Continuous extract fans (dMEV) in Kent

A dMEV (decentralised mechanical extract ventilation) fan is a low-energy extract fan that runs continuously at a quiet trickle speed and boosts automatically when it senses humidity or a light switch. Because it never fully switches off, moisture is removed steadily instead of building up between showers.

Every job in Kent gets a written quote before it starts and a commissioning record when it finishes. We cover Royal Tunbridge Wells, Folkestone, Margate, Ashford and Canterbury and the villages around them.

dMEV fans in Kent at a glance

Area: Kent
Towns listed: 32, largest Maidstone
Postcode districts: CT5, CT13, CT14, TN13, TN14 and ME1
Price region: South East
Survey: Free survey (UK mainland)

What the work involves

On trickle speed they are barely audible and use very little power; on boost they reach the higher continuous-extract rates in Approved Document F (in England, at least 13 litres a second for a kitchen, 8 for a utility room or bathroom and 6 for a WC). Landlords and housing associations often choose them because tenants cannot switch them off and forget them. Under Approved Document F, continuous mechanical extract systems need commissioning: the airflow on both trickle and boost is measured and recorded.

Commissioned and recorded

Trickle and boost rates measured and written on a commissioning sheet.

Bathroom and en-suite

Through-wall or ceiling fans with humidity-controlled boost.

Kitchen

Higher-rated continuous fans where a ducted hood is not practical.

Guide prices in Kent

Continuous extract fans (dMEV) guide prices in Kent
Work	Guide price
Continuous-running extract fan (dMEV) with humidity boost, flow tested (per fan)	£380–£650 inc VAT
Airflow testing and commissioning sheet for extract fans (up to 6 fans) (per home)	£160–£325 inc VAT

These ranges use our South East rates. Prices include VAT at 20%. You get a fixed written price before any work is booked.

When to get it looked at

You are refurbishing several wet rooms at once
An energy retrofit has made the house more airtight
Building control has asked for continuous extract

Rules in England

English building work follows Approved Document F (2021 edition) for ventilation rates, installation and commissioning. It sets extract rates for kitchens, bathrooms and utilities and asks for mechanical ventilation to be commissioned and recorded.

How the job runs

Survey
Specify
Fit
Commission
Record

Towns we cover in Kent

Questions about continuous extract fans (dMEV) in Kent

Which rules apply to ventilation in Kent?

In England, ventilation in new and altered homes is covered by Approved Document F of the Building Regulations. Landlords also have duties under the Housing Health and Safety Rating System, and workplaces must be ventilated under the Workplace (Health, Safety and Welfare) Regulations 1992.

Can dMEV fans be fitted where a fan already exists?

Usually yes. Most fit the existing hole or duct, which keeps the cost and mess down.

How much does a continuous extract fan cost?

A dMEV fan usually costs £345 to £595 including VAT per room, supplied, fitted and commissioned. Converting several rooms in one visit brings the cost per fan down.

Which towns in Kent do you cover?

All of Kent, including Royal Tunbridge Wells, Folkestone, Margate, Ashford and Canterbury. If your town is not listed, send the postcode and we will confirm.

Are prices different in Kent?

Our guide prices are adjusted by region. In Kent we use South East rates, so continuous-running extract fan (dMEV) with humidity boost, flow tested is typically £380 to £650 inc VAT per fan.