Zehnder fault code A5
Fault code A5 on an Zehnder MVHR unit (including WHR) means: The bypass damper does not open. Reset the appliance once. If the code comes back, a part is usually faulty. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code A5 on an Zehnder MVHR unit indicates: The bypass damper does not open.
Applies to
Zehnder WHR, 930 Basic, 930 Luxe, 950 Basic, 950 Luxe, 960 Basic, 960 Luxe.
Matching parts
Zehnder parts are available from Instalpunt; shipping to EU countries from €17.95 (€24.95 for more distant countries), usually 3–5 working days.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- Zehnder sensor WHR 950 fan € 27.44
- Zehnder sensor bypass/heater € 39.20
- Zehnder sensor WHR 950 Byp € 52.27
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does Zehnder MVHR unit fault code A5 mean?
The bypass damper does not open.
How do I fix fault code A5 on an Zehnder MVHR unit?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for Zehnder fault code A5?
That depends on the exact cause. In the Zehnder parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code A5 myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All Zehnder MVHR unit faults and codes at a glance →