Isolation - Before commencing work make sure
that the unit, and any control are
electrically isolated from the mains supply.
4
5.0 Maintenance - Fan unit
Maintenance Intervals
The first maintenance should be carried out three months
after commissioning and thereafter at twelve monthly
intervals. These intervals may need to be shortened if the
unit is operating in adverse environmental conditions, or in
heavily polluted air. Access to the unit internals is gained by
removing the top cover(s).
Motors
Brush away any dust or dirt from the motor housings and
ensure that the motor vents are unblocked.
Bearings
Lubrication is unnecessary as the motors are fitted with
sealed for life bearings.
Impellers
Remove any dust and check that the impellers are securely
fixed to the motor shafts. Take care not to disturb any
balance weights fitted. Check sealed for life bearings for
excessive wear.
Figure 10. Shutter detail.
Shutter Assembly
Remove any dust and check that the shutters operate freely
and that they seal the appropriate fan outlet effectively.
Anti Vibration Motor Plate Mountings
Each motor plate is supported on ten individual resilient
mountings. Check that all the mountings are secure and in
good condition. (See figure 11).
Figure 11. Adjusting the Drive Belts (smaller units).
Adjusting Drive Belt Tension (smaller units).
To check the correct tension of a drive belt, apply a force at
right angles to the centre of the belt span sufficient to deflect
the belt 16mm for every metre of span length (see figure 11).
The force required to deflect the ‘V’ belt should be from
0.5kg to 0.8kg.
Changing a Drive Belt
To replace a belt, remove the two bolts from the motor
mounting furthest from the fan and slacken the remaining
two bolts. Lift the motor plate and remove the belt. Replacing
the belt is the reverse of this procedure.
Figure 12. Adjusting the Drive Belts (larger units).
Adjusting Drive Belt Tension (larger units)
All belt drive units incorporate belt tensioning devices.
To adjust the belt tension, slacken the pinch bolt on the sides
of the motor plate. Turn the adjusting bolt clockwise to
tighten the belt and counter clockwise to loosen it.
The drive should be tensioned until a slight bow appears in
the slack side of the ‘V’ belt when running under load.
To check for correct tension, proceed as follows.
1.
Measure the span length (See figure 12).
2.
At the centre of the span, apply a force at right
angles to the belt sufficient to deflect one belt
16mm for every metre of span length
(see figure 12). The force required to deflect
the ‘V’ belt should be from 0.5kg to 0.8kg.
3.
Tighten the pinch bolts.
General Cleaning and Inspection
Clean and inspect the exterior of the fan unit and associated
controls etc. Remove the access panel from the fan unit.
Inspect and, if necessary, clean the fan and motor assemblies
and the interior of the case. If the unit is heavily soiled it
may be more convenient to remove the fan/motor
assemblies. If NuAire controls and or remote indicators are
fitted, remove the covers and carefully clean out the
interiors as necessary. Check for damage. Check security of
components. Refit the access covers.
General
1.
Check that all fixings are tight.
2.
Check sealing strips around the fan outlets are
tight up against the bulkhead.
3.
Check that duct connections are not leaking.
NALTF/TRF
Roof and Plantroom Twinfans
15. 05. 17. Leaflet Number 671269
