{"id":11243,"date":"2026-03-03T09:05:07","date_gmt":"2026-03-03T07:05:07","guid":{"rendered":"https:\/\/filtermarkt.at\/?p=11243"},"modified":"2026-03-03T09:05:09","modified_gmt":"2026-03-03T07:05:09","slug":"what-happens-if-you-dont-replace-your-filters-for-6-9-or-12-months-real-facts-and-consequences","status":"publish","type":"post","link":"https:\/\/filtermarkt.at\/en\/what-happens-if-you-dont-replace-your-filters-for-6-9-or-12-months-real-facts-and-consequences\/","title":{"rendered":"What Happens If You Don\u2019t Replace Your Filters for 6, 9 or 12 Months? Real Facts and Consequences"},"content":{"rendered":"\n

Many people assume that an MVHR system is something that \u201cjust works\u201d \u2014 you switch it on and forget about it. The reality is very different.<\/strong> An MVHR system is only truly beneficial when the filters are clean<\/strong>. Once MVHR filters become contaminated, the system not only stops protecting you from pollution, but starts working against you: the air feels heavier, odours linger for longer, and electricity consumption increases.<\/p>\n\n\n\n

Let\u2019s look at how this plays out in real-life situations \u2014 depending on property size, system type and living environment.<\/p>\n\n\n\n

Example 1:<\/strong><\/h2>\n\n\n\n

50 m\u00b2 flat with a Paul Climos 200 MVHR unit<\/strong><\/h3>\n\n\n\n

The\u00a0Paul Climos 200<\/a><\/strong>\u00a0is an enthalpy MVHR unit supplying up to 200 m\u00b3 of air per hour, with around 84% heat recovery and humidity retention in winter. For a 50 m\u00b2 flat, this is more than sufficient capacity, meaning the air should feel light, fresh and clean. The system is typically equipped with an\u00a0M5 extract filter and an F7 supply filter<\/strong>.<\/p>\n\n\n\n

In cities<\/strong>, especially in Vilnius, filters clog the fastest. F7 filters often need replacing every 3 months. If you delay, airflow can drop by more than 20%, and you may begin to notice bathroom or cooking smells spreading through rooms, with air that feels stale and stagnant.<\/p>\n\n\n\n

Living close to nature<\/strong>, filters usually last around six months, sometimes even longer. However, during pollen season in spring, the F7 filter may clog more quickly. The first signs of dirty filters are lingering cooking smells, air that feels less fresh in the morning, and a stuffy feeling in the bedroom.<\/p>\n\n\n\n

In suburban areas<\/strong>, the situation becomes more serious. Here, F7 filters often clog within 3\u20136 months. A contaminated filter can restrict airflow by 10\u201315%, forcing the system to work harder. It may become noisier, and you may start feeling that the air is heavier, with a growing urge to open windows more often and a sensation of not being able to breathe deeply.<\/p>\n\n\n\n

Example 2:<\/h2>\n\n\n\n

80 m\u00b2 house with a Zehnder ComfoAir Q350<\/strong><\/h3>\n\n\n\n

The\u00a0Zehnder ComfoAir Q350<\/a><\/strong>\u00a0is a highly efficient unit, supplying up to 350 m\u00b3\/h of air with around 90% heat recovery. In an 80 m\u00b2 home, it operates quietly and efficiently, with capacity to spare. The standard setup includes\u00a0G4 and F7 filters<\/strong>.<\/p>\n\n\n\n

In urban areas<\/strong>, the realistic replacement interval is every 3\u20134 months. If you delay, you will quickly notice that odours linger, the air feels stuffy, and you increasingly want to open windows.<\/p>\n\n\n\n

Living in a natural environment<\/strong>, filters usually last around six months. However, if they are not replaced in time, dust begins to accumulate not only in the filters but inside the system itself. This results in reduced efficiency and increased indoor humidity, with occupants noticing a heavy feeling in the air, particularly in bedrooms.<\/p>\n\n\n\n

In suburban locations<\/strong>, filters typically need replacing every 4\u20136 months, and even sooner if there are gravel roads, construction sites or dense vegetation nearby. A clogged filter increases system resistance, leading to higher electricity consumption \u2014 often without occupants realising why.<\/p>\n\n\n\n

Example 3:<\/h2>\n\n\n\n

160 m\u00b2 house with a Zehnder Q350<\/strong><\/h3>\n\n\n\n

In a larger house, significantly more air passes through the filters each day. This leads to one simple outcome: filters clog faster, even if you live outside the city.<\/p>\n\n\n\n