Review · Air Quality
ComfoAir Q350
The reference MVHR unit for a genuinely airtight UK project; the choice we would specify without hesitation on any home aiming below three air changes an hour at fifty pascals.
Review · Verified · Last reviewed 2026-07-17 · Evidence verified 2026-07-17
Right for
Deep retrofits and new-builds with the airtightness detailing to justify a proper MVHR system; households who care about the difference between a heat-recovery percentage on a datasheet and one measured in the commissioned house.
Wrong for
Draughty homes above roughly five air changes an hour; MVHR into leaky fabric is expensive theatre and a positive-input alternative will do more good for less money.
How we assessed it
Method, not marketing
Assessed against the SAP Appendix Q listing rather than the manufacturer datasheet; cross-read against BSRIA-style commissioning expectations and the Energy Saving Trust's ventilation guidance. Feasibility gating checked against the site's own MVHR triage rules.
Scored on four axes
Comfort in the room
5 / 5
Running character
5 / 5
Installation reality
4 / 5
Service life
5 / 5
Every score is defended in the finding it belongs to; a numeral is not an argument.
What we found
- 01
Heat-recovery performance is honest in the SAP listing, not just the brochure.
The Q350 sits at the top of the domestic MVHR pack on the SAP Appendix Q register; the specific-fan-power and heat-recovery figures used for energy modelling are Zehnder's own laboratory values verified by an approved test house, not marketing figures.
Evidence · Editorial judgement
- 02
Duct design is the review, not the box.
Every MVHR unit at this tier is only as good as the ductwork wrapped around it; kinked flexible duct or badly balanced valves will destroy the Q350's numbers as thoroughly as any cheaper unit's. Judgement on the product cannot be separated from the installer.
Evidence · Editorial judgement
- 03
Serviceability is the quiet reason to specify it.
Filter access is toolless from the front of the unit; a homeowner can change filters twice a year without a service visit, which is the boring behaviour that decides whether MVHR keeps performing in year five.
Evidence · Manufacturer datasheet
What we would buy instead
- Sentinel Kinetic Advance SX
The pragmatic mid-range pick when the project is real but not top-of-the-market; still SAP-listed, still serviceable.
- Drimaster-Eco Heat HC
The correct answer for older, leakier terraces where MVHR is the wrong technology; a positive-input system trades ventilation heat recovery for a much lower install cost.
The evidence behind this guide
Sources for the factual claims on this page.
Sources support factual claims about ComfoAir Q350. They do not stand in for editorial judgement; the verdict, suitability calls and price stance on this page are our view, labelled as such. If the evidence weakens, so does the confidence rating.
Evidence verified · 2026-07-17
Official register
- SAP Appendix Q listed products
BRE / DESNZ · Accessed 2026-07-17
Supports · Technical claim · Primary
Independent publication
- Heat recovery ventilation
Energy Saving Trust · Accessed 2026-07-17
Supports · Technical claim · Primary
Manufacturer information
- Zehnder ComfoAir Q350 MVHR unit
Zehnder UK · Accessed 2026-07-17
Supports · Technical claim · Product range · Secondary
The reference MVHR unit for a genuinely airtight UK project; the choice we would specify without hesitation on any home aiming below three air changes an hour at fifty pascals.