All about wtw filters aims for a sustainable future, which means that for we only purchase and process ISO certified filter material, develop new products or incorporate already developed products into our range.

A great example of this is the bioHoKu® filter frame.

The first bioplastic filter frame! With bio HoKu®, Tecnofil AG Filtertechnik is setting new standards! The proportion of organic content is more than 80%. PLA (polylactic acid), which is made from renewable raw materials, is used here. A recycled PLA without microplastic is used.


Plastics obtained from biomass give off only as much CO2 after use in conventional disposal as the plants absorbed from the atmosphere during their growth phase. Bio-plastics are therefore climate-neutral and have only a minimal impact on the environment. Depending on the type of plastic, CO2 savings of 60% to 80% are achieved compared to conventional petroleum-based plastics.

A proper ventilation system ensures a healthy and comfortable indoor climate. To maintain a healthy climate in your living environment, WTF filters should be replaced periodically with the right type of filters.

This ensures fresh air in your living environment and is also beneficial for your energy consumption! This allows you to achieve the highest possible efficiency and save costs on maintenance.
WTW-FILTERSHOP.NL supplies original wtw filters for a large number of brands.
Original replacement filters are a not insignificant cost factor, therefore compare our house brand replacement filters HQ-FILTERS.NL as a cheap and high-quality alternative for your ventilation device.

What do WTW filters do?

For a properly functioning WTW(HeatRecovery) system , WTW filters are needed. Almost every heat recovery unit has two filters, one for the supply and one for the return air.
(Sometimes there are more than two filters, but the principle remains the same).
A ventilation system that only supplies air from outside has one filter that filters the outside air before it enters your home.
One of the two WTW filters ensures that the air is filtered before it enters the house. Depending on the filter class of these WTW filters, soot particles, (fine) dust, pollen, bacteria as well as smells and insects are stopped. The other WTW filter filters the air leaving your home. The main purpose of this filter is to protect your ventilation unit from dirt being vented out of your home, whereby your CHW unit lasts longer and requires less maintenance.

How a WTF filter works

This may seem simple in theory, but in practice they are extremely complicated products. The filter fibres, without offering too much resistance, have to let just enough air through and capture harmful particles at the same time.

What are wtw filters made of? supplies wire frame filters and filter covers made of high-quality polyester fibres, which are heated on one side during production. In the process, the fibres partially fuse, increasing the filter efficiency. The build-up also ensures that a dust cake forms in the filter within a foreseeable time. This layer is beneficial for efficiency.
Our Z-line filters contain filter media made of 100% synthetic materials and offer a very large filter surface area.
The minipleat filter features an even much larger filter surface area . These air filters can therefore store more dust particles, reducing the need for frequent filter changes.
Carbon filters are impregnated with highly active carbon that filters chemical contaminants and odours out of the air.
With wire frame, the filter cloth is sewn around a galvanised wire.
Z-line filters feature a perforated waterproof cardboard , plastic, Bio plastic, or galvanised metal frame.

When should you replace wtw filters?

For your health, it is important to replace wtw filters regularly.
Dirty filters create more resistance, which will cause the system to consume more energy.
In a newly built house, we recommend replacing the heat exchanger filters after the first month of operation and then at least every 2 months. This is because of all the building dust still present in your house.
Normally, it is recommended to replace the WWTP filters at least twice a year.
It varies per environment and thus per house how quickly the heat exchanger filters become dirty.
When the filters are very dark or black, they should be replaced immediately.

After replacing the filters a few times, you will know yourself when it is necessary.
By replacing the wtw filters on time, you will save on maintenance costs for cleaning the wtw unit and air ducts.

Can you clean wtw filters?

WTW filters are air filters, and cannot be washed out.
By some manufacturers of cogeneration units, the manual recommends vacuuming the cogeneration filters, for hard filters this could be done with a soft brush, for softer filters this is definitely not recommended as it breaks down the structure of the filter medium, making it less effective. Moreover, cleaning does not remove the bacteria. These will therefore continue to multiply lustily and eventually end up in your indoor environment.

Bacteria and fungi

Contaminated WTF filters are bad for your health and it costs your ventilation unit more energy to maintain its air exchange capacity. Health problems arise because bacteria and fungi start growing in the wtw filters and air ducts. It is recommended anyway to disinfect the system with Protect spray at the same time through the filter holder openings at the bi-monthly check-up and/or filter change.

The right heat exchanger filters for every need

The right WWT filters for every need
By default, most WWT units are equipped with filter class G3 ISO Coarse 50% or G4 ISO Coarse 60% also called a coarse filter.
The standard filter can be used to clean the air on both the inlet and outlet sides of all ventilation systems. The filter can effectively remove particles larger than 10 .m, including visible dust. You can read more about filter ratings here.
Do you have sensitive airways or are allergic? Then an F7 ePM1 70% pollen or particulate filter literally brings relief. The pollen filter minimises the amount of dust and smaller particles like. pollen in the fresh air in your home sent.
The hq power filter is an upgrade for your ventilation system. If you live near busy roads, industry or large ports with freight or ferry traffic, the hq-powerfilter is something you should be interested in.
The structure of the hq power filter is finely pleated in minipleat technology, separated by hot-melt separators that allow the formation of rigid pleats. The filter package is then securely glued into the waterproof cardboard housing.
The filter material is polyester, which ensures the physical durability of the filter, even in places with humid air
This minipleat technology provides the largest possible filter surface area, ensuring maximum filtration performance.
The minipleat medium with increasing density on the air outlet side of the filter ensures very low resistance throughout the entire period of filling the filter with impurities.
Our hq power filters are made from materials that comply with high energy classes to ensure the lowest possible electricity consumption by your ventilation system.
Or a carbon filter (carbon) that filters out chemical pollutants and odours from the air of, for example, fireplaces, wood stoves and in environments close to industry. The filter is very effective against nitrogen oxides (NOx) and sulphur dioxide (SO2). If you want to get rid of unwanted odour nuisance, you can choose to install a carbon filter in your ventilation system. You can use a carbon filter all year round or just while you are firing.

Filter standards (these are the same for both ventilation filters and filter cloth)

The filter standard : EN799:2012 has been replaced since 1 July 2018 by the filter standard : ISO16890
Here, filters are classified into so-called ePM categories.
This classification gives an accurate indication of which particle sizes are filtered out of the air.
PM1 stands for all types of particulate matter smaller than 1 micron (μ = one thousandth of a millimetre):
  • PM1: 1μ = 0.001 mm
  • PM2.5: 2.5μ = 0.0025 mm
  • PM10: 10μ = 0.01 mm
The 'e' for PM1 stands for 'efficiency' and indicates the efficiency of the air filter in capturing PM1.
Using these values, the standard now splits filters into four groups that filter different dust particles:
  • ISO Coarse < 50% (sand, lint, hair)
  • ISO ePM10 ≥ 50% (pollen, stone dust)
  • ISO ePM2.5 ≥ 50% (mould spores, toner dust)
  • ISO ePM2.5 carbon filter (carbon) filters chemical pollutants and odours from the air of e.g. fireplaces, wood stoves and in environments close to industry. The filter is highly effective against nitrogen oxides (NOx) and sulphur dioxide (SO2).
  • ISO ePM1 (combustion particles, nanoparticles, viruses)
The old standard EN779:2012 and the corresponding filter class G3-G4-M5-F6 etc. serve as a reference to the new standard ISO16890.

Changing filters

For air filters to work properly, the filters must be placed correctly, all air filters have a suction and a clean air side
For wire frame filters and filter covers, the suction side is fluffy and the clean air side is smooth, the clean air side is also often printed and should be placed towards the heart of the unit. PPI mats as found in the first wtw units have no difference and can draw air from both sides.
For cassette or panel filters, there is an arrow on them for the air direction, this arrow should point towards the heart of the unit.
Before changing filters, read your manual, or ask for information from our support desk.
For most appliances, the same actions apply:
Remove the power from the appliance by unplugging the plug.
Remove the dirty filters from the appliance (note how they are placed)
Place the new filters back in the appliance in the same way
Plug in the power supply and the WWTP unit will automatically start the start-up programme or follow the instructions on the display.
reinigen met green xl


Maintenance is essential for all HVAC (Heating, Ventilation and Air Conditioning) systems. With our cleaning and protection products, you can perform this maintenance in a safe and environmentally friendly way and save on maintenance costs.
A WWT unit should be cleaned on average every three years and ventilation ducts every eight years.

Protec spray - Green XL - 200ml. - PROBIOTIC PROTECTION

For perfect protection between maintenance intervals.
This spray is perfect to use for cassette units, among others, but also for on the filters of WTW or Airco.
  • Maintenance and protective spray with probiotic-based biological protector
  • Powerful protective cleaner with long-lasting effect
  • Dries streak-free and leaves healthy microflora behind
  • Removes dirt effectively without damaging the surface
  • Improves indoor air quality
  • DO NOT rinse with water ! Leaves a fresh scent

FOAM CLEAN - Green XL - 500ml - PROBIOTIC CLEANER (for indoor use)

- Powerful foaming - Produces a healthy environment - Biodegradable
Powerful probiotic foam cleaner with microscopic deep cleaning technology that cleans and degreases with long-lasting effect. A non-aggressive biodegradable cleaner that is safe to use on all surfaces and promotes a healthy indoor environment.
Where is Green XL Foam Clean used?
Green XL Foam Clean can be used to clean various surfaces. Such as the heat exchanger and the inside of your WTW-Unit. In addition, you can also safely use it to clean the inside unit of your air conditioning system.


Powerful protectorPromotes a healthy EnvironmentLong-lasting effectLeaves a wonderful scent behind
  • Maintenance and protective gel with probiotic-based biological protector
  • Powerful protective cleaner with long-lasting effect
  • Dries streak-free and leaves healthy microflora behind
  • Removes dirt effectively without damaging the surface
  • Improves indoor air quality
  • DO NOT rinse with water ! Leaves a fresh scent

What is probiotics

This cleaning and protection product from Green XL allows you to carry out maintenance of all HVAC systems in a safe and environmentally friendly way. Probiotics is a formulated biological product containing detergents, enzymes and probiotics. This product cleans the "surface" 0and neutralises all odours, effectively reducing the risk of harmful fungi and allergens. This cleaner therefore works better than conventional chemical products and organic cleaners. Green XL cleaners contain a concentrate of beneficial bacteria that have a cleansing effect and reduce the risk of germs in your air-conditioning system.


Filter cloth is available from G2 ISO Coarse 50% to M6 ISO ePM10 70% (see filter standards) in any size in the 2 x 20 metre range.
The most commonly used filter cloth is synthetic filter cloth. This filter material is often used as pre-filter in paint shops, forced air convectors, window vents, small air conditioners. ventilation systems and for heat exchangers and fan coil units.
The suction side is fluffy and the clean air side smooth, the clean air side is also often printed. With blue/white filter cloth, the white side is the clean air side.
Paintstop is mainly used in paint shops to capture dry or wet paint particles from the exhaust air stream.
The successful secret of this paint mist filter is the finely spun glass threads, progressively constructed with great resilience. This Paintstop paint mist filter meets all quality provisions and is fully compliant with the applicable environmental standards. Here, the white side is the clean air side

PPI filter cloth

is a foamed plastic filter medium with an open cell structure that is somewhat cleanable and is often used for situations where coarse dust particles need to be removed from the airflow. In air conditioning systems, hoovers, air filtration for cars and engines, extraction of machinery. Their 3D effect allows them to handle the airflow on both sides.

Window ventilation filters

HQ ventilation filters are a foamed plastic filter media and can handle airflow on both sides due to the 3D effect.

Active carbon mat

This is a carbon-impregnated filter foam and can handle airflow on both sides.
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