Question 1

How much does MVHR cost compared to extract fans?

Accepted Answer

A full MVHR system typically costs £3,000-5,000 installed for a 3-bed house, including the unit, ductwork, diffusers and commissioning. By contrast, individual extract fans for a kitchen, bathroom and en-suite cost £200-500 total installed. The payback for MVHR comes from reduced heating bills through heat recovery.

Question 2

How much energy does MVHR actually recover?

Accepted Answer

Modern MVHR units recover 85-95% of the heat from extracted air. In a well-insulated home (e.g. fabric-first design or Passivhaus), this can save £200-400 per year on heating bills. However, in a draughty older property, the recovered heat is offset by uncontrolled air leakage, reducing the benefit significantly.

Question 3

Does my house need MVHR or will extract fans do?

Accepted Answer

MVHR works best in airtight buildings (below 3 m³/h/m² at 50 Pa). For buildings with air permeability above 5 m³/h/m², intermittent or continuous extract fans (System 1 or 3 per Approved Document F) are more practical and cost-effective. Most existing UK housing stock suits extract fans unless undergoing deep retrofit.

Question 4

What maintenance does MVHR need vs extract fans?

Accepted Answer

MVHR filters need replacing every 6-12 months (£20-40 per set), the heat exchanger needs annual cleaning, and ductwork should be inspected every 5 years. Extract fans need occasional cleaning and replacement every 8-12 years. MVHR has notably higher ongoing maintenance requirements.

Question 5

Can MVHR be retrofitted into an existing house?

Accepted Answer

It is possible but challenging and expensive. Retrofitting MVHR requires routing large-diameter ductwork (typically 125-150mm) to every habitable room and wet room, usually through ceiling voids or bulkheads. A retrofit typically costs £5,000-8,000. Decentralised MVHR units (wall-mounted) are an easier retrofit option at £300-600 per room.

Feature	MVHR	Extract Fans
Installation cost	£3,000-5,000	£200-500
Heat recovery	85-95%	None
Running cost (electric)	£30-60/year	£15-30/year
Heating saving	£200-400/year	None
Installation complexity	High — full ductwork required	Low — core through wall
Filtration	Filters pollen, dust, PM2.5	No incoming air filtration
Ideal airtightness	Below 3 m³/h/m² at 50 Pa	Any building
Part F system	System 4	System 1 or 3

MVHR vs Extract Fans — Ventilation Compared

Side-by-Side Comparison

When to Choose MVHR

When Extract Fans Are Better

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