Noisy exhaust fan: the number one causes (and how to fix them)

Noisy exhaust fan: the number one causes (and how to fix them)

If your extractor fan is making a lot of noise, in most cases the problem isn't a "weak motor"—it's the installation/ductwork : wrong diameter, too many bends, and a long pipe.

1) Never "strangle" the exhaust fan: smaller diameter = more noise.

Reducing the duct diameter increases turbulence and puts strain on the motor, which increases noise and reduces performance .

Typical example: extractor fan designed for 150 mm and installed with 120 mm → “choking”: more noise, less extraction.

2) Short duct with few bends (this changes everything)

Installation manuals recommend:

  • shortest possible route

  • avoid unnecessary turns

  • Maintain proper conduct (minimum recommended in many cases: 120 mm)

3) Better duct material for less noise.

Faber itself recommends smooth metal ducting and maintaining the same diameter throughout the entire length; smaller ducts worsen suction and make the exhaust fan noisier.

4) Correct height helps (and prevents vapor "leakage")

A manufacturer's reference indicates:

  • gas: minimum 75 cm

  • electric/induction: minimum 65 cm
    Wrong height → you need more power → more dB.

5) “Boost” is not meant to be left on all the time (and that’s normal)

The EU requires that exhaust fans with a maximum flow rate above 650 m³/h automatically revert to ≤650 m³/h after a limit (temporary boost).
✅ This is great for explaining to the customer "why the turbo kicks back in automatically".

FAQ

Why did the exhaust fan become noisier after installation?
Typically, this is due to reduced diameter, longer tube length, and numerous bends—this increases turbulence and dB.

What is the best type of exhaust duct?
Smooth metal duct, constant diameter and short run (typical recommendation from manufacturer manuals and FAQs).

The Boost power supply shuts off by itself: is this a defect?
No. It is an EU requirement when the exhaust fan has an airflow rate >650 m³/h.