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Misleading clearance specs below Bosch induction cooktop

Posted by grumpydave (My Page) on
Thu, Jan 12, 12 at 18:56

I'm installing a Bosch induction cooktop in my new kitchen. All the literature says it needs 4.25" of clearance below. In fact it's only 3.25" to clear the unit and 1" extra at the rear right for the power cord that sticks out the bottom.

Great! With that clearance I'll be able to use the top drawer of the cabinet underneath.

Not so fast! When installing the unit there's a heat shield flap that needs to be lowered. It spans the entire width of the unit about six inches from the front. This flap hangs down 2.5" from the bottom of the unit effectively making the needed clearance 5.75" from the countertop. At that depth the drawer is no longer usable.

I did send Bosch an email asking why they document the clearance as 4.25" when in fact it's greater than that. I asked if I really needed the shield. You can imagine how useless their response was.

So, I'm not hear to bag on Bosch about the quality or anything. I'm just here to say if you're comparing the clearances needed by various induction cooktops the Bosch needs more than they say they do. If you're hoping to use a drawer directly under the cooktop you'll need to take this into consideration.


Follow-Up Postings:

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RE: Misleading clearance specs below Bosch induction cooktop

thanks for the info.. do you have any pics of the said shield... also which model?


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RE: Misleading clearance specs below Bosch induction cooktop

I agree with your frustration and found the same thing with mine when installed. But after making my cabinet decisions based on their published specs, I decided to try to use the drawer with the heat shield up - periodically opening the drawer to see how warm it was in there. While I typically don't have multiple pots going for hours on end, over the last year of use it has never become more than a tad lukewarm in the drawer.

In order to ensure enough air flow in there, I just keep a well spaced row of knives (which would fit even with the shield down) and a few non combustible turners and stirs. A repairman who was at my home (for another appliance) shortly after it was installed looked at the drawer and told me that while he obviously can't recommend ignoring the manufacturers instructions, I should be OK with what I kept in the drawer. He said that his past overheated induction cooktops were almost always with drawers underneath crammed full of stuff.

If you search through old threads here, you'll find one where someone built their own heat shield into the drawer. (Instead of attached to the unit, it's like a divider that sits in the drawer where the heat shield is located and performs the same function of protecting the control area while leaving the rest of the space usable.)


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RE: Misleading clearance specs below Bosch induction cooktop

jmith, I think all the Bosch induction cooktops have the same shield as they all share the same installation guide. Mine is the 36" 500 series NIT5665UC.

skitdel, I'm glad someone else with direct experience responded. I've been debating leaving the shield up and seeing how it goes. I wasn't planning on stuffing the drawer either. I suppose I could put a divider across the drawer where the shield is and it might perform the same basic function. I'll look into that. Thanks!


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RE: Heat shield diagram

Forgot to include the diagram of the heat shield. It's just a flap of sheet metal that hinges down and hangs from the bottom of the cooktop after you remove one screw holding it up.


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RE: Misleading clearance specs below Bosch induction cooktop

We have the 800 series and have the heat shield up. I didn't even know about it until reading this thread. I asked DH about it tonight and he showed it to me ..he is not too worried about it. The drawer below the cooktop just has utensils in it. There is lots of air flow and I have never noticed the drawer getting warm. I think it depends what you plan on storing in the drawer. Just don't pack it full of linens and things that impede the flow of air.


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RE: Misleading clearance specs below Bosch induction cooktop

I have the Bosch 30" 500 induction top. I gave my custom cab maker the appliance model numbers and he built cabs to fit.

Under the cooktop, I have a thin utensil drawer. The cab maker knew the clearance needed, including space for the heat shield.

My gc installed the appliances and I was emphatic that he correctly install the heat shield. It was a big deal to me as I researched the below clearances required for the various brands. And I was aware of the heat shield. I did not watch the install tho.

We have a relatively small kitchen and the cabs were made to fit with little or no wiggle room. For example, the dw opens with only 1/4" clearance.


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RE: Misleading clearance specs below Bosch induction cooktop

I am so glad this thread is here! I'm trying to pick my unit now and was looking at the Bosches yesterday. Does anyone know if this is a problem with any other makes as well?


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RE: Misleading clearance specs below Bosch induction cooktop

I have the 30" 500 as well, and could've written westsider40's post. However, the cabinet guy put in a false front of 6" or so, with two deep drawers below. I looked underneath and the cooktop's flush, so maybe they didn't install the heat shield? There's enough clearance (and it's pots/pans in the top drawer) that it's not a concern for us.


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RE: Misleading clearance specs below Bosch induction cooktop

bishop8, the shield doesn't have to be "installed". It comes from the factory attached to the bottom of the unit but a single screw holds it up. See the small hole in the middle of the shield in the diagram above? Remove the screw there and the shield flaps down on its own. Since you have the empty space below the cooktop you might as well use the shield just in case.


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RE: Misleading clearance specs below Bosch induction cooktop

It sounds to me lit something they added because they weren't getting enough ventilation space.

If your unit gets overwarm you can always just open your drawer a few inches. :)

Burntfingers, GE/Monogram require 12" of airspace in the cabinet underneath, but they assume a cabinet, not drawers. Gaggenau and Miele only require a few inches from top to bottom, similar to what Grumpydave was expecting, but they require an air channel behind the drawers to have a volume of space.

Basically, if you want a top drawer which is only an inch or two from the unit, you should have something between. Many people make shields out of plywood. That keeps your utensils from getting hot, and anything else from possibly combusting from the heat of the electronics, or something like that. That's what people say anyway. The part I do know from experience, is that whether you have the air channel behind the drawers, or a void in the top of a cabinet, you need to have air for the fan to cool the electronics with unless your unit vents out of the surface (at least one does, but I can't remember which) and also the installation instructions don't say they require the air space.

I have a lot of space because my drawers are 48" wide. When I'm making stock, however, and have a 20qt. pot just under a boil for hours on end, all of the air in the channel can get too warm to actually cool the electronics. That's how I learned about opening the drawer. If I open one of the lower pot drawers just a bit to let the cooler air in, the cooktop doesn't shut down from overheating.

Almost all of the manufacturers have PDF files of their installation, planning and use manuals (sometimes combined) on their websites. You can easily check out the exact data for the models you're looking at that way.


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RE: Misleading clearance specs below Bosch induction cooktop

Does anyone know what this will mean in relation to having a wall oven under the Bosch cooktop? Do you need the heat shield if its over an oven?

I am not concerned about the drawer, as I understand is the concern on this thread, but I came across this researching the clearance required for the Bosch cooktop and now I'm concerned about it going over my wall oven.


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RE: Misleading clearance specs below Bosch induction cooktop

Just FYI, I was able to install a Wolf induction cooktop directly over (2) Wolf ovens. Their clearance is quite small, and all is working perfectly. If you're tight on space, you might consider Wolf. The appliances work great, too.


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RE: Misleading clearance specs below Bosch induction cooktop

Repac
Interesting. I still have hopes to have a functioning drawer under my wolf induction. Manual says 6 inches from top of counter to combustible surface. I saw some creative ideas on another post.
For now, my top drawer is a tip out.
The clearance is there but I have to find a metal drawer that isn't too deep.
BTW- I do miss grumpydave's posts


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RE: Misleading clearance specs below Bosch induction cooktop

This flap is less heat shield than air deflector. It is to keep the exhaust hot warm air from circulating back to the intake of the fan.


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RE: Misleading clearance specs below Bosch induction cooktop

I concur with weedmeister, and wonder why Bosch called it a heat shield. What it tells me, however, is that the issue is providing enough replacement air so that the electronics are adequately cooled. Unlike the Electrolux and its Kenmore clone, from the drawing above the air seems to be drawn and removed from the same space. I think this is an issue of electronics longevity and not of risk of a mass of molten metal settling on one's drawer contents.

Opening the drawer will help, of course. A high thermal mass of metal utensils will help for a while. In the interest of electronics longevity, I would want the air space under the unit to be poorly sealed from the cabinet area below it; that is, no panel under the drawer sealing it from the cabinet space below.

Use of an oven in the cabinet space would motivate me to consider more complex arrangements to assure air replacement. This would require drawer sealing to the space below as well as another source of replacement air.

I would specifically inquire from Bosch what the maximum intake air temperature can be and design accordingly. I know from Cooktek that for their wok unit the value is 40C. Clearly, ambient temperature will affect how fast the air in a small space is heated to a given temperature, so successful operation under an air conditioning diffuser may lead to different results than operation in an outdoor Texas kitchen.

kas


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RE: Misleading clearance specs below Bosch induction cooktop

A2gemini,
6 inches from top of counter to combustible surface seems similar to what I have with the induction over the ovens. Don't know if I got away with less clearance having an oven vs drawer below the induction unit? At any rate, it was all done according to Wolf's specs--the GC had Wolf technical help on the phone while we planned out the installation, and we then used a Wolf installer.

Hope you can get your drawer below the induction to work. Isn't it amazing how the last 5 or 10% of the kitchen can take forever to complete? We're still waiting for pulls and knobs to be installed, and now I want to change out the door on the beverage frig to fit a wood overlay door to match the cupboards. By the time I finish this redo, it'll be time for the next!


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RE: Misleading clearance specs below Bosch induction cooktop

repac - thanks - you might have been able to get away with a bit less if it is metal. I have to put a hold on changes for now - we went way over budget (and what DH doesn't know won't hurt him...) He knows we went over as I pointed out the reasons but he never asked the amount...


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RE: Misleading clearance specs below Bosch induction cooktop

No doubt DH realizes you got the deal of the century--a kitchen that looks like a million dollars for a lot less than that! ;) Your kitchen is really beautiful, and worth whatever it cost.


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RE: Misleading clearance specs below Bosch induction cooktop

Repac - thank you for your support. I will have to hunt for a picture of your ovens and cooktop.


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RE: Misleading clearance specs below Bosch induction cooktop

kaseki,

You sound so extremely knowledgeable, I only wish I had someone like you working at my local appliance stores to help me with these decisions. However, I've been to 4, no one seems half as knowledgeable as most of the GWs so I am trying to get all answers I can from those of you on here who really know your stuff.

With that said, I ask you to please, in laymans terms, explain to me what you meant when you said this...

"Use of an oven in the cabinet space would motivate me to consider more complex arrangements to assure air replacement. This would require drawer sealing to the space below as well as another source of replacement air.

I would specifically inquire from Bosch what the maximum intake air temperature can be and design accordingly. I know from Cooktek that for their wok unit the value is 40C. Clearly, ambient temperature will affect how fast the air in a small space is heated to a given temperature, so successful operation under an air conditioning diffuser may lead to different results than operation in an outdoor Texas kitchen."

I am trying hard to educate myself on these topics and I am willing to call Bosch or hound the appliance guy, but I want to really know what I'm talking about when I call. If I asked what you suggested I ask, I'd probably end up sounding like a fool because I do not actually understand what any of that means!

Basically I'm asking, do I or don't I need to account for the extra 2.5" that this flap takes up if I'm installing a wall oven underneath? If that's so, and I want to install the Bosch wall oven underneath, I figure I'll definitly need extra high counters...4" toekick, 28.25" oven, 5.75 cooktop = 38" counters...? thank you for any clarification you can provide!


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RE: Misleading clearance specs below Bosch induction cooktop

I am planning to buy Bosch induction cook top, and install X built in oven under the cook top. Any 'not so expensive' recomendation of built in oven brands that can be installed with the Bosch induction cooktop?


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RE: Misleading clearance specs below Bosch induction cooktop

The hotter the air pulled into the induction unit, the hotter the unit's electronics will run. This can degrade the electronics lifetime, and at some point either cause the unit to fail, or (if properly protected) cause it to shut down temporarily for its own good. The limited time that so-called power boost modes are allowed to run is due to the cooling not being adequate for that level of output to operate continuously.

So, if a particular design is intended to work up to 40 degrees celcius (104 degrees fairenheit) intake air (your unit's specified maximum air temperature may be different), and one exceeds that temperature, one is exceeding the design point of the electronics, which may or may not have any negative effect depending on the design margin.

How might one exceed that air temperature at the unit intake?
a) Operate in a hot climate
b) Provide little air volume below the unit so that the induction unit's exhaust air is pulled into the unit's intake with negligible mixing with other air
c) Another heat source is installed below the induction unit and some heat leaks upward to the air space that the induction unit depends on for cooling.

Ways of ameliorating the air heating include (a) making the volume of air available larger and (b) providing a flowing supply, e.g., providing a small fan that either pulls air from inside the cabinet or pushes fresh air into the cabinet. Small quiet fans such as Rackmountsolutions.net and many others sell might be suitable for this purpose.

In our experience here, questioning the induction unit manufacturer about the suitability of installing another manufacturer's oven below the unit will lead to a response that such an installation is unapproved. This is because the induction manufacturer cannot be responsible for other manufacturer's products, and generally wouldn't have tested all of the possible ovens that might be mounted below their unit.

This is why I thought that the proper question was the intake air temperature limit, from which you and/or your GC could infer whether you needed to do more than nothing.

I recognize the merit of having an oven below the cooktop; for one thing the hood can capture more of the oven effluent when the door is opened. However, this is the worst place to put it from the point of view of the induction unit. So, if I were to install an oven there (in my case I had a double wall oven, and would have to be very tall to use that configuration), I would consider how I could ensure that the air available to the cooktop electronics was cool enough. What I did under my 36-inch cooktop was leave the entire cabinet internally empty and installed wire shelving for pots and pans. This made the entire cavity under the cooktop available for cooling air. Under the Cooktek wok hob, a narrower cabinet is similarly configured.

Instead of raising the counter to a non-standard height, I might decide that I would blow air into that space or pull it out of that space and control the fan power with a temperature sensor suitable for switching the fan power. I consider the dangling metal strip to be a truly minimal bandaid to reduce recirculation of hot air. But all of this depends on what maximum air temperature the unit is designed for and how much heat the oven will induce into the air above itself and below the induction unit.

I cannot remotely engineer a solution. You can follow your design and measure after to determine if there is a problem. If so, you can implement some pre-planned scheme to get some fresh air into that space.

kas


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RE: Misleading clearance specs below Bosch induction cooktop

Kas wins best answer !!!


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RE: Misleading clearance specs below Bosch induction cooktop

Or instal a 'cross fall blower' fan in place of the back wall of the drawer and even go so far as to cut an opening in the back of the cabinet (if it is not tight to the wall, many are pulled forward at least a few inches) would gain at least the cabinet volume of air, and possibly much more (if there is space behind the cabinet).

Having low voltage DC leads running to the moving drawer will be far safer than trying to get 120 VAC in to the drawer.
The link below is to an arbitrary fan, there are multiple others.

A common killer of any electronics is heat.

That is why microwave ovens often have complicated kits to build them in and provide for ventilation.

The rise of electronic controls for gas ovens has led to cooling fans (some louder than others)being required.

'Consumer grade' electronics have classically been rated for 70 C, industrial to 80 C.

One of the weakest parts in electronics remains large aluminum electrolytic capacitors.

They are commonly used to filter power supplies to create stable DC voltages from the AC line.

Solid tantalum capacitors have better temperature performance, and far long er life at a price premium.

There is also a new generation of 'super capacitors' (they can be 1 Farad in a very small package) but they are very low voltage devices.

And when you put them in series to get more voltage, their capacitance tumbles badly (Four 1 farad caps in series to get 20 V results in only 1/4 of a farad).
They also have temperature life cycle problems.

The price point likely will remain aluminum electrolytic for some period.
You can look forward to their failure in about 10 years of 'hours a day' usage.

Here is a link that might be useful: 10 W cross flow blower fan, 24 V


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RE: Misleading clearance specs below Bosch induction cooktop

Facing this very issue this week. Planning on a shallow utensil drawer directly below Bosch 500, with two pot/pan drawers below that. Trying to decide on depth of top drawer right now. 6" OK? I promise not to stuff it with towels. Also, would it be a good idea to vent that drawer into the drawers below (cut slots at the back in the drawer bottom?) to promote additional circulation?


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RE: Misleading clearance specs below Bosch induction cooktop

I would consider using a drawer without a wood bottom, but instead use a wire screen bottom. (A fairly open mesh such as a quarter of an inch would be good.) Maybe Rev-a-Shelf makes something like that, or alternatively, cut out much of the wood bottom and use wire cloth or ravish an old wire rack from something. Slots are also possible, but tend to either be too large to hold smaller items, or provide too little area for passive air motion.

I would also consider using a similar approach on the middle drawer bottom.

kas

This post was edited by kaseki on Tue, Dec 10, 13 at 10:36


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RE: Misleading clearance specs below Bosch induction cooktop

Kaseki, that is an interesting idea! From what I read on the thread above, I wonder if it would be adequate to use the mesh just toward the back of the drawer? (If that's the location of the electronics we are trying to keep cool.)


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RE: Misleading clearance specs below Bosch induction cooktop

I think you would find that all the guts of the cooktop are electronics of various sorts and heating levels, and cooling air has to go into their space, pass by whatever heat transfer devices are present, and exit from their space. If both intake and exhaust are on the same edge, (presumably on different sides) then maybe a more limited mesh area would work.

Basically, though, you want passive air circulation in the cabinet space that supports the active air circulation (fans) within the unit.

I think the saving grace for most people and installations is that very rarely will anyone actually use the 10 kVA that these units can pull with all hobs on full power. Under such use the cooktop could dissipate about a 1 kW into its cooling air. This would heat up most cabinet spaces in a minute or so.

If you contemplate five full-power canning operations at once, open the cabinet drawers/doors slightly to allow air replacement.

kas


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RE: Misleading clearance specs below Bosch induction cooktop

kaaseki: "I think you would find that all the guts of the cooktop are electronics of various sorts and heating levels, and cooling air has to go into their space, pass by whatever heat transfer devices are present, and exit from their space. "

One alternative is to bypass the brands that advertise on the shopping channel and get the low-prestige LG LCE30845 cooktop instead. It is thinner than the Bosch (and all other cooktops), and there is virtually no required minimum clearance above the drawer below. Part of the reason that it works is that the cooling air that is blown across the electronics is not drawn from the same space as the space that the exhaust air from the cooling fan is sent to. The LG exhausts through slots at the back of the cooktop above the counter, so the cooling air that the fan draws from underneath the cooktop is not preheated by the exhaust.

This post was edited by herring_maven on Wed, Dec 11, 13 at 10:54


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RE: Misleading clearance specs below Bosch induction cooktop

Lori, why not just follow what Bosch recommends, as opposed to all these theories? Bosch as in Bosch Siemens is a huge company which makes highly sophisticated, very technical, medical testing equipment such as MRI and ct scan machines. Those machines must be accurate to the teensiest fractions, and they are. If Bosch calls it a heat shield then I believe that's what it is. Are these guys highly trained scientists?

I have my Bosch for over 2.5 years with a wood cabinet drawer and not a smidgen of heat below. Nothing. Granted, I don't cook that much but I would expect there to be some warning about long usage, some kind of disclaimer. These things are built for cooking. Not like those gas stoves where your hand gets hot if you touch the oven door. That, I don't understand.

I, frankly, trust all the major brands of induction, lg being one.--no gas explosions, fumes, fried hands, singed hair. I don't get the warning hoopla in this thread. But, we all believe what we believe.

Lotta pseudo science, fancy words here.


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RE: Misleading clearance specs below Bosch induction cooktop

To be trolled, or not to be trolled -- that is the question. Whether 'tis nobler in the mind to suffer the slings and arrows of outrageous trolling, or to take umbrage against a belief that scientists perform actual engineering.

kas


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RE: Misleading clearance specs below Bosch induction cooktop

Ah yes, well I do know the difference between science and engineering and work in an area highly dependent on both. And yet, with this particular question, what comes to my mind is a colloquial expression familiar to many, whose acronym is "CYA." I think one issue is the designation "heat shield." It sounds at first as if it is protective of the drawer surface or its contents. But if it is about shielding the electronics from overheating, then it is possible, and even likely that there are other ways to do that.

The other ways might even be more effective. Of course it is easier for the company to add on something (that looks like an afterthought) than it is to tell you to make sure your drawers vent. Seems to me you could gain more available air volume with the venting option than the flap-down gizmo. Again, that would depend on leaving airspace in the drawers, not stuffing them with towels.

Long answer to the question of "why not just do what they say?" I'm a questioner. I need to understand the "why" before I follow the rules in general. My husband is much more of an obliger, so I'm sure we'll be having some follow-up discussions on this!

Here is a link that might be useful: questioner, upholder, rebel, or obliger?


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RE: Misleading clearance specs below Bosch induction cooktop

Certain engineers are scientists and many scientists are engineers. I am referring to electrical, aeronautical, biomedical, mechanical engineers like the bright, geeky, neighbor kid at Johns Hopkins or the cousin with NASA.

Lori, absolutely question those issues raised in this thread. It's your stove, your money, your kitchen. Gw has great forums with lots of contributors and many ideas. People here are generous with their time. The spirit is one of helpfulness.

I am not condescending. Kaseki and Weedmeister have been exceedingly helpful and many, many readers have greatly benefitted. I benefitted from Kasekis posts.


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