MVHR bathroom condensation and mould
Updated: 22 October 2026
Steaming mirrors, black specks on the sealant and a musty towel cupboard push you toward bathroom MVHR on amazon.co.uk. Heat recovery is not the same thing as a high-rate shower extract, and ventilation cannot fix a leak. This page separates moisture you can ventilate from water you must trace, then sets expectations for the wall and ducted rows on the [MVHR comparison](/hub/heating/mvhr). Peter F. checked the listings and public UK sources. There was no lab test. A qualifying purchase can earn a commission at no extra cost to you.
Steaming mirrors, black specks on the sealant and a musty towel cupboard push you toward bathroom MVHR on amazon.co.uk.
Steaming mirrors, black specks on the sealant and a musty towel cupboard push you toward bathroom MVHR on amazon.co.uk. Heat recovery is not the same thing as a high-rate shower extract, and ventilation cannot fix a leak. This page separates moisture you can ventilate from water you must trace, then sets expectations for the wall and ducted rows on the MVHR comparison. Peter F. checked the 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 | Airflow stated | System type | Wet-room note | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  LIRAST LIRAST EER100 white | Not stated | Single-room wall | No IP stated; warm when left on | 8.5 | about £123.12 | View offer |
| Best value |  EUROPLAST EUROPLAST EER100 | 29 m³/h | Single-room wall | Bathroom bullet, no IP stated | 8.0 | about £189.90 | View offer |
 Vent-Axia Vent-Axia HR100R | 18 l/s FID | Ducted loft unit | One review: shower room cleared | 6.8 | about £319.00 | View offer |
On this page
Condensation, mould and leaks
Condensation forms when humid air meets cold glass or a cold wall. Ventilation lowers humidity over time only if the air path is real and the fabric is not wetting faster than you extract.
Mould needs ongoing moisture. Cleaning what you can see, without fixing humidity or a leak, often brings it back. A leak from failed tanking, a joint or water from outside can look like a weak fan. If a patch grows when nobody is bathing, trace the water first. NHIC ties persistent condensation to competent installation and a realistic system, not to a badge on a box.
Shower airflow versus heat recovery
A shower extract targets a short peak of steam. Homebuilding guidance often cites a minimum 15 l/s where a bath and shower exist. That is boost context, not a map onto every wall fan here.
Approved Document F (2021 edition) gives 8 l/s as the continuous high rate for a bathroom. An alternate-flow fan is not automatically a 15 l/s boost unless measured flow shows it. EUROPLAST states 29 m³/h, about 8 l/s if you convert that figure, and the conversion is not a Part F result. Vent-Axia HR100R states 18 l/s FID. The LIRAST listings do not state airflow.
Heat recovery does not pause a twenty-minute shower. About 40 m³/h in Passivhaus Trust wet-room notes is a design aim for an engineered system, not a legal minimum for a budget wall fan.
Running a wall unit in a wet room
Most rows mention a bathroom and do not state an IP rating. IPX4 is not confirmed on the LIRAST, EUROPLAST, Brookvent, LINGGONGAIR or Envirovoid fields. Shower-zone wiring stops unless the manual certifies the zone. Where DIY ends is on how to install a single-room MVHR.
LIRAST buyers note a warm bathroom when the unit is left on. A LINGGONGAIR cottage still had a wet window after three weeks. Units reverse about every 70 seconds, and Brookvent reviews mention a click. Envirovoid’s HEPA line has no standard number. The HR100R suits a small shower room when the ducts and condensate drain are right. Supply air on a wall fan can still feel cool.
When to call a professional
Call an installer when several wet rooms need rates together, the work is notifiable, mould returns after a fan that is actually running, or an IP-rated extract is mandatory and the listing is silent. BEAMA’s Part F sheet is the pattern for measured airflow.
A whole-house system extracts kitchen and bathroom moisture in one network. The Centre for Sustainable Energy sets that against a single hole, at installed cost far above these shelf prices. A unit at about £123 is not a designed system from about £3,000. A high-rate extract is the safer fix for peak steam only, a wall under about 300 mm, or electrics that cannot be certified.
Common questions
Will a heat-recovery fan stop mould?
It can reduce humidity from here on if it is sized for that room, left running, and the air path is real. Mould already on the sealant still needs treatment. If the patch grows when you are not bathing, look for a leak first. A new fan does not dry a saturated wall on night one, and it does not repair failed tanking.
Is MVHR enough for a shower with no separate extract?
For light use in one external-wall room, sometimes, if you leave it running through the hours you produce steam. A long power shower in a closed room can outpace one alternate-flow cycle. If the mirror is still blind after a proper run, you need boost extract or a ducted layout. Opening a window clears steam and also dumps the heat the core just saved.
Why is the window still wet after I fitted it?
Cold glazing, a unit left on a speed that barely moves air, or one fan trying to dry moisture from the whole flat. A LINGGONGAIR cottage install still had wet windows after three weeks of continuous running. Heat recovery does not warm the glass. If the mark spreads with the fan off and nobody showering, treat it as a possible leak and trace the enclosure and the pipework.
Do I need IPX4 for a wall fan in a shower room?
If the unit sits in a splash zone, you need a product mark for that zone. IPX4 is the splash claim people look for, and these listings do not state an IP rating. Check the manual before you cut. A bathroom word in the title is not the mark. If the documents are silent, do not fit the fan there.
Is a click about every minute normal?
A reversal about every 70 seconds is typical of an alternate-flow unit. Brookvent reviews note a click each cycle. That click is the fan changing direction, not a failed core. Run it overnight before you finish the sealant if a bedroom shares the wall.
When is a standard high-rate extract the safer fix?
When the problem is a short peak of shower steam, when the wall is thinner than the sleeve, when there is no external wall, or when the electrics in the zone cannot be certified. The LIRAST sleeve is about 300–555 mm. Heat recovery is the wrong first spend in those cases. A high-rate extract fan is a different product from the nine MVHR rows in this comparison.
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)