Heat Recovery System

VSN also cleans Heat Recovery Systems, or simply WTW systems. In this system, air is extracted from the so-called wet areas such as the kitchen, toilet, and bathroom.


Characteristic of a home with a WTW system is the absence of vents above the windows. All airflows run through the ventilation ducts.
The warm air leaving the house heats up the incoming air from outside through the heat exchanger, achieving an efficiency of up to 95%.
Fresh outdoor air enters the home through clean air supply grilles in the so-called dry areas such as the living room, bedrooms, and hallway.
The warmed air drawn in from outside is filtered for a comfortable and healthy indoor climate. Because the polluted air releases its heat to the fresh supplied air, this results in significant energy savings. It is important to regularly clean the filters in the WTW unit with a vacuum cleaner (never wash) and replace them with new filters once a year.


It is also possible to install a pollen/fine dust filter. The type of filter depends on the brand/type and year of manufacture of the WTW unit.


Maintenance service
Our approach:
We use rotating brushes that are inserted into the exhaust ducts through a flexible hose. The rotating brush loosens all the dirt in the exhaust ducts. This dirt ends up on the filter of the WTW and is then vacuumed away. Ultimately, both the ducts and the WTW unit are clean again. This way, you can enjoy a properly functioning WTW system and a healthy indoor climate. To prevent the formation of bacteria, the heat exchanger and filters are treated with probiotics.


The benefits of cleaning with a rotating brush are:

  • Quick results
  • Professional cleaning
  • Removal of all dirt from the exhaust ducts


When using the rotating brushes, it is crucial to ensure that no cables/electrical wiring, such as those from solar panels or internet, have been pulled through the ventilation ducts. If this is the case, we will discuss how and whether these ducts can be cleaned.

During the cleaning of the WTW system, it is essential to clean the entire system, including both the unit/motor and the entire exhaust duct system. If only the WTW unit is cleaned, the dirt present in the exhaust ducts will quickly dirty the unit/motor again.


If there are other tasks that need to be performed, we are happy to assist, but always in consultation with you. For example, replacing or repairing the system due to malfunctions.

Complete major maintenance for the WTW system, excluding the supply ducts:

  • Set the system to the highest setting and perform a baseline measurement.
  • Remove and clean all existing exhaust valves per household.
  • Seal off and brush clean all existing exhaust ducts.
  • Remove and clean all existing supply valves per household.
  • Rebalance and reinstall all existing ventilation valves.
  • Clean the heat exchanger (with probiotics), clean motors, and check the condensate drain.
  • Treat the filters with probiotics.
  • Brush clean the supply and return ducts exiting the house.
  • After everything is cleaned and reinstalled, measure the function and balance of the exhaust and supply valves per household using a measurement report.


Complete cleaning of the WTW system takes up to 2 hours.
We perform the above-mentioned tasks for €195.00 including VAT, excluding travel expenses and any materials/filters.


Air supply ducts
If you reside in an area surrounded by airports or industries, it’s advisable to have VSN also clean the air supply ducts.
Cleaning the air supply ducts requires temporarily rerouting the duct system of the WTW. Please inquire about the possibilities, as this may not always be feasible.
For cleaning the air supply ducts, VSN charges an additional fee of €90.00. The extra work will take approximately 1/2 hour.


If your WTW unit displays an error code or if there are issues with the motors, please contact us for possible repairs or servicing.


This is a cleaning agent composed of beneficial bacteria that prevent the growth of harmful bacteria. Probiotics represent a completely new alternative to conventional disinfectants. It is a composite biological product containing detergents, enzymes, and probiotics. In other words, good bacteria fighting against bad bacteria. Harmless to humans and animals, these probiotic agents ensure a stable and healthy microbial environment. They are beneficial for protecting your system and improving your indoor air quality, thus contributing to your overall health.

Need questions answered or more information?

Transistorstraat 58C
1322 CG Almere


088 536 0 536
(local rate)





Office Hours
Monday to Thursday:
09:00 – 12:00 and 13:00 – 15:00
09:00 – 12:00

Upload a photo of your current installation (max 20mb) (preferably: from one meter away)
Drop files here or
Max. file size: 20 MB.
    This field is for validation purposes and should be left unchanged.