It's not critical, but a double-deck oven and convection oven put out a decent amount of steam and heat, which is best funneled out of the room. If you use a fryer and produce smoke (not steam), then you need a Type I hood, which is far more expensive and complicated. That's because it needs fire-suppression. Luckily, this is a Type II hood.
Actually the hood requirements have to do with what you stated but also open flames or gas cooking.
True!
You need a hood even if you don’t have a fryer?
It's not critical, but a double-deck oven and convection oven put out a decent amount of steam and heat, which is best funneled out of the room. If you use a fryer and produce smoke (not steam), then you need a Type I hood, which is far more expensive and complicated. That's because it needs fire-suppression. Luckily, this is a Type II hood.