Single room heat recovery fan install
Updated: 22 October 2026
You have chosen a unit from the [MVHR comparison](/hub/heating/mvhr) and you are standing at an external wall with a core drill and a cable route in mind. This page is the through-wall sequence for a decentralised fan, then the point where a ducted loft unit stops being casual DIY. It is not a second product ranking. Peter F. checked the amazon.co.uk listings and public UK sources. There was no lab test. A qualifying purchase can earn a commission at no extra cost to you.
You have chosen a unit from the MVHR comparison and you are standing at an external wall with a core drill and a cable route in mind.
You have chosen a unit from the MVHR comparison and you are standing at an external wall with a core drill and a cable route in mind. This page is the through-wall sequence for a decentralised fan, then the point where a ducted loft unit stops being casual DIY. It is not a second product ranking. Peter F. checked the amazon.co.uk listings and public UK sources. There was no lab test. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Route | Depth to check | Controls and power | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  LIRAST LIRAST EER100 white | Through-wall sleeve | 300–555 mm | Recuperator, plug not stated | 8.5 | about £123.12 | View offer |
| Best value |  EUROPLAST EUROPLAST EER100 | Through-wall | Not stated | Wall switch, Type G and Schuko | 8.0 | about £189.90 | View offer |
 Vent-Axia Vent-Axia HR100R | Loft, ducted | Not a core-drill sleeve | Two speeds, drain to plan | 6.8 | about £319.00 | View offer |
On this page
Before you drill
Measure the wall and put it against the listing. LIRAST specifies 300–555 mm. A minimum of about 300 mm caught people who assumed a thin partition. LINGGONGAIR reviews cite about 40 cm and a 125 mm core. Envirovoid allows 100–160 mm. Check lintels and the cavity before you cut. If a title and a size field disagree, follow the template for the core you are drilling.
Open the carton first. EUROPLAST includes a wall switch. Brookvent says one unit, and buyers bought a switch elsewhere. LIRAST says recuperator. Swiftair buyers got a two-room kit against a four-room title. In a bathroom, treat the wiring as Approved Document P work unless you are competent and the manual certifies the zone.
Through-wall sequence
Core on the marked centre and keep the barrel square. On a LIRAST, set the 300–555 mm duct to the measured thickness before the outside grille. Leave access if you must open the unit to change speeds.
Seal the sleeve, keep the breaks the manual asks for, and fit a hood that sheds rain. Alternate-flow fans reverse about every 70 seconds, and Brookvent buyers hear a click. Trial-run a bedroom before the final sealant. LIRAST paper instructions are often thin, so use the seller’s PDF. EUROPLAST buyers report reversed buttons. Test direction before you label the switch, and leave room to change filters.
Power, switches and bathroom rules
These are mains appliances on a nominal 230 V supply. EUROPLAST prints Type G and Schuko. Identify the connection on delivery before you adapt it. A spur should follow BS 7671 and Approved Document P. A bathroom is not a casual joint.
If the photos show a switch and Brookvent’s carton does not, stop. EUROPLAST is the switch-in-the-box example. Swiftair lists a cord. A wall fan may need a permanent connection. After switch-on, check direction and whether supply air feels cool. Note the date and speed if the dwelling is commissioned later.
Ducted and loft units
Vent-Axia HR100R is not a core-and-grille job. Plan loft mounting, two speeds, 18 l/s FID, insulated ducts and a condensate drain. One drain arrived bent. Treat it as installer-led unless you already route ductwork.
The CFLO250 lists no duct kit. Swiftair needs the room count checked, with the fan lower than the terminals. One 1980s-flat install stayed above 60% moisture for weeks. NHIC stresses a competent install when condensation persists after a swap.
When a competent person takes over
Hand the job over when several wet rooms need balanced flows, the work is notifiable, or you cannot prove installed airflow. BEAMA’s sheet is the pattern for that measurement. The parcel is not the record. How a sleeve differs from a ducted box is on single-room and whole-house MVHR.
Common questions
Can I install a through-wall MVHR myself?
Often the masonry core and the sleeve, in a room that is not notifiable, if you are competent and you know the wall build-up. The electrical connection may not be DIY, and a bathroom zone is not a casual spur. If you cannot tell what the drill will meet, stop. Fixed wiring follows BS 7671 and Approved Document P. A product title is not a certificate for a shower zone.
Do I need an isolation switch?
Good practice for a fixed fan, and required where the wiring rules say so. EUROPLAST includes a wall switch in the box. Wire it and test which button is actually off before you write the labels. Reviews on that unit describe off and on reversed. If another brand’s photos show a controller and the carton does not, do not improvise a joint inside a bathroom zone.
What if the core hole hits an obstruction?
Stop. Do not weaken a lintel, chase through a pipe, or angle the barrel to force the sleeve. Cavity ties, cables and a change in wall thickness are reasons to halt. Patch the plan and move the centre, or change to a ducted route if the only clear external wall is blocked. A telescopic duct cannot make up for a hole in the wrong place.
How do I seal the external grille?
Follow the manufacturer’s fall and rain-hood guidance. Seal the sleeve to the wall without covering the path you need to change filters. The hood should shed rain off the cladding. Run the fan through several reverse cycles before the final sealant, especially in a bedroom, so you know whether the click is acceptable. A crooked barrel leaves a gap the sealant will not reliably close.
Can I fit a wall fan in a bathroom zone?
Only if the product mark and the manual certify that zone. These listings usually do not state an IP rating, even when a bullet says bathroom. A splash zone needs that mark, not a room word in the title. If the documents do not cover the zone, stop and use a product that does, with wiring that matches Approved Document P. Do not assume shower-zone compliance from the amazon page.
When do I need Part F commissioning?
When the ventilation work is notifiable, and on many new-build sign-offs that demand measured airflow. Retail delivery is not a commissioning record. BEAMA’s Part F sheet is the industry pattern for those measurements. Keep a note of the speed you left running and the date you energised the fan, so a competent person can complete the sheet if the dwelling scope grows beyond one wall.
Related pages
Sources
Public UK sources named below. amazon.co.uk prices, stars and review counts on these nine listings were taken from the listing files read on 20 October 2026. Page updated October 2026.
- Approved Document F, Volume 1 (2021 edition) (retrieved 20 October 2026)
- GOV.UK ventilation: Approved Document F (retrieved 20 October 2026)
- Centre for Sustainable Energy: mechanical ventilation with heat recovery (retrieved 20 October 2026)
- NHIC: why ventilation is important (retrieved 20 October 2026)
- Passivhaus Trust MVHR good practice guide (2018) (retrieved 20 October 2026)
- Passivhaus Trust: the case for MVHR (retrieved 20 October 2026)
- BEAMA Part F ventilation commissioning sheet (retrieved 20 October 2026)
- Approved Document P (retrieved 20 October 2026)