Continuous extract fans (dMEV) in Derbyshire

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 Derbyshire 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 Heanor, Derby, Chesterfield, Long Eaton and Ilkeston.

dMEV fans in Derbyshire at a glance

Area: Derbyshire
Towns listed: 21, largest Derby
Postcode districts: DE56, DE5, DE75, DE5, DE55 and S8
Price region: East Midlands
Survey: Free survey (UK mainland)

What the work involves

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. We do that as part of the job, so you have a record for building control, a landlord file or a future buyer.

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 Derbyshire

Continuous extract fans (dMEV) guide prices in Derbyshire
Work	Guide price
Continuous-running extract fan (dMEV) with humidity boost, flow tested (per fan)	£340–£575 inc VAT
Airflow testing and commissioning sheet for extract fans (up to 6 fans) (per home)	£140–£290 inc VAT

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

Common reasons people call

Building control has asked for continuous extract
Occupants switch fans off because of noise
Mould keeps returning in a bathroom with a working fan

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 Derbyshire

Questions about continuous extract fans (dMEV) in Derbyshire

Are prices different in Derbyshire?

Our guide prices are adjusted by region. In Derbyshire we use East Midlands rates, so continuous-running extract fan (dMEV) with humidity boost, flow tested is typically £340 to £575 inc VAT per fan.

Is it expensive to run a fan all the time?

No. dMEV fans use very little electricity on trickle speed, typically a few watts, so running costs are low compared with the condensation and mould they prevent.

Are continuous fans noisy?

A correctly sized dMEV fan is very quiet on trickle; most people only notice it on boost. Noise usually means the wrong fan or a poor duct.

Is the survey free in Derbyshire?

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.

Which rules apply to ventilation in Derbyshire?

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.