Continuous extract fans (dMEV) in Surrey

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 Surrey 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 Woking, Guildford, Esher, Redhill and Staines.

dMEV fans in Surrey at a glance

Area: Surrey
Towns listed: 35, largest Woking
Postcode districts: KT13, KT15, KT7, KT8, KT8 and KT12
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.

Kitchen

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

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.

Guide prices in Surrey

Continuous extract fans (dMEV) guide prices in Surrey
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

An energy retrofit has made the house more airtight
Building control has asked for continuous extract
Occupants switch fans off because of noise

Rules in England

In England, ventilation is covered by Part F of the Building Regulations and its guidance, Approved Document F (2021 edition). 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 Surrey

Questions about continuous extract fans (dMEV) in Surrey

Is the survey free in Surrey?

For new installations on the UK mainland, yes. The survey is free and the quote that follows is fixed and in writing. Servicing, testing and repair visits are charged, and we confirm the cost before booking.

What is the difference between dMEV and MEV?

dMEV uses one small fan in each wet room. MEV uses one central fan, usually in the loft, ducted to all the wet rooms. Both run continuously.

Do I still need trickle vents?

Yes. With continuous extract, Approved Document F still expects background ventilators in habitable rooms so replacement air can get in.

Which rules apply to ventilation in Surrey?

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.

Which towns in Surrey do you cover?

All of Surrey, including Woking, Guildford, Esher, Redhill and Staines. If your town is not listed, send the postcode and we will confirm.