Extractor Fans

Frequently asked questions

What is the difference between an extractor fan and a ventilation fan?

An extractor fan removes air: it pulls moisture, steam, odours or fumes out of a room at source and discharges them outside. "Ventilation fan" is the broader term and also covers fans that supply fresh air in, or move air around a building. In practice most people searching for a ventilation fan for a bathroom, kitchen, toilet or utility room need an extractor fan. Where a whole property needs continuous balanced ventilation, look at MVHR and heat recovery instead.

Which type of extractor fan do I need?

Wall and window fans are axial fans that sit in an outside wall or pane and discharge straight out, the simplest option where the room has an external wall. Ceiling fans sit in the ceiling and duct to an outside wall or roof terminal. Inline duct fans fit in the duct run, usually in a loft or ceiling void, so the motor noise stays out of the room and one fan can serve more than one grille. For commercial buildings, plate and cased axial fans move large volumes over short runs, mixed flow fans handle longer ducting, and roof fans discharge at roof level where there is no suitable wall.

How powerful an extractor fan do I need?

Approved Document F (Building Regulations Part F) sets minimum intermittent extract rates for a dwelling: 15 l/s for a bathroom, 30 l/s for a utility room, 6 l/s for a toilet, and for a kitchen 30 l/s through a cooker hood or 60 l/s for a fan sited elsewhere. Those are delivered rates, not the free-air figure on the box, so allow for the duct: a small fan on a long run with bends can fall well short. For commercial spaces, size from the room volume and the air change rate the application needs, then check the fan against the resistance of the ductwork. If the numbers are marginal, choose the larger fan and turn it down with a speed controller.

Inline or wall mounted extractor fan?

A wall or ceiling fan is cheaper and simpler to fit, and is fine where the room is on an outside wall and the run is short. An inline extractor fan sits in the duct away from the room, which makes it quieter at the grille, lets it handle longer runs, and means one fan can extract from a shower and a bathroom ceiling, or two rooms, at once. Inline fans are the usual choice for wet rooms, en suites without an outside wall, and anywhere noise matters. Mixed flow inline fans hold their airflow better than axial fans as the duct gets longer.

Axial or centrifugal extractor fan?

An axial fan moves a lot of air against little resistance, so it suits a fan straight through a wall or a duct run of a metre or two. A centrifugal fan develops much more pressure, so it keeps extracting through long ducts, several bends, grilles and roof terminals where an axial fan would stall. Mixed flow fans sit between the two and are the common compromise for inline use. If the fan has more than about 3m of ducting or several bends to push through, choose centrifugal or mixed flow over axial.

What extractor fan can I use in a wet room or over a shower?

Check the fan against the bathroom zone it will sit in. Zone 1, directly above a bath or shower up to 2.25m, needs a fan rated at least IPX4, and many manufacturers require a SELV (12V) model with its transformer outside the zones. Zone 2 also needs IPX4. In a wet room the whole floor area can be a wet zone, which is why an inline fan in the ceiling void, with only the grille in the room, is often the neater answer. The IP rating and zone suitability are listed on each product page.

Do all extractor fans need ducting?

No. A wall or window fan discharges straight outside and needs only a short wall sleeve. Ceiling, inline and most commercial fans rely on ducting to reach an outside wall or roof. Keep the run as short and straight as you can, match the duct to the fan spigot rather than reducing it, and insulate any duct that passes through a cold loft so condensation does not run back down into the fan.

Should I choose an extractor fan with a timer or humidistat?

For bathrooms and en suites, yes. A timer keeps the fan running for a set period after the light goes off, usually adjustable up to around 20 to 30 minutes, which clears the steam a shower leaves behind. A humidistat switches the fan on when humidity rises, so it works even when nobody remembers the switch. PIR models start when someone enters. Low-energy continuous running fans are another option and are common in new build and social housing. For commercial fans, control usually comes from a separate speed controller, timer or BMS signal.

Can I fit an extractor fan myself?

Mains extractor fans are hard wired, normally through a fused spur with an isolator, and should be installed by a qualified electrician, especially in a bathroom. Swapping a like-for-like fan on existing wiring and ducting is usually a quick job for an electrician or M&E contractor. A new install takes longer where it needs a core drill through the wall, a new duct route or a new supply. Plug-in fans exist but are not suitable for bathrooms or anywhere near water.

Do you supply extractor fans for trade and project work?

Yes. We supply M&E contractors, electricians, installers, housing providers and facilities teams, and hold stock across the main domestic and commercial ranges for next working day delivery. Send over a schedule, drawing or duty list and we will price the lot, confirm phase, IP rating and controls where they matter, and quote ducting, grilles and controllers alongside. Call 0161 399 3825 or email hello@efans.co.uk.