Thank you! I ordered a Broan as well.It's for a small 20" range but I'm sure the clearance will be the same. I haven't received it yet but I wanted to get started with the rough opening to mount. Thanks again.
You may really want to rethink this. 18-20 inches above the cooktop is very low and may well hit you in the face when cooking. Ours is about 28 inches above the cooktop. It is also a Broan but is the higher volume model (Allure III). Also, we are tall and have our countertops about 2 inches above 'normal' (38 inches). This works great for us but you need to get comfortable with whatever height is good for you.
This site is great! I hope that some day I can give others solutions to their dilemas as you guys have me. Just so you get a better idea of what I have. This is a cottage on a lake and the range is only 20 inches wide and the hood is ductless and only 24inches wide. I have decided to go with the bottom of the hood at about 22 inches above the range