When it comes to finding the right size hood for your 36 inch cooktop, there are a few things you need to take into account. The first is the width of your cooktop. The second is the height of your cooktop, and the third is the type of ventilation system you have in place.
The width of your cooktop is going to be one of the biggest factors in determining what size hood you need. If your cooktop is less than 30 inches wide, then you can probably get away with a smaller hood. But if it's any wider than that, then you're going to need a larger hood that can accommodate the increased width.
The height of your cooktop also plays a role in determining the size hood you need. If your cooktop is taller than usual, then you might need a taller hood so that it can properly ventilate all of the smoke and steam that will be produced during cooking.
Finally, you also need to take into account the type of ventilation system you have in place. If you don't have an exhaust fan or range hood installed above your cooktop, then chances are good that you'll need a larger hood so that it can properly ventilate all of the smoke and steam produced during cooking.