Do the dampers seal in a way that they are waterproof, prevent rain from coming in?

Coolair belt-driven upblast power roof exhaust fans are designed to discharge vertically so that air velocity seals the opening against rain and snow while the unit is in operation. When the fan is switched off, counterbalanced dampers close by gravity to provide a weather-resistant closure. If you have any further questions, please give us a call, thanks!