Continuous extract fans (dMEV) in Dorset

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.

Across Dorset the job is priced the same way wherever you are: what is fitted, how long it takes and how far we travel. Towns we cover include Dorchester, Wimborne Minster, Canford Heath, Bournemouth and Poole.

dMEV fans in Dorset at a glance

Area: Dorset
Towns listed: 14, largest Bournemouth
Postcode districts: BH19, BH15, BH17, BH1, BH2 and BH14
Price region: South West
Survey: Free survey (UK mainland)

What continuous extract fans (dMEV) involves

dMEV fans replace ordinary intermittent fans in bathrooms, kitchens, utility rooms and WCs. 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.

Whole-home dMEV upgrade

Every wet room converted at once, with trickle vents checked in the habitable rooms.

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.

Guide prices in Dorset

Continuous extract fans (dMEV) guide prices in Dorset
Work	Guide price
Continuous-running extract fan (dMEV) with humidity boost, flow tested (per fan)	£360–£625 inc VAT
Airflow testing and commissioning sheet for extract fans (up to 6 fans) (per home)	£150–£305 inc VAT

Guide prices using South West rates. Prices include VAT at 20%. A guide price is not a quote: we confirm a fixed price in writing first.

Signs it is time to call us

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. For homes, it sets minimum extract rates such as 15 litres a second for a bathroom and 30 or 60 for a kitchen, and expects mechanical systems to be airflow-tested.

How the job runs

Survey
Specify
Fit
Commission
Record

Towns we cover in Dorset

Questions about continuous extract fans (dMEV) in Dorset

Which rules apply to ventilation in Dorset?

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 Dorset do you cover?

All of Dorset, including Dorchester, Wimborne Minster, Canford Heath, Bournemouth and Poole. If your town is not listed, send the postcode and we will confirm.

Are prices different in Dorset?

Our guide prices are adjusted by region. In Dorset we use South West rates, so continuous-running extract fan (dMEV) with humidity boost, flow tested is typically £360 to £625 inc VAT per fan.