What is an Extractor Fan?

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

  1. Intermittent Extract Fans – Operate only when needed (e.g., during cooking or showering).
  2. 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

  1. Mechanical Ventilation with Heat Recovery (MVHR) – Extracts stale air while recovering heat to warm incoming fresh air.
  2. Background Ventilators – Passive vents (e.g., trickle vents) providing whole-dwelling airflow.
  3. Purge Ventilation – Rapid air exchange via windows (min. 1/20th floor area for hinged windows).
  4. Air Permeability – Measure of airtightness (≤3 m³/(h·m²) @50Pa for highly airtight dwellings).
  5. Part L (Conservation of Fuel and Power) – Overlaps with ventilation efficiency requirements.