Continuous extract fans (dMEV) in Oxfordshire

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.

We carry out continuous extract fans (dMEV) across Oxfordshire, including Banbury, Abingdon, Bicester, Didcot and Witney. Prices use South East rates. The survey is free for new installations on the UK mainland, and the quote that follows is fixed and in writing.

dMEV fans in Oxfordshire at a glance

Area: Oxfordshire
Towns listed: 13, largest Oxford
Postcode districts: OX6, OX25, OX10, OX11, OX8 and OX28
Price region: South East
Survey: Free survey (UK mainland)

What continuous extract fans (dMEV) 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.

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.

Whole-home dMEV upgrade

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

Guide prices in Oxfordshire

Continuous extract fans (dMEV) guide prices in Oxfordshire
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

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

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. 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 Oxfordshire

Questions about continuous extract fans (dMEV) in Oxfordshire

Are prices different in Oxfordshire?

Our guide prices are adjusted by region. In Oxfordshire 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.

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.

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.

Is the survey free in Oxfordshire?

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 Oxfordshire?

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.