Maintenance/troubleshooting
MRH 06.04.2017
15
10.1
Malfunctions and troubleshooting (generally)
Possible reasons
Action
The ventilator
does not run
Connection to the mains fault.
Thermal protection triggers.
Motor fault.
Check connection to the mains and thermal protection. If
ok. check electric motor (winding resistance, resistance to
ground). If necessary get the electric motor repaired.
Air volume is
too low
Wrong direction of rotation.
Too high pressure drop in system.
Obstacles in duct.
Check the direction of rotation. If wrong, swap the supply
connection of any 2 phases. Check if current is similar all
phases. If ok. check operating point and system design.
Thermal pro-
tection of the
fan switches
off
Short-circuit.
Damage to the bearings.
Impeller blocked or grinding.
Compare connection with wiring diagram. Compare the
data of electric motor with setting of thermal protection.
If ok. check power supply and electric motor. Get the
electric motor or if necessary the complete fan repaired.
Overcurrent
Check the direction of rotation. If wrong, swap any 2
phases. Check if current is similar all phases.
Noise
Damage to the bearings.
Impeller blocked or grinding.
Get the electric motor or if necessary the complete fan re-
paired.
Loose fit on the base plate or mo-
tor support.
Tighten the bolts, look for the cause of vibrations.
Vibrations
The actual pressure drop of the
system is higher than supposed,
the fan could operate in an unsta-
ble area of the fan curve.
Check operating point and system design. Consult cus-
tomer service of the manufacturer.
Damage or dust layer on impeller.
Clean the impeller, if necessary balance it or replace it.
The hatch
cover doesn`t
fully open
(~70°) ore fully
close
Obstacle.
One or both actuators is faulty
(MRH 1120).
Check, if the actuator is (are) powered.
Limit switch indicates, if the end position is reached.
Replace faulty actuator.
The hatch
cover opera-
tion is oppo-
site
Wrong polarity on the actuator`s
service switch.
Swap it, check the control cabinet.
If the reason for malfunction cannot be clearly determined, consult the customer service of manufacturer.
10.2
Cleaning
Regular cleaning prevents unbalance.
Keep casing and accessories clean and clean them if necessary with a brush (do not use a steel brush or high-
pressure cleaner). Do not use any detergents for interior cleaning.
10.3
Maintenance, service
Basically the fan or MRH may be repaired at the manufacturer only! Exceptions are non-relevant components. For fur-
ther instructions consult the manufacturer.
The fan is by built-in for-life lubricated ball bearings as far as possible low-maintenance product. After their life time
(app. 20.000 h up to manufacturer, but expected 30.000 – 40.000 h due to low load), a replacement of the bearings is
necessary. Observe attached instructions of motor manufacturer/specific fan instructions.
Pay attention to a non-typical noise from bearings.
For damages (e.g. damage to winding) please contact our Service Department. You will find the address on the
back of these operating instructions.
Expected lifetime of actuators is at least 10.000 cycles.
