Support and FAQs
Do you have a question about your bought products (HRV Filters and probiotics), then you can use our support page to contact us. At the right of this page you can find a form that you can fill out to contact us. You can keep track of the status of your ticket in your account and by using your e-mail address.

Frequently Asked Questions (FAQ)

Find your answer to most of your questions on HRV filters and maintenance, replacement of HRV Filters, what and how on Heat Recovery Systems and how HRV works. If your question is not amongst the FAQ's then please feel free to contact us. We are happy to assist you.
1 What is MHRV
1.1 MHRV stands for Mechanical Heat Recovery Ventilation. But what is it exactly?
Heat recovery (HRV) ventilation is a ventiolation system for the discharge of polluted air and the supply of clean air inside homes and offices. The exhaust valves are in the bath room, toilet and kitchen. The heat recovery system then uses the heat from the exhaust air to warm up the supplied air. Of course without mixing with the dirty exhausted air. The warmed fresh air is supplied via the ducts into the homes.
2 MHRV Maintenance
2.1 What would be the best way to maintain my HRV system

Check and replace your filters regularly. The frequency for replacing the filters depends on your living situation (rural or in the city) and your health. In between maintenance will not only benefit your health but also that of your heat recovery unit. Learn more about the importance of (small) maintenance.
In addition to replacing the filters yourself  you can also easily clean your heat recovery unit. You remove the HRV filters from your system and screw the front cover loose.
You will then see the heat exchanger, which you can easily take out yourself for cleaning See how here.

2.2 How often should i maintain my Mechanical Heat Recovery Ventilation System (MHRV)

You can easily do minor maintenance yourself. However it is recommended to maintain you system more extensively every 3 to 4 years. Including the inspection and cleaning of air ducts internally and the valves. The degree of maintenance depends on your environment. 

3 Replacing HRV Filters
3.1 When should I replace my HRV filters
it is advised to replace your HRV filters 2 times a year. Depending on your living situation. In cities or close to public roads or high ways it is adviced to replace them more often than in a rural setting. Don’t vacuum clean the filters or wash them in the washing machine. The structure of the filters will damage and the density of the filters will drop. Which means that they capture less dirt and dust. Replacing filters can be easily done by yourself. 
3.2 How do I replace the HRV filters

There ae roughly 2 types of filters. With or without wired frames. The wired frame type is a frame with stitched filter cloth around it. AWB, Brink, Orcon, NedAir, Rucon and Velu are brands who used these type of filters.

Folow these steps to replace wire frame filters in your system. 

  • Remove the power plug from the socket
  • Remove the panel from the front by sliding or rotating. For exact removal we refer to the manual of your MHRV unit. You can find it on our user guide page.
  • Pull the dirty filters from the systeem.
  • Trek vervolgens de vervuilde filters uit het systeem. Place the new filters in the unit.  We advice to syringes the filters with probiotic filters spray against fungi and bacteria.  Good for your system and good for your indoor climate.

Filters without wire frame are produced by the following manufacturers
Zehnder J.E. StorkAir, AGPO Ferolli, ITHO Daalderop, Bergeschenhoek and Zehnder 

Folow these steps to replace wire frame filters in your system.

  • Remove the power plug from the socket
  • Remove the filters by pulling the handles on the front side.
  • Remove the dirty filters from the frames
  • Place the new filters on the frames and slide them in your unit. We advice to syringes the filters with probiotic filters spray against fungi and bacteria before you put them back in your system. Good for your system and good for your indoor climate.
  • Place back the front panel of your system. Power up the system by inserting the plug in socket.


3.3 What type of filter do I need for my HRV unit

There are many brands and types of filters. There are also types which are the same but have a different brand name. If you don’t exactly know which brand HRV system you have then there is another way to find the correct filters for your unit.

  • Measure the size of your filters and search in our shop.
  • Do you have wired framed filters? (metal wire frame with stiched filter cloth)
  • Do you have a ‘washing mitt’ model? (stiched filter cloth in the shape of a washing mitt.)
  • Do you have a ‘plug-in’ model? (filter hems which slides over metal pins)

If you search on sizes in our shop you will see different filters. Each filter has its own specifiactions. When you are not sure you can contact us by email. Send us the details or picture of the filter and we are happy to help you further.

3.4 Which HRV system do I have

Different Ventilation systems:

  • Ventilation system where only polluted air is discharged. This system does not supply clean / fresh air. These systems do not have filters.
  • A ventilation system where polluted air is discharged and which supplies fresh air. These systems have filters as incoming air needs to be filtered. Deze systemen hebben filters.  

When you’re still not sure which system you have or you might have additional questions please send an email to [email protected]


3.5 Why are clean filters important

Clean filters are important for your and the people around you. But also important for maintaining your system. Dirt, bacteria and fungi accumulate in the filters, the system and the air ducts. Over time, the filter becomes saturated and your system has to work harder to get airflow around. This costs more energy and therefore money. 
In addition you don’t want bad bacteria, germs and fungi back in your indoor climate as this is bad for health conditions. 

3.6 Where can I find user guides and manuals about replacing HRV filters
User manuals can be found on our user manuals page. Fairair has collected many different types and brands on this page. When your system is not listed please send us an email. 
3.7 Which filter types and classes are there

Filter class is a term used with air filters to display the efficiency of a filter.
A filter class is determined and awarded by tests which are part of the European EN779 norm.  For G1 t/G4 the capture of test dust is measured. For fine filters (F5 –F9) DEHS efficiency tests are part of the EN779 norm. (see norms). 

Depending on the percentage of captured pollution a filter class is awarded. Here you can see an overview of types and classes.

Filter classes are indicated by G and F

  • G1 - G4
  • F5 - F9
4 Shipping
4.1 When will my order be delivered

When will my order be delivered?

Depending on weight, volume and the delivery address your order will be sent by TNT or DHL. Letter mail is delivered the next day by TNT (in NL). Orders placed over the weekend will be delivered on Tuesday or Wednesday. PostNL does not process packages on Sundays and Mondays. The delivery time by DHL is 2 to 4 days. Depending on the time of order. 

4.2 Which couriers are used to ship my order
Depending on the chosen product and quantity packages will be delivered by PostNl, DHL or DPD. Mailbox mail will be delivered the next day in NL. Other packages will be delivered in NL and the rest of Europe by DHL or DPD.
4.3 Is my order insured?

Is my order insured?

When your oder is payed with your creditcard then it is insured by your credit card company. When you encounter problems during the delivery of your order please contact our service department. Together we will find a solution to take care of he occurred problems

4.4 Which costs are charged for shipping

In our shop you can calculate the shipping costs. Enter the product, quantity and address and see the delivery costs. When ordering above a certain amount discounts will be given during checkout. Check our web store to see the discounts given.

5 Payments
5.1 How can I pay at


How can I pay at

In our web shop you can pay with PayPal, Sofortbanking, Mister Cash and Ideal. Within the PayPal environment you can pay withouth having an PayPal account. It is also possible in the PayPal environment to pay with Mastercard and Visa credit cards.

On our payment methodes page we have described the payment methods in more detail. 

5.2 Is it safe to pay at

Yes! Fairair uses Sisow as their payment Service Provider. They are specialist in online payments and provide high security methods. They handle all payments of fairair. You are secured that your payments are processed within a safe environment.

Sisow is licenced by the DNB, De Nederlandsche Bank. Would you like to know more in detail about payment methods we provide then you can check these on our page payment methods.
6 Returning
6.1 What is the ultimate deadline for returning an onder

The deadline for cancelling is 14 days. After this term you have another 14 days to return the product in original unused state and packing. For details check our page send and returning.

6.2 How Can I return my HRV filter

You can send an email to [email protected] to inform us that you would like to return your ordered products. We will be then in contact to process your return request. 

6.3 Can I receive back my money when returning goods
If you are not satisfied about the ordered products and would like to return the goods than this is possible. It is also possible to receive replacement products without any costs. Please contact [email protected] to apply for the returning.
6.4 Can I receive another HRV filter when I am not satisfied

If you are not satisfied about the quality of our products we would like to know why. Together with you we will look for  an acceptable solution which could be that we send you a new set of filters.

7 Probiotics
7.1 What are probiotics?

Probiotics is a totally new alternative to conventional desinfectants. It is a complex biological product that contains detergents, enzymes and probiotics. i.e. Good bacteria in fight against bad bacteria. Harmless to humans and animals. These probiotics ensure a stable and healthy microbial environment. Good to protect your HRV unit and good for your indoor climate and therefore for your health.

7.2 Why are probiotics good for my HRV system and HRV filters?

Filters, ventilation ducts and the ventilation unit itself are an ideal environment for bacteria and fungi. This pollution is bad for your health and your system. By using probiotics you make sure your filters and unit stays clean longer and therefore stays in good condition longer. Also these bad bacteria and fungi  can’t get into your indoor climate anymore.

7.3 Which probiotic product can I use best for my HRV filters

For impregnating your filters it is recommended to use the f’air filterspray.
Spray your filters lightly before you place them in your system. Id is advisable to spray your filters in between time as well. You’ll see that your filters last longer. As well as your system. 

7.4 Which probiotic product can I use best for my MHRV system
Depending on the amount of pollution you can use f’air probiotica Power cleaner for the more heavy pollution and the f’air foam cleaner for the more light pollution. Would you like to see how you can maintain your MHRV system yourself? Have a look at our following page where you’ll find the instructions.