292278-UIM-A-0108
Unitary Products Group
25
ADJUSTMENT OF TEMPERATURE RISE
The air temperature rise, or difference between the return air tempera-
ture and the heated supply air temperature from the furnace, must be
within the air temperature rise range shown on the furnace rating plate
and in Table 5.
After about twenty minutes of operation, determine the furnace temper-
ture rise. Take temperature readings of both the return air and the
heated air in the ducts about six feet away from the furnace, where they
will not be affected by radiant heat. Increase or decrease the tempera-
ture rise by changing the ATR jumper on the furnace control board. The
jumper is factory-set to deliver an air temperature rise near the midpoint
of the nameplate temperature rise range. If more air is desired (lower
temperature rise), move the jumper to the -10 position. If less air is
desired (higher temperature rise), move the jumper to the +10 position.
ADJUSTMENT OF FAN CONTROL SETTINGS
Cooling -
The airflow delivered by the furnace during cooling operation
can be adjusted to match the cooling capacity of the A/C condensing
unit. This is done by moving the COOL and ADJ jumper on the control
board to give the desired airflow.
The COOL jumper has four positions, which will deliver sufficient airflow
in cooling mode for the cooling capacities shown in the Table 15. The
CFM delivery on each jumper position is shown in Table 16.
the ADJ jumper has three positions which can be used to make further
adjustments to the cooling blower airflow. See Table 16 for further infor-
mation.
Continuous Fan Operation -
The airflow delivered by the furnace dur-
ing continuous fan operation can be adjusted as desired. This is done
my moving the RECIRC jumper on the control board to give the desired
airflow.
The jumper has three positions. The "A" position delivers maximum air-
flow, 100% of the blower capacity. Position "B" delivers approximately
70% of the blower capacity. And Position "C" delivers minimum airflow,
approximately 40% of the blower capacity.
WITH BURNER BOX COVER IN PLACE
FIGURE 24:
Reading Gas Pressure
The temperature rise, or temperature difference between the return
air and the supply (heated) air from the furnace, must be within the
range shown on the furnace rating plate and within the application
limitations shown in Table 5 “ELECTRICAL AND PERFORMANCE
DATA”.
The supply air temperature cannot exceed the “Maximum Supply
Air Temperature” specified in these instructions and on the fur-
nace rating plate. Under NO circumstances can the furnace be
allowed to operate above the Maximum Supply Air Temperature.
Operating the furnace above the Maximum Supply Air Temperature
will cause premature heat exchanger failure, high levels of Carbon
Monoxide, a fire hazard, personal injury, property damage, and/or
death.
6
5
4
3
2
1
0
1
2
3
4
5
6
BURNER BOX
WITH COVER
OUTLET
PRESSURE
TAP
GAS VALVE
U-TUBE
MANOMETER
TEE
FITTING
BURNER BOX
PRESSURE
REFERENCE
HOSE
3.5 IN
WATER
COLUMN
GAS PRESSURE
SHOWN
TABLE 15:
Cooling Airflow - A/C Capacity in Tons
Models
Cool Jumper Position
D
C
B
A
60/1200
1-1/2
2
2-1/2
3
80/1200
1-1/2
2
2-1/2
3
80/1600
2-1/2
3
3-1/2
4
100/1600
2-1/2
3
3-1/2
4
100/2000
3
3-1/2
4
5
120/2000
3
3-1/2
4
5
FIGURE 25:
Furnace Control Board
LOW VOLTAGE
TERMINALS
DIAGNOSTIC
LIGHT
TEST
BUTTON
ERROR
BUTTON
CONTINUOUS FAN
SPEED JUMPER
COOLING
SPEED JUMPER
HUMIDIFIER
TERMINALS
EAC
TERMINALS
DELAY COOL
ADJUST
HUMIDISTAT
CONNECTED
YES NO
AIR
RECIRC
ERROR
TEST
CFM
CFM
INDICATOR
ADJUST
JUMPER
DELAY
JUMPER
