Daikin RDT Installation And Maintenance Manual page 88

Adjustment #1:
Moving the weight stack along the length of the mounting
bracket slot (Figure 92) will effect the full open balance of
the blade assembly. Moving the weights further away from
the blade pivot point will cause the blades to become more
balanced so that at some point, and with enough weight, the
blades would remain open. Care must be taken to ensure that
when the weights are moved outward from the blade pivot
point they will not interfere with the adjacent blade when the
blades close. Moving the weights back towards the blade pivot
point will allow the blades to close.
Adjustment #2:
The damper is assembled with the counterbalance weights
and bracket installed such that, when the blades are closed,
the counterbalance weights and bracket are positioned directly
inline with the blade pivot points. This position of the weights
will provide a slight load that will hold the blades in the closed
position. To reduce this load, the counterweight-mounting
brackets can be bent (Figure
blade surface. Bending the counterweight mounting brackets
will move the counterweight stack behind the blade pivot
point and therefore allow the blades to start opening at lower
airflow rates. This adjustment should be performed in small
increments since the blades will not fully close if the brackets
are bent to far.
NOTE: Performing adjustment #2 will have a small effect on
adjustment #1. Therefore, if adjustment #1 is critical,
then adjustment #1 may need to be repeated.
Figure 92: Counterbalance Adjustment
Mounting
Bracket Slot
IM 893-10 • ROOFPAK SINGLEZONE UNITS
92) away from the adjacent
Bend Here
Belts
Premature belt failures are frequently caused by improper belt
tension (either too tight or too loose) or misaligned pulleys. The
proper tension for operating a V-belt is the lowest tension at
which the belts will not slip at peak load conditions. For initial
tensioning, the proper belt deflection half way between pulley
centers is 1/64ʺ for each inch of belt span. For example, if the
belt span is 64 inches, the belt deflection should be one inch
using moderate thumb pressure at midpoint of the drive, See
Figure 93.
Check belt tension two times during the first 24 hours of
operation and periodically thereafter. To adjust belt tension,
simply loosen four fasteners (two on each side of the motor
plate) and slide the motor plate away from the fan shaft until
proper belt tension is attained. On some fans, fasteners
attaching the motor to the motor plate must be loosened in
order to adjust the belt.
It is very important that the drive pulleys remain in proper
alignment after adjustments are made. Misalignment of pulleys
results in premature belt wear, noise, vibration, and power loss.
See Figure 94.
Figure 93: Belt Adjustment
Figure 94: Drive Pulley Alignment
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