For reduced noise the blower can be moved to a remote location in the vent ducting.

For even more reduced noise, a silencer (e.g., Fantech LD-[duct diameter]) can be installed between blower and hood.

Please read a significant portion of the myriad hood and make-up air (MUA) threads on this forum. Here are a few quasi FAQ links that may be of interest.

https://www.houzz.com/discussions/2328297/range-hood-faq-personal-notes-updated-10-31-2007#n=20

https://www.houzz.com/discussions/5161173/hood-faq#n=101

https://www.houzz.com/discussions/6099827/exhaust-hood-faq-ii#n=113

https://www.houzz.com/discussions/6040827/range-hood-noise-project

And I recommend first reading the 'Greenheck Guide' for insight. The first dozen pages or so should be sufficient.

https://www.tagengineering.ca/wp-content/uploads/2015/02/KVSApplDesign_catalog.pdf

When you are ready, information-wise, we will be happy to go over performance requirements for your specific needs in the context of your residence's architecture.

While at first glance, the advice appears to be "first get a college degree in mechanical engineering," I would strongly recommend doing some of this homework. Understanding why you want a hood, how to plan what you need, and how to choose and install the system is crucial to getting the best performance. Without it, you're at the mercy of your appliance sales person and wil end up with a Vent a Hood :-)

Ideally I'd like a quieter fan

A very important factor of the noise level of the hood exhaust is the size of the duct that goes from the hood to the outside. If the duct is too small, you could have the quietest hood made on earth, and it will still be noisy. Your duct to the outside should be 8" diameter.

I've read it should be a couple inches larger than cooktop so i was thinking 40"

The ideal width is 6" wider than your cooktop, so ideally your hood should be 42" wide. However, if you have upper cabinets on either side of the hood, that will help corral the cooking effluent so a 36" hood would be fine in that case.

But, I think it is more important that your hood be deep enough front-to-back. So many "custom" hoods are very shallow, like 18-19". Meanwhile, your cooktop is at least 24" front-to-back. That means that the smoke and grease from your front burners will land onto the front of the hood, not up the hood's exhaust. Ask your hood maker how deep are they making the hood - insist on 24" front-to-back. They may balk because it's more work for them. And no, you won't hit your head.

Most people get hoods the size of their cooktop and do just fine. Bigger is better but especially with a 36" cooktop, you can cook the stinky, greasy, and steamy stuff in the middle.

The hood maker is my husband, haha. I did just see how the shallow vents are not great as the hotter/more powerful burners tend to be in front (from the Yale appliance YouTube I think)

Overlap determines capture; flow rate determines containment; lack of greasy wet effluent throughout the house determines contentment.

Clinresga are you saying there is something wrong with VentAHood?

If you have tall walls, lots of space, and want to install your cooktop higher than normal (especially if it's over an island), go big. For example, a 48" hood over 36" cooktop could work great with no head bumping or line of sight hindrance.

@clinresga may not have seen your comment, Maggie. It is generally good to tag the name with @ to get a notice out to them.

Years ago, clinresga compared a conventional hood in one residence to a VaH "Magic Lung" hood in another residence, and found the VaH much noisier. He also observed more difficulty cleaning the VaH. The cleaning contention became somewhat contentious on this forum, as different members cleaning different versions differed.

There have been changes over the years, including VaH expanding their hood line to more conventional hoods. The squirrel cage grease extraction and air moving blower design of the Magic Lung configuration has less tolerance for added hood system pressure losses than the radial or axial fans used in more conventional hood systems. None of this rises to "something wrong" in my opinion, but I would agree with 'something less optimal.' :)

FYI if you’re on an iPad you can’t tag anyone ever on this site.

36 should be fine for an induction cooktop. If it were gas I'd say it definitely needs to be larger

Thanks to kas for speaking up for me--as usual, his comments are on the money. I find our VAH is disappointing--mediocre exhaust performance and loud enough to be a constant annoyance. For what they charge, you could do better. In particular if you are able to mount a remote blower, say in attic or on roof, the noise level plummets, particularly if a silencer is used. It's a radically different experience. Plus a well designed hood liner in combination with a properly sized remote blower will far outperform a VAH, oftent at a surprisingly small upcharge vs off the shelf VAH. The cleaning thing is personal preference but I hate cleaning my VAH.