Continuous extract fans (dMEV) in Bedfordshire

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 Bedfordshire 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 Leighton Buzzard, Ampthill, Kempston, Biggleswade and Flitwick.

dMEV fans in Bedfordshire at a glance

Area: Bedfordshire
Towns listed: 10, largest Luton
Postcode districts: MK45, SG15, SG16, SG18, SG19 and LU1
Price region: East of England
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 Bedfordshire

Continuous extract fans (dMEV) guide prices in Bedfordshire
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–£310 inc VAT

These ranges use our East of England 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 Bedfordshire

Questions about continuous extract fans (dMEV) in Bedfordshire

Which rules apply to ventilation in Bedfordshire?

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.

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.

Which towns in Bedfordshire do you cover?

All of Bedfordshire, including Leighton Buzzard, Ampthill, Kempston, Biggleswade and Flitwick. If your town is not listed, send the postcode and we will confirm.

Are prices different in Bedfordshire?

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