Page 32 - IOM / Rooftop Smart and Linéa™ Range
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FAN SECTION
AN SECTION
AN SECTION
AN SECTION
AN SECTION
FAN OPERATION
To reset the Fan Control, use the KP02 (refer to the
CLIMATIC section of this document).
FAN ACCESS
- Disconnect the fan drive plug as well as the “overheat”
plug on the LG_/LD_ units.
- Remove the screws on each side of the mounting base
plate.
- Pull the mounting base plate out of the unit.
ESTABLISHING AIRFLOW RATE (m
3
/s)
- The following measurements are made with a dry coil.
Switch the fan on without any cooling demand. The air
filters must be in their position when the measurements
are made.
- With all access panels in their position measure the static
pressure outside the unit.
- Measure the inside fan rotation (r.p.m).
- Use the static pressure and the measured r.p.m. to
calculate the volumetric flow rate (m
3
/s).
- The fan rotation (r.p.m.) can be adjusted with the drive
pulley. Loosen the Allen screw and turn the adjusting
pulley to the right to reduce the air flow rate (see figure
35).
FAN BELT ADJUSTMENT
The pulley alignment and tension must remain constant to
ensure a long life. Tension new belts 24 to 28 hours following
their first service. Any increased stretch and extra flexibility
can then be taken up.
- Loosen the 4 safety bolts securing the chassis.
- To increase the belt tension, turn the adjusting button to
the right. Pull the drive outside and tension the belt. This
will increase the distance between the fan drive and the
fan housing. To reduce the belt tension, turn the adjusting
button to the left.
- Tighten the two bolts on the drive motor (pulley side).
NOTE: The upper part of the fan drive base plate must
be parallel with the mounting chassis base plate before
tightening the two bolts on the other side of the base
plate. The drive and fan spokes must be parallel.
- Tighten the two bolts on the other side of the base plate.
BELT TENSION CONTROL
Too much tension reduces the belt life and resistance.
Control the tension as follows:
- Measure the overall length X (see figure 36).
- Apply some pressure at the centre of the overall length
(X) to deflect the belt by 1.5 mm over an overall length of
100 mm. For a 400 mm belt, the deflection should be 6
mm.
- Measure the belt deflection force. The deflection force
must be 32 N for a used belt and 48 N for a new belt.
The belt needs to be tensioned more when the deflection
is below the value and must be slackened when the
deflection exceeds the value.
NOTE : An under-tensioned belt will slip, heat and wear
prematurely. On the other hand, if a belt is over-tensioned,
the pressure on the bearings will cause them to over-heat
and wear prematurely. Incorrect alignment will also cause
the belts to wear prematurely.
Figure 35
FAN MOTOR MOUNTING FRAME
Align top edges
parallel before
tightening motor in
place
Fan motor base
adjustment bolts 2
each side
Remove screws from front before
sliding fan assembly out of unit
Belt tension
adjusting
bolt.
Turn
clockwise to
tighten belt
Figure 36
MEASURE BELT TENSION
Span length x
Force
Deflection 1,5 mm per 100 mm of span
