Mechanical Ventilation with Heat Recovery systems, commonly known as MVHR systems, have become an essential feature in modern energy-efficient homes and commercial buildings. As building regulations across the UK and Europe continue to prioritise airtight construction and lower carbon emissions, the role of MVHR systems has expanded significantly. Brands such as Vent-Axia, Zehnder and Nuaire are widely installed in both residential and light commercial properties. While these systems are designed for durability and long service life, MVHR repairs inevitably become necessary over time due to wear, installation issues, or lack of maintenance.
An MVHR system works by extracting stale air from wet rooms such as kitchens and bathrooms while supplying fresh filtered air into living spaces and bedrooms. The heat exchanger transfers warmth from outgoing air to incoming air without mixing the two air streams, significantly improving energy efficiency. When functioning correctly, an MVHR unit maintains consistent indoor air quality and temperature while reducing heating demand. However, when faults arise, homeowners may notice symptoms such as reduced airflow, unusual noises, increased energy consumption, or condensation buildup.
One of the most common reasons for MVHR repairs is motor or fan failure. Over time, continuous operation can cause bearings to wear out or electrical components to degrade. When fans begin to fail, airflow becomes inconsistent, leading to poor ventilation and possible moisture issues. In some cases, the control board may also malfunction, resulting in error codes or complete system shutdown. Professional diagnosis is important, as replacing individual components rather than the entire unit can often be more cost-effective.
Another frequent repair issue involves MVHR repairs blocked or heavily soiled filters. Although filter replacement is technically part of routine maintenance rather than repair, neglected filters can strain the system and lead to overheating or motor damage. When filters remain clogged for extended periods, airflow resistance increases and internal components may suffer premature wear. In these situations, what could have been simple maintenance escalates into a more complex repair requiring part replacement.
Heat exchanger faults can also develop, though less commonly. Cracks, frost damage, or internal contamination may reduce heat transfer efficiency. In colder climates, improper commissioning or poor insulation around ductwork can lead to condensation freezing inside the unit. This can damage the heat exchanger core or surrounding seals. Skilled technicians assess whether cleaning, resealing, or full core replacement is required. Because the heat exchanger is central to the system’s efficiency, accurate repair is essential to restore performance.
Ducting issues are another source of MVHR repair work. Poor initial installation, loose connections, or crushed flexible ducts can restrict airflow and create imbalances in the system. Over time, vibrations may loosen fittings, causing air leakage and noise. Repairing ductwork often involves resealing joints, replacing damaged sections, and recalibrating airflow rates to ensure the system operates as originally designed. Balanced airflow is critical, as pressure differences can reduce efficiency and comfort.
Control systems and sensors may also require attention. Modern MVHR units frequently integrate humidity sensors, boost switches, and smart home compatibility. Electrical faults, wiring issues, or sensor calibration errors can cause the system to run continuously at high speed or fail to respond to changing humidity levels. Proper troubleshooting involves checking voltage supply, verifying sensor readings, and updating firmware if applicable. In some cases, a simple reset restores functionality, while in others, component replacement is necessary.
Preventative servicing significantly reduces the likelihood of major MVHR repairs. Annual inspections allow engineers to test airflow rates, check condensate drains, inspect fans, and verify heat exchanger performance. Early identification of minor issues prevents costly breakdowns. Many manufacturers recommend servicing intervals to maintain warranty coverage, and professional servicing helps ensure compliance with building performance standards.
Ultimately, MVHR repairs should always be handled by qualified ventilation specialists. While some minor tasks such as filter replacement can be undertaken by homeowners, diagnosing internal mechanical or electrical faults requires expertise. A properly repaired and balanced MVHR system not only restores comfort but also protects the long-term energy efficiency of the building. As airtight construction becomes more common, reliable ventilation performance remains essential, making timely MVHR repair and maintenance an important investment in healthy indoor living.