5750156-UIM-B-0919
20
Johnson Controls Ducted Systems
After about 5 minutes of operation, determine the furnace temperature
rise. Measure the temperature of the return air and the heated air in the
ducts about 6 ft (1.83 m) from the furnace, where they are not affected
by radiant heat. Increase the blower speed to decrease the temperature
rise. Decrease the blower speed to increase the temperature rise.
The blower speed tap connections are located on the motor plug in the
blower compartment. To change the blower speed, see Tables 13 and
14 and the unit wiring diagram. To use the same speed tap for heating
and cooling, connect the white Heat speed wire and the yellow Cool
speed wire terminal to the required motor lead using a jumper wire or Y
terminal.
DIRECT DRIVE BLOWER
All units have direct drive, multi speed standard ECM blower motors.
Connect manometer as per the EXTERNAL STATIC PRESSURE
SETUP section. Place the unit in cooling mode and adjust the blower
speed accordingly as per Table 13 or 14.
EXTERNAL STATIC PRESSURE SETUP
To measure external static pressure:
1.
Measure the supply air static pressure and record this positive num-
ber.
2.
Measure the return air static pressure and record this negative
number.
3.
Treat the negative number as a positive and add the two numbers
together. This is total system static.
FIGURE 11:
Measuring External Static Pressure
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