Mitsubishi Lossnay VL-250 filters

Lossnay is the name of Mitsubishi Electric's heat exchange element, not of the filter itself, so Lossnay VL and LGH series units use standard G4 or F7 class filters, just like other heat recovery units. The name Lossnay simply helps you recognise the right ventilation product line when looking for filters. The exact filter size is confirmed by the model number on the unit's housing sticker.

Most residential Lossnay VL and LGH series units come with a G4-class filter as standard, designed to capture larger dust particles. Some models also offer an F7-class filter as a supply-air upgrade option, which is better at capturing fine dust and pollen. Before choosing, check which class fits your specific model, as not all Lossnay variants support the F7 upgrade.

Lossnay units follow the standard 3–6 month interval, although many models have a built-in maintenance indicator that warns when airflow drops due to a dirty filter. It's worth treating this indicator as a useful reminder rather than the only criterion for when to replace the filter — especially in urban environments or near busy streets, where the filter gets dirty faster than the calculator suggests.

Filter compatibility generally stays within the same series and the same housing generation, but Mitsubishi has changed internal filter dimensions in some model updates, even while keeping a similar product name (e.g. within the VL or LGH-RVX series). The safest approach is to choose a filter based on the exact model number, or, if you can't find it, to measure the old filter directly before ordering a new one.

Yes – Lossnay filters are designed to be replaced by the user without tools or a technician. Switch the unit off, open the maintenance cover or slide out the filter cassette, remove the old filters and note their orientation, then fit the new ones the same way, following the airflow arrow on the frame. Close the cover and switch the unit back on; if your model has a filter reminder on the controller, reset it afterwards. Take care not to knock the Lossnay core while the cover is open – it's the most delicate part of the unit.

A properly matched F7-class filter is made for the same housing dimensions as the standard G4, so the change in air resistance is usually small and practically unnoticeable in everyday use. If you notice reduced airflow or increased noise after switching to F7, it usually means the filter needs to be checked more often — not that the F7 class is unsuitable for your unit.