Thanks - I am tempted by those as well, but my wife doesn't love the "beam me up Scotty" aesthetics of those hoods (which is why we are going with the paneled cabinet approach). Given how supportive she has been about all of the other toys in this project, I think this is an OK tradeoff! As you say, first world problems.

I'll take a look at the models you suggested.

I appreciate the feedback!

Joe

Good luck Joe! I hope you find something that works wonderfully. The exterior mounted blower would also be quieter.

There are requirements for good capture and containment (the function of kitchen vent hoods). They have been extensively addressed here. Rather than write yet another overview, I'd rather answer specific questions raised after the OP reads the previous material. You may search on 'kaseki' and 'capture' and 'containment' to find many examples.

Thanks @kaseki!

I did some searching through your past posts and really appreciate the pointers from that material. I definitely haven’t absorbed all of the information but I think I follow well enough.

The Miele KM 6375 36" induction cooktop dimensions are 35 7/8” x 20 3/16”.

The (presumably finished) dimensions of the Miele liner (Dar 1130) are 33 7/16” x 22 13/16”.

I guess my questions boil down to:

1) Does this liner provide for a sufficient capture area?

2) Does this fan provide sufficient CFM?

3) Are there downsides to external blowers?

4) Are there other clear standard/standout recommendations for liners/blowers that would meet my requirements? (Effective, quiet, aesthetically pleasing, relatively cost effective)?

In more detail:

1) Capture

I can’t find the measurement of the aperture of the unit, but from the pictures, it seems like the baffles go width to width with a relatively small metal finish on the edges. It seems like a standard recommendation is to go +3” wider in each direction than the cooking surface. (i.e. ~42" width hood). This is an option since we are doing custom cabinets, but I am somewhat disinclined to do this due to aesthetics and how this would potentially impinge on the surrounding cabinets. I’d likely also have to go with a different insert liner since it seems the next size up on the Miele line is 48”. But if a 42” (vs 36”) liner would make a significant/critical difference in effectiveness, I could look more closely at whether this works in the design.

2) CFM

It seems like there is a lot of detail that goes into calculating the exact necessary CFM that I can likely work with the HVAC folks on when we get to this point, but it seems that using the dimensions of the unit (34” x 23”, 5.43 sf) x 90 x 1.5 yields a recommended blower of 733 CFM. So, if I go the 1100CFM blower with this setup, I should easily meet this requirement. Is this blower appropriate, or overkill? Can upping the CFM over recommended compensate for not having an oversized capture area (point #1)? BTW, I haven’t looked closely at MUA requirements based on guidance from architect that since we are likely replacing furnace and some ducting as part of this remodel project and doesn’t seem phased by adding MUA. He also stated we have room for 10” ducts.

3) External blower

I have been biasing towards an external blower based on desire to ensure the unit has sufficient CFM and to reduce noise in the kitchen. The potential mounting locations include the sides of the house (which are somewhat close to neighbors) and the exterior roof of the house. How far away from the exterior location does noise/smell of exterior blower become a big concern?

4) Other recommendations

Besides salesperson suggestion, I don’t know much about the Miele liner/blower. Any insights on how these perform? Are there some other clear standard/standout recommendations for liners/blowers that would meet my requirements? (Effective, quiet, aesthetically pleasing, relatively cost effective)? I realize from other threads that trying to get all of these is a recipe for failure :-).

The Modernaire/Abbaka combination seems to come up in a lot of the threads I saw.

5) Other stuff

* It seems like a silencer is a common addition?

* Are blowers paired and tightly coupled to the liner, or can this be mixed and matched at all? For example, I liked the aesthetic and lower profile of the Abbaka external blowers but didn’t know if that could be used with the Miele liner, or whether I had to switch to the Modernaire or another model.

Thanks a ton for any insight. We are at the construction document stage and aiming to start construction in early September and it will be a 6-9 month project, so have a bit of time. I am really happy with architect and contractor, but wanted to do my own research on the kitchen stuff so that I make sure I am happy with everything, hence my desire to give into the details here even though I don’t have any expertise in this area.

Thanks!

-joe

1. & 2. Best is overlap, although for many this is not a convenient or aesthetic option. Without overlap, some rising effluent will be missed and either deposit grease and moisture somewhere (as well as spread odor) or will hang in the air until the ventilation slowly removes it. With excess CFM, one may argue that there is an "aura" of air flow around a given aperture that effectively extends its size. This aura will be small, but might reach 3 inches. However, given baffles that had, say, an inch of water column pressure loss at 90 ft/min, and hence a big part of the 1.5X factor (with good MUA) for choosing the blower rated flow rate, if the flow through the baffles were significantly increased the pressure loss would also increase (not necessarily linearly) so the point on the fan curve would change, partly negating the excess flow.

In other words, whereas an 1100 CFM blower might yield 700 cfm when used with an 8 sq. ft. baffled aperture, reasonable MUA, ducting, etc., with a 6 sq. ft. baffled aperture it might only move 600 CFM. Still more than the 540 recommended for six square feet, but not overkill. Assuming a continuous blower control (300 - 1100 say), you can just not turn it all the way to full speed.

Now, as the real aperture dimensions start getting smaller and smaller due to cabinet factors and dimensions of standardized inserts, turning down the blower may also prove useful just for reduced baffle turbulence noise that the silencer cannot help.

Your contractor may be fazed by the MUA when he finds out that it needs to be separate from the furnace system for a variety of reasons that jwvideo spelled out in a recent thread. Sorry I don't recall the thread name. Best is to have the furnace have its own MUA to avoid backdrafting. Ditto hot water heater if separate. Or use a mechanical room to house such stuff with its own MUA and closed path to the kitchen.

3. & 5. The most important reason for an external blower in my view is the ability in some cases to fit a silencer in the duct path. This is the most useful addition to the ventilation if one likes to chat while cooking. Typically, this requires an attic space and a roof blower, but some duct schemes (through garages, for example) may allow room for a silencer in a below kitchen ceiling horizontal path, or potentially one could be used in an external chase rising to a top-mounted blower. Note that a Fantech 10-inch silencer is about 14 inches in diameter.

External blowers like the Abbaka and similar shaped Broan and Wolf blowers are typical because they have low profiles and blow down the roof. Commercial up-blast designs can also be used, and may have advantages depending on types and depths of snow. (I have a Wolf/Broan 1500 CFM unit.)

If you want to use Abbaka, for example, but buy an ModernAire liner, for example, then ModernAire needs to know that they have to provide a control, or space for a control, compatible with the Abbaka blower. I think Abbaka, Broan (and hence Wolf) blowers are all induction motors, so appropriately sized triac/diac or more sophisticated semiconductor continuous controls should work. I think I could rip of my Wolf (Broan) blower and substitute an Abbaka and use the Wolf hood (actually made by Independent) triac/diac motor control with it.

These blowers are not too noisy on the roof relative to nearby areas, but can be heard. For consideration of mounting on the side of a house: one would have to ask, are you in Londonderry, NH where the lots are 2 acres, or in a suburb of San Francisco, CA where 2 meters separates the house from the property line.

4. I have no information or experience about Miele liners. I only have a Miele dishwasher.

I don't have a ModernAire ventilation hood either. Their name comes up because they are known to build custom hoods that many are pleased with. They are not the only such source however, so serious trolling of the Internet may be useful. I found in my reno it useful to buy everything early so I could carefully measure details that are hard to otherwise determine that influence the cabinetry and outlet locations. However [prime caveat], your warranty may start when you take delivery (Wolf is rather generous on this point) and in at least one claim raised here, Modernaire would not correct a problem after many months of the liner not being opened and inspected (as I recall). So, try to avoid taking a few years to finish your reno.

Also, on that point, you may find it helpful to make lower cabinets deeper than standard to more easily fit plumbing, electrical, refrigerator depths, etc. It just costs a little more to do so.

If I forgot to answer something, don't be shy about bringing it to my attention.

kas

Wow, thanks a ton for this information Kas.

Based off this, I think I'll:

• Look for 1100+ CFM low profile roof mounted blower with a silencer (I think this strategy will work with my situation)
• Look at option for increasing the capture area (primary concern is the aesthetic one but this might be worth doing for reasons you stated)
• Research hood liners a bit more extensively. Given that this is a liner, the aesthetic concern is a bit less, although I did like the visible appearance of the Miele liner and the fact that the removable baffles apparently fit well in Miele dishwasher. I didn't love the appearance of their external blower - seemed a lot larger than others
• Work with architect/contractor/mechanical sub on MUA strategy per your comments. I think we have a lot of flexibility here given scope of this remodel. I'll look for the thread you mentioned.

With respect to other things you mentioned:

• We live in Seattle. So rooftop snow isn't a big concern. Our house is fairly close to neighbors on both sides (~15 feet?) and we like our neighbors so rooftop mount seems preferable if that works.
• We played around a lot with the cabinet/island dimensions to ensure there was adequate clearance for the space so a little reluctant to increase cabinet depth but will pass that suggestion along to architect for consideration.

Thanks again for all your feedback and insights, I really appreciate it!

-joe

My Wolf baffles fit OK in my Miele Optima. However, since I have 10 of them, I need to run two loads.

Based on this thread + others, I am leaning more towards the Modernaire PSL-034 or PSL-040 (depending on whether I choose the advised +3" cover) + the Abbaka 1400 CFM blower, with a silencer as well. The quote I received from them was comparable to the Miele hood, and the aesthetics look pretty good/similar. If I decide to go for the wider option, I think I have to abandon the Miele hood, since their next size up is 48". I also like the exterior aesthetics of this blower better than the Miele and the fact that it is explicitly paired with this liner, as well as the fact that it has continuous controls, as opposed to four fixed speed options.

I need to work with architect/contractor on the overall venting/placement/MUA strategy before I commit to this design.

Are there any other options I should consider for better price or aesthetic reasons? The Wolf one looks nice too so I might check that out as the local store.

Thanks!

-joe

I was curious if you went with the Modernaire and if you could give me an update on how it is working? We have almost the same appliances, live in the same area and are trying to pick our insert?

Hi Deanna,

We did purchase the Modernaire PSL-040. We are still in the midst of construction still (in fact the unit just arrived on site!) so I can't really comment on its performance but I am hoping it will work out. Based on guidance from this thread, decided to go with the 42" size liner for the Miele 36" induction cooktop so the capture area was a bit wider than the cooktop.

Beyond that, we also went with:

• * Abbaka 1400 CFM external blower, mounted on roof - I chose this based on the power, ability to mount externally (less sound), and the overall aesthetics / profile of it for the roof. To be honest, it was a bit of a pain ordering this because I believe Abbaka was recently acquired and it was hard to get accurate inventory / delivery time, but ultimately was able to get the unit ordered onsite.

• * Fantech LD10 duct silencer

• * Fantech MUA system (http://www.fantech.net/globalassets/downloads/leaflets/english/e1574-makeup-air-system.pdf). I think we got the 1200, but I am not positive. It returns air via the toekick underneath the range

• The hardest part was figuring out the MUA system since contractor + mechanical sub weren't super versed in this, but I am hoping via this thread + other research that we have a reasonable setup. We were especially concerned about having proper MUA given code requirements (> 400 CFM) + the fact the rest of the house is being remodeled and should hopefully have a fairly sealed building envelope, and we have a wood burning fireplace not too distant from the kitchen that we didn't want to risk backdrafting.

• I highly doubt that I'll need to use the full 1400 CFM most of the time, but I liked the option (particularly given the blower mounted on the roof).

• Based on this thread + other research I am pretty confident in my selections, but won't be able to give you real world perspective until ~July or so.

• Hope this helps - let me know if I can answer any questions about my setup. Good luck with your remodel!

• Joe

We're planning to install the 36" Miele induction cooktop along with the Miele 15" super burner LP gas combiset, for a total of 51" of cooktop. Can we use two 30" liners & connect them to an external blower? We want the liners to go inside what looks like cabinetry, no hood. I'm also not sure how powerful this needs to be, given the combination of induction & gas. This will be in an open kitchen, so noise & smoke control are important. What will accomplish this & be easy to clean?

".... 36" Miele induction cooktop along with the Miele 15" super burner LP gas combiset, for a total of 51" of cooktop" So these two units are going to be mounted so they touch? Will the sides of the supporting cabinets be at exactly the correct point and will they allow clearance for the parts under the counter? Will the countertop be stone, and if so, will it be adequately supported in that configuration?

I have a 36-inch induction cooktop and a Cooktek induction wok hob separated to work with two cabinets (of differing size). The hood is Wolf's largest Pro Island hood (66 inches) and I would consider it just long enough.

With two inserts or one larger insert, and with one external blower (and assuming appropriate merged ducting, dampers, etc., either configuration will need in general 90 CFM per square foot of insert entrance aperture when accounting for pressure losses.

To reduce blower fan blade tip turbulence noise a Fantech silencer can be used in the duct path.

@Joseph Fitzgerald, would love to know how you like your set up! I also have a contractor who isn't versed in the MUA system (it's not required by code where I live), and we also don't have a gas fireplace, so I'm debating whether or not to pursue this. If we did, I like your toekick concept and wondered how it works and also - this may sound silly - but whether it makes your feet cold when you're cooking in front of it! :)

Where MUA is not needed for safety reasons, it is still needed in some form to allow the hood blower to operate at the desired flow rate. Open windows can work with modest additional pressure loss if screened. Otherwise, the house will be at negative pressure relative to the outside and air will be pulled through wall gaps and ceiling gaps in undesirable ways while the hood air flow is restricted.

When using a toe kick areas for MUA insertion, care should be taken to use enough area for low pressure loss, and also to consider whether the flow from toe kick area to hood will be smooth, or turbulent such that it disturbs the rising plumes one is trying to collect. One responder here reported some issues with this due to the air flow crossing an isle to another peninsula or island and flowing upward to the hood in a way that was disturbing to the plumes. Best when using toe kick area is to insert the MUA well away from the hood and let it become a bit more laminar as it sorts itself out in the room volume traveling to the cooking zone.

Thanks so much for your response @kaseki! You impressively appear to be the Houzz expert on all things vent hood, so can I ask another question? We have an island mount hood with 10" duct. The duct is run for about 9 ft with one 90 degree turn (4' up to ceiling joists and 5' directly out the exterior wall, venting directly above our kitchen windows). My question is, should we go with a) an internal blower (1200 cfm) or b) an external blower (150 cfm) + silencer? Based on reading these forums, I'm not sure how much quieter the system would operate with the external blower + silencer combo given our relatively short duct run. I am also concerned that the external blower would end up being noisier because it's mounted only 3' above our kitchen window (tho we may not end up operating those windows often); it'd also be mounted within a few feet of second story bedroom windows. I am also concerned about noise for the neighbor, whose house is approx 10' away. Would welcome any comments on internal/external noise and functionality. Thank you!!!

I am the resident expert only because real HVAC systems engineers don't frequent this forum, as far as I know.

Noise introduced into the kitchen will be significantly reduced if an external blower with silencer can be fitted. A lot of the high frequency blade tip turbulence caused noise will be removed. This is also true of an in-line (duct mounted) blower.

The issue of the neighbor is difficult to assess. What is the configuration of his or her windows relative to your potential external blower (1500 CFM I assume you meant). Your own window sound transmission is also an unknown.

Generally, the external noise could be abated by (a) using a silencer on each side of a duct mounted in-line blower, or (b), using a deliberately under-driven* "up-blast" commercial blower (mounted as a side blast). (I think opaone is using an under-driven blower for his new system.) It is also possible to use a chase to move the blower up to roof level.

I have a 1500 CFM nominal Wolf (Broan) blower on my roof. Its sound level is detectable but not obtrusive from the ground, but it might be if in a wall location where the sound is "trapped" between two houses. Possibly a more expensive but similar in design Abbaka downslope unit would be marginally quieter.

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* commercial blowers of this type can use a pulley system between motor and fan that allows for different ratios. By choosing a ratio that operates the fan blades below their rated speed when the motor is receiving maximum voltage, significant turbulence noise can be avoided. The physical cost is a larger unit than would otherwise be required for the desired flow rate. Residential blower fans are directly coupled to their motors.

Thanks so much! I found another thread where a user measured the decibels with a remote blower and silencer. Please see photo. Can I compare those measurements to what Modernaire posts as the sound measurements they have on their internal blowers, or is that not really comparable? Because it looks like the internal may be comparable in noise, if so!

Previous post

Modernaire’s internal blower data

Comparative sound evaluations based on different equipments are fraught with hazard due to many factors that I am incompletely familiar with. I think these values are indicative of the two systems having similar noise levels. The type of noise, irritability of the noise, and variations in measurement technique and microphones used make direct comparison difficult. In particular, two very different sounds could have the same A-weighting value (perceived loudness), but unequally interfere with conversation.

Thanks so much! Because we can't run a chase up to the roof, and because I'm worried about exterior noise, I'm leaning toward an internal blower motor. Hoping to get some feedback from the community regarding ModernAire's internal blower motor (1200 CFM) and their experience of its noise level, and also any tips for improving sound control such as adding acoustic absorbing foam between the liner and the surrounding millwork/cabinetry.

@kaseki - or should I consider an inline blower with a silencer??

There may be code requirements for residential hood exhaust duct spacing from combustibles, so that should be checked so proper materials are selected.

W.r.t. the neighbors, how many hours a week do you expect to need to run the blower at full power. Several minutes per event for wok cooking, searing, and other such high plume velocity tasks should be a small part of the week's blower operation. The rest of the time the blower will be off or partly on and the noise level will be negligible. Cutting the grass may be noisier and longer lasting per week. Even electric leaf blowing is noisier.

Very true- maybe I shouldn't worry so much about the external blower noise! I wonder...would an inline blower be a good middle ground? We would have room for one silencer and then the inline blower all within that 9' total of duct run. The location of the inline blower would be in that duct run directly above the kitchen ceiling. What do you think about noise abatement etc?

I raised the in-line blower option to allow for dual silencers. I would otherwise use an exterior blower as it will be more accessible. Also, the Wolf/Broan/(and probably) Abbaka blower housings contain their own automatic dampers. You should still have one at the hood, if possible.

Horizontal ducting should have a slope to keep grease and moisture from pooling, although this is likely rare for residential usage.

For my ducting, I used automotive sheet metal dampening material available from automotive parts dealers that also support the body shop trade. This material gives one the impression of being lead or tungsten embedded plastic, but I don't know its actual composition. Brand is Evercoat Q-pads.

In my use, the pads reduce vibration in the duct skin. They will have no significant effect on acoustic noise propagation in the duct air. This is what the silencer is for. Also my situation involves a pine board roof that is not as rigid as I would like where the blower is mounted and I haven't tried to further stiffen it yet. (In the fullness of time.)

You could also check http://www.acoustiproducts.us/ for suitable materials.

You could pull the blower's fan casting and have an automotive or industrial balancing shop touch it up to truly minimize vibration. (This is likely easier to do between delivery and installation.)