16
For 063C and 073C models, the Indoor Fan speed is field
adjustable by changing the adjustable motor sheave. See
Figure 9.
Note :
Do not exceed F.L. Amps listed in the
Product Specifications Table of
Service Facts.
Filters
Access to the filters is made by removing the evaporator fan
access panel. Each downflow unit ships with one-inch filters,
as determined by unit size. To modify the unit filter racks to
accept 50 mm (two-inch) filters, the L-shaped angles (which
are held in place with screws and formed tabs) on the racks
must be rotated. Remove the screws, turn the angles 90
degrees, and reinstall the screws. Refer to the unit Service
Facts for filter requirements.
Important Note:
Do not operate unit without filters in place.
Evaporator Fan Adjustment
Use the following procedure to determine the proper adjust-
ment of the evaporator fan for a specific application.
1. Determine total system external static pressure (in inches
water column) with accessories installed. To accomplish
this:
a. Obtain the design airflow rate and the design external
static pressure drop through the distribution system.
Your sales representative or the design engineer can
provide you with these values.
b. Using the table from unit Service Facts, add static
pressure drop of the accessories installed on the unit.
c. Add the total accessory static pressure drop (from Step
1b) to the design external static pressure. The sum of
these two values is the total system external static
pressure.
2. Use the table(s) in the Service Facts to find the external
static pressure (in inches water column) that most closely
approximates total system external static pressure. Then
locate the appropriate airflow rate (in cfm) for your unit. The
value obtained represents the brake horsepower for the
evaporator fan motor and the fan RPM.
FILTER INSTALLATION
TO INCREASE m
3
/h (CFM)
Loosen pulley adjustment
set screw and turn sheave
clockwise
TO ADJUST BELT TENSION
Loosen adjustment bolt - Pull motor mounting plate back until
belt is tight - Tighten adjustment bolt after belt has correct
tension.
Electrical Connections
— Electrical wiring and grounding must be installed in
accordance with local national codes.
Electrical Power
— It is important that proper electrical power is available for
the unit. Voltage variation should remain within the limits
stamped on the nameplate.
TO DECREASE m
3
/h (CFM)
Loosen pulley adjustment
set screw and turn sheave
counter-clockwise
Figure 9
Typical fan, motor, and sheave assembly for 063 & 073
Power Entry
Holes are provided for low-voltage and high-voltage wiring. It
is not necessary to punch any new holes in either the interior
or exterior unit panels. If new holes are punched, performance
will be adversely affected unless they are resealed to be both
air- and watertight.
