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www.DaikinApplied.com 87
IM 893-10 • ROOFPAK SINGLEZONE UNITS
Propeller Exhaust Fan Option
Economizer units may include propeller exhaust or centrifugal
return fan options. This section covers maintenance and
operating instructions for the propeller exhaust option.
Centrifugal return fan construction, maintenance and operation
is similar to that for supply fans and covered in other sections
of this manual.
Figure 90: Two Fans with Back Return Shown
Prestarting Checks
Check all fasteners and set screws for tightness. This is
especially important for bearing set screws.
The propeller should rotate freely and not rub on the fan panel
venturi. Rotation direction of the propeller should be checked
by momentarily turning the unit on. Rotation should be in the
same direction as the rotation decal affixed to the unit or as
shown in
. For three-phase installations, fan rotation
can be reversed by simply interchanging any two of the three
electrical leads.
The adjustable motor pulley is preset at the factory for the
specified fan RPM. Fan speed can be increased by closing
or decreased by opening the adjustable pulley. Two or three
groove variable pitch pulleys must be adjusted an equal
number of turns open. Any increase in fan speed represents
a substantial increase in horsepower required from the motor.
Always check motor load amperage and compare to name
plate rating when changing fan speed.
Figure 91: Fan Rotation
Once the fan is put into operation, set up a periodic
maintenance program to preserve the reliability and
performance of the fan. Items to include in this program are:
• Belts
• Bearings
• Fasteners
• Setscrews
• Lubrication
• Removal of Dust/Dirt
Damper Counterbalance Adjustment
The following instructions should be followed when attempting
to maximize the counterbalance effect on the dampers. Be
aware that when the balance setting is highly sensitive, friction
wear and contamination will have an adverse effect to the
operation of the damper. The sensitivity of the counterbalance
should only be set to meet the application requirements. The
damper must be mounted square and plumb and operate freely
before any weight adjustments are performed.
Adjustment #1 will effect the balance of the blades in the open
position. Adjustment #2 will effect the balance of the blades
in the closed position along with a small change to the open
position balance.
If the damper blades do not achieve full open position under
airflow and you want them to open further or all the way,
then adjustment #1 will need to be performed. If the damper
blades do not open completely and adjustment #1 has been
addressed, then more weight is required.
If the airflow through the damper is light and the blades only
slightly move from the closed position, then adjustment #2 and
#1 are required.
Fans and motors
VFD
Starters
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