KOJA 0603, Instruction For Operation And Maintenance

Page: 46 / 52

AIR HANDLING UNIT FUTURE
INSTRUCTIONS FOR OPERATION AND MAINTENANCE
Air flow meter FIZM
46 V. 2.0 2017-02-13
14.1. Fan malfunctions and their possible causes
14.1.1. Casing fans (AC, EC, PM)
Fault condition of the AC fan The fan vibrates, produces noise or resonates.
• Check that the impeller rotates freely by rotating it by hand, and that it does not come into contact with the
shaped inlet or other parts of the unit.
• Check that the impeller is clean and has no external damage. Clean the impeller with a vacuum cleaner
that has a soft brush nozzle, if necessary. Contaminants on the impeller may cause imbalance and ulti -
mately damage the fan.
• Rotate the impeller by hand and listen to the sound from the bearings. A broken/damaged bearing
makes an abrasive or rasping sound.
• Check the condition of the bearings by pulling the upper edge of the impeller back parallel to the
shaft. The shaft should not move. If the shaft moves inside the motor frame, it is likely that the bearing
has broken.
• Check that the EMC shielding applies to the whole connection chain (see Instructions for operation
and maintenance, page 31).
• Check that the bearing bush is tightly attached and the mounting bolts have been tightened properly.
• Check the condition of the vibration dampers. The material of the rubber dampers should be soft, and
the fan should ‘float’ on the rubber. This can be checked by swinging the fan laterally, whereupon the
rubber dampers should follow the movement of the fan. When rubber hardens, it loses some of its
damping capacity and the vibration in the fan is transferred to the frame of the unit.
• Check that the flexible connector of the fan is installed correctly so that the connector allows move -
ment in both directions. If the connector is installed incorrectly, it will stress both the shaped inlet in
the fan and the fan wall.
Fault condition of the EC fan The fan vibrates, produces noise or resonates.
• Check that the impeller is clean and has no external damage. Clean the impeller with a vacuum cleaner
that has a soft brush nozzle, if necessary. Contaminants on the impeller may cause imbalance and ulti -
mately damage the fan.
• Check the condition of the vibration dampers. The material of the rubber dampers should be soft, and
the fan should ‘float’ on the rubber. This can be checked by swinging the fan laterally, whereupon the
rubber dampers should follow the movement of the fan. When rubber hardens, it loses some of its
damping capacity and the vibration in the fan is transferred to the frame of the unit.
• Check that the flexible connector of the fan is installed correctly so that the connector allows move -
ment in both directions. If the connector is installed incorrectly, it will stress both the shaped inlet in
the fan and the fan wall.
The EC motor does not rotate/start:
• Check that the supply voltage is in accordance with the rating plate.
• Check that the motor has the enable device input (Ziehl EC only) and external speed set point (0…10 V).
• Check that the impeller is not stuck.
Fault condition of the PM fan The fan vibrates, produces noise or resonates.
• Check that the impeller is clean and has no external damage. Clean the impeller with a vacuum cleaner
that has a soft brush nozzle, if necessary. Contaminants on the impeller may cause imbalance and ulti -
mately damage the fan.
• Check the condition of the vibration dampers. The material of the rubber dampers should be soft, and
the fan should ‘float’ on the rubber. This can be checked by swinging the fan laterally, whereupon the
rubber dampers should follow the movement of the fan. When rubber hardens, it loses some of its
damping capacity and the vibration in the fan is transferred to the frame of the unit.
• Check that the flexible connector of the fan is installed correctly so that the connector allows move -
ment in both directions. If the connector is installed incorrectly, it will stress both the shaped inlet in
the fan and the fan wall.