Paul MVHR filters

Paul heat recovery units are divided into several series – we stock filter sets for the Climos (F) 200, Novus 300/450 and Focus 200. The exact model is shown on the label on the unit's front panel, not just the series name.

The Novus 300 and Novus 450 share one filter set, while the Focus 200 and Climos (F) 200 each take their own size, so check the full model name or measure the current filter – that's the surest way to get an exact match when ordering.

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.

The Paul ISO Defroster is a separate duct-mounted component (DN 160) rather than an internal part of the heat recovery unit itself, and it has its own filter. We stock a G4 replacement filter for the ISO Defroster DN 160.

This filter does not replace the unit's own filter set – both need changing on schedule. When ordering, go by the defroster's DN diameter rather than the heat recovery unit's model.

Yes, as long as the filter is made to the same ISO 16890 standards and matches the original's dimensions exactly. Our equivalent Paul filters:

• are manufactured in the EU from the same quality filtering fibre
• are cut to the same tolerances as the original filter
• fit without any modification to the housing

Since filters need to be replaced several times a year, and in a passive house they play a particularly important role in air quality, an equivalent lets you save money without reducing either filtration efficiency or the unit's operating reliability.

The standard interval is 3–6 months, but in passive houses, where the recovery unit is the sole source of fresh air, it's recommended to check the filters more often – every 2–3 months, especially the F7 filter on the supply air side. A clogged filter not only worsens indoor air quality but also increases the load on the fan and energy consumption, since the unit has to work against greater resistance.

During pollen season (April–June), it's worth checking the filter every month.

Yes. Unused filters keep their properties for a year or more as long as they're stored correctly: in their original packaging, in a dry, dust-free room, away from direct sunlight and strong odours. Avoid unheated garages, cellars or outbuildings, where humidity can affect the filter media. Since Paul units in Passive Houses rely entirely on the MVHR unit for fresh air, keeping a spare set at home means you can replace a saturated filter immediately instead of waiting for a delivery.