Im not sure why miele would specify 12" but the general rule of thumb is to oversize by 6". So basically make the hood 42" instead of 36". You can use a 36" hood over a 36" range with no code issues, but it won't be able to capture as much of the air.

Best makes a very nice hood. They do not offer an infinite speed controller at this time. Their quietest line of inserts are the CP55 units which has the IQ designation. These will all have LED lighting and their DC blower system which is quieter than standard blowers.

Keep in mind that you most likely will need a makeup air unit and be sure to plan for that too.

I am curious where you found the 12" as on miele's website they pair the 36" range anf 36" hood

I looked at the install directions and it says to add 6" on each side. It is interesting that they pair it differently on the site versus in the install directions, but I do see that. BTW, does anyone know anything about the Miele Inserts? It looks pretty nice and has an external blower you can hook up. I read somewhere in here that external blowers are not recommended for runs under 8', what is the reasoning for this? Is it just that you won't get the noise cancellation? And is there a reference where I can find how loud each blower is so I can look for a quiet one?

Final question :). How much should I budget for a make up air unit? I would have to think it is less than the hood?

Thanks,

Austin

Heh! Most of the answers to your questions are in messages on this site, but you would have to commit a significant amount of time to come up to speed on the subjects of your questions.

On the topic of over-sized hoods: No, the physics is the same, but the effectiveness of capture and containment is not the same. Cooking effluent plumes expand as they rise, hence to remove all of the greasy vapor requires a hood that overlaps the pan bases that you might use by the amount of expansion (ten degrees half angle, say) at the hood height you are using. Larger overlaps help when there are cross drafts or other air disturbances and you have low tolerance for escaped grease and odor.

On the topic of duct length: While there is some attenuation of blower fan blade turbulence noise with duct length, there is also an increase in duct non-laminar flow turbulence noise. To remove a reasonable amount of blade and up-stream duct noise an in-line silencer is necessary. Otherwise, an external blower can terminate a duct whether one-foot in length or 100-feet in length. Obviously, the latter will have higher pressure loss. Cost wise, the external blower cost (includes a housing) should be compared with the internal blower cost plus a duct cap that keeps out the weather.

On the topic of MUA cost: This depends on what the MUA complexity has to be to deal with replacement air demands in the context of your house design, number of exhaust fans, fireplaces, combustion appliances, etc., or merely complying with minimal code requirements. This is a very complex topic difficult to address in a brief comment. There are circumstances where the cost can be low.

kas

MUA is a whole house calculation-yes math -which no one wants do....which is why you need to know what is involved as most places just want to sell you a hood and install it next week. Local codes determine CFM max, most stores won't tell you the local rule or let you know that you are exceeding it and need to do the MUA calculation to see if you need to install a system. Instead, they let you figure out you need better airflow when embers are being sucked out of your fireplace across your kitchen floor....at which point you will panic and turn the hood off and they will sell you an MUA for a lot of money rather than the $300-$500 (installation extra) I've seen mentioned. Again another reason to understand more about MUA and there are tons of threads on GW about this.

6" on each side would be preferred, if you run the burners at full the grease and heat should be sucked up without impacting the surrounding cabinets. Less than 6" involves more yuk and potential for damage to the cabinets. The usual advice is 3" per side....so 6" is a really nice safety margin for your $$$ cabinets.