Paul Focus filters

It depends on the model. The Paul filter sets we stock come in these combinations:

• Novus 300/450 and Focus 200 — G4+G4, or G4+F7 with a fine F7 (ePM1) supply filter
• Climos (F) 200 — M5+M5, or M5+F7

Because Passive House buildings get all their fresh air through the MVHR unit, the version with the F7 supply filter is usually the better choice for indoor air quality.

Paul Wärmerückgewinnung is a German pioneer of ventilation systems designed for Passive House and low-energy buildings, with several unit series built around very high heat-recovery efficiency. Depending on the model, Paul units use G4, M5 and F7 filters.

Two pieces of information on the unit's front panel confirm your exact Paul model:

• The series name, such as Novus or Focus
• The longer alphanumeric model code, which specifies airflow capacity

Both help match you to the correct filter set, especially where multiple airflow variants share a series name.

No. The Focus 200 takes its own filter size, while the Novus 300 and Novus 450 share one set. The Climos (F) 200 uses a different size again. Check the series name and model number on the unit before ordering, then choose the G4+G4 or G4+F7 version (M5+M5 or M5+F7 for Climos).

Check them every 3 months and replace them at least every 6 months. In a Passive House the MVHR unit supplies all the fresh air, so a clogged filter shows up quickly as stuffier air and more fan noise. Change the supply filter sooner during pollen season or if you live near a busy road, and keep a spare set at home so you never run the unit on saturated filters.

For most households it is enough, and changing it on time matters more than making it finer. In an airtight modern Finnish house practically all the fresh air arrives through the ventilation unit, so the supply filter is the only barrier between outdoor air and your rooms — which argues for keeping it fresh rather than for making it denser. Finnish guidance sets ePM1 50% as the level for living spaces in normal outdoor air. Going finer raises the pressure drop and loads faster, so it earns its place mainly where the outdoor air is genuinely worse — a busy road — or where symptoms persist with a clean standard filter, and only if the unit's fan capacity allows it.