MVHR cost in the UK, and when it is worth it

Mechanical ventilation with heat recovery is a single quiet unit, usually in a loft or utility space, that continuously extracts moist warm air from the kitchen, bathrooms and utility rooms, and supplies tempered fresh air to the bedrooms and living rooms. The two air streams pass each other through a heat exchanger inside the unit, recovering most of the heat from the outgoing air without mixing the two streams. The ductwork connects every wet and habitable room into the central unit; the diffusers in each room are what the homeowner actually sees.

For a typical UK three-bedroom retrofit where ductwork can be routed through the loft and service voids without major structural work, expect £5,000 to £9,000 fully installed, commissioned and filter-checked. The unit itself is roughly a fifth of that; the ductwork, the labour and the commissioning carry most of the cost.

New builds typically come in toward the lower end because ductwork can be designed in from the structural stage. Retrofits where ductwork has to cross multiple ceilings, run inside cupboards or boxes, or be acoustically isolated from a sleeping space, will push the figure toward the upper end of the band.

Deep retrofits with whole-house balanced ventilation and acoustic treatment can land above £10,000, particularly when paired with an airtightness package; that is a different conversation, sized alongside the fabric budget.

MVHR pays for itself in comfort and air quality, not in pure energy savings. Below about 5 ach @ n50 the heat-recovery figure starts to pull meaningful warm air through the heat exchanger rather than losing it through fabric leaks; above 8 ach the system is fighting the building and the benefit collapses. The honest test is the airtightness number, not the EPC band.

A well-installed system delivers a noticeably calmer indoor environment in winter: lower humidity in the bathrooms, fewer condensation problems on cool external walls, and a steady supply of fresh air without the cold draught that comes from opening a window. Those benefits matter most to households where someone is at home a lot, where indoor air quality is a daily concern, or where the home is being deliberately taken to a low energy demand.

Where it does not earn its place: a leaky pre-war house with a single damp bathroom is better served by a sensibly sized extract fan or a single-room heat-recovery unit. Forcing whole-house MVHR into the wrong fabric is the most common way these systems disappoint.

MVHR filters need changing on the schedule the manufacturer specifies, typically every six to twelve months. A unit running on clogged filters loses heat-recovery efficiency and gets steadily louder; eventually it begins to feel draughty at the supply diffusers, and the homeowner often blames the system at that point rather than the maintenance. Set a calendar reminder, buy filters in twos, and the system will hold its performance for fifteen years.