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MVHR Systems: A Complete Guide

Approx. 8 min read

Mechanical Ventilation with Heat Recovery (MVHR) is a system that keeps your home well-ventilated without wasting heat. It draws out stale, damp air from wet rooms and brings in fresh, filtered air to living spaces. A built-in heat exchanger captures up to 95% of the warmth from outgoing air and passes it to the incoming fresh air, so your home stays comfortable year-round.

How MVHR Works

An MVHR system uses two separate sets of ducts: one to remove stale air and one to bring in fresh air. Both connect to a central unit.

  • Stale air is pulled out of kitchens, bathrooms, and utility rooms.
  • Fresh air is delivered to bedrooms, living rooms, and offices.

Inside the unit, a heat exchanger moves warmth from the outgoing air to the incoming fresh air without mixing them together. High-performance units can recover up to 95% of this heat, which means lower heating bills and a better energy rating for your home.

System Components

A standard MVHR setup includes:

  • Central unit -- houses the fans, filters, and heat exchanger.
  • Ductwork -- rigid or semi-rigid pipes that carry air around the property.
  • Wall or roof terminals -- where fresh air enters and stale air exits the building.
  • Controls -- speed settings, boost switches, and optional humidity or CO2 sensors.

Benefits of MVHR Systems

  • Lower energy bills -- heat recovery means less money spent on heating.
  • Cleaner air -- filters remove pollen, dust, and outdoor pollution.
  • No more condensation -- removes excess moisture to prevent damp and mould.
  • Comfortable temperatures -- no cold draughts from vents or open windows.
  • Quieter home -- sealed system reduces outdoor noise coming in.

Design Considerations

How well an MVHR system works depends largely on how it is designed and set up. Key factors include:

  • Airtightness -- MVHR works best in well-sealed homes with low air leakage.
  • Duct layout -- smooth, balanced pipework that keeps airflow even and quiet.
  • Unit efficiency -- choose a model with proven heat recovery performance.
  • Noise levels -- correct fan sizing and sound insulation keep things quiet.
  • Easy filter access -- filters need regular cleaning or replacement.

Compliance and Standards

MVHR installations must meet Building Regulations Part F (Ventilation) and Part L (Energy Conservation). The following standards also apply:

  • BS EN 13141-7 (performance testing)
  • BS 5250 (condensation control)
  • Domestic Ventilation Compliance Guide

Proper setup and documentation are needed for Building Control sign-off and accurate energy assessments.

Is MVHR Right for Your Property?

MVHR is best suited to new builds and major renovation projects where the home is well sealed. In older, draughtier properties the heat recovery benefit is reduced, though other ventilation options can still help.

Flexivent Expertise

Flexivent designs, supplies, installs, and commissions MVHR systems across Gloucestershire and nearby areas. Our engineers make sure every system meets current regulations, performs at its best, and fits neatly into your home. Get in touch for expert advice on choosing and specifying the right MVHR system.