Connecting the AOV system to the fire alarm allows smoke-control equipment to respond without waiting for someone to operate a manual switch. Consequently, the correct vents may begin opening shortly after fire detection.

Nevertheless, connecting the two systems requires more than installing a cable between the panels. The interface must follow the building’s fire strategy, approved cause-and-effect requirements and equipment manufacturers’ instructions.

At

AK Fire Safety
,
we provide professional

AOV installation, commissioning, maintenance and interface testing

for commercial and residential buildings throughout the United Kingdom.

How the Fire Alarm and AOV Connection Works

This sequence may happen within seconds. However, the exact timing and operation depend on the approved design.

What Is an AOV Fire Alarm Interface?

An AOV fire alarm interface is the electrical connection that allows the fire alarm and smoke-control system to exchange signals.

Depending on the system design, the interface may consist of:

• A fire alarm input/output unit
• A monitored relay module
• A volt-free contact
• A dedicated smoke-control interface
• Monitored cabling between control panels
• A networked connection approved by the manufacturers
• Separate signals for different floors or smoke zones
• Fault and status signals returned to another panel

A volt-free contact is commonly used because it allows one system to signal another without directly supplying operating power. Nevertheless, the required interface method must be confirmed by the system designers and manufacturers.

Does the Fire Alarm Panel Power the AOV?

Usually, no. A commercial fire alarm panel generally sends an activation signal but does not directly power roof-vent actuators, smoke dampers or extract fans.

A dedicated AOV or smoke-control panel normally provides:

• Power for actuators and control equipment
• Standby battery support
• Monitoring of AOV circuits
• Control of opening and closing sequences
• Inputs from manual smoke-control switches
• Inputs from fire alarm interfaces
• Fault and status indications
• Environmental ventilation control where applicable

What Is AOV Cause and Effect?

Cause and effect describes what the smoke-control system must do when a particular event occurs.

The cause might be:

• A smoke detector activating on a particular floor
• A manual call point being operated
• A firefighter control switch being used
• A smoke detector activating inside a smoke shaft
• A sprinkler flow switch operating
• A signal from another fire-safety system

The required effect might include:

• Opening the corridor vent on the fire floor
• Opening the smoke-shaft damper on the fire floor
• Closing dampers on unaffected floors
• Opening a vent at the head of the smoke shaft
• Starting a mechanical extract fan
• Opening replacement-air inlets
• Closing environmental ventilation openings
• Sending a status signal to a building-management system

Therefore, the cause-and-effect schedule is one of the most important documents for commissioning and maintaining an integrated fire alarm and AOV system.

Should Every AOV Open When the Fire Alarm Activates?

Not necessarily. Opening every smoke vent at the same time may interfere with the intended airflow and smoke-control strategy.

For example, in a multi-storey smoke-shaft system, the damper on the fire floor may need to open while dampers on unaffected floors remain closed. At the same time, a roof vent or extract fan may operate to remove smoke from the shaft.

In another building, vents at the head of a stairway and within a corridor may need to open together.

Consequently, engineers should never assume that a universal opening sequence is correct. The system must follow the building’s approved fire strategy.

Can One Fire Alarm Panel Control Several AOV Zones?

Yes. An addressable fire alarm panel can provide separate outputs for different floors, zones or smoke-control areas.

For example:

• Fire on floor one activates the floor-one smoke damper.
• Fire on floor two activates the floor-two smoke damper.
• A stair detector activates the stair-head vent.
• A basement detector activates mechanical smoke extract.
• A manual firefighter switch overrides an automatic sequence.

Separate interfaces allow the AOV system to identify which response is required. However, the outputs, cables and inputs must be correctly labelled and documented.

Can an AOV System Have Its Own Smoke Detectors?

Yes. Some AOV systems include dedicated smoke detectors connected directly to the AOV control panel. Other systems receive their activation from the main building fire alarm.

In some installations, both arrangements may be present. For example, an AOV panel may have dedicated detection while also receiving a signal from the fire alarm system.

The correct arrangement depends on:

• The fire strategy
• The type of building
• The smoke-control design
• The selected equipment
• The required level of monitoring
• The approved cause-and-effect sequence

Duplicate detection does not automatically improve a system. Therefore, designers must ensure that different signals do not create conflicting operations.

Can a Conventional Fire Alarm Activate an AOV?

Yes. A conventional fire alarm may activate an AOV system through a suitable relay or interface.

However, a conventional fire alarm generally identifies an activated zone rather than an individual detector. As a result, the available control sequence may be less precise than an addressable system.

For example, all detectors on one zone may produce the same AOV output. Whether this is acceptable depends on the building design and fire strategy.

Can an Addressable Fire Alarm Activate an AOV?

Yes. Addressable systems are commonly used to provide individual smoke-control outputs for specific floors, compartments or areas.

An addressable input/output unit can be programmed to operate when:

• A particular detector activates
• Any detector within a defined zone activates
• Two separate detection signals are received
• A manual call point operates
• A combination of programmed conditions occurs

Nevertheless, programming should match the agreed cause-and-effect schedule. Clear text descriptions should also be entered at the fire alarm panel so that engineers and building staff can identify the function of each interface.

Can the AOV Send a Fault Back to the Fire Alarm?

In some designs, yes. An AOV panel may provide a common fault or status output to the fire alarm panel, building-management system or remote monitoring service.

Returned signals may include:

• Common AOV fault
• Mains power failure
• Battery fault
• Actuator circuit fault
• Vent-open status
• Fire mode active
• Fan-running confirmation
• Damper-position confirmation

However, not every system provides detailed feedback. Some installations may show only a common fault indication. Therefore, the AOV control panel should also be inspected directly when a fault is reported.

What Happens If the Fire Alarm Interface Fails?

If the interface fails, the fire alarm may operate normally while the AOV system receives no activation signal. Alternatively, an interface fault could cause an unwanted activation or prevent the system from resetting.

Common interface problems include:

• Open or short circuit cabling
• A failed input/output module
• Incorrect relay configuration
• Loose terminals
• Incorrect end-of-line monitoring
• Programming changes
• Wrong panel input settings
• Loss of communication
• Unlabelled or disconnected wiring
• Conflicting signals from environmental controls

For this reason, pressing an AOV manual switch alone does not fully test the fire alarm interface. A complete test should prove operation from the initiating fire alarm device through to the final vent, damper or fan.

Fire Alarm and AOV Interface Examples

Does Resetting the Fire Alarm Close the AOV?

It depends on the system design. Some AOV systems remain in fire mode until they are reset locally at the smoke-control panel. Others may follow a defined reset sequence after the fire alarm is reset.

Automatic closing is not always appropriate because:

• Firefighters may still require smoke ventilation.
• The building may still contain smoke.
• A vent may need to be inspected before closing.
• The smoke-control system may require a separate authorised reset.
• Closing equipment immediately could interfere with incident operations.

Therefore, building staff should follow the operating instructions for their particular system.

Can Manual AOV Controls Override the Fire Alarm?

Smoke-control systems often include manual control points for firefighters or authorised personnel.

Depending on the design, a manual control may allow a user to:

• Open a vent
• Close a vent
• Start or stop a fan
• Open or close smoke-shaft dampers
• Reset the smoke-control system
• Select automatic or manual operation

The priority between automatic and manual controls must be clearly defined. Firefighter controls should not be altered, obstructed or used for routine ventilation without authorisation.

Can AOV Systems Connect to Building-Management Systems?

Yes. A smoke-control system may provide signals to a building-management system, commonly called a BMS.

A BMS may display:

• AOV system healthy
• Common fault
• Fire mode active
• Vent position
• Fan status
• Power-supply condition

However, a general building-management system should not replace the dedicated life-safety controls required by the approved smoke-control design.

Furthermore, normal environmental ventilation commands should not prevent the required emergency fire operation.

Can AOVs Be Connected to Sprinkler Systems?

A smoke-control system may receive a signal associated with sprinkler operation where this forms part of the approved fire strategy.

Nevertheless, smoke ventilation and sprinkler systems can affect fire conditions in different ways. Therefore, their interaction must be considered by the fire engineer and system designers.

An engineer should not add a sprinkler interface simply because it appears beneficial. The required sequence should be documented, commissioned and tested.

How Is an AOV Fire Alarm Interface Commissioned?

Commissioning should prove that every required signal produces the correct smoke-control response.

Testing should be coordinated carefully because vents, dampers and fans may move automatically. Building users should be informed before testing begins.

How Often Should the Interface Be Tested?

The interface should be included within routine testing and professional smoke-control maintenance. The precise frequency depends on the system design, manufacturer instructions, fire strategy and applicable guidance.

Importantly, the test should confirm more than a relay clicking or a panel light changing. Engineers should verify that the correct final devices operate.

For example, an effective test may confirm:

• The fire alarm detects the test activation.
• The correct interface changes state.
• The AOV panel receives the input.
• The correct actuator, damper or fan operates.
• The equipment reaches the intended position.
• The correct status is displayed.
• The system resets correctly.

Read our guide to

how often AOV systems should be serviced
.

Who Should Connect an AOV to a Fire Alarm?

The work should be designed, installed, programmed and commissioned by competent engineers who understand both fire alarm and smoke-control systems.

This is important because separate contractors may be responsible for:

• The fire alarm panel
• The AOV control panel
• Mechanical smoke extract
• Smoke-shaft dampers
• Building-management controls
• Electrical power supplies
• The building’s overall fire strategy

Therefore, responsibilities should be agreed before work begins. One contractor activating a relay does not prove that the entire smoke-control sequence works.

What Information Should Be Available?

Engineers maintaining an integrated AOV and fire alarm system should have access to suitable system information.

Relevant documents may include:

• The building fire strategy
• The smoke-control design
• The cause-and-effect schedule
• Fire alarm zone plans
• AOV schematic drawings
• Interface diagrams
• Control-panel manuals
• Commissioning certificates
• Previous maintenance records
• Records of alterations and software changes

Missing or inaccurate information can make fault diagnosis difficult. Therefore, documents should be updated whenever the system is altered.

Common AOV Fire Alarm Interface Faults

What Standards and Regulations Apply?

The exact standards depend on the system type, building and approved fire strategy. Relevant documents may include:

• BS EN 12101 series – smoke and heat control systems and their components.
• BS EN 12101-2 – natural smoke and heat exhaust ventilators.
• BS EN 12101-8 – smoke-control dampers.
• BS EN 12101-10 – power supplies for smoke and heat control systems.
• BS 7346-8 – recommendations for planning, design, installation, commissioning and maintenance of smoke-control systems.
• BS 5839-1 – fire detection and fire alarm systems in non-domestic premises.
• Approved Document B – fire-safety guidance supporting the Building Regulations in England.
• The building fire strategy and equipment manufacturers’ instructions.

Learn more about the

BS EN 12101 smoke and heat control series
.

Current statutory fire-safety guidance is available from the government’s

Approved Document B publication page
.

Who Is Responsible for Maintaining the Connection?

Responsibility generally sits with the building’s responsible person, owner, landlord, employer, managing agent or facilities-management team.

They should ensure that:

• The fire alarm and AOV systems receive planned maintenance.
• The interface is tested from end to end.
• Faults are investigated promptly.
• Alterations are properly designed and documented.
• Cause-and-effect information remains accurate.
• Access to panels and manual controls remains clear.
• Testing and repair records are retained.

Article 17 of the Regulatory Reform (Fire Safety) Order 2005 requires necessary fire-safety facilities, equipment and devices to be suitably maintained and kept in efficient working order.

Read

Article 17 of the Fire Safety Order
.

Frequently Asked Questions

Professional AOV and Fire Alarm Interface Testing

AK Fire Safety provides professional testing, maintenance, commissioning and fault diagnosis for integrated fire alarm and AOV systems.

Our services include:

• Fire alarm and AOV interface testing
• Cause-and-effect testing
• AOV control-panel inspections
• Fire alarm output-module testing
• Smoke detector activation testing
• Roof-vent and window-actuator testing
• Smoke-shaft damper testing
• Mechanical extract-fan testing
• Replacement-air inlet testing
• Manual firefighter control testing
• Battery and power-supply testing
• Interface fault diagnosis
• Panel programming and text reviews
• System recommissioning
• Planned preventative maintenance
• Nationwide multi-site support

Conclusion

AOV systems can be connected to fire alarm systems so that smoke-control equipment operates automatically when a fire is detected.

Usually, the fire alarm sends a signal through an interface module to a dedicated AOV control panel. The AOV panel then operates the required windows, roof vents, smoke-shaft dampers, extract fans or replacement-air inlets.

However, successful integration depends on the correct cause-and-effect design. Not every vent should automatically open during every alarm, particularly in multi-floor smoke-shaft systems.

Most importantly, the entire sequence should be tested from the initiating fire alarm device through to the final smoke-control equipment. This end-to-end approach helps confirm that both systems will work together when needed.