Fault rectification
Fault finding and repairs only permissible when carried out by qualified electricians.
Danger to life from electric shock.
- Prior to accessing the connection terminals, switch off all supply circuits. Switch off mains fuse, secure against being accidentally switched back on and position a visible warning sign.
Fault | Cause → Measure |
|---|---|
Fan performance inadequate. | Dirty filter. → Replace filter. Locking hook not engaged. → Engage fan insert correctly. Incorrect duct diameter. → Check diameter of the main duct. Supply air cross section is too small. → Increase the supply air cross section. |
VZ-, VZ 15-, VZC-, F-, H- and I models: No fan overrun. | The external conductor L connected to terminal 1 is interrupted when the unit is switched off. → Connect unit as per wiring diagram. |
VZ, VZ 15, VZC, I models: “Fan starts up immediately and stops immediately if is switched off. | Terminals 1 and 3 are reversed. → Connect unit as per wiring diagram. |
Fan doesn’t start up. | Check whether the fan insert is correctly inserted. |
Fan is too loud. | Dirty filter. → Replace filter. Fan insert incorrectly installed. → Insert fan insert correctly in accordance with these instructions. The main duct is undersized. → Re-calculate pressure losses. |
H model does not switch from base load to full load operation despite there being moisture in the room. | There was no rapid increase in humidity (7% in 2 minutes). |
H model no longer switches back to base load operation or off even after a long period in full load operation. | The value has not yet fallen below the reference value. After 1 h, the valve automatically switches from full-load operation to base-load operation after a follow-up time of 15 minutes and resets the reference value. |
Additional consumers connected to terminal 4. | Damage to the unit if connected incorrectly. Do not connect additional consumers to terminal 4. The unit may only be connected according to the wiring diagrams (Wiring diagrams). |
If the fault persists or reoccurs: Disconnect the unit completely from the power supply. Let a qualified electrician determine the cause of the fault and eliminate it. If you have any question relating to troubleshooting: Service: +49 7720 6940.