536636-UIM-A-1209
Johnson Controls Unitary Products
13
SECTION VIII: AIRFLOW AND COMFORT
SETTING SELECTION
AIRFLOW SELECTION
The airflow and comfort setting selection jumpers must be set properly
at the time of installation for proper system operation. Place jumpers in
the proper locations based on the information shown in Table 16 and
Figure 10.
Inputs to air handler control board are passed to the motor which deter-
mines the target CFM to be delivered. The following inputs will produce
the CFM per the appropriate table and selected tap settings.
NOTE:
Incorrect airflow and comfort settings may result in decreased
system efficiency and performance.
These variable speed air handlers are designed to deliver constant air-
flow (CFM) regardless of the external static pressure (ESP) in the duct-
work. 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.
To Set Cooling Airflow:
Refer to the outdoor unit technical guide for the recommended airflow
with the matching evaporator coil. Refer to Table 16 for the possible
high speed cooling and heat pump airflow selections.
Find the recommended system airflow in Table 16 for the installed air
handler model.
Select the COOL airflow you need from Table 16. Set the COOL and
ADJUST Jumpers on the control as indicated in Table 16.
To Set Heat Pump Airflow:
The heat pump airflow setting is the same as the cooling airflow setting.
No additional airflow setting is required. However, you must set the
MODE jumper to the HP position for proper system operation (See Fig-
ure 5).
To Set Electric W1 Heat Airflow:
The blower speed required for 1st stage electric heat is different than
cooling. Refer to Table 16 for the possible CFM selections. Refer to
Table10 for the minimum required airflow for the electric heater
installed. Find the desired airflow in Table 16 for low heat. Set the HEAT
jumper on the control as indicated in Table 16.
To Set W2 Electric Heat Airflow:
Airflow for any W2 input, which is for Stages 2 & 3 of electric heat, is the
indicated CFM for high heat tap selection on Table 16.
Fan Only CFM:
When the connection is made from "R" to "G", the fan only mode is acti-
vated. In this mode, the airflow will depend on the position of the CONT
Fan jumper. In the “H” position, the blower will deliver 85-90% of full
capacity. In the “M” position, the blower will deliver 60-65% of full
capacity. In the “L” position, the blower will deliver 30-35% of full capac-
ity.
Blower Ramp-Up /Ramp-Down:
To minimize the sound made by the blower when it speeds up or slows
down, the blower will slowly ramp up or down from one speed to
another. Changes in blower speed during A/C or heat pump heating
can take up to 30 seconds. Changes in blower speed during electric
strip heating can take up to 15 seconds.
COMFORT SETTINGS
Normal
The normal setting provides a ramp-up from zero airflow to full capacity
and a ramp-down from full capacity back to zero airflow.
Humid
The humid setting is best-suited for installations where the humidity is
frequently very high during cooling season, such as in the southern part
of the country. On a call for cooling, the blower will ramp up to 50% of
full capacity and will stay there for two minutes, then will ramp up to
82% of full capacity and will stay there for five minutes, and then will
ramp up to full capacity, where it will stay until the wall thermostat is sat-
isfied.
Dry
The dry setting is best suited to parts of the country where excessive
humidity is not generally a problem, where the summer months are usu-
ally dry. On a call for cooling the motor will ramp up to full capacity and
will stay there until the thermostat is satisfied. At the end of the cooling
cycle, the blower will ramp down to 50% of full capacity where it will stay
for 60 seconds. Then it will ramp down to zero.
Temperate
The temperate setting is best suited for most of the country, where nei-
ther excessive humidity nor extremely dry conditions are the norm. On
a call for cooling, the motor will ramp up to 63% of full capacity and will
stay there for 90 seconds, then will ramp up to full capacity. At the end
of the cooling cycle, the motor will ramp down to 63% of full capacity
and will stay there for 30 seconds, then will ramp down to zero.
DO NOT change the ADJUST tap position on the control as this will
change your cooling airflow previously selected.
TABLE 6:
Comfort Setting Selection
DELAY TAP
COMFORT SETTING
A
Normal
B
Humid
C
Dry
D
Temperate