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Checking Temperature Rise
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 high-
er 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 cor-
rect 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.
Total External Static Testing
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 pres-
sure of the return duct at the inlet of the unit (Nega-
tive Pressure).
2. Measure the Static pressure of the supply duct (Posi-
tive Pressure).
3. Add the two readings together.
NOTE: Both readings may be taken simultaneously
and read directly on the manometer if so desired.
4. Consult proper table for quantity of air.
If the external static pressure exceeds the minimum or
max imum allowable statics, check for closed dampers, dirty
fil ters, undersized or poorly laid out ductwork.
Total External Static
Blower Speed Adjustments
Blower speeds are changed at the indoor blower. The igni-
tion control board has four blower speeds: LOW HEAT, HI
HEAT, LOW COOL and HIGH COOL.
EEM Blower Speed
NOTE: FAN ONLY energizes at LOW HEAT speed. The
GPGM5 models are equipped with EEM motors. EEM
motors are constant torque motors with very low
power consumption. This motor is energized by 24
VAC. Adjust the CFM for the unit by changing the
24 VAC leads to the speed terminal block on the
motor.
NOTE: Heating airflow must be adjusted to provide
the temperature rise shown on rating plate. Blow-
er speeds are programmed to deliver adequate
airflow at rated external static pressure (ESP).
Refer to airflow table provided in the Appendix
for details.
To avoid personal injury or death due to electrical shock,
remove electrical power from the unit before changing
speed taps on the blower motor.
17
.
Mode
WARNING
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