The manufacturers will specify a certain fan output for safety. The store has a book, they just look it up.

I don't have an encyclopedic memory of model numbers, but a stove with 4 15,000 btu burners, plus an oven, is going to need more than 300. Even if you just have more than a couple going a few times a year, like at holidays, that's all it takes.

You could melt/damage the microwave and have to replace it anyway.

My fan (the one recommended by the manufacturer) turns itself on surprisingly often, even when I'm just using one burner.

You don't have to buy a Viking hood, just one of the right cfm.

It's always a good idea to give the local shop a shot, sometimes prices are just as good and service is usually better. You might be very surprised.

Good luck!

The hood doesn't cool the range - but it does remove heat, smoke, grease and odors from you kitchen. The 300 CFM MW won't be sufficient.

Growlery is correct. Also, an exhaust hood is not really for "cooling" as you said, it's for exhausting the smoke and grease from your cooking. Your over-the-range microwave ("OTR MW") would be inappropriate for your new Viking range. The rule of thumb is 100 cfms for every 1000 btu's. Your range has four 15,000 btu burners = 60,000 total, which means you need a hood that is 600 cfms. I know you said you only use one burner at a time, but with such a nice range, you may find yourself cooking more on it as you come to realize how much easier/better it is.

Furthermore, a microwave hood will not project over the front burners of your Viking range and so, will not capture anything from your front burners. And, as Growlery pointed out, an OTR MW is not meant to be installed over such a powerful range, and the 15,000 btu's will likely, at best, buzz out the MW's electronics due to the heat, and at worst, actually melt the bottom of the MW.

The Viking manual says "it is recommended the unit be set under a powerful, vented exhaust hood of sufficient size and capacity". An OTR MW does not fit that description.

I myself switched out my OTR MW for a hood after I bought a new powerful range, and I would recommend it to everyone. It made a huge difference in exhausting cooking smells and grease. Before I removed my OTR MW (an expensive "top of the line" model), its electronics had buzzed out twice--the MW was still under warranty so the repairs were free, but I had the aggravation of getting it fixed, the downtime, staying home for the repairman, waiting for the part, etc. and then it broke again. It just wasn't meant to be installed over a powerful range. So, I replaced it with a hood. I sold my OTR MW easily on Craig's List. Also, a hood really looks better. Your Viking range is a beauty, costs a lot of money, and really deserves the looks and the fuctionality of a hood.

ok thanks for the advice.