FLEXIT Nordic S2/S3 F7+F7 Filter set (Efficient)

Reference: FLEXITNS23

delivery in 1-3 working days

Ex Tax: €11.88

Filter dimensions 166x272x48
Class EN779 F7+F7
Class ISO16890 ePM1 70%
Protection level High: fine particles, dust, pollen, mold spores, combustion particles, smog particles, insecticide dust.
Quantity of filters 2
Advantages check Made in the EU.
check Premium class certified synthetic filtering material (SANDLER AG, Germany)
check Tested according to ISO16890 at the accredited laboratory in Germany.
check Top filtering efficiency: ePM1 70%. Higher protection from smog particles, than using ePM1 50% or ePM1 55% filters.

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Data sheet

Model size
Air handling unit
FLEXIT Nordic S2
FLEXIT Nordic S3
Filter dimensions
Class EN779
Class ISO16890
ePM1 70%
Protection level
High: fine particles, dust, pollen, mold spores, combustion particles, smog particles, insecticide dust.
Quantity of filters
Made in the EU.
Premium class certified synthetic filtering material (SANDLER AG, Germany)
Tested according to ISO16890 at the accredited laboratory in Germany.
Top filtering efficiency: ePM1 70%. Higher protection from smog particles, than using ePM1 50% or ePM1 55% filters.
Manufacturer product number

The set includes 2 pcs. of high-quality F7 class filters for the supplied and extracted air filtration. Classification according to ISO 16890: F7: ePM1 70%.

F7 class filters are designed to filtrate fine particles, like solid smog particles, thus ensuring the high quality of indoor air even in heavily polluted areas.

This filter set is best suited in areas with heavy pollution: intensive traffic zones, city centers, industrial zones, and districts with solid fuel heating.

The filtering efficiency of the F7 filter:

  • Coarse particles: >99% (dust, pollen)
  • PM10 particles: >93% (mold spores, animal dander)
  • PM2.5 particles: >80% (combustion particles)
  • PM1 particles: >70% (solid smog particles, virus carriers)

Filter construction:

  • Type: MPL (deep pleat). Extra-large filtration surface.
  • Filtering material: 3-ply synthetic fiber (premium, SANDLER AG).
  • Moisture-resistant cardboard or synthetic frame (depends on filter). Operates even at 100% RH. Opposite to metal or plastic frames, such filters adapt to the construction of filter holders. Thus, ensuring airtightness and do not damage AHU's construction. 
  • Filtering material corresponds to hygienic requirements (resistant to microorganisms' growth). Certified according to VDI 6022 standard (Germany).

Advantages with other filters

  • Moisture-resistant frame, which works at 100% relative humidity. Designed to wet European climate. 
  • Airtight construction. Material is firmly glued to the frame. Hazardous particles do pass through the frame and material connection. 
  • Adapts to the construction of the equipment. As in the original filters synthetic or cardboard frame adapts to ventilation unit construction and does not damage it (especially EPP casing).
  • Filters made in the EU and tested according to ISO16890.  Cheap filters from China mostly are not tested and only theoretical filtering efficiencies are being provided. 
  • Filters are made from premium 3-ply synthetic material. Unlike glass fiber, it is safe and not fragile. 3-ply material ensures high dust holding capacity and longer servicing term. 
  • Top filtration efficiency – ePM1 70% (most analog filters 55% or even in the lower class ePM2.5).

Replacement period: replacement period depends on outdoor air contamination. Expected service term: 4-6 months. Do not wash or clean. Single-use only. 

Additional information:

  • Packing: filters are packed in plastic film suitable for long-term storage.
  • Warranty: 2-year storage warranty if kept in proper condition and package.
  • Storage conditions: internal premises, RH<60%, low dustiness.
  • Made in the EU.

For an extra discount for higher quantities of filters please contact us directly.

The filter is high quality for analog, perfectly suited to your air handling unit. 

General recommendations:

  • Filter contamination is monitored by the timer in the control device. Filter change alerts are shown in the control panel or the mobile application. 
  • Filter change indication works as a reminder. AHU will operate despite this warning. 
  • The replacement period depends on outdoor air contamination. You might be needed to replace filters up to 1.5-2 times more frequently, if you live near intense traffic roads, paved roads, construction sites, industrial areas, working fields, etc. 
  • Most manufacturers recommend changing filters at least twice a year: before and after the heating season. 
  • Recommended replacement terms: activated carbon filters: up to 3 months, F7 filter - 4-6 months, M5, G4 filters - 5-8 months. Energy-efficient filters last 1.3-2 times longer. F7, F8, and F9 filter servicing terms can be prolonged up to 2-3 months if an additional G4 class prefilter is being used in the ventilation system. 
  • The extracted air filter can be changed less frequently, if you are using efficient F7, F8, F9, or activated carbon filters for outdoor air filtration.  
  • Panel/pocket filters are single-use only. Vacuuming or cleaning will not provide the desired effect, only can damage the filter. Efficient filtering material captures small particles inside and it clogs the filter. 
  • Wire-framed filters and filtering materials can be vacuumed up to 3 times before replacement if the user manual allows it.
  • Keep the flanges of your new ventilation unit covered before its first launch, in order to avoid quick filter contamination. 

Universal instruction

  • Always check the user manual if changing filters for the first time. 
  • Before proceeding turn off the ventilation unit and wait until the fan stops rotating completely.
  • Remove the front cover or filter cover.
  • Remove old filters.
  • Clean the unit with a vacuum cleaner and clean filter holders with wet wipes.
  • It is recommended to check other AHU components also: rotor belt, heat exchanger, fan impellers, etc. And clean if necessary.
  • Check the airflow direction before placing the new filters. Filters have airflow arrows on the labels they must match airflow direction. Usually, filters are installed before the heat exchanger, so arrows must point toward the center. However, if 3 filters are used there might be exceptions: if F7 or F8 filter is on the opposite side of the heat exchanger from that G4 filter, the airflow must point away from the heat exchanger. Most manufacturers placed arrows on the ventilation unit in order to install filters correctly. If filters are installed in the opposite direction, pressure resistance may increase up to 15%.
  • If you have filters of different efficiencies, e.g. F7 and G4. F7 filters must be installed on the Outdoor air side, and G4 on the Extract air side. The manufacturer marks them nearby duct connection flanges. Usually, the outdoor air duct is insulated and the extract air duct is not. Also, you may check the user manual, but pay attention, that it might be the right and left versions on the unit.
  • After installing new clean filters put the cover back. Then turn the device on.
  • Also, you will need to restart the filter timer on the control device according to user manual instructions.

Do not operate the air handling unit without filters, it will clog your heat exchanger and contaminate the ventilation system. Also, your warranty will be void.

Contaminated filters provide higher airflow resistance, and it lead to lower airflow volumes, higher energy consumption, and higher sound emissions. Change them on time and the ventilation unit will operate longer.

We are keen to supply you with top-quality air filters for the perfect indoor climate at the best price. We offer more than just a filter:

  • Experience and professional support: our consultants have long-term experience in HVAC production and service fields.
  • Wide range:  multiple options, including activated carbon, and energy-efficient filters for the most AHUs.
  • Fast delivery: over 40000 filters in our production warehouse are ready to be shipped next/same working day.
  • Quality materials:  filtering materials are made by leading companies such as SANDLER AG and have high efficiency and dust-holding capacity.
  • Top quality: all the filters, including of G4 class are glued to the frame to ensure maximum airtightness. 
  • Low prices: due to the short supply chain and high volumes we offer probably the best prices for quality filters in the EU.
  • Made in the EU. Over 85% percent of the ventilation filters sold in the EU are made in China from low-quality materials. 
  • Tested efficiency. Filters are tested in an accredited laboratory in Germany according to ISO16890 standards 


Filter is a replaceable component of any ventilation equipment therefore sustainable production and logistics play a key role.


  • High-quality 3-ply filtering material has a larger dust-holding capacity. Therefore, filters serve longer, and less material can be used in production.
  • We do not use glass fiber material in filters. Glass fiber is fragile, potentially hazardous, and non-recyclable.
  • Panel filter frames are made of moisture-resistant cardboard. The supplier uses the maximum possible amount of recycled cardboard production.
  • Energy in production plants comes from renewable sources.
  • Filter frames for certain Zehnder ComfoAir models are made of eco plastic with organic materials content of more than 80%.
  • Offer filter options made of energy-efficient materials, with 1.3-2 times longer replacement periods.
  • Due to patented technology, we use 30-50% less glue than used in other alternative filters.


Shorter delivery distance:

  • Materials for production are made by factories located in the EU countries.
  • Filers made in the EU (more than 80% of filters in the market are made in China or other Asian countries).
  • We deliver directly from the production warehouse.

We are constantly searching the ways to provide more sustainability to your filter!

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