Continuous extract fans (dMEV) in Wiltshire

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 Wiltshire, including Warminster, Calne, Westbury, Swindon and Salisbury. Prices use South West rates. We survey first, free of charge for new installations on the mainland, then send a fixed written quote.

dMEV fans in Wiltshire at a glance

Area: Wiltshire
Towns listed: 14, largest Swindon
Postcode districts: BA13, BA14, SN10, SN12, SN13 and SN12
Price region: South West
Survey: Free survey (UK mainland)

How we do it

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.

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 Wiltshire

Continuous extract fans (dMEV) guide prices in Wiltshire
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

South West rates shown. Prices include VAT at 20%. The fixed price is confirmed in writing after we have seen the job.

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 Wiltshire

Questions about continuous extract fans (dMEV) in Wiltshire

Are prices different in Wiltshire?

Our guide prices are adjusted by region. In Wiltshire 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.

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.

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.

Is the survey free in Wiltshire?

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 Wiltshire?

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.