Well, going to BBY.com was your first mistake. :-)
Sorry, I couldn't resist.

I went over to some major online appliance retailers (abt dot com and a j madison dot com, but this is not an endorsement of them) and most of the OTR microwaves had CFM ratings listed.

An extremely cursory look tells me that 300 CFM is the going capacity for the high end micro hoods, including a very expensive GE Advantium, Electrolux ICON, a Viking and a Dacor.

I don't know of any OTR MW's with 600 cfm's. I do know that Samsung makes some with 400 cfm's. Just go to the Samsung website, and you can sort their microwaves by cfm's.

Here is a link that might be useful: Samsung Website Microwaves

This one in the link below is rated as 600 CFM, but I wanted to see what other choices are avialble with near the same ratings.

I just found the CFM of my current model after a Google search and it is already 300CFM which is higher than average for OTR microwaves. Still not good enough to do the job though, so I want at least 450 CFM.

Here is a link that might be useful: 600 CFM Microwave

I just remembered after I posted above, that Sears has a Kenmore OTR MW with 600 cfm's (Model #88523). I don't know who makes it for Kenmore, and don't know if it's any good, but I'll provide a link. I bet the microhood has a really high noise level. Think about the noise caused by pushing 600 cfm's through those little microwave mesh screens, and then through the narrow MW duct.

Here is a link that might be useful: Sears Kenmore Microhood with 600 cfm's

Well, they need to rate the fan noise in specs too then. Bathroom exhaust fans list both CFM and noise.
The Samsungs claim they are quiet in their description on the web site. I will have to see if Sears has the 600CFM hooked up and running so I can hear the fan, but it may not sound the same in the store as installed in a real kitchen.

frankly - I don't believe Sear's claim about the CFM's of that micro/hood. If you dig a bit and find the orig. manuf. of that hood you can look up the specs of their branded one to compare. Perhaps it is 600 cfm.

Anyhow, There is a reason that microhoods don't have high CFMs. Physics. It's hard to force that much air through the fairly small openings allowed by these units. It addition they have very poor capture areas - shallow and flat - that barely take advantage of the CFMs they have.

Bottom line is that if you really need 600CFMs for your cooking needs , you need to get a proper hood and find another spot for the microwave.

I don't have counter space for both a toaster oven and microwave and I can't find a toaster oven microwave combo that's isn't poor quality. So, I need the most effective exhaust fan available in a OTR microwave.
It may not need to be a full 600 CFM, but it needs to be significantly more effective than the 300 CFM I have now.

There was a post about a user that had found a 600 CFM OTR, They lived with it about a year, hated it, and after a year they installed a regular type vent, and found a place for a MW. Try searching for 600 cfm Otr, using the search at the bottom (Previous page from here).
We have seen a lotta posts about OTR's and Antss is "Right On" with his advice----if you are like most, you just never will be happy with an OTR, It limits both MW choices as well as Vent Choices.

Gary

Even a "600" CFM (highly doubtful numbers) will be darn near useless when faced with a prosumer level range. A 300 CFM one is darn near useless when faced with a consumer level range with 12,000 BTU burners or a standard electric coil range. What makes you think that having an additional "300" CFM will magically make any OTR be truly functional as a vent? It won't happen. All that will happen is that it will be LOUDER!

You have your tradeoffs in any kitchen. If ventilation is important, you junk the useless OTR and put in a real hood with real capture area and accurately rated CFM and vent it externally. If space saving is more important, you go with the OTR (hoping you don't melt it!) and open the window when you cook. This isn't a case where you can have it all by throwing more money at a longer list of suspect specs.

I went through the same thing! Couldn't find an OTR micro that could handle a 15,000 btu range, and everyone told me I was nuts to try. Not that you should do this, but I found an "affordable" built-in microwave on closeout from Austex, and got a 600 cfm vent for OTR.

If you are interested in my solution, check out Fulgor. They are an OEM company that decided to enter the American market soon before the housing bubble burst. They have since bailed back to Italy/Europe I think, although their fancy-pants USA website is still up. The unit itself is/was made by Sharp, so there are no parts worries. http://austexhd.com/products/apo/aomwbi324r1ass.html
http://www.fulgorusa.com/
I couldn't spring $800 on a built-in micro, so this works for me at $350 including the trim kit. Installation is next week, so I'll let you know if it's a dud.

Drew

I have the sears otr microwave / hood that alwayfixin posted above.

We have been using it for 2 months and it works absolutely fine and is not noisy at all. I do some high heat stir frying but do not do any deep frying. It seems to me that this model is perfectly adequate for a regular home cook.

The microwave is great also and I love how the door opens from both sides. Also, it is very easy to wipe clean because everything except the stainless is smooth glass. It is also very functional for a short person as the controls are on the bottom and very easy to see and operate.

I would be happy to answer any specific questions if you have any.

the Sears mw has no turntable. I've always had a turntable with pretty good results. Are you happy with the cooking ability without a turntable?

Thanks

It does have a turn table - sort of - it is rectangular and moves side to side. I don't really do any cooking in the microwave apart from oatmeal, reheating and making popcorn. No problems with anything so far. It is more powerful than my old microwave so I have had to adjust some of the heating times.

My opinion is put in a real range hood and buy a 99.00 microwave and put it on your counter somewhere. Trying to combine these ends up giving you the worst of both.

Jaxo, I did research months ago about this same topic with the same constraints (space mostly). I feel your pain. You didn't mention:
- what kind of cooking do you do (high heat?) and on what (gas, electric)?
- how important is smell and grease capture to you (OTR micro do not extend to the front burners/elements and low CFM)

OTR microwaves are not good for many reasons already cited by others, however they are a compromise that lets you have 2 appliances in one.

If you really must have one, the 2 that are in the 500/600 CFM range are by Panasonic and Sears respectively. Dacor has one that can go up to 600 CFM with an inline blower option.

Maybe I'm remembering wrong, but I believe my Bosch allegedly hits 600.

I remembered wrong.

I do not recommend Electrolux EI30MH55(GS) OTR microwave (300 cfm). Horrible customer service/service repair. Microwave has been repaired 4 times and still doesn't work. Not worth the price paid ($650 but now retails for $350 only 6 months later). Get another brand!

And it doesn't even match the ranges, which is the main reason I purchased this model to match my range.

Hi, threebees, I need a OTR MW and we are choosing WOLF range (30" and 16,000 btu), I do some deep fry and high heat cooking and I am worried if OTR would be ok. I understand the best solution is to have a hood but unfortunately I don't have that as an option. A few questions regarding your sears MW:
1) what type of range are you using?
2) are you venting outside or recirculation?
3) do you find it's noise?
4) do you usually use the 600cfm mode or ?

thank you.

Wenxin5, tell us more about your situation. Because a Wolf range with 2 or 3 burners going on high is going to melt an OTR microwave hood.

Bumping this up because I have the same question----am wondering the results for the OP and others...
Thanks,
RoseWest

I decided that a dedicated vent hood would be what I wanted since I was able to make space for a countertop microwave and I wasn't really satisfied with my previous 300 CFM Kenmore Elite Microwave/Hood which was already a bit better than the average microwave exhaust.

The new hood is a Zephyr with 800+ CFM through a 7 inch duct to the outside. It works very well at exhausting air from all burners.

However, if you absolutely don't have any space at all to use a countertop microave like this kitchen:

Then I would say get an induction range if you can (to limit how much heat is generated) and then get the Samsung SMH9187 400 CFM microwave/hood and try to limit cooking things that need a good exhaust fan to the back burners since there is little coverage towards the front. The Samsung will probably do well enough if you avoid using the front burners when you need exhaust and especially if you can also open a window.

This microwave will fit in the tiniest kitchen.

It would easily fit in the pantry of that last kitchen !

"can't find a toaster oven microwave combo that's isn't poor quality"

BUt.......you are willing to live with a poor quality hood/micro that is more expensive and fairly permanent? This is a bit on the foolish side considering the range you've selected.

Don't take this the wrong way but, you might consider dropping the typical American view of "give me the BIGGEST prettiest and cheapest thing" and focus on getting item that REALLY meet your needs and budget.

At least the OP did the smart thing and got a proper hood. Folks who don't have counter or upper cabinet space for even a GE spacemaker (wrong width for us) should look at the micro drawers. Folks are not used to them and they are more expensive, but so are the OTRs and they don't work well. I'm wondering about the person who said they were getting a Wolf range and putting an OTR above it. That's a no and for a reason.

I'm glad my kitchen was large enough for everything to fit.
Microwave drawers are interesting but if you have a really tiny kitchen, you may not be able to give up the drawer and cabinet space.
There will be some people who only have the choice either to use an OTR microwave or move to a bigger place and moving may not be a realistic option.

It has plenty of power, but if you use the high speeds to get that power, it gets noisy.

[This message originated at GardenWeb]

I'm considering purchasing a Zephyr hood like you had posted in the past. Could you let me know your thoughts on it and if you think it's worth getting? I'm worried it won't pull the steam from the front burners of my gas stove.

Any advice would help. Thanks!

http://ths.gardenweb.com/forums/load/appl/msg0622143631328.html

Whirlpool has a countertop microwave that is a bit wider than a diner plate. Looks cute too. We had an OTR and... never again.

I am also looking for a decent otr microwave and thought I found the perfect one-- the LG 2016. It has excellent reviews and I was all ready to get it until I noticed the chicken nuggets and hot dog button. I'm sure these are conveniences for some but since my family and home is vegetarian, it seems inappropriate and out of place. Can anyone recommend a comparable otr that would not have meat references? BTW, I contacted LG to ask if there was anything they could do and they said no.

Great joke. I like your sense of humor!

I am tempted to just go with a hood with higher cms and get a counter top microwave. The most important feature to me is the microwaves ability to clear out odors. Anyone makes a decent microwave. But seems NONE of them do decent exhaust.

Bobbiewhitten, it's perfectly okay here--encouraged, actually--to start your own thread. You'll get many more looks in than at the end of an old thread.

Just about any microwave you encounter is made by Sharp or Panasonic. The other brands contract with them, so have different features and looks, and sometimes different build quality, but they're basically all the same.

NO OTR microwave does a good job as a vent. Some are worse than nothing.

Your feelings are correct on all accounts. If you want your microwave off the counter, you can put it on a shelf, in a cubby or open cabinet, or on mounting brackets, and they also make ones like OTRs that don't have the vent and mount under a cabinet over the counter.

Get the hood.

As a manufacturer of range hoods since 1980, having seen 1000s of hoods (full-size, undercabinet, built-in, and OTR/microhood style) pass by in the market, we can confirm with 100% certainty the opinions of pillog, antss, and everybody else who says that microwave hoods simply do not work well.

Tiny filter capture area, small motor, tiny duct - all those restrictions contribute to making the ventilation part of the microhood an afterthought, rather than the main feature. Also, consider the noise level - a 300CFM motor running "at redline" will be much noisier than a 900CFM motor running at 1/3 speed.

What's the use of having a ventilation solution if you'll rarely use it because it's too loud? Very few kitchens are so cramped that you can't allocate a couple of cubic feet to a full-size microwave, located somewhere other than over the range. Unless you're renovating a boat, do yourself a favor & get a separate hood and microwave.

Last but not least, microwaves aren't exactly the most exciting appliances, whereas a designer range hood and a cool backsplash can totally transform the cooking area into a focal point of the room:

36" Acqualina Glass - Wal Range Hood · More Info

Designer Range Hoods - "Capri Wall" Series · More Info

Designer Range Hoods - "Rainbow" Series · More Info

36" Solaris Wall · More Info

Thanks for the answers. This is for a tiny kitchen in a townhouse recently purchased. There is no way to vent to the outside so it looks like I'm stuck, since counterspace at a premium also.

If you can't even vent to the outside, then an over-the-range microwave/hood is of even less use. There apparently finally are ventless hoods that are more than just glorified noise makers. But they need big bulky filters and cost a pretty penny. A microwave isn't going to come anywhere close to doing this job

Yes, ductless hoods do exist (for example, all of our hoods are designed in such a way that they can be connected to an outside duct, or installed in ductless mode, with additional charcoal filters).

But, as we point out in our FAQs and so on, while ductless is better than nothing (at least the hood will capture the grease, and move the air around so you get some sort of circulation), it's at least 30-40% worse than ducted, since the charcoal filter kills airflow. Kills. It.

The moment you see "charcoal" or "ductless", take the CFM rating of the blower and subtract 40%. At least with a full-size hood, you're subtracting that from 800-900-1000 CFM. With a microwave/hood combo, you're starting with 300-400 CFM and ending up with... not much.

Oh man just catching up here. I noticed the new microwave oven is pulling air in about half what it used to be. We just want to prevent the buildup of grease on the cabinet above the mircrowave and it does seem to be well greased up already.

This OTR microwave we just recently installed has a 400CFM fan and we run the duct through the roof. The microwave comes with two normal metal mesh filter without the charcoal, I hope that it can run up to 90% of the fan performance whirlpool stated. We did consider the vent hood however, we didn't want to redo the carpentry of the cabinet because it's another expense and labor intensive. Is there any suggestion how to cover the duct ? It does look a little ugly.

Fans used for ventilation blowers are normally rated for their free air (zero static pressure) performance, not the actual flow rate achieved in some restrictive configuration that includes the microwave's tortuous path pressure loss, the mesh filters' pressure loss (increases with grease and lint accumulation), and the duct's pressure loss. You might achieve 250 CFM with clean meshes, but potentially significantly less.

On the other hand, you may only have 2 square feet of mesh, or even less, so at the filters the flow rate will be over a recommended 90 CFM/sq.ft. The effluent reaching the meshes should be contained and ejected from the kitchen through the duct. The problem is that the microwave oven base is not a hood capture volume, and only the parts of the rising cooking plumes that intercept the mesh filters are likely to be contained. The rest will reflect away and, depending on plume velocity (much higher for grease than steam) will escape into the kitchen. The microwave front-to-back overlap of the stove shown in the image suggests that front burner plumes will not even be intercepted.

Sounds pretty depressing to me but anyway, we've already installed it. You are right about the front burners. I will need to use the back ones for heavier cooking. Thanks for the heads up. I personally like vent hood way much more but due to the expense and time to convert everything when we don't really go through a major remodeling, it's just better for us to go with what is already there. However, I think I might buy a slide in gas range in the future which will, hopefully, have a better allignment with the Mw.

"we didn't want to redo the carpentry of the cabinet because it's another expense and labor intensive"

"due to the expense and time to convert everything when we don't really go through a major remodeling"

I am sorry, but this doesn't make sense. You can swap out the OTR MW for a 30" wide hood that is 9" high. There are many of these on the market. There'd be zero carpentry needed, you wouldn't need to "convert" anything, and the labor to do this swap could be DIY, or you can pay your appliance store a couple hundred to do it.

Here is a hood from Costco that would fit the bill, but there are many others:

https://www.costco.com/Ancona-Advanta-Pro-Elite-Series-Under-Cabinet-30%22-or-36%22-Range-Hood-with-625CFMs-and-3-Speed-Electronic-Controls.product.100290934.html

Do I have install another fan to make up for the air got sucked out from a range hood that is over 400 CFM? There is no window near the kitchen at all.

In many places, make-up air (MUA) requirements are enforced. This is independent of whether windows are available or not. Safety is the consideration. If house leakage is insufficient for the blower flow rate, the house pressure will drop and potentially back-draft combustion appliances.

What actually happens is that the realized flow rate of the hood equals the total house leakage at the reduced house pressure such that the blower is "strangled" to a particular flow consistent with its "fan curve" (flow rate vs. pressure) performance. If there is no combustion appliance risk, then the issue is just poor hood performance. Generally one wants a source of MUA that allows the house pressure to not fall too much. This can be as simple as a hole in a wall with a damper, or more a complex system that includes air heating. Fantech sells complete residential MUA systems and would be a good place to see what might be involved. Reading the first dozen or so pages of Greenheck's guide at the link below can provide a big picture overview of kitchen ventilation.

http://www.greenheck.com/media/pdf/otherinfo/KVSApplDesign_catalog.pdf

Hi All - I know this is an old thread, but I have an Samsung OTR with a 400 CFM fan and was planning to vent it out. Anything above 400 CFM will require MUA and it will cost $$$ I was going to get a hood extension and then vent it out - https://www.amazon.com/Microvisorhood-extension-microwave-range-STAINLESS/dp/B01GVYYO3C/ref=cm_cr_arp_d_product_top?ie=UTF8

The gas-range sits on a exterior wall, so it shouldn't be too much of duct work. Thoughts on this?

I don't believe the "microvisor" does what you think it does. It appears to just extend the capture area of the microwave oven's own ventilation function. Because microwave ovens cannot (for reasons you may have read above) adequately perform the two primary functions of a cooktop hood -- capture and containment -- adding what is effectively a tiny eyebrow hood only extends an inadequate system to inadequately deal with the front burners, rather than the baseline of ignoring the front burners altogether.

Is your microwave oven already ducted outside?

Futuro Futuro Kitchen Range Hoods comments above apply and should be reread. For more background, read other hood threads on this site.

Thanks for the response. No my microwave is not currently ducted outside but since in my state, we are required to take care of make-up-air if we go for a hood above 400 CFM. Our current microwave can be ducted outside and it has a 400 CFM fan. I agree the microvisor is just an eyebrow but wouldn't it block the air from going up to the ceiling and surrounding cabinets and if I turn the vent of the microwave to pull air, wouldnt it be able to capture some of the air? I met somebody who had a MUA installed in his house and the equipment costed him $1200 and had a handy-man do the installation. I thought the MUA was going to be in the $7000 ball-park. Given that the microwave is not powerful, would a 400 cfm under-cabinet range hood do a decent job when compared to a microwave OTR ?

A real hood, mounted under-cabinet, will surely be better than an OTR microwave oven attempting to perform kitchen ventilation. A real hood rated at 400 CFM, and not too restricted by the house's ability to provide MUA, given short duct to outside without too many bends, might flow 250 - 300 CFM. I am confidant that any microwave oven claimed to be 400 CFM is actually just a 400 CFM in open air fan buried in the MW's tortuous duct path. I'd be surprised if it could flow even 200 CFM net.

Note that the 400 CFM MUA rule is for hoods ducted outside; if a filtered (surely) recirculating hood were used, there is no MUA issue. VaH make an expensive but reportedly adequate for real cooking ARS recirculating hood. It might not fit your circumstances.

ralph_zone8_ncwrote: "I agree the microvisor is just an eyebrow but wouldn't it block the air from going up to the ceiling and surrounding cabinets and if I turn the vent of the microwave to pull air, wouldnt it be able to capture some of the air?"

With respect to eyebrow capture, it will (temporarily*) capture any part of the cooking plumes that strike it. However, they will reflect out again into the room if the blower flow rate is not high enough. Flow rate needed to assure successful capture and containment depends on the temperature of the grease being vaporized and the area over which the grease plume is being generated and whether combustion products are entrained. I recommend for most a value of 90 ft/min under the entire hood aperture when cooking with gas. This corresponds to 90 CFM per square foot of aperture. The value 60 may suffice if an induction cooktop is being used. But please note from the Figure 4 table on page 9 of Greenheck's guide -- your needed (or at least recommended) flow rate (CFM) may vary.

http://www.greenheck.com/media/pdf/otherinfo/KVSApplDesign_catalog.pdf

-----

*Because this eyebrow has minimal depth, the blower flow rate in its vicinity will be less than the average over the capture area. Reflection, at least of hot grease vapor may be insurmountable with a microwave oven fan system. Water vapor might be adequately dealt with if it makes it that high.

Thanks so much for the detailed response. We will be venting it to the outside and the gas-range is on a exterior wall. I am going with a under-cabinet range hood and considering Broan BCSQ130SS .(300 CFM). I read somewhere that if the fan is a centrifugal type, it is supposed to be more powerful. Also does it matter if I get a convertible versus a ducted range-hood? I read that a ducted range-hood's fan mechanism is better. Thoughts on this?

I don't think I can answer this question. I do not deal in specific hoods, or recommend any I haven't used, and my recent (last decade) personal experience is with larger flow rates using a roof mounted blower.

A centrifugal type blower usually refers to a design that uses fewer large blades (often mounted on a disk) as compared to a squirrel cage blower that uses many small blades. Both are more or less tangential air-path wise as compared with axial (axial as typified by the compressor blades visible at the front of a modern high bypass jet engine). VaH blowers are squirrel cage type, I believe, as are Broan/NuTone bathroom exhaust blowers. Centrifugal fan designs for a given motor may be superior to squirrel cage type operating against significant pressure loss. At low pressure loss, the flow rate advantage may be negligible. Relative noise likely depends on details of the blade design.

In a kitchen ventilation system with an adequate diameter short duct to outside and adequate make-up air, the hood baffles and/or mesh filters dominate the pressure loss list. For a VaH "magic lung" hood, there are no filters, and if (!) the other losses are low, the squirrel cage blower will operate at near its rated (in the hood) flow rate. Where the VaH squirrel cage style blower can have problems is with higher pressure loss conditions of long ducts, constricted ducts, many bends, poor MUA, etc. In those cases the Broan/Abbaka style of centrifugal blowers seem to be better performing. In any case, I recommend obtaining the fan curves for whatever blowers are candidates for your application and comparing them.