I wonder if it would be uncomfortable for the chef in colder climates?
@@jmlcolorado in colder climates a good option is to pre heat if needed and deliver the make-up air into the pantry where it cooler air would have a chance to mix with the conditioned air. The pantry would stay cool and dry and the occupants would be shocked with cold unconditioned outdoor air.
@@mennomateo Exactly, this placement is terrible.
Hi Matt,
Gr8 topic. That was a major concern for me when I was building my ICF house 4 years ago which is very tight and with a balanced flow from an ERV. You might recall advising me on that. Well, We just a normal range hood with an inductive cook top, nothing so elaborate. But we also have a whole house Vacuum & Dryer which blow out air.
My solution was to use my UltraAire XT105 (another item you recommended) & its very handy auxiliary fresh air intake.
The cool part is i have 3 current sensing switches that sense if the hood, vacuum or dryer are on... the then activate & open the 100cfm XT105 auxiliary air intake.
I love the UltraAire XT105 for some important reasons... the make up air is a big one.
Thx for your years of advice!
As a operating HVAC tech, I'd definitely frown upon putting that damper in a tight space. It's not a question of if it will fail but when. That and I've already seen a few other members of the trade noting the actual ductwork. I love the channel, Matt, but I'd take a closer look at what the difference is between a good setup installed sub-par versus a good setup installed to spec.
I wondered about that also, low voltage verses a simple mechanical one ?
I am not a fan of "tight envelopes" this is how we got sick building syndrome and had to start monkeying with airflow to deal with the issues cause by plugging all the air gaps/leaks.
@@thmsmgnm That's why we have whole home ventilators. You shouldn't be pulling in outside air through gaps in your envelope.
It would make more sense to locate it at the base of your range, creating a curtain of air that moves upward.
Make up air down that low can disturb the burners and oven flame propagation.
@@TomJones-uf5sl .
Not a concern at all with induction cooking.
@@TomJones-uf5sl Only with gas cooktops.
Based on the codes, make up air is supposed to be minimum 8 feet away from the hood.
I would like to see more about this topic specifically for retrofit applications. My wife cooks in the house just about every day and the smells linger. I also just put in some new panasonic bathroom fans and when they turn on you can tell they are causing the house to pull in air from various locations. I would like to be able to sync up a make up air system when either a kitchen or bathroom an comes on.
What you want is a chimney effect with range hood exhaust. Bringing in air right there pointed at the source of the smoke and smells is going to blow that air and smoke all throughout the room, and displace some of the air you are trying to exhaust when some of it makes a hard U-turn up the vent.
Replacement air just needs to makeup for the negative pressure the exhaust is creating in the room, and should be anywhere else than near the exhaust source. It's like pointing a HVAC supply register right at a return.
Exactly.
I'm thinking to cut some vent holes through the wall behind the kickboard under the cooktop, ant then putting a grille in the kickboard to tidy it back up
I'm not really sold on this setup. In a tightly-sealed modern house, you are already going to have an ERV/HRV. I would say just put a fresh air supply _somewhere_ in the kitchen (not even near the stove necessarily) and let _that_ system temper the incoming air. Granted, it would lower the ERV/HRV efficiency since the air going out through the hood wouldn't be going back through the heat exchanger, but you wouldn't be be dumping unconditioned air right on the person in front of the stove. There also wouldn't be a potential "short-circuit" problem either.
Exactly what I was thinking too. You already have "make up air" from the ERV. Why don't you just up the capacity of the ERV to supply the exhaust hood and you're done.
But aren’t ERV/HRVs designed to push out the same amount of air they pull in for essentially a net-zero difference?
What if the make up air came out the back, and the exhaust fan was in the front? That way the hot makeup air doesn’t dump on the person at the stove?
I think they try to avoid using the ERV as the makeup air, because that’s not fully conditioned air. So if you don’t do makeup close to the hood, it’ll suck up all your conditioned air, dump it outside, and it gets replaced with slightly humid, warmer air from the ERV all throughout the house
99% of the air will be sucked straight out with the dirty moist air from cooking, this is how it's done In commercial, with a perfectly balanced hood air conditioning is unaffected
Glad to see you trying to actually to bring make up air into the equation. When I did new hvac construction, the builders didnt care about the heating or cooling the house correctly, much less make up air for an exhaust system.
Thank you so much for posting this, I didn't consider this location, I have specified under the range, under the refrigerator, other places, but not right next to it. I love it!!
The path of return air vs suction induced by the vent is just short circuiting the cooktop. Ideally the path of fresh, return air would be under the stove or in the kick of the cabinet below the cooktop. This would create a path that pulls air past the cooking surface. I have a window near my vent hood. Opening it causes the air to go from the window to the hood, bypassing the cooktop. It tends to not help remove smoke or steam very well. This will be a similar weakness in design. Yet I understand the constraints of design and structure and as shown this is much better than no fresh air return.
the vent in the kick is not a bad idea
I was planning to copy this idea, but there are some concerns brought up on a Green Building Advisor Q&A: "Kitchen Exhaust and Make-up Air in One Range Hood" and while it looks good, is not such a good idea. Thanks so much for all your great videos Matt. I have learned so much over the last several years and it was you who set me on this journey, and I am a bit of an evangelist telling people to look into it.
Yeah it's terrible placement, it makes it way to easy for the vent hood to suck air from the make up air vent instead of the cooking area.
Great video Matt, I put the make up air in my kitchen in the floor near the range, it works so well and is so much better than heating or cooling all the air going up and out the hood.
It appears as though someone didn't follow the manufactures specs when they installed the hood fan. The hood will not function as designed. Usually, they require a 27" to 30" max/min distance above the cooktop (cooktops are usually at 34.5" to 36" off the floor) and unless Matt shrunk a whole bunch and is now under 5'6", the hood will not function as designed. All the air that was supposed to go up the duct will be just the makeup air and the steam and grease will find somewhere else to go.
By adding the makeup ducting in the front; you have to make the hood surround huge and thus have to raise it so you can cook without smacking your head on it. The fan hood is for residential and not made for this application (unless I am mistaken- doubtful, provide model number).
I suspect a shroud will be built around which will come closer to the stove.
yup. the hood is only 300cfm. ive seen a higher cfm fan closer to the range fail to expel enough smoky air from cooking. this would have needed a more "professional kitchen" approach. actually surprised if this will meet local code, but I guess it will otherwise matt wouldn't have installed it.
You are correct.
@@Foche_T._Schitt The manufactures specs of 66" off the floor apply to the actual fan unit, not the shroud.
If the shroud is built lower/closer to the stove you will not be able to do any actual cooking. That shroud sticks out from the wall at least as far as the cooktop. If it is built to the specs, it has to come down to a maximum of 66" off the floor. Most people would have to contort themselves trying to get the head under shroud (your design idea) to see in a pot or do any stirring, making for a very unsafe situation. Next time you are in front of the stove, put a box at 66" off the floor and out from the wall as far as the front of the cooktop/stove and you will see what I am talking about.
This design and application is a no-win situation.
It's also possible that this is a high end house getting spec'd with commercial quality hardware. If I could afford a house of this size, I wouldn't be putting in appliances I bought at the big box store.
My range hood is 3 speed, 250cfm, 500cfm, 1,000cfm, I use the first setting if using 1 or 2 burners, 2nd setting is 3 or 4 burners and oven, 3rd setting is if I burnt something or cooking something like salmon in a skillet, lol. If I have to use 3rd setting I will open a window, there is no returns in the kitchen or adjacent hallway.
Opening a window doesn’t “meet” building code.
@@victorvek5227 my house is 51 years old, it doesn’t meet a lot of codes, captain obvious.
I find these videos interesting, but I must say the real take-home lesson is that I am very lucky to live somewhere where you can actually open a window occasionally. Apparently, Houston is not such a place. You have to think all these people living in sealed up houses with their carpets and paint and such slowly off-gassing are going to end up with long-term lung problems or worse. I have a whole house fan, and while there are plenty of days I button up tight because it is too hot or too cold, I rarely go more than a week or two without opening up the windows, flipping on that fan and replacing all the air in the house with fresh air. Even hot summers occasionally have a cool evening or the occasional warm afternoon in winter, allowing this to happen at minimal or no cost. The idea that I should be afraid of pulling a bit of fresh air from outside when running the range hood for 20 minutes or so is just insane to me.
Houston, or Florida where I live, yeah those days are few and far between where you’d actually want to open a window. Even if the outside temp is nice, humidity, pollen, pollutants, smog, etc are likely present and just makes it all the more work on your AC to cool your house again. This is a super smart idea for what Matt cooked up to prevent depressurization and not exhaust all the air you just paid to condition.
Wouldn't a setup like this create a short-circuit where the vent will actually just be pulling only the outside air our of the house without much of the particles from the range being captured?
the path of the molecules are corelated to convection path, the molecules density in corelation with the atmosphere molecules density and the intake and outake position...if you'd want to get rid of heavy and or cold particles you'd want the air outtake to be under the intake... TL'DR' : now that mean if the particles are hotter or and lighter you'd want the outake to be above the intake
I would think even if there is a short circuit, it would still create a Venturi effect pulling in the dirty air into the hood. 🤔
No. In order to exhaust air, you must have make up air. In a very tight house like they build today, that exhaust fan would do very little in terms of cfm exhausted without it. Kurt Zimmerman. Former hvac contractor and lead mechanical Inspector for st. Louis county Missouri.
Ok smart guy, bring logic to the argument why dontcha!
@@teaforbastards It's more a matter of air density than a venturi effect that inhibits a "short circuit". The cooler bypass air is denser and falls onto the stove area. It's then heated and rises; picking up particle along the way. You won't see a venturi effect until the air gets closer to the exhaust inlet where the velocity of the air increases. There may be some slight circulation that bypasses the stove, but it would be negligible.
have you or can you do a video on all the ventilation systems on these tight builds? IE: dryer vent, bathroom humidity fan, etc
Do not forget to include an air heat exchanger. It will be cheaper than separately heating the make-up air.
I guess if there's room for a filter bank there's room for a Heat recovery system
It's not really a "air conditioned" vent, it's just a filtered vent. It doesn't appear to go through the AC system in the house at all.
50 years ago having a makeup air vent next to your 60% gas furnace combustion chamber was a huge saving in not bringing cold air into house where you didn't want it, then it went up the chimney with flue gases. Maybe next is concentric exhaust pipes for bath fans, for make up air, fresh air blows in (static w/damper) on 1 vent and other side exhausts. With houses becoming so tight would 70 CFM's be a problem?
A D the there is not enough thermal heat generated and cooking duration is too short in residential applications. This was a thing in commercial systems 20 years ago, but the issue was that ductwork could not be sealed, cleaned or fire wrapped, and was a potential fire hazard. Plus seasonality made this a good idea in winter, but poor in summer.
Eliminate bathroom fan by installing HRVs with enough capacity to ventilate a steamy bathroom.
This looks like it would short circuit the air path and not remove air/particulates coming off the range hood efficiently. Wouldn't it be better to have a makeup air vent somewhere else in the kitchen. Also the added filter, while nice to remove incoming particulates, is going to further hamper the hood's effectiveness. I would double or triple the filter media surface area (more filters) to get as little resistance as possible if a filter is a must.
Looked at the filter On the inlet side of the filter and the leaving side of the filter the contractor who designed, installed the system just taped into a sheet metal pan of the filter box.. What a bunch of people who really do not knot the art of suck and blow There should have been rectangle to round transitions at a minimum of 12" to capture the full area of the filter. What i see is contractors who operate out of there truck , no sheet metal shop, what a shame the homeowner is screwed again Sorry Matt
Coincidentally, I have the same honeywell filter box on my furnace - I get 4-6 months depending on seasonal air conditions (farm country - summer/fall have a higher dust load). Its probably overkill in this particular application, even when properly installed, but that's $25 a pop for the merv 11 filter. It probably translates to a $100 loss over the life of the unit, considering unused media area (and a filter replacement every couple of years). The real screw here is the foil tape job - I got a chuckle out of that. I'm surprised that passes code as a failure of the foil tape (which I've seen with hot/cold cycle applications) could result in what amounts to a chimney exhausting into the attic. Also - how many home owners are going to remember to replace that filter, in the attic, every couple of years?
In this setup 63% of the filter element is in the flow path. What does the rectangular to round transition cost in comparison to the filter element? Am I ever going to recover the difference? After running it in the intake I could take it out and run it in my furnace for a few months to use up the remaining capacity, until I get the DP alarm. Flow will take the path of lowest resistance.
@@paulchevako :) kind of my point as well... the tape failure risk, the extremely long service interval, and the fact that this filter resides in the attic are bigger concerns - IMO.
Arnold Elgort Arnold, you sound like a real tradesman who takes pride in his work. thank you. Robert.
Is there a motor in the makeup air duct or it is just a electrified gate that opens and shut ?
About time make up air is being added to homes! Commercial kitchens have active blowers to supply air, and some plenums in front of the hood have a separate plenum that also supplies conditioned air. So most of the makeup air going into the hood is just outdoor air, but there’s a thin stream of cool air coming straight down to keep workers cool in a hot kitchen.
Or warm(ish) on a cold winter day. Here in mn, a commercial hood will have a make up air u it with something like a 60 or 70 deg Delta t. Still chilly if you're a short order cool on a -20f day, but better than nothing, and eliminates condensation in the mua supply duct
One of the important reasons to do this is not the effectiveness of the exhaust fan -- that hood creates a powerful negative pressure on the envelope and so a would pull water through any holes. Any house built as tight at Matt makes should probably have a Z-duct for makeup air (without a damper) -- negative air pressure will be made up either by an uncontrolled and unlocatable leak, (or the ineffectiveness of the exhaust fans.)
Only point that was missed was how you are tempering your make up air. Thermolec has a pretty good modulating make up air system. Other than that good setup and design.
Filtered fresh air but not tempered. Wonder what the comfort of cooking in the winter will be. A follow up video with a theatrical fogger through the fresh air intake with the exhaust fan running would be welcomed.
No doubt make up air is needed. Likely we have all been to a restaurant that lacks make up air... hard to get the door open those first few inches and then you feel like you are in a wind tunnel.
With a tight house, one should also consider make up air for fireplaces, gas/oil furnaces water heaters, and bathroom exhaust fans?
Make up air can be tempered. There are makeup air units with natural gas direct fired heaters for the winter time.
RyanHamilton You can also just use a 100% outdoor air package unit too, so you get cooling in the summer and heat in the winter.
As an HVAC owner/operator this is code to have make up air for anything over 400 cfm (Michigan code). I find it extremely wasteful to use anything over 400. In the winter you have extremely cold air being put into your home and in the summer, extremely hot /humid air. ERV are an option but not very effective/efficient and very costly. People need to stop trying to make their residential kitchen be a commercial kitchen! If you want a commercial kitchen, buy a restaurant or become a chef.
it also creates an air curtain of sorts, we use them in commercial kitchens.
Dang Matt I wish I would have seen this a year ago. I have to do the crack the window drill before I turn on my range hood. Good info!
Cheaper better and it works. Homes need to breathe. Toughen up.
That’s really cool. The relay on the duct is key.
Brian Merrick good idea too
@@brianmerrick8260, That's what I'm talking about, simple, fail safe.
Not to code in California? Does not move air out of the kitchen and not conditioned sourced from other rooms.
I've done make-up air in a few client's homes.... however, it's important to note it's only really necessary for high end hood fans pumping out 600cfm or higher.
That’s according to local code. My county is making me do it because my hood is over 400CFM.
We have a 60" hood in our new house (foamed insulation) and had makeup air installed not as close but near by in kitchen like this. I requested that it have a filter on it like you did but they (Casa Mechanical) told me the filter would prevent it from working as it would be too hard for air to come through so it would come from undesirable places. I have a passive makeup air vent like you describe that simply opens a damper when the hood is activated. I'm intrigued to learn that the passive style can be filtered as I really didn't want to be bringing pollen or bugs into the house as we took so much care every where else to prevent that with the ERV and such.
large filters like these pleated filters do not block the movement of air.. Smaller ones that much move a lot more air over a given size will require a much higher velocity and will act as its own damper cutting down the ability to supply enough make up air
Although the larger media filter has a low resistance to flow in comparison to a standard 1" filter it is still resistant. Air is lazy and will always take the path of least resistance. If the house is submarine tight then in theory it's a good idea, in reality that filter will likely cause just enough resistance to encourage the air to enter from unwanted infiltration. Essentially the filter makes the small bad holes bigger if their resistance to flow is lesser than the filter. This would only apply for passive ventilation which it appears to be in the video. If you are going to filter than you should have forced air. A better approach would be a wall stack with passive fresh air inlet located near the cooktop, put a mechanical damper with a pressure switch connecting it to the exhaust system or simply a well balanced barometric damper would do the trick. If your worried about critters just ensure your intake is screened and well positioned. I wouldn't overly concern myself with worry over pollen, etc. Its intermittent temporary source control that when set up properly should not impact IAQ no more than if you were to open the door to go inside.
@@dustincole2625 Thanks, that has been my working theory with the setup I have. The intake vent is on kitchen ceiling near the hood and has a very short run of duct work to the outside. It has the pressure sensor you mention inside the hood duct work so the damper opens when I turn on the hood. I figure and hope that the ERV and general AC cleans up the air pretty quick anyway.
@@realpdm you should be fine, just remember that it's only bringing in the untreated air during times of use. So long as the damper closes after each use the amount of untreated air is relatively small so your existing systems should handle it.
What about the bath fans and clothes dryer? They need a supply of outside air as well. Wouldn't an exchanger connected to the HVAC system be the best for all of these, including the range hood? I understand the concept of a dedicated air supply from outside not needing to be conditioned for the range hood in this application, as it's theoretically exiting the building immediately, thus not causing much of a heat/cooling issue.
Yup, that's what makes ERVs magic.
And for the dryers, use heat pump dryers that don't need to vent. They use a lot less energy too.
Yup. Heat pump dryer. Also, looking into Lunos eGo for bathrooms. Self contained, through-wall ERV. Not sure if cfm is technically big enough for a large bathroom, but worth looking into
This set up drastically reduces the capture efficiency of the hood. I.e. Not going to suck up air from the range as well. The make up air inlet needs to be further away. This is why they are often tied to the home air ducting or coming in under the range.
it would be wise to install the make-up air into the plenum of the return air to condition AND filter the air so requiring only 1 filter to service which should be changed 2-3 times a year anyway.
Yes, this is what I was thinking. If the outside air is very different in temperature, humidity and contaminants than the inside air then why would you dump it into the living space? Seems best to condition it before letting it come into contact with inhabitants. Introduce it directly to the return supply and get it over with.
Otherwise save the expense and just open a window!
Great topic thanks. Been wondering about this for a while.
Though we are going to have the make up air coming through a flat duct just below the stove top.
What about makeup air for the dryer
Yo ski, I was thinking the same thing. I live in Arizona, and I was going to create a way to take hot/dry air from the attic in the summer, to put INTO the dryer, and exhaust to the outside as normal. Then in the winter, take the air from the house, run it thru the dryer, and exhaust it to the inside of house. I have electric dryer (not gas) and I could use the humidity and heat in my house in the winter, and use the hot/dry attic air to quickly dry my clothes in the summer. (The HOA prevents hanging of clothes outside to dry)
It’s a closed-loop in either case. No net movement of inside and outside air. Thereby Cooled air stays inside in summer, and heated air stays inside in winter.
It does seem like a good idea to manage the air flow for an exhaust hood. I like that it has both a damper and a filter. However, I wonder how much the system, hood included, contributes to the house's total leakage. I think I might personally prefer to avoid the penetration altogether. Which is why I am leaning toward an induction range with an air handler that merely filters and recirculates the air. What do you all think? Pros and cons? I live in an extremely hot environment, so the overall goal is to keep the heat out.
@@treyfarmer1551 thank you for answering. That is very little. Much less than I expected. Not bad at all.
This a standard in resturants..fresh air is pulled in near the hoods so the huge exhaust fans wont suck out the ac
I think this should have fan assist to at least 70% of the hood vent cfm at what ever stage it is turned on to
I'm wondering about this myself. Matt has another video where he shows the science behind matching the makeup flow, but it was in a different scenario with the makeup being at the other end of the kitchen.
Placing the inlet air immediately adjacent to the draft inlet reduces some of the draft forces above the pots and pans on the burners. This will result in needing to use a higher fan speed than might have been necessary.
Adding inlet air is a good idea, but if the inlet air can be placed somewhere other than right next to the draft inlet, the efficiency of the draft fan is not reduced.
They really need to make ERVs compatible with kitchen exhaust hoods. Maybe better filtering?
Why would we have to use a separate filter for the kitchen range hood makeup air?
Would it be a good (or bad) idea to allow for kitchen hood makeup air by using a whole house ERV system?
I would think that this type of setup would also allow the homeowner to control the incoming makeup air temperature, humidity, cleanliness, only need to stock one type of filter and not disturb a normal kitchen hood exhaust airflow pattern.
Hopefully someone has the knowledge and/or real workd experience to let me know if my thoughts are completely wrong here.
I've been pondering a bit on how to deal with kitchen exhaust in an airtight construction. Basically my current thinking is that makeup air defeats the entire purpose and circumvents any efficiencies and advantages gained from an ERV/HRV. You're instead going to directly put potentially freezing or sweltering outdoor temps directly indoors, at whatever humidity level.
Instead it's likely better to put ERV/HRV into boost mode and put a return at or near the kitchen. Plus not using gas, or cooking very grease heavy foods.. maybe use an oudoor kitchen/grill for that. Basically, just don't use a hood.
Edit: Forgot to mention the option of a recirculating hood. Not bad if you REALLY want to cook foods with lots of particulates/smoke, but keep in mind the ongoing filter costs.
You cannot successfully setup an erv unit for your whole house to supply air for a unit that runs for such a short period of time, that being said all passive design projects I work on here in nyc call for electric stoves- no gas at all- to be used in such an air tight house to eliminate having to install an exhaust that would lead to heat loss
I own Restaurants we have tempered make-up air. Which means the intake air is heated/cooled according to the season. The last thing you want is 10 degree air in the winter blasting on your cooks freezing them and getting them sick. In the summer hot humid, sticky air making your cooks miserable sweating and dripping sweat on the food. Un- tempered air over works your heating and cooling systems. I have seen restaurants with untempered air over working their kitchen's A/C roof top unit to the point where they have a sprinkler running on them so they don't over heat. Also my hood co. Has a specual device that measures the air pressure so you can balance the air flows on the intake/exhaust fans. This guy Knows nothing about a proper exhaust system with make-up air. Your system needs to be certified. Not some home made nonsense. We spend $30,000 to $50,000 on an exhaust hood system, the best one made is Captiveaire. They make small ones for above dish washing stations that might work as a home system. Your idea of using air from a whole house air exchange system is a much more sound.
All the above. Work for a commercial HVAC company. Usually the engineer specs tempered makeup air. But, on a house if done right, it probably could be done with an ERV / HRV. The ERV would be interlocked with the kitchen hood and would then provide the makeup air that way. Again, it doesn’t have to be from a duct right next to the hood, just the hood needs that extra air to come from somewhere.
Kevin Murray- in theory it “can” work but a homeowner would have to take on more expense to get an oversized erv unit which will effect the whole house for a singular unit that runs for a short amount of time, this whole makeup air system is really over engineering houses to solve an issue you can really fix by just opening up a kitchen window since this air system isn’t bring in temperature controlled air anyway
I just did one of these, ended up retrofitting and moving the make-up air in the back. Customer complained the make-up air was unconditioned and blowing hot/cold air on their hands and face when cooking. About a $2500 CHANGE ORDER.
Did you move it in the back behind the stove or ducted the same way next to the hood, just the make-up duct against the wall instead of in the front? Did it solve the customer's problem?
@@chvitaly Ended up running it into the AC supply for around 4 diffusers in the kitchen area with a flow diverting valve to make sure it never put back pressure on the air handler. No complaints so far.
Brilliant idea! Thanks for sharing
What do you do to temper the air? In the north in winter that would be very very cold air coming in. A commercial unit would normal have a direct fired heater to preheat the make up.
I hope someone fixed that one wonky fastener on the inside of the inlet duct...
How much CFM is the fan on full blast
I could be wrong, but won’t having make up air immediately next to the exhaust cause turbulence and disrupt the flow out the hood as well as scatter the air you want to exhaust? Seems like make up on opposite side of room would create smooth flow and capture more particulate from cooktop.
Make up air should come from below, it's just gonna make a quick "U-turn" with that setup and not actually pick up the fumes from below very effectively. 😉👉
I'd like to see a demonstration with a smoke pencil showing that it is not short cycling and actually pulling the particulates from the range.
Matt, love your show, I learn new stuff all the time.
My two cents: Maybe a little guitar slide as you start to say your outro, might help tighten it up a bit and make it not sound as "silly" for lack of a better word. You got the right idea though, keep up the great work!!
You need to start putting square to round transitions to make better use of the filters and not generate such a pressure drop across them
Pretty much code everywhere with a ginormous hood. But honestly you don’t need anything greater than that in a residential house. Save yourself the money and get a 400 cfm fan. I had one in my passive-ish house and it was fine. Also had a makeup air in my restaurant and it was *really* expensive.
👍🏻 on the build show 👍🏻 Always tops on videos 🏁
Without a fan pushing this "makeup air", this is still relying on negative pressure INSIDE the space to draw the air through the filter. Look at ANY commercial set of prints and you'll find when an exhaust system is used whether it be for car-mon, dust collection, restaurant kitchen hoods, lab hood, paint spray booth etc, they have a POWERED MUA, not just a hole in the structure with a powered damper. This would be classified as relief air not makeup. To be makeup air, you MUST have a fan pushing the air back into the space in equivalent volume or your depressurizing the space which is the ENTIRE point of "makeup air". So, not a killer system but a lazy workaround that will limit the efficacy of your hood and cause other issues due to the depressurization. It's kinda the whole point of an MUA system. Is there a follow up video where you test the home's pressurization before and after the exhaust fan is on? And a smoke test to make sure your hood isn't just short cycling? Builders and HVAC pros already don't think about the V in HVAC enough so I can't say I'm surprised.
Make-up air for hood fans with more than 300 cfm has been code in Canada for years now. Usually connected to the furnace and (filtered) fresh air intake. Why is this a better system? You would think the incoming air would disrupt the flow of the exhaust, and make it less efficient?
So, is he suggesting that if my house was built in the ‘50s and I’m installing a completely over powered 900 CFM fan that I probably have enough air leakage to forego an intake fan?
I didn’t realize this was an issue when I bought the fan. I’ve never had good ventilation in a kitchen and I don’t ever want smoke in my house again so I bought the most powerful fan I could buy.
The more I find out about what's necessary to make a good HVAC system work, the more I'm starting to wonder if it's actually a good idea for code to require all that in the first place.
They want this stuff to be as tight as a submarine, which is great for keeping pests out but terrible due to trapping mold and harmful fumes instead.
I can't help but think for every 2 problems a seal house & good HVAC system solve, they create 2-3 more to replace it
We all know what you're saying, be we all know that giving up is the wrong answer. Building better buildings takes work, but it's worth it in the end when they're more efficient, more comfortable, and longer lasting.
Doesn't the makeup air need to be pressurized to balance with the negatively pressurized exhaust?
Is there a video showing this system in its finished state?
Thank you! How do you prevent drafts from going up the exhaust vent? What type of damper can be installed that is oil and fire proof?
If you had a choice, why wouldn't you put it at the base of your oven?
Make up air should really be done somewhere else like the basement. Far away from the range makes it to where if your make up air is really hot or really cold like Michigan weather, that uncomfortable air gets acclimated before a human feels the discomfort while still giving the appliance what it needs.
Filter is definitely a good idea, I wouldn't want all the pollen and crap blowing over my cooking food!
you should be able to manually close the hood from the inside, the top vents and other are not tight enough for the dead of winter with winds blowing
Yo ski, i contemplated similar. I live in Arizona, and I was going to create a way to take hot/dry air from the attic in the summer, to put INTO the dryer, and exhaust back outside as normal. Then in the winter, take the air from the house, run it thru the dryer, and exhaust it to the inside of house. I have electric dryer (not gas)
I could use the little bit extra humidity and heat in my house in the winter, and use the hot/dry attic air to quickly dry my clothes in the summer. (The HOA prevents hanging of clothes outside to dry)
It’s a closed-loop in either case. No net movement of inside and outside air. Thereby Cooled air stays inside in summer, and heated air stays inside in winter.
This will become another filter that just doesn’t get changed because it looks like it’s buried in the attic! Next issue is another electrical component hidden away (24v damper motor) that will never get fixed if these owners or even next owners don’t know what the vent is for. Too high tech for people who just want simple!
Maybe I am not seeing this correctly. But, won't the incoming air just be sucked up the range exhaust?
i hate how most range hoods have a CFM rating of 400, which is a code requirement. But these range hoods are pretty useless - they dont suck up heavy smoke, grease, and pungent odors. I prefer the Chinese range hoods with 900CFM made by Sakura, Pacific, or Accela. Captures grease and its really effective. I'd just use it with the window open.
You mean the 399 CFM hoods?
Interesting- being so close to each other I would had thought it’d short cycle. I have been thinking about reversing the flow from a down draft for make-up air but it could interfere with gas ranges. I like your idea, have you seen it in action?
This is basically how it’s done in every restaurant and commercial kitchen.
it looks like a mini commercial restaurant grade hood LOL how much does something like that cost??? i find normal residential ones witht he tiny mesh filter are garbage
I want to put this system on an island with all stainless steel. Have you set up one like that.
Sorry, Matt, but the placement of the fresh air inlet makes no sense at all. This placement of the air coming in from the outside would just lead to it going right back to the outside. You want to suck up what's below though (i.e. the smells coming from the cooking). So the fresh air should come out from below the sealing. This way you produce an airflow that would provide fresh air to the room, while all the air from the smelly cooking is sucked in and transported to the outside.
Hey Matt, love your videos. I'm a mechanical contractor in NC and I am trying to make myself into one of the high quality (instead of low cost) contractors. I was wondering what made you decide to stick with a passive make up air instead of active. Is the hood a low CFM (400-600) hood or is it higher? I'm about to install make-up air for a home where they are installing a 1,100 CFM hood, so I'm going active, and putting my outside air vents in the floor below the cabinets in several toe kicks...
I watch your stuff, especially when it comes to mechanical and building envelopes. Any thoughts would be really appreciated... or if you already have a video on this that i've missed...
I doubt he'd do it this way again, I think in his house he has an active makeup system.
I’d say do a test. see the cfms without the fresh air. Then measure the cfms with it. It looked like the flex duct was rather long.
I’m a little concerned about the fire code safety of putting an exhaust vent, supply duct, and gas stove in such close proximity, particularly in a non sprinklered residential installation. You typically don’t want to create the opportunity for a runaway fire to constantly be fed by both oxygen and gas fuels. Is there a fire damper on the supply side unit to mitigate this risk?
wouldn't the pressure drop across a merv 13 filter be too much? no in-line fan needed?
It’s possible. But in theory if the opening is engineered right, it might not need an inline fan.
This is an important topic that I'm sure many builders have never heard of. Thanks for highlighting this topic.
dahveed284 -It’s code everywhere, HVAC company will def tell the builder!
@@lisao3041 IIRC, code calls for make-up air for only certain sized vents. With new houses getting tighter and tighter, even the ineffective vent hoods track homes have can create a negative house pressure. Of course, a lot of those cheap units don't actually pull the air from the house, but instead pass it through a simple filter and back into the kitchen. I'm eating dinner with a HVAC engineer tonight. I'll ask him.
@@dahveed284 yes, I know. Code everywhere for over 400 cfm. Perhaps I should have clarified that. Matt should definitely have clarified that too.
Interesting setup. We're in the midst of planning renovation of a 1940s brick cape cod, and my wife wants a hood in the kitchen - but I've been resisting after listening to many of your videos and Joe Lstiburek video/articles. We're hoping to reno the house and new addition to Passive House 0.6 ACH@ 50 Pa (or better as you seem to have accomplished on some recent builds).
So here's my question or maybe challenge: Why not just ramp up the home ventilation system during use of the hood to balance the airflow - instead of installing yet another mini-ventilation system? Is the overall performance better/cheaper to install the system you're showing? How does the use of that dedicated ventilation for the hood system affect the performance of the whole-house ventilation system (HRV or ERV)?
northavealum - that would be nice if it could tie into an HRV system when the hood is turned on. This does seem like an unnecessary addition.
I'm so not convinced having the supply right next to the event well actually remove the particulates. Your fresh air is going to go straight to the outside missing what year really after.
My thoughts exactly. The airflow doesn't cross the particulate area at all. I'd be interested to see a smoke test to see what air mixture actually ends up happening.
It works in commercial kitchens. This is literally the same setup used in restaurants and commercial kitchens. The Makeup Air being right there, creates what is basically an “Air curtain”, the force of the air being pulled downward extends past the grill and then allows the heat and particulates from the range to be pulled out. I’ve worked on both ends of this. I spent time in the restaurant design industry doing work in New Mexico, Arizona, and Las Vegas, NV and now I’ve been working for a commercial HVAC company doing project bidding for the last 14 years.
@@RobertDylina see here for the smoke test from a similar setup: ruclips.net/video/u2uVaTMXd_8/видео.html&ab_channel=NSBuilders
Why not put the air intake in that wall directly behind the exhaust? Would be a tighter space and wouldn't allow for such an enormous filter (is that huge thing really necessary?) but would save a lot of flex duct.
Did you have a supply fan to get consistent air flow through the filter, or is it just passive?
Matt. I have a wood burning grill in my mid century kitchen. The master builders put an air return right next to it. 🤦♂️
Is there a Make-up air unit that has a dx coil to temper the air? Those 100+ temps in the south could make cooking miserable, plus tax your central air unit
love it ! Thanks !
Nice damped acoustics. I wish all your onsite videos were like this. :)
Any advice for someone who wants to get into carpentry, but not have to build fast houses? I joined a union after high school, but quit a few months in because of getting tired of hearing things like "it's not a church, just put it up there" I quit a $50/hr job to make $14/hr to do shotty work. Needless to say I went back to making $50-60/hr, but the work is boring and lazy. I'd rather learn craftsmanship the proper way the first time, instead of having to relearn it later. Is it a matter of putting in the time? If so, I'll pass and keep earning a high wage, and try to learn it on my own.
Lower would probably be better. When I worked in a commercial kitchen it was behind the cooking surfaces.
In theory, at least for restaurant code, the hood should be flush to the back wall and should extend at least 6” past the cooking appliance on the other 3 directions. For an island without a back wall, the hood should extend at least 6” from all 4 sides, not including makeup air.
For our commercial projects we put cement board around the hood, is cement board necessary for a residential kitchen?
i am confused regarding exterior wall installation,which one is the best to the value and cost effective like STO German or BASF or rock wool or glass fiber , please help us out thanks
Something i haven't quite understood over the time i've been watching. I get the benefits of keeping the house tight...but are there any drawbacks? And if the majority of your air intake and filtration is through your a/c etc are there any negative effects from extended power lose like low air levels and co2 buildup etc. Obviously one could open a window or a door but at the same time if it is below freezing outside this could be an issue or if you are asleep or your kids are home alone and don't know what to do. Is there some sort of safety system built in to prevent these kinds of problems?
If all you did was make your house tight and not do everything else that goes along with that, yes, there are drawbacks. The house has to be managed as a system. And along with airtightness comes ventilation and other things.
Do you install makeup air for clothes dryers?
Heat pump dryer. No makeup air required, huge energy savings.
Does it reclaim the moisture and exhaust the air inside the house? A regular dryer blows a steady stream of air outside that has to be replaced.
How do you air seal or even insulate the hood exhaust? Same question for bathrooms, dryers.
Commercial kitchen hood systems have been designed that way for decades
Why don't you have a heat recovery system built into this system?
Why wouldn't you want the make-up air come in from the bottom of the Stove with the hooded vent and come in from the top with a downdraft system?
Of course the best thing is to go back to the old ways and actually have a cook house.
What happens when there is a grease fire with that downdraft?