Zehnder malfunction
Zehnder ventilation unit is making noise
Is your Zehnder ventilation unit, HRU, or ventilation motor making more noise than usual? A humming, grinding, rattling, or whirring sound often indicates wear, fouling, imbalance, or a motor that is no longer running smoothly.
- Humming or grinding sound
- Vibrations or resonance
- Overhaul often possible
What do you notice?
- The ventilation unit or HRU is making more noise than before.
- You hear a humming, grinding, rattling, or whirring sound.
- The sound gets louder at a higher ventilation setting.
- The unit vibrates or resonates through walls, ceilings, floors, or ducts.
Possible causes
- Worn bearings or rotating parts.
- Dirt, dust, or imbalance in the fan.
- Wear on the motor, rubbers, or mounting points.
- Age of the ventilation motor or control system.
What can you safely check yourself?
Listen carefully to the type of sound. A grinding or whirring sound often indicates bearings, while humming or vibrating can also be caused by imbalance, fouling, or resonance. Always switch off the unit before opening or inspecting it.
Are you unsure about the cause?
Use our troubleshooting guide to determine step-by-step which malfunction best suits your Zehnder ventilation system.
Start the troubleshooting guideWhen is an overhaul possible?
An overhaul is often worthwhile when the noise is caused by wear to bearings, motor components, or rotating parts. Many Zehnder motors can be overhauled, meaning replacement is not always necessary.
Choose the right solution
Is your problem or model not listed?
Use our troubleshooting guide or parts finder. We are happy to help you find the right solution.
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