Range Hood for a Tight House
I am currently building a pretty good house and need help selecting a range hood. We have a 36″ Wolf gas range on order that will be built into a cove, like the attached image.
If I follow standard guidelines and appliance salesman recommendations, I am looking at a 600cfm range hood. However, everything I read on GBA suggests that I should be shooting for lower in a very tight house.
My intention is to find something that can be electrically interlocked with a motorized damper and makeup air that is then brought into the return duct of our air handler for distribution.
– What CFM do I ACTUALLY need?
– Any suggested units for a “built into the cabinet style?”
– What other things should be considered when selecting a range hood?
– Is that makeup air solution a good idea?
Thank you in advance!
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Replies
> air handler for distribution.
Make sure you have the capacity to condition this air. The BTU/hr is substantial. Better to deliver make up air near the range.
Add "powered makeup air fan" to the options. If nothing else, it pulls less moist Summer air into your walls (than a passive intake). And the duct needed is much smaller (eg, 6" with fan vs 12" passive).
Do you have any combustion devices that are sensitive to negative building pressure?
Hi Jon,
We have a Stuv wood fireplace insert, but that has its own combustion air.
I haven't settled on a dryer yet, but am leaning towards a standard vented dryer and using one of the relatively airtight outlet covers.
What else might we be talking about? I haven't settled on a water heater yet, that is another thing I need to scour GBA for advice on...
Our heat is coming from a heat pump and air handler.
Don't count on the Stuv's combustion air intake air to be all you need overall. The depressurization of the house by any unmatched exhaust air (passive makeup or mismatch mechanical) can still affect the Stuv - they're aren't 100% airtight (and you have to open it once in a while).
Thanks Cramer. Based on all of the below comments (and yours), I have some figuring to do with regards to makeup air. I will circle back to the Stuv once I am more clear on makeup air needs for the range hood and the dryer (unless we go heat pump dryer).
By "standard vented dryer" do you mean gas or electric? As far as a water heater, if you go with a heat pump there you will avoid backdrafting issues while also getting much better efficiency than with other electric options.
Hi Charlie,
I would go with an electric one. Do you have any first-hand experience with heat pump dryers? I am certainly open to going that route, I just have no experience with them.
Hi Michael - I've been enjoying following your posts as I'm building a very similar house at a similar stage in a similar climate, Vermont.
Hate to be a wet blanket on heat pump dryers (see what I did there), but we have one at our current house and I hate it. Which is a real bummer because our new house would be so much easier if I was open to a ventless dryer again. We have the Blomberg units, purchased three years ago. They work, but I have two complaints:
1. They're tiny. It's just me, my husband and the dog and I still feel like I'm constantly doing laundry. These units do not tolerate *any* overloading beyond what's listed in the manual. I have to do the fitted and flat sheets off of our bed as separate loads to get them clean and dry.
2. In addition to the normal lint trap you clean out on every dryer, ventless dryers have an additional filter that captures everything that would normally be sent outside. This has to be washed in the sink every three cycles. It's annoying and I hate having them sitting around drying.
If you've found another model that magically solves both these problems, I would love to hear about it!
Oh - and relevant to this thread - go induction! We switched from gas to induction at our current house and LOVE it, no regrets. Putting in a 36" induction cooktop at the new one.
we've had a Whirlpool heat pump dryer for six years. It works well. Takes longer, but so what? Unlike Emma's, ours is enormous. It has two lint filters, but both are easy and quick to clean.
We bought a Miele T1 about a year ago or so. Yes, slightly smaller but haven’t really noticed it since we hang some of our clothes such as wool or elastic garments. Yes, you have to clean 2 lint traps but it’s not a big deal. We are cleaning the foam filter every month or so. Less fire risk, no hole in your envelope and more efficient. It sits near our HPHW heater.
CFM is in part based upon the maximum BTUs of ALL BURNERS operating at the same time. Obviously the more burners you have and the higher the output of each burner the more CFM's you're going to need.
https://www.prolinerangehoods.com/blog/cfm-need-range-hood/
You're going to need to duct make up air. I imagine it's code required at the CFM's you're looking at. https://www.buildingscience.com/documents/insights/bsi-070-first-deal-with-the-manure
The vast majority of posters around here would install a 30" induction or electric range. That would significantly lower your CFM's because you'd have significantly less waste heat to evacuate.
From the same source:
"To vent cooking exhaust from your kitchen efficiently, we recommend a range hood with at least 600 CFM."
Evidently this minimum is independent of range size or type. It's repeated in the recap.
If you dig deeper they also indicate scenarios where less is ok. However they definitely believe it's always better to run a high capacity fan at lower speeds rather than barely having enough at max speed combined with a duct which is too small to accept a larger fan. (ex, 4" duct vs 6" duct)
I understand 36 inch Wolf is the crown jewel of the upscale kitchen but do you really want byproducts of combustion in your home for a fashion statement that seem kind of long in the tooth at this point.
Consider an induction cook top they boil water faster, they are more responsive in that when you turn down the heat the boiling stops faster, the outside of the pans stays much cleaner in that almost nothing burns onto the pan because outside of the pan stays much cooler so cool I put a sheet of paper towel between the burner and the pan and boil water and the towel never changes color. When something boils over you just wipe it up when it happens nothing is burned.
Most kitchen stores have an induction unit hooked up for you to demo do yourself a favor and give one a test drive and time boiling a quart of water on gas and induction.
The only real down side is most of your favorite pans will not work so you have to let them go.
It has been my experience that most people do not turn on the fan unless something is burning.
Consider cutting the gas line all together and save the monthly $30 fees.
Walta
If he's a serious cook, his pans will probably work with induction. All Clad and its many imitators and cast iron are fine.
I always suggest people buy a $50 single burner induction unit to try it. Most people, like me, who always cooked on gas, are convinced induction is far superior. It's nice not dumping all that CO2 and water vapor into your air.
Micheal,
It's important to determine on what basis the range hood is being sized. If it is to control odour or humidity it may still leave dangerous levels of particulates and combustion byproducts in the indoor air. As Walter said: gas stoves aren't generally compatible with the aims of building a PGH.
https://www.greenbuildingadvisor.com/article/the-hazards-of-cooking-with-gas
This is more a philosophical objection than a practical one. I don't know what people think happens with gas ranges, but cooking with them is simple practical and safe. Induction cooktops are a hug PITA, they beep constantly and freeze up and change settings if water hits the surface etc. and are not precisely controllable. There is a reason no serious chef or restaurants uses them.
Jason,
What happens with gas ranges is the subject to the link in the post you are replying to. If after reading it you are going to assert they are safe, you should probably try and back that up with something more than your opinion.
Many of my friends are chefs. Two teach at the college level. The restaurant 0ne works for, and their school kitchens all have induction burners The next generation of chefs already have experience with them.
The fact they have been used for hundreds of years without people dropping dead isn't enough for you? Humans have been around the by byproducts of combustion for most of our existence. You are all acting like most of these homes don't have aggressive HRV's. It is clear as day that this is a propaganda piece aimed at fossil fuel consumption and nothing more. Weakly linking supposed health effects from weak associational data is poor science, period.
What Ted Clifton of Zero-Energy Home Plans in Seattle recommends is having two outdoor fans, one sucking the air out and an identical fan pushing the same amount of air back in the house to balance the kitchen exhaust air. The reason for the outside location is to reduce the noise of the fans in the house. I recently built two houses using his plans in the far north and ran the incoming air through a hydronic heat exchanger, primarily to heat the incoming air in the winter, but it could be used to cool incoming air in the summer as well.
Even though your wood burner has a fresh air intake it is still not a sealed combustion device. This generally means limiting depressurization to 5PA, which is very small.
Say you have a 700CFM hood (pretty common size for 36" units).
To limit pressure drop to 5PA (0.02" wg), you are looking at keeping velocity bellow 300FPM. This means for 700CFM, you are looking at around a ~2 sqft open area, so 18" damper. Not very realistic. Never mind ducting it all the way to your air handler.
About the only way to make this work is Mark Rob's solution with a matched blower for makeup air.
The in between solution is a largish passive vent with a motorized damper for normal use but always open a window when the stove is running.
Since you are looking at an insert, the actual insert doesn't effect capture efficiency all that much since most of that is driven by the cabinet design. Having a wider cabinet (ie 42" for a 36" stove), side panels that come down and the insert raised up to create a large capture volume is the best.
The rest of the choice comes down to blower noise, which is usually listed in the specs.
If you want super quiet go for one with a remote blower and add a duct silencer between the blower and the hood insert.
Most passive makeup air kits comes with a current sensing relay to pick up when the hood is running. This tends to be the simplest for integration.
Hi Akos,
We are planning to switch to a 36" induction range which calls for 300cfm of ventilation. With that, I am looking at options for exhaust and make up air supply and in the interest of not creating too negative a pressure, it sounds like the "matched blower" approach might be best. Does the change to 300cfm requirements change your thoughts on the negative pressure concerns related to the Stuv?
Additionally, are there any other measures I should take with regards to the Stuv wood burner? It has a fresh air supply, but it is only a 4" duct.
Thanks much!
A well sealed house has a leakage rate of around 400CFM@50PA. So even going down to a 300CFM hood, it will still depressurize the house a fair bit without any makeup air.
Assuming the above 400CFM, you can safely pull only 40CFM to maintain 5PA pressure, so that leaves 260CFM of makeup air. If your return duct pressure is around 25PA, a 10" passive makeup air system might just squeeze by. That is still a very big hole, so a balanced fan setup might still be the best.
If you are going with an active setup, I would go for a larger exhaust fan, the small Fantech MUA is rated at 750CFM.
I don't have much experience with wood burners outside of the cottage, which is not sealed enough to have issues. With a tall chimney, you generally won't have problems when the stove is running hot as it can develop a fair bit of pressure. The usual problem is back drafting when starting a fire or when the stove is not running.
This isn't a simple issue. Here's an excellent video with detailed information on a system for a tight house that matches the quality of your gas range.
https://www.youtube.com/watch?v=bMkvCn1sGvk
(see: "How to Design, Install, and Test a Perfect Kitchen Exhaust and Make Up Air System" if the link is deleted)
Even if you don't go all out with a similar system, it's worth knowing what the parts of a full system are. In this, I particularly liked the "drip" hood system - he uses a Fantech HL 36 Kitchen Hood Liner. I'd like to construct a filter-based system with no external air intake, and this might help solve the grease issue.
Wow. A lot of really good feedback here everyone.
We are very serious cooks and are doing our best to plan a professional kitchen in our Pretty Good House. Based on your feedback, I am going to reopen the investigation into induction. It sounds like there is pretty broad consensus from all of you that this is a much better idea.
Wolf has an induction range that we could switch our existing order to. Looking up their specs, they want 300 cfm of ventilation.
So the question becomes, if we switch to induction, what should I use for a range hood liner and what should I use for make up air?
The solution from the Home Performance YouTube video that Johngfc posted looks incredible. That does seem like quite a Cadillac of a system. Is that necessary for the 300 cfm needed for the induction range?
Can I integrate things a bit more with any of the rest of my mechanical system? I already have an air handler with ductwork throughout the house. It is a Mitsubishi SVZ-KP30NA with an electric heat kit. It seems like I should be able to piggy back on that to supply conditioned make up air when the range hood comes on.
Thank you!
Can you build the cove deeper than shown? If you have good capture on the hood (extends out at least to the front of the range and out past the sides) you won't need as much CFM to move the air. Based on studies I've seen and just watching steam at my house you're going to need some CFM's to get much into that hood with it that high and that far back from the front of the range. To me if you get the capture right and have a good hood you won't be using that much CFM and won't require makeup air.
If the Mitsubishi doesn't have a fresh air intake I don't see how that could help. .
We've been happy with our Whirlpool HP dryer. I've used Zephyr hoods with DCBL motors on 7 houses and not had a problem. Also happy with our Rheem HP water heater especially if you can find the older model.
One benefit of induction cooktops that hasn't been mentioned is the ease of cleanup. Ours gets a lot of use and it is a big benefit to me.
Be warned, this is an incredibly finicky system and very difficult to implement correctly. Talk to your local inspector, we were supposed to have a 600 cfm system on paper but were passed with a 400 cfm one. We have a very tight house but no fireplaces. and guess what, we haven't died or suffocated like everyone on thinks we would have.
My cooktop has both induction and gas burners. I got this combo because the usual assumption "real cooking needs a lot of heat a big flame".
After living with the cooktop for a bit, the induction burner become the main heat source, about the only time the gas burners were running is when I needed more space.
When my wife to be moved in, she refused to use the induction burners and was using the gas burners all the time. It was a slow process, but she is now also using the induction burners for most of the cooking. Pretty much the same reasons as me, much faster, easier heat control and way more heat.
My only beef with induction is that most (mine included) are touch controlled. This is nice for a clean look but can get annoying if you try to adjust anything with wet fingers or any condensation drip from a lid.
Even with that, I would still recommend induction over gas any day. Having gone mostly teflon free in the kitchen, most of the pots and pans are either cast iron or stainless clad which work great on the induction burner.
On the induction unit, I can make an omelet in a cast iron skillet, by the time I'm done, the handle of the skillet is just getting warm. Unlike a gas burner, you can see and feel that all the heat is going into heating bottom and very little is lost. As an engineer, I really appreciate that efficiency.
We had the opposite experience. We were advised by greenies that anything but induction was ludicrous. We found they are fussy, noisy and hard to control. We can deal with boiling water taking 50 seconds longer.
Hi Jason,
I am curious about your experience with induction as most of the commenters here only have positive things to say.
Was this perhaps due to a particular model of induction that was pretty finicky?
No I don't think so. everyone I've encountered has the same goofy failure prone touch screen control. I find it hilarious everyone is focussing on the byproducts of combustion from the gas flames and is completely ignoring what happens to burnt food etc, induction prevents none of that.
Okay all. On the jobsite all day today and after a catch up you've got my sold on a heat pump dryer, heat pump water heater and an induction range.
Now, will I need makeup air for an induction range that calls for 300 cfm ventilation? Then, how should I execute the makeup air?
I had mentioned previously: --
Can I integrate things a bit more with any of the rest of my mechanical system? I already have an air handler with ductwork throughout the house. It is a Mitsubishi SVZ-KP30NA with an electric heat kit. It seems like I should be able to piggy back on that to supply conditioned make up air when the range hood comes on.
--
Can I have makeup air just go into the return of the air handler to be distributed? Should I have it be dedicated and ducted straight to where it is used or is that unnecessary now if we're just doing induction?
Let me know your thoughts on venting and makeup air now that we'll be switching to induction. Thanks!
I would research each. I have heard good things about Miele heat pump dryers, but they are smaller than a typical “American dryer.” They also take longer to dry. Make sure the family understands that up front.
For heat pump water heaters think about noise when you choose placement and the required room area needed for it to operate correctly. My AO Smith is kind of loud. Rheem units were reportedly quiet, but the newest model has had complaints.
For the range hood I would get one that can turn down to 100 cfm. You should be able to use that without dedicated make up air. If you find out you can’t you can go back and add a motorized damper in the basement perhaps. Maybe run the communicating wire during construction. But I wouldn’t add one before you know you need one.
Btw I think you are making the right choices.
If you aren't the one who does laundry, you better let the one who does know what the implications of a HP dryer are for their daily schedule.
“Okay all. On the jobsite all day today and after a catch up you've got my sold on a heat pump dryer, heat pump water heater and an induction range.”
So will the house be total electric with no gas line for anything?
My question remains do you often turn on the hood in your current home?
Few people do and when they do it is because something is burning. If your favorite dish is blacken something then get the big hood and put in makeup air. If your style means you rarely blacken, I say skip the makeup air unless the inspector is pushing for it and crack a window when you happen to run the fan on med or high.
The makeup air becomes a matter of life and death when you have gas appliances like a water heater that could back draft and kill you.
Yes I do have the enormous fan over my stove it has more hours on it playing blower door than as a range vent.
Walta
Hi Walter,
Yes, at this point the home would then be entirely electric.
We do still have the Stuv wood fire insert though. So, in theory, negative pressure could cause that to backdraft if it became enough. That has its own fresh air supply but as Akos suggested above, that may not be enough for the Stuv. He said: "This generally means limiting depressurization to 5PA, which is very small."
We don't often turn on the range hood in our current home but that is mostly because it is very ineffective. It is a downdraft with about a 4" pipe and doesn't seem to really even pull anything down. I want to prioritize clean indoor air in this home and make sure our kitchen doesn't slowly get caked with grease the way our old home has.
We have a falmec hood insert with charcoal filters and have it piped to recirculate. I think this is all you need unless you deep fry or blacken often. We don't and it's worked out well.
https://youtu.be/RJ-WF7gaiXA
https://youtu.be/Gyph72_y8wQ
https://youtu.be/NsSvMB9bJeE
https://youtu.be/bMkvCn1sGvk
If you exhaust it right, all the bad stuff goes out and the fear of it floating and killing you is irrational. The 3 links above all have great ways to accomplish what you want. I would say I would put a hepa or at least very high MERV filter on the intake, but intake fan or not, it can be done where you aren't poisoning your home with gas. Even induction will give off bad things. It comes from the food cooking, not just the heating source.
Thank you. All these gas phobic commenters never burn food or cook more than ramen on a simmer, it seems.
Curious what model range hood you decided to go with as I would like to buy the same one.