Automatic Opening Vent (AOV) FAQ’s

Smoke and Heat Vents are installed in buildings as an active fire protection measure. They are openings in the roof that are designed to open and vent the heat and smoke developed by a fire inside of a building. They are sometimes known as “gravity vents” as they are opened  by the action of buoyancy. AOV’s are designed to open automatically when the system is triggered, usually by a Smoke Detector or Manually triggered when a person sounds the alarm. 

AOV is simply an abbreviation for “Automatic Opening Vent”. An AOV system is a control system designed to vent air or smoke for use in natural & smoke ventilation.

Smoke Vents usually are supplied in 2 systems for AOV control; AOV single zone or AOV multi zone. Each panel can be triggered by Smoke Detectors or a Manual Call Point. This will then activate actuators to open or close.

At Circle Fire & Electrical we offer Smoke Vents from the UK’s leading manufacturers and all of our Smoke Vents are available with Smoke Detectors, Fire Alarm Control Panels, Manual Call Points and Firemans Priority Switch which may all be needed for the installation.

Smoke Vents and AOV’s have their own set of Building Regulations, so these must be adhered to, to avoid any issues.

Basic Requirements for installing an AOV Smoke Vent

Only BS EN12101 certified and CE marked smoke vents (AOVs) comply with the UK building regulations. When choosing an AOV, make sure to check for the CE marking.

Smoke Control and Ventilation – Approved Document F

• This document describes the requirements of the specific ventilation methods used in specific types of buildings.
• What type of ventilation is deemed adequate depends on
  • the type of building,
  • its purpose,
  • the number of floors,
  • how you can reach the upper floors (elevators/stairways etc)
  • the number of occupants that are regularly within the building.

The main aim of smoke ventilation and control is to avoid the build-up of smoke within the building.

Having the correct number of AOVs in place (mainly above the staircases in multi-storey buildings) is a significant factor in achieving this outcome.

Conservation of Fuel and Power – Approved Document L

• This document contains information on how much heat insulation should be present within the roof opening.
• Smoke Vents especially should have the correct design for trapping heat and preventing it from escaping through the roof.
• The unit of measurement which is given to measure heat loss is called the U Value, and the lower the U Value means the less amount of heat which is being lost.
• In order to meet the regulations, any Smoke Vent or Roof Hatch must have a U-Value of 3.5 W/m2.K or lower.
  BS EN12101 and CE Marking

Any smoke vent (AOV) which is chosen, purchased and installed in the UK needs to meet with the European Standards as set in BS EN12101 and must have the CE Marking.

• BS EN12101 stipulates that the vent must have an additional source of energy in case the electricity fails.
• Even with a heavy load of snow on top of the vent, it still needs to be able to open far enough to allow a large enough airflow to be able to extract the smoke. The CE Mark certification indicates that the AOV has passed all the tests required.

Fire Safety – Approved Document B

As a rule of thumb, the very basic requirements for a residential building are as follows:

1: Installation of fire detection and fire alarm systems

• In the event that a fire does occur, it is of the utmost importance that there is an immediate detection and alarm system in place to let you know there is a problem.
• The quicker that immediate action is taken, the better chance there is to prevent further damage or even tragic consequences

2: Means of escape

• There should be more than one escape route, ultimately to destinations in the open air.
• It is recognised that, it is not always possible to have more than one escape route or to have a safe destination in open clear air.
• Therefore in certain situations, it is acceptable to have a single escape route leading to a place of relative safety.

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