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BLOWERS
Direct Drive:
Listed below are the color codes for the different
motor speed taps:
High Speed — Black
Medium Speed — Blue
Medium-low Speed - Yellow
Low Speed — Red
Wiring Diagram, Figure 10 shows these furnaces as
wired at the factory. Remove the transformer (two
screws) from the junction box and expose the termi¬
nal block. Check the fan control lead to see if it is
connected to the motor speed tap that will give the
blower speed needed for the installation. If the fan
control lead is not connected to the proper motor
speed tap, or if you wish to change to another
speed, simply switch the lead to the motor speed
tap that you want connected. The lead is equipped
with a spade connector.
Important:
If there are variations in voltage at the motor,
there will be significant variations in the air de¬
livery and temperature rise values. If the supplied
voltage is less than 115 volts the blower will run
slower and the temperature rise will be greater. On
the other hand, if the voltage is greater than 115
volts the blower will run faster and the temperature
rise values will be lower. If there is doubt about
the value and fluctuation of voltage consult local
electric utility. The Number 4 tap should be used
on installations where the voltage is 125 volts or
higher.
Belt Drive:
The motors supplied with the belt drive have an
adjustable motor pulley. The air delivery rate is
controlled by the position of this adjustable motor
pulley. When the pulley is in the fully open position,
the air delivery rate is at a minimum, and conse¬
quently the temperature rise across the furnace is
at the maximum.
When the pulley is in the fully closed position, the
air delivery rate is maximum and consequently the
temperature rise across the furnace is at a minimum.
In order to change the opening on the pulley simply
loosen the set screw with an Allen wrench. Screw
the pulley clockwise to close, and counter-clockwise
open. Once positioned, tighten the set screw on the
flat of the motor shaft.
Larger Motors:
For some installations the installer may wish to
substitute a larger motor than the one supplied the
furnace. A separate mounting hole is provided in
each end plate of the blower cage to be used when
motors larger than 1/3 HP are installed. This is an
extruded hole requiring self-tapping bolts. Figure 7
is a photo of a 1/2 HP motor mounted in place of a
smaller motor. Note that the lower mounting hole is
used. When ordering a 1/2 HP motor for installation
be sure that the frame is a size 56. When ordering
still larger motors, be sure that the frame size is
compatible with space available in the blower com¬
partment.
When the lower mounting holes are used it will, of
course, be necessary to use a longer belt than the
one supplied with the smaller motors.
Figure 7
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393U
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