Limited time for comment at the moment, but make-up air is supplied to the house to make up for what goes out the vent hood. Generally it is introduced from a source on the roof, or a wall. It needs to be ducted to the kitchen and dispersed such that it not create a lot of turbulence around the cooktop where undisturbed plume rise is desired. The MUA may need to be heated. If you have combustion appliances in the house that take their air from the house and not from a dedicated MUA system of their own, then a blown MUA system may be required, depending on a bunch of things you can find searching 'MUA' threads here or waiting for me to have time to pontificate more exhaustively.

I’m pretty sure I don’t need to have the air heated as I live in Texas. Do you think it’s best to have the HVAC company out to discuss my options? I have not yet purchased my vent hood.

If they will be involved, then they should be involved early.

It can be very difficult to find anyone who knows anything about makeup air!! My appliance salesperson knew nothing. None of the GC’s I interviewed knew anything about it. Fortunately, Kasecki has fantastic info in his posts (and an amazing amount of patience and passion for educating these forum users about the subject). So I knew I needed to keep searching until I found the right contractor.

My advice for your situation is to find an HVAC contractor who works on new builds of homes that would be likely to have ranges and vent hoods of the size needing makeup air. In many new homes it is required by code, so those contractors are more familiar with it. The remodeler-type GC’s don’t seem to have much experience with it, if any.

Thanks for the info. I’m not using a GC but I have found a local HVAC company that does commercial and residential and it looks like they do commercial kitchens. I’m thinking I will start here.

Okay back with another question. To meet code I am now thinking that the best way to duct my vent is to go along the cabinets on the back wall and into my pantry and out this exterior wall. This will ensure that the vent is 10 feet from out second story windows. Will this be too many turns and decrease efficiency?

Turns and length add pressure loss and thus decrease performance for a given blower. Perhaps not very much, relatively, in view of the baffle pressure loss and the MUA potential pressure loss. Where possible sweeping turns should be made. Aim for 1000 to 2000 ft/min duct velocity, but go for the low end, even under, if the bends have to be sharp. Duct velocity follows from achieved CFM, which should match the flow rate needed for performance. Recursively, one chooses a blower based on the anticipated pressure losses to achieve the performance needed for the hood ventilation system.

Choose your hood to overlap the cooking zone, and taking its entry aperture area, design for 90 CFM per square foot of entry aperture. The blower rated flow then follows from the pressure losses (usually estimated) and the fan curves of candidate blowers.

You haven't addressed combustion appliances taking air from the house interior. MUA must be considered in concert with the ventilation system as it affects the overall pressure loss that the hood blower has to work against. It is also sometimes a bigger "deal" than the hood system due to having to interact with the house architecture in even less convenient ways. And, worst case, it will need a control system more complex than the hood system.