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279550-YIM-A-0207
Unitary Products Group 21
Blower Speed Selection
The variable speed blowers are designed to deliver constant
CFM regardless of the external static pressure (ESP) in the
ductwork. Therefore, if too many supply registers are closed, a
filter becomes clogged, or there is a restriction in the ductwork,
the motor will automatically operate at a higher speed to
compensate for the higher ESP. This may result in a higher
operating sound level.
These units have variable speed motors that automatically
adjust to provide constant CFM from 0.2" to 0.6" w.c. static
pressure. From 0.6" to 1.0" static pressure, CFM is reduced by
2% per 0.1" increase in static. Operation on duct systems with
greater than 1.0" w.c. external static pressure is not
recommended.
To Set Cooling CFM for DNX Units:
Refer to Airflow Performance Tables 13 and 14 for the possible
cooling speed CFM selections.
Set “COOL” and “ADJ” Jumpers on the CFM selection board as
indicated in Tables 13, 14 and Figure 14.
NOTE: CFM indicator light flashes once for every 100 CFM
(i.e. 12 flashes = 1200 CFM).
To Set Delay Profile:
Every unit has multiple cooling “blower off delay” profiles to
optimize system performance and efficiency. Refer to Table 17
for the regional climate in your area. Place the “DELAY” jumper
tap on the CFM selection board on the appropriate pin setting.
Factory Set Gas Heat CFM:
The blower speed required for gas heat is different than for
cooling. The heating CFM is factory set, but is adjustable.
Table 15: Additional Static Resistance
Size
(Tons)
CFM Wet Indoor Coil Economizer
1
1. The pressure drop through the economizer is greater for 100% outdoor air than for 100% return air. If the resistance
of the return air duct is less than 0.25 IWG, the unit will deliver less CFM during full economizer operation.
Filter/Frame Kit Electric Heat
024
(2.0)
500 0.01 0.00 0.01 -
600 0.01 0.00 0.02 -
700 0.01 0.00 0.04 -
800 0.02 0.01 0.06 -
900 0.03 0.01 0.08 -
1000 0.04 0.01 0.10 -
1100 0.05 0.01 0.13 -
1200 0.06 0.02 0.16 -
036
(3.0)
700 0.01 0.00 0.04 -
800 0.02 0.01 0.06 -
900 0.03 0.01 0.08 -
1000 0.04 0.01 0.10 -
1100 0.05 0.01 0.13 -
1200 0.06 0.02 0.16 -
1300 0.07 0.03 0.17 -
1400 0.08 0.04 0.18 -
048
(4.0)
1100 0.02 0.02 0.04 -
1200 0.03 0.02 0.04 -
1300 0.04 0.02 0.05 -
1400 0.05 0.03 0.05 -
1500 0.06 0.04 0.06 -
1600 0.07 0.04 0.07 -
1700 0.07 0.04 0.08 -
1800 0.08 0.04 0.09 -
1900 0.09 0.05 0.10 -
2000 0.09 0.05 0.11 -
Table 16: Indoor Blower Specifications
Size
(Tons)
Motor
HP RPM Eff. SF Frame
024
(2.0)
1/2 Variable 0.8 1.0 48
036
(3.0)
1 Variable 0.8 1.0 48
048
(4.0)
1 Variable 0.8 1.0 48
Do not change the "ADJ" tab position on the CFM
selection board as this will change your cooling CFM
previously selected.