Paul Novus 300/450 filter set G4+G4 (original)
Paul Novus 300/450 filter set G4+G4 (original)
Filter protection level indicates efficiency in blocking particles or contaminants, varying by standard and application.
General dust and particle filtration
Protects against allergens and urban pollution
Filter protection level indicates efficiency in blocking particles or contaminants, varying by standard and application.
Certified quality to international ISO standards
Manufactured entirely within the European Union
Effective filtration for up to 6 months.
Model compatibility
Compatible with the following models:
- Paul Novus 300
- Paul Novus F 300
- Paul Novus 450
- Paul Novus F 450
What filter set protects against
Filter set includes 2 filters:
- Extract filter – G4 (Coarse 70%) – for MVHR protection
- Supply filter – G4 (Coarse 70%) – for indoor air protection
This filter set follows the ISO 16890 standard for particle filtration efficiency.
The G4 filters capture up to 70% of coarse airborne particles that are larger than 10 microns, such as soil particles, large pollen grains, plant debris, insect wings, sawdust, sand and textile lint. One of them filters the air extracted from your indoor space and protects the MVHR unit; while the other cleans the outdoor air supplied into your premises, improving indoor air quality and protecting your health. This helps reduce visible dust, lowers energy consumption, keeps the system running quietly, and extends its lifespan.
Usage and maintenance
Paul recommends replacing the filters every 6 months, to ensure optimal air quality and system performance.
However, replacement frequency may vary depending on factors such as:
- Air pollution levels (e.g. urban vs rural areas)
- Allergies or respiratory sensitivities
- Indoor pets or smoking
- Dust from nearby construction sites
If your system includes a filter change indicator, follow its alerts. Otherwise, check the filters visually – if they appear very dirty or clogged, it's time to replace them.
Manufacturing quality
This filter set is manufactured by Paul, part of the Zehnder Group. We’ve worked with this trusted partner for many years and purchase all products directly from them - ensuring authenticity and consistent quality. Paul’s filters are produced in Europe at Zehnder’s manufacturing facilities in the Netherlands, France, and Switzerland, upholding high production standards.
These panel filters are made using Z-line technology, with densely folded filter media mounted in a cardboard frame. Such design maximises the filtration surface area, enhancing particle retention and airflow efficiency. This kind of construction offers a larger effective filtration area, more uniform airflow distribution, improved particle capture, and a lower pressure drop.
By choosing original Paul filters, you ensure that your MVHR system operates in line with the manufacturer’s stated technical data, maintaining both optimal air quality and energy efficiency.
Original product codes
- 527004250
Filter Type / EN 779 Class | ISO 16890 Class | Efficiency (%): Coarse (>10 µm) | PM10 (≤10 µm) | PM2.5 (≤2.5 µm) | PM1 (≤1 µm) | Gas/VOC Removal | Real-Life Particle & Pollutant Examples |
---|---|---|---|---|---|---|---|
G1 | ISO Coarse | ~40% | <10% | ~0% | ~0% | Sand, textile fibers, carpet fluff, plant debris, insect wings, visible lint | |
G2 | ISO Coarse | ~50% | <15% | ~0% | ~0% | Sawdust, hair, coarse textile particles, large flakes of paint or rust | |
G3 | ISO Coarse | ~60% | <25% | ~5% | ~0% | Coarse dust, lint, animal hair, some pollen | |
G4 | ISO Coarse | 65-75% | 25-35% | 10-15% | <5% | Large pollen grains, soil particles, textile lint | |
M5 | ISO ePM10 ≥50% | ~80% | 50–65% | 20–30% | 10–15% | Pollen, mold spores, pet dander, house dust | |
M6 | ISO ePM10 (60–80%) | ~90% | 65–80% | 30–45% | 15–25% | Building/construction dust, concrete dust, ash particles, fine cement dust | |
F7 | ISO ePM2.5 (50–65%) | >90% | 75–90% | 50–65% | 30–45% | Bacteria, smog, tobacco smoke particles, combustion dust, spores, wildfire smoke particles | |
F8 | ISO ePM2.5 (65–80%) | >95% | 85–95% | 65–80% | 45–60% | Fungal spores, air pollution aerosols | |
F9 | ISO ePM1 (80–95%) | >95% | >95% | >90% | 80-95% | Diesel soot, airborne viruses, smoke from traffic and industry, combustion particles, ultra-fine dust, secondary organic aerosols from chemical reactions in air | |
Activated Carbon | Not classified (gas filter) | Varies (combined with prefilter) | Varies | Varies | Varies |
High Efficiency |
Volatile Organic Compounds (VOCs), formaldehyde, ozone, nitrogen dioxide (NO₂), sulfur dioxide (SO₂), benzene, toluene, cooking odors, cigarette smoke odors, pet smells, perfumes |
Instructions for changing the filters are provided in the manual below:
Frequently Asked Questions
Frequently asked questions ordered by popularity.


Filter class refers to the size and amount of particles a filter can trap. The higher the classification, the more effectively the filter removes particles from the air.
For incoming outdoor air, it’s generally recommended to use higher-class filters. However, we always suggest following the manufacturer’s guidance and using the specific filter sets outlined in your unit’s eco-commissioning documentation.
For more information, take a look at our comprehensive guide to filter classes for heat recovery units.




It is recommended to change the filters in your HRV every 3 to 6 months, depending on how dirty they become. However, the key signs that your filters need replacing include:
- An increase in noise from the HRV
- A reduction in the amount of air being supplied or extracted
Smart HRVs with an electronic control panel and display screen show the volume of air supplied and extracted per hour.
For example, if a Zehnder ComfoAir Q350 HRV in a 140m² home operates at an optimal rate of 190m³ per hour but drops to 150–170m³, the filters should be replaced.


- Check the label on the unit itself, which usually displays the manufacturer and model number.
- Contact your installer or the developer/builder of your property for details.
- Measure the width, length, and height of the filter, then use these measurements to browse our online shop. Our system will suggest the correct recuperator filters for your unit.
- If none of the above help, please get in touch via the chat box at the bottom right of the page, and we’ll be happy to assist you.
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