Wolf CWL-300/400 filters

We stock filters for the Wolf CWL range — the main residential heat recovery ventilation line from this German manufacturer, often installed together with Wolf heating systems. The catalogue covers both compact models (CWL-150, CWL-225) and higher-performance variants (CWL-300, CWL-400, CWL-2000). The exact CWL model code is shown on the sticker on the unit's front panel.

CWL models typically use two-stage filtration in line with German indoor air quality guidelines:

• M5-class filter for coarser particles
• F7 (ePM1) class filter for fine particles

Filters of both classes fit the same filter housing with no additional modifications, so you can choose the more budget-friendly option without changing the holder itself.

From a filter-maintenance perspective, ventilation and heating functions operate independently, but in combined Wolf systems the recovery unit often runs continuously to support overall home climate control. Because of this, it's worth checking CWL filters towards the shorter end of the standard 3–6 month interval rather than waiting for the maximum period. This is especially relevant in winter, when ventilation intensity combined with heating tends to be higher than in summer.

No — filter dimensions within the CWL range depend on the unit's capacity, so the CWL-300 uses a smaller filter than the larger CWL-400 or CWL-2000 models. Before ordering, be sure to check your exact CWL variant on the front panel sticker, since the series name "CWL" alone doesn't guarantee the right size — a filter ordered for the wrong model simply won't fit into the housing.

No. The filter is a consumable part, not a structural component, so using a correctly sized, correctly classed compatible filter does not affect the warranty on the CWL unit's heat exchanger, fans or electronics – that warranty covers manufacturing defects, not the brand of filter you fit. What matters is that the compatible filter matches the original's dimensions and filtration class (typically G4/M5 on the extract side and F7 on the supply side) so airflow and pressure drop stay within the unit's design range.

Yes, ordering a full season's or even a year's worth of CWL filters in one go is a common choice, especially for those who already have a maintenance schedule for their Wolf heating system and want to plan everything together. Ordering several sets at once usually brings the per-unit price down compared to buying one at a time. All you need to do is specify your exact CWL model code so that every filter in the set fits without any issues.