Mechanical Ventilation with Heat Recovery systems, commonly known as MVHR systems, have become an essential feature in modern energy-efficient homes. As building standards continue to improve and airtight construction becomes the norm, these systems play a critical role in maintaining indoor air quality while conserving energy. Leading manufacturers such as Vent-Axia, Zehnder, and Nuaire have developed advanced units designed to provide consistent airflow and heat recovery performance. However, like any mechanical system, MVHR units require maintenance and occasional repairs to operate efficiently over the long term.
An MVHR system works by extracting stale air from wet rooms such as kitchens and bathrooms while simultaneously supplying fresh, filtered air to living spaces and bedrooms. The heat exchanger at the heart of the system transfers warmth from outgoing air to incoming air, significantly reducing heating demands. When the system is functioning correctly, it operates quietly in the background, providing a constant supply of fresh air without noticeable drafts. When faults arise, however, performance can decline quickly, affecting both comfort and energy efficiency.
One of the most common issues requiring MVHR repair is reduced airflow. This can be caused by clogged filters, blocked ductwork, or failing fans. Filters are designed to capture dust, pollen, and airborne contaminants, and over time they become saturated. When this happens, airflow is restricted and the fans must work harder, increasing energy consumption and noise levels. Replacing filters is often a straightforward task, but if the issue is left unresolved, it can lead to strain on internal components and eventual fan motor failure.
Fan motor faults are another frequent MVHR repairs cause of repair calls. MVHR units rely on two continuously operating fans, and although they are designed for durability, bearings and motors can wear out over time. Symptoms of fan failure include unusual vibrations, rattling noises, or inconsistent airflow. In some cases, the unit may display fault codes, depending on the manufacturer. Prompt diagnosis is essential because continued operation with a failing motor can cause overheating or damage to the heat exchanger.
Electrical and control system issues also contribute to MVHR repair requirements. Modern units often include digital controllers, humidity sensors, and boost functions. Wiring faults, sensor malfunctions, or software errors can cause the system to run continuously on high speed or fail to respond to changing humidity levels. Professional technicians typically use diagnostic tools to identify whether the problem lies in the control board, wiring connections, or external switches. Replacing electronic components requires specialist knowledge to ensure compatibility and maintain warranty conditions.
Another area that sometimes requires attention is the heat exchanger itself. Over time, dust and condensation can accumulate within the exchanger core. If not cleaned regularly, this buildup can reduce heat transfer efficiency and restrict airflow. In extreme cases, freezing may occur in very cold weather if the frost protection system is not working correctly. Repairs in this area may involve removing and cleaning the core or addressing sensor faults that control defrost cycles.
Ductwork problems can also affect MVHR performance. Leaks, disconnected joints, or crushed ducts reduce system efficiency and may create imbalanced air pressure within the property. Identifying these issues often involves inspecting accessible duct runs and checking airflow rates at valves. Proper sealing and insulation of ducts are essential to prevent heat loss and condensation problems, especially in unheated loft spaces.
Professional servicing plays a vital role in reducing the likelihood of major MVHR repairs. Annual inspections allow technicians to check airflow rates, clean internal components, test electrical systems, and ensure the unit is operating within manufacturer specifications. Regular maintenance not only prolongs the lifespan of the system but also preserves indoor air quality and energy savings.
Ultimately, MVHR repairs should never be ignored. Because these systems are integrated into the fabric of modern airtight homes, their performance directly affects comfort, health, and heating costs. Timely intervention by qualified professionals ensures that the system continues to deliver fresh, filtered air while recovering valuable heat. With proper care, a well-maintained MVHR system can provide reliable service for many years, supporting a healthier and more energy-effic