AHU maintenance
During the colder months, the performance of a heat recovery ventilation unit depends strongly on the type of heat exchanger used. Rotary exchangers usually operate more continuously, but the supply air may feel cooler, meaning additional heating is sometimes needed for comfort. Plate heat exchangers, on the other hand, may switch to protective modes more quickly in low outdoor temperatures, and without a preheater, stable ventilation can become limited. In this article, we explain real-life scenarios: when reducing airflow makes sense, why filters clog faster in winter, and how to lower energy consumption while maintaining a healthy indoor climate.
In winter, outdoor air becomes very dry once it is heated indoors, and mechanical ventilation often reduces indoor relative humidity to 20–30 RH or even lower. This article explains why this happens, how different heat exchanger types (plate, condensation rotor, enthalpy, sorption) affect indoor moisture balance, and what you can do in practice. We cover smart ventilation control during cold nights, protection against excessive drying, when a humidifier is really needed, and simple ways to increase or reduce humidity naturally. You will also find an FAQ with common real-life situations and climate-specific recommendations for different countries.
Cold outdoor air and warm, humid extract air can create condensation that may freeze inside the heat exchanger. Learn what “defrost” does, why airflow balance matters, and how to reduce frequent frost cycles.
Did you know that an incorrectly installed filter can cut your heat recovery unit’s lifespan in half? Learn which mistakes to avoid and how to replace your filters correctly at home.
Autumn is the perfect time to check your indoor air quality. HVAC installers share expert tips on choosing the right filters for your MVHR system. Learn when to use G4, M5 or F7 filters, when activated carbon filters are worth it, and how proper maintenance helps your unit last longer.
As the heating season begins, make sure your ventilation unit (air handling unit) is working efficiently and delivering clean, fresh air throughout your home. Check the filters, airflow, heat exchanger, and condensate drain to prevent unpleasant odours and system faults. A well-maintained unit saves energy and ensures a healthy indoor climate all winter long.
Manufacturers recommend changing them every 6 months under normal conditions, or every 4 months in polluted areas. Learn the key signs that your filter is clogged and how to choose the right replacement interval.
September is a transitional month when sharp temperature and humidity fluctuations create additional challenges for your ventilation system. During the day the air is still warm, while at night it becomes much cooler. Improperly adjusted ventilation can lead to discomfort, condensation, or even mold risk.
Most people replace filters only when they become visibly dirty. However, even a filter that looks “still usable” may already fail to clean the air properly. Sometimes people try shaking, vacuuming, or blowing through the filter – but that only helps for a short while. Why is that, and what is the real difference between old and new filters?
Properly maintained filters are essential to ensure you always breathe clean air at home. Changing the filters isn’t difficult – you just need to follow a few simple steps.