Stairwell AOV Kits
A stairwell ventilator / stairwell AOV is an automatic opening ventilator (AOV) that provides at least 1.0m² of free area when open. The installation is always located at the highest point in an evacuation stairwell and can take a number of forms.
The stairwell ventilator usually serves one of two purposes; removing any smoke that gets in the stairwell of small buildings or more commonly, it provides replacement air for a lobby smoke extract system in large buildings.
If a fire breaks out, resulting in smoke getting into communal lobbies or corridors adjoining the escape stairwell, there needs to be some means of removing smoke from these areas. Solutions to this include the installation of an automatic opening ventilator (AOV) or a natural / mechanical smoke shaft system.
Compliance with Building Regulations
Stairwell ventilators are commonly used in the stairwells of flats where protecting the common escape routes is of paramount importance. The exact requirements for ventilating such buildings are stipulated in Approved Document B of the Building Regulations 2019.
Paragraph 3.49 of Approved Document B details the requirements for smoke vents to stairwells as follows: In small single stair buildings, a single openable vent with a free area of at least 1m² at the head of the stair, operable remotely at the fire and rescue service access level is required.
In taller buildings, the following applies:
A vent to the outside with a minimum free area of 1m² should be provided from the top storey of the stair. In single stair buildings, smoke vents on the storey where the fire is initiated, and the vent at the head of the stair, should be activated by smoke detectors in the common parts.
In buildings with more than one stair, smoke vents may be activated manually. The control system should open the vent at the head of the stair before, or at the same time as, the vent on the storey where the fire is located. Smoke detection is not required for ventilation purposes in this instance.
In practice, it is customary to provide a manual switch for fire and rescue service use at the access level within the stairwell for all stairwell smoke vents.  Smoke vents must comply with BS EN 12101-2:2017 – Smoke and heat control systems. Natural smoke and heat exhaust ventilators; and be CE/CA marked.
Stairwell vents control requirements
Stairwell Vents must be provided with a standby power source, CE marked to BS EN 12101-10:2005 – Smoke and heat control systems. Power supplies. This will usually take the form of a battery backup supply housed within a control unit. Additionally, control panels should be certified to ISO 21927-9:2012 – Smoke and heat control systems. Specification for control equipment.
In buildings with lobby AOV systems, the stairwell vent should be activated automatically when a lobby ventilator is opened so controls will be networked.
The EV-301 control panel that features in the AOV kit range meets all of the above standards and is designed to be networked to give the correct control sequence. There are many additional features that can be added to the panel including thermostatic control and wind and rain-sensing control for summer ventilation.
Stairwell vent AOV Kit options
There are several models available within the AOV kit range including glazed units for internal daylighting and aluminium vents for thermal insulation. We do not recommend single skin aluminium ventilators as these are likely to result in condensation inside the stairwell.
AOV Kit A includes the following equipment:
- 1 x Modular Control Panel
- 1 x 1.0m² Louvred Window
- 2 x Fireman’s Override Switch
AOV Kit B includes the following equipment:
- 1 x Modular Control Panel
- 1 x 1.0m² Louvre Vent
- 2 x Fireman’s Override Switch
AOV Kit C includes the following equipment:
- 1 x Modular Control Panel
- 1 x 1.0m² Hatch Vent
- 2 x Fireman’s Override Switch
AOV Kit H includes the following equipment:
- 1 x Modular Control Panel
- 1 x 1.0m² Casement Window
- 2 x Fireman’s Override Switch
