A lot of people here prefer a hood to be larger than the cooktop, and others, like me, think having them both at the same size works fine...Never heard of smaller, but I don't know about code. The idea is having adequate capture area, and a lot of the smells, steam, and any smoke or grease particles are going to get past a narrower hood and travel and hang around your house, settling on your windows, furniture, cabinets, etc.

My 48" Wolf rangetop has 8 burners each at 16,000 BTUs, so a total of 128,000 BTUs...Am I misunderstanding your number? I use a hood with a max of 1200 CFM.

I know this doesn't answer your question about code, but I hope it helps.

I'd love to see that range (from a distance)!! Like, 10 or 15 miles away.

Seriously, I assume your 420K BTU rating is a typo. I believe the 36'' Berta has 6 burners. By your math, each burner is putting out 70K BTU. Man, all those Bluestar guys out there with only 22K BTU are crying :-)

At any rate, outside of the code issue (not being from Cal. I have no ideas there), it comes down to whether you want a hood that looks cute, or one that actually works. The latter in turn is dependent on how you cook. If your kitchen is more about making a style statement, and you use the range mainly to boil water for tea, then any hood, or even no hood, is likely adequate.

If on the other hand, you intend to cook seriously, and particularly if you like to cook on high heat searing, stir frying, deep frying, etc, and like to cook with aromatic foods, then good ventilation is critical.

You are under a common misconception that inadequate capture area can be compensated for by using a larger blower. This is incorrect. It's like trying to clean your dining room floor by vacuuming your kitchen floor. Even if you use a bigger vacuum cleaner, you're still not going to get the dining room floor clean. You can't exhaust what you don't capture first.

Rather than reiterate this topic again, I'd direct you to other threads on this Forum. There is a shockingly large amount of information here on ventilation hoods, a sign that many of us do not have enough gainful work to do. I'll start you with one of my favorite threads, because it contains the definitive discussion by kas of capture area. I've just bumped it up to keep it on the Forum as well.

Here is a link that might be useful: Please help with ventilation

Nope, the Bert has 5 burners, not six. And yes, my math is twisted...hehe..sorry, I added an extra zero just for fun! Actually just under 40k.

I searched for a while but couldn't find exactly the answer, which you have partially supplied. Thanks.

Whether or not it is dictated by code, I can't see how choosing a hood smaller that the cooktop wouldn't be a BAD idea. You couldn't have cabinets protruding over the cooktop (fire hazard) so you wouldn't gain any extra storage space. When you consider that hot air and fumes expand as they rise, you would have a lot of leakage and your kitchen would become coated in grease as time goes on. If you're doing an island installation, the leakage will be amplified because there won't be a wall behind the burners to help dirct the fumes towards the hood.

I have a feeling that if you put aesthetic considerations above technical ones, you will end up with a system that does not measure up to the exhaust capacity you need. There is little doubt that a rangehood smaller than the cooktop will compromise the exhausting capacity of the hood, which should be at least the same width as the cooktop. This is especially true in an island installation compared to installations against the wall, because exhausting from the middle of the room is more demanding.

The other issues you need to be concerned about is the depth of the rangehood's basin and the distance between the rangehood and the cooktop. For the basin idea, think of the hood as an upside down sink -- if the basin is about 6" deep that's good. But some shallow basins do not draw as well, especially in island installations.

Then of course if you want QUIET you should seriously consider a rangehood with the blower installed anywhere but inside the hood, preferably some distance away so you cannot hear the motor. You will, however, still hear the rush of air.

Then you need to make sure that you "match" the cfm capacity of the blower to the size of the duct. If the duct is too big, there is a risk that some of the gook that you want to exhaust will get stuck in the duct because the blower is not strong enough to carry it all. If the duct is too small, you'll lose some of the cfm capacity of the blower and it will make more noise.

Lots to think about. Make sure your installer really knows his stuff. General contractors may not give you the level of expertise you need for a complicated installation. If you are intent on getting a hood that's smaller than the cooktop, you should plan to favor the burners directly under the hood, especially for heavy frying, because the burners that are only partly under the hood will not get exhausted well.

Decisions ... decisions. Good luck

Good advice. I guess it's best to match sizes at the very least, and respect height. I will attempt to also match CFM's to my current ducting, which is already installed, but had been drywalled up by the previous owner (I think it's 6" duct).

thanks again - and looks are still important, as always.