AOV and Smoke Vent Servicing: Keeping the Forgotten System Alive
By the DC Fire & Security engineering team — installing and maintaining fire and security systems since 2010. Updated June 2026.
Quick answer
AOV systems — the smoke vents keeping escape routes tenable in blocks — need professional servicing at least twice yearly (£300–£600/year typical blocks) plus periodic function checks by building management. They fail silently (actuators seize, batteries age, control panels fault unnoticed) and their failure converts protected stairs into chimneys. Responsibility sits squarely with the responsible person.
What AOV servicing actually covers
- Function testing: vents opened/closed via control panel and detection triggers — actuator travel, seals, weather performance (the corridor-detection purpose the communal alarms guide explains finally exercised)
- Control systems: panel health, battery standby (the backup that ages like every battery in these guides — load-tested, replaced ~4-yearly), fault log review
- Detection interfaces: the corridor/lobby heads triggering vents (often the building's least-understood detectors — serviced within or alongside, coordination per system design)
- Manual controls: fire service override switches (ground-floor panels) tested and labelled — brigade-facing kit that must work for visitors under stress
- Mechanical estate: vent hardware (chains/rams/hinges), rooflight seals, louvre operation — weathered moving parts on roofs nobody visits
- Records: service certificates, fault/remediation logs into the block's compliance file (the FRA's smoke-control line answered with paper)
Why AOVs are the forgotten system (and what that costs)
The neglect pattern our takeover surveys document: blocks know their alarms and extinguishers, while the AOV — installed at construction, triggered never, serviced sporadically — sits with seized actuators and dead standby batteries until an FRA asks 'when was this last tested?' and silence answers. The stakes mismatch the neglect: smoke control protects the single escape route most blocks possess (stairs filling with smoke being the kill mechanism stay-put architecture exists to prevent — the strategy guides' physics), fire crews depend on override controls functioning, and enforcement treats failed smoke control as the serious finding it is. The 2022 regulations' monthly-check expectations for relevant buildings (lifts/key firefighting equipment over 18m) and FRA scrutiny generally have begun correcting the amnesia — service contracts are how it sticks.
Costs, checks and responsibility
Budget lines for agents/RMCs: twice-yearly professional servicing £300–£600/year typical single-core blocks (multi-core/complex systems scaling), remediation from findings (actuators £150–£400 replaced, batteries, control repairs — the first-service discovery economics every neglected system exhibits), and the in-house layer (periodic function checks by site staff where systems/training permit — weekly-to-monthly per risk profile and guidance; we train and template per the clipboard-empowerment habit). Responsibility clarity: smoke control is the responsible person's general fire precaution — service contracts in the block's name, records in the block's file, no orphan systems (the 'who maintains the AOV?' question from our flats guide answered: contractually, you — practically, us). Bundling continues its march: AOV + detection + emergency lighting + doors on one block calendar (the compliance packages architecture for residential) — single rhythm, single file, no forgotten systems by design.
Frequently Asked Questions
How often must AOVs be serviced?
Our AOV opens when it rains — fault or feature?
Who can service AOV systems?
What does AOV failure mean for our FRA?
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