An extractor fan is a mechanical ventilation device designed to remove stale, moist, or polluted air from an enclosed space (e.g., kitchens, bathrooms, utility rooms) to the outside. It is a critical component in maintaining indoor air quality (IAQ) and preventing condensation, mould growth, and pollutant buildup.
Types of Extractor Fans #
- Intermittent Extract Fans – Operate only when needed (e.g., during cooking or showering).
- Continuous Extract Fans – Run constantly at a low rate, with boost functionality when required.
Key Requirements (UK Building Regulations, Approved Document F 2021) #
Extractor fans must comply with Part F (Ventilation) of the Building Regulations. Key provisions include:
| Room Type | Intermittent Extract Rate (l/s) | Continuous Extract Rate (l/s) |
|---|---|---|
| Kitchen (with cooker hood extracting externally) | 30 | 13 (high rate) |
| Kitchen (no cooker hood or recirculating hood) | 60 | 13 (high rate) |
| Utility Room | 30 | 8 (high rate) |
| Bathroom | 15 | 8 (high rate) |
| Sanitary Accommodation (WC) | 6 (or purge ventilation) | 6 |
(Source: Approved Document F, Volume 1: Dwellings, Tables 1.1 & 1.2, 2021 edition)
Installation & Compliance #
- Location: Must be installed as high as practicable (max. 400mm below ceiling).
- Controls: Manual (user-operated) or automatic (humidity/pollutant sensors).
- Noise Limits: ≤30 dB(A) in bedrooms, ≤45 dB(A) in kitchens/bathrooms.
- Ducting: Rigid ducts preferred; flexible ducts limited to 1.5m for final connections.
Related Terms #
- Mechanical Ventilation with Heat Recovery (MVHR) – Extracts stale air while recovering heat to warm incoming fresh air.
- Background Ventilators – Passive vents (e.g., trickle vents) providing whole-dwelling airflow.
- Purge Ventilation – Rapid air exchange via windows (min. 1/20th floor area for hinged windows).
- Air Permeability – Measure of airtightness (≤3 m³/(h·m²) @50Pa for highly airtight dwellings).
- Part L (Conservation of Fuel and Power) – Overlaps with ventilation efficiency requirements.