How are the vents or hatches controlled? You are here: Main Products - Stairwell AOVs How are the vents or hatches controlled? View all FAQsAs well as the AOV window or AOV ventilator you’ll also need a smoke control unit, manual switches and in some cases smoke detectors. Last Updated On12th October 2021 Previous What products can be used for stairwell ventilation? Next Do I need to buy specific products depending on the type of ventilation chosen?