Servicing your Zehnder ventilation unit
Zehnder is one of the heat-recovery ventilation brands most often found in Belgian homes. It comes in several generations: the WHR and ComfoD units from the StorkAir era, then today's ComfoAir Q and ComfoAir E.
We service all of them. The principle is the same, filters, heat exchanger, fans, condensate drain and valves, but each generation has its own points to watch.
The Zehnder units we service
ComfoAir Q (Q350, Q450, Q600)
Current generation, run from a display.
ComfoAir E (E300, E400)
The brand's other current range.
ComfoD (150 to 550)
Previous generation, still very common.
WHR 930, 950, 960
Older StorkAir units, still running in many homes.
Independent of the brand
What matters on a Zehnder
The filter change reminder
On a ComfoAir Q, the display tells you when the filters are due. After the service we reset that counter so the next reminder comes at the right time.
The condensate trap
In winter the exchanger produces water, which drains through a trap. If the trap dries out it lets air through: the unit whistles and can smell. We check it and refill it on every visit.
Zehnder-size filters
Each generation takes its own filter sizes. We note the exact model and reference. Filters are not included in the price: you are told their cost before the visit.
What this service costs
One price per system, published before you book, with no questionnaire to fill in to get it. Anything out of the ordinary (a lot of valves, an unreachable unit, a system never opened) we tell you before the visit, never on the invoice.
Prices exclude VAT. 6 % on servicing in a private home over ten years old, 21 % otherwise.
What the service includes
Filter replacement, on request
Filters are not included in the displayed price: what they cost depends on the model. Ask for replacement when you book and we tell you the amount before the visit. We fit the classes recommended by the manufacturer (typically ISO Coarse on extract and ePM1 on supply) and note the exact reference for your future orders.
Unit and heat exchanger cleaning
Casing stripped down, impellers de-dusted, plate or rotary exchanger cleaned, condensate tray and drain checked.
Valves and grilles
Extract and supply valves removed, cleaned and refitted without altering their original setting, a frequently missed detail that unbalances the whole system.
Airflow measurement, optional
Room-by-room measurement with a flow meter, before and after the work, added for 15 € when you book. Readings are compared with the design flow rates (NBN D50-001) and recorded in the report.
Electrical and mechanical checks
Motor, bearings, direction of rotation, humidity and CO₂ sensors where fitted, and the controls (switch, remote, home automation).
Service report
A written document covering the condition found, the parts replaced, our recommendations, and the measured airflow if you took the option. Useful for a building manager, a landlord or a future sale.
Prefer to change the filters yourself between services? Our catalogue lists the filters that fit each Zehnder model.
Frequently asked questions
Can I change the filters on a ComfoAir myself?
Yes, and it is a good habit between services. We show you how during our visit, and you will find the filters that fit your model in our catalogue.
Do I need a Zehnder-approved installer?
Servicing a ventilation system is not restricted to the brand's installers. If your unit is still under warranty, check its terms: some require regular, documented servicing. Our written service report is there for that.
How often should a Zehnder be serviced?
Manufacturers generally recommend a filter check every 3 to 6 months and a full service once a year. After a first visit, we tell you the realistic interval for your system.