Mechanical Ventilation with Heat Recovery

Mechanical Ventilation with Heat Recovery Explained

MVHR stands for Mechanical Ventilation with Heat Recovery. It is a type of mechanical ventilation system commonly used in buildings to provide controlled and energy-efficient ventilation while recovering heat from the outgoing air to preheat the incoming fresh air. MVHR systems consist of a heat exchanger, fans, and ductwork to ensure a continuous exchange of indoor and outdoor air, maintaining indoor air quality and reducing heat loss.

For Building Regulations Part F in the UK, which deals with ventilation requirements, MVHR systems must meet specific testing and performance requirements to ensure compliance. These requirements may include:

Balancing MVHR Systems

Airflow Testing of MVHR systems are typically subject to airflow testing to confirm that they provide the necessary ventilation rates for the building’s size and intended use. This includes verifying that they can provide adequate fresh air supply and exhaust stale air effectively. For efficient running of the system, supply and extract terminals are required to be adjusted to ensure the system is balanced – in addition to setting the overall fan speeds.

Heat Recovery Efficiency: Part F may also specify minimum heat recovery efficiency requirements for MVHR systems. This efficiency indicates how effectively the system can recover and reuse heat from the exhaust air to preheat incoming fresh air. Higher heat recovery efficiency helps reduce energy consumption and heating costs.

Acoustic Testing: Acoustic testing ensures that MVHR systems operate at acceptable noise levels. Compliance with noise level standards is essential to provide a comfortable and quiet indoor environment.

Airtightness Testing: MVHR systems require airtightness to prevent uncontrolled air leakage, ensuring that the ventilation system operates as designed. Airtightness testing may be required to confirm that the system and ductwork are properly sealed.

Compliance with System Design: MVHR systems must meet the design specifications outlined in the Building Regulations and relevant standards. This includes correct sizing, placement, and configuration of components to ensure effective ventilation and heat recovery.


These testing requirements are in place to guarantee that MVHR systems effectively provide ventilation, heat recovery, and indoor air quality, while also promoting energy efficiency and compliance with building standards. It is crucial to work with qualified professionals and consult the specific guidelines and regulations in your region to ensure that your MVHR system meets all the necessary testing and performance requirements.