Quick answer
To clear shower steam automatically and stop bathroom mould, a 100 mm extractor that switches itself on with a humidity sensor and extracts at least 15 litres per second is the right choice, and the VENTS Silenta 100 with humidity sensor and timer is our pick: rated 4.3 stars across 4,094 Amazon.co.uk ratings, it moves 78 m³/h (22 l/s) at 26 dBA. If you only need a timer, the Manrose QF100T is a quiet Amazon Best Seller. All of these need an electrician to wire.
A bathroom extractor fan that only runs while the light is on stops too early, and the steam left behind turns to mould on the ceiling. A humidity sensor (a humidistat) keeps the fan running until the air is dry, then switches it off, without anyone remembering to. In England, Approved Document F sets an intermittent extract rate of 15 litres per second for bathrooms. These four 100 mm fans were read on Amazon.co.uk on 15 October 2026.
Our picks
Pick 1 · Best overall with humidity sensor
VENTS Silenta 100 mm Extractor Fan with Humidity Sensor and Timer
Best for: Bathrooms and en-suites where mould returns after showers.
Check price on Amazon.co.ukThis is the fan to buy if mould keeps coming back on the bathroom ceiling. The built-in humidity sensor starts the fan when steam rises and keeps it running until the room is dry, while the timer adds a run-on after the light goes off. At 22 l/s it clears the 15 l/s Building Regulations rate for bathrooms comfortably, and 26 dBA is quiet. It needs a permanent live as well as a switched live, so replacing an older light-switched fan may mean new cable. Have an electrician fit it.
Pros
- Humidity sensor and timer built in
- Meets the 15 l/s bathroom rate with headroom
- Quiet and low power
- 5-year warranty
Cons
- Needs a three-core supply, so older wiring may need upgrading
- Must be fitted by an electrician
Key specs (from the listing)
- Size:
- 100 mm
- Extraction:
- 78 m³/h (22 l/s)
- Noise:
- 26 dBA at 3 m
- Power:
- 5.5 W
- Controls:
- Humidity sensor and timer
- Back-draught shutter:
- Yes
- Wiring:
- Permanent live, switched live and neutral
- Warranty:
- 5 years (listing)
Pick 2 · Quietest timer fan, Amazon Best Seller
Manrose QF100T Quiet Fan 100 mm with Timer
Best for: Replacing a basic fan where a timer run-on is enough.
Check price on Amazon.co.ukManrose's QF100T is a timer fan rather than a humidity-sensing one, but its 1–20 minute run-on does most of the same job if you set it to 15 or 20 minutes. It is quiet at 27 dB(A) and draws only 5 W. Extraction of 21 l/s meets the bathroom rate. Choose it over the VENTS if your bathroom is used at predictable times and you prefer a simpler fan; choose the VENTS if steam lingers or the bathroom is used at night.
Pros
- Very quiet
- Adjustable run-on timer
- Low power
- Slim faceplate
Cons
- No humidity sensor
- Needs a 3 A fused isolator
Key specs (from the listing)
- Size:
- 100 mm
- Extraction:
- 75 m³/h (21 l/s)
- Noise:
- 27 dB(A)
- Power:
- 5 W
- Timer:
- Adjustable 1–20 minutes run-on
- Shutters:
- Backdraught
- Compliance:
- Part F and L (listing)
- Warranty:
- 3 years or 30,000 hours (motor)
Pick 3 · Highest extraction
Envirovent SIL100 Silent-100 Timer Model
Best for: Larger bathrooms and shower rooms with no window.
Check price on Amazon.co.ukAt 26 l/s, the SIL100 moves the most air of the four, which helps in a windowless shower room or a bathroom with a long duct run that saps performance. It is a timer model, so set a long run-on. The listing notes important wiring requirements, so check them with your electrician before ordering. EnviroVent also sells humidistat versions of this fan if you want automatic control.
Pros
- Highest extraction rate on this page
- Quiet Mark award
- IP45 rated
Cons
- No humidity sensor on this timer model
- Spigot projects 80 mm, check the wall depth
Key specs (from the listing)
- Size:
- 100 mm
- Extraction:
- 96 m³/h (26 l/s)
- Noise:
- 26.5 dB(A) at 3 m, Quiet Mark 2013
- Power:
- 8 W
- Protection:
- IP45
- Controls:
- Adjustable timer
- Faceplate:
- 158 × 158 mm
Pick 4 · Add a humidity sensor later, Amazon Best Seller
Airflow iCON 15 Bathroom Extractor Fan
Best for: Draughty bathrooms and anyone who wants to upgrade controls later.
Check price on Amazon.co.ukThe iCON 15 runs from a light switch out of the box, and you can snap in a humidity sensor, timer, motion sensor or pull cord module later without replacing the fan. Its iris shutter closes like a camera lens when the fan stops, which fixes the cold draught that louvred fans let in. At 19 l/s it meets the 15 l/s bathroom rate but has the least headroom here.
Pros
- Iris shutter stops cold draughts and outside noise
- Snap-in humidity module can be added later
- Round design is easy to fit in tiles
Cons
- Humidity sensor module is a separate purchase
- Lowest airflow of the four
Key specs (from the listing)
- Size:
- 100 mm duct, 110 mm core drill
- Extraction:
- 19 l/s (69 m³/h)
- Noise:
- 28.8 dB at 3 m
- Power:
- 9.4 W
- Shutter:
- Iris shutter seals when off
- Controls:
- Optional modules: timer, humidity sensor, PIR, pull cord
- Warranty:
- 3 years
Buying guide
Humidity sensor, timer or both?
A timer keeps the fan running for a set time after the light goes off, which works if showers are short and regular. A humidity sensor (humidistat) watches the air and runs the fan until the steam has cleared, however long that takes, then stops. For bathrooms where mould keeps returning, a humidity sensor is the better choice, and a fan with both gives the most control. Fans that run only while the light is on rarely extract long enough.
Extraction rate and noise
Approved Document F in England sets 15 litres per second as the intermittent extract rate for a bathroom. Every fan here meets that, but long duct runs, bends and flexible ducting reduce real-world airflow, so a fan with some headroom, such as 20 l/s or more, helps. Noise figures quoted at 3 metres under 30 dB are quiet enough that people leave the fan running rather than switching it off.
Wiring and installation
Bathroom extractor fans are fixed electrical installations and should be fitted by a qualified electrician who can certify the work. Humidity-sensor and timer fans need a permanent live as well as a switched live, plus a fused isolator switch outside the bathroom zones. The fan's IP rating must suit its position relative to the bath or shower. Duct the fan to the outside, never into the loft.
Who should not rely on a fan alone
An extractor clears steam from the bathroom, not damp from the rest of the house. If mould is in bedrooms and on outside walls throughout the home, you also need wider ventilation or a dehumidifier. If the bathroom ceiling stays damp with the fan running, check that the duct actually reaches the outside and is not blocked, and look for a leak from the bath, shower tray or a pipe in the floor above.
Questions people ask
Are humidity sensor extractor fans worth it?
Yes, in bathrooms that get mould. A humidity sensor runs the fan until the steam has gone, rather than stopping when the light goes off. That keeps the ceiling and grout dry without anyone needing to remember.
What extraction rate do I need for a bathroom?
At least 15 litres per second, the intermittent rate set by Approved Document F in England. Choose a fan with some headroom above that, around 20 l/s, if the duct run is long or has bends.
Can I fit a bathroom extractor fan myself?
It is safest to use a qualified electrician. Bathroom electrics carry extra rules about zones and IP ratings, and humidity-sensor fans need a permanent live as well as a switched live. A registered electrician can certify the work.
How long should a bathroom fan run after a shower?
About 15 to 20 minutes after a shower ends, or until the mirror clears. A humidity sensor decides this automatically. On a timer fan, set the run-on to the longest setting.
Why does my bathroom still get mould with an extractor fan?
Usually because the fan runs too briefly, is too weak for the room or its duct is blocked or vents into the loft. Check that air is pulled strongly at the grille, extend the run-on time or fit a humidity-sensing fan, and wipe down the shower after use.