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Temperature Rise Check
NOTE: Air temperature rise is the temperature difference
between supply and return air.
With a properly designed system, the proper amount of
temperature rise will normally be obtained when the unit
is operated at rated input with the recommended blower
speed.
If the correct amount of temperature rise is not obtained, it
may be necessary to change the blower speed. A higher
blower speed will lower the temperature rise. A slower
blower speed will increase the temperature rise.
NOTE: Blower speed MUST be set to give the correct air
temperature rise through the unit as marked on the rating
plate.
External Static Pressure Check
The total external static pressure must be checked on this
unit to determine if the airflow is proper.
1. Using a digital manometer measure the static pressure
of the return duct at the inlet of the unit, (Negative
Pressure).
Total External Static
2. Measure the Static pressure of the supply duct,
(Positive Pressure).
3. Add the two readings togther.
NOTE: Both readings may be taken simultaneously
and read directly on the manometer if so desired.
4. Consult proper table for quantitu of air.
If the external static pressure exceeds the minimum or
maximum allowable statics, check for closed dampers, dirty
filters, undersizd or poorly laid out ductwork.
Blower Speed Adjustments
T
O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRIC SHOCK, REMOVE
ELECTRICAL POWER FROM THE UNIT BEFORE CHANGING SPEED TAPS ON THE
BLOWER MOTOR.
Refer to the wiring diagram and airflow data in the appendix
to verify speed tap settings.
Depending upon the model, blower speeds are changed
at the indoor blower. The ignition control board has four
blower speeds: LOW HEAT, HI HEAT, LOW COOL and
HIGH COOL.
NOTE: FAN ONLY energizes at LOW HEAT speed.
The A/GPDM3 models are equipped with EEM motors.
EEM motors are constant torque motors with very low
power consumption. This motor is energized by 24VAC.
Adjust the CFM for the unit by changing the 24VAC leads to
the speed terminal block on the motor.
NOTE: Heating airflow must be adjusted to provide the
temperature rise shown on rating plate. A higher speed
tap may not provide more airflow. Blower speeds are
programmed to deliver adequate airflow at rated external
static pressure (ESP). Refer to airflow table provided in the
Appendix for details.
GAS HEATING
Lead
Speed
Definition
Color
Tap
Low
White
T1
Speed Heat
High
Brown
T2
Speed Heat
Multi-speed ECM is controlled by three 24V low voltage
leads:
T1, T2, and T4.
T1 - Low speed Heating
T2 - High speed Heating
T3 - Low Speed Cooling (optional)
T4 - Medium speed Cooling
T5 - High Speed Cooling (optional)
NOTE:To adjust the blower to high speed, move T4 to T5 in
cooling operation
20
WARNING
COOLING
Lead
Speed
Definition
Color
Tap
Cool/HP
T3
Optional Low
Speed
Cool/HP
Yellow
T4
Speed
T5
High Static
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