Page 38
W1 on the integrated control must be connected to W1 on
the thermostat.
FIGURE 54
Automatic Heat Staging
Humidifier
Terminals are provided on the integrated ignition/blower
control for connection to a 120-volt humidifier. The “HUM”
terminal is energized whenever the thermostat calls for
heat. See the furnace wiring diagram for specific connec
tion information.
Electronic Air Cleaner
Terminals are provided on the integrated ignition/blower
control board for connection of a 120-volt electronic air
cleaner. The “EAC” terminal is energized whenever the
thermostat calls for heat, cooling, or continuous blower.
See furnace wiring diagram for specific connection infor
mation.
Variable Speed Features
This furnace is equipped with a variable speed circulation
air blower motor that will deliver a constant airflow within a
wide range of external static pressures. Other features of
this variable speed motor include
:
Soft Start
The variable speed motor will slowly ramp up to normal op
erating speed. This minimizes noise and increases com
fort by eliminating the initial blasts of air encountered with
standard motors.
Soft Stop
At the end of a cooling or heating cycle, the variable speed
motor will slowly ramp down after a short blower “off” delay.
If continuous blower operation has been selected, the vari
able speed motor will slowly ramp down until it reaches the
airflow for that mode.
Passive and Active Dehumidification
Both the passive and active dehumidification methods de
scribed below can be utilized on the same furnace.
Passive Dehumidification
For situations where humidity control is a problem, a dehu
midification feature has been built into the variable speed
motor. At the start of each cooling cycle, the variable
speed motor will run at 82% of the rated airflow for 7.5 min
utes. After 7.5 minutes has elapsed, the motor will in
crease to 100% of the rated airflow.
Active Dehumidification
To achieve additional dehumidification, clip the jumper
wire located below the DEHUM terminal on the integrated
ignition/ blower control board and connect a humidity con
trol that opens on humidity rise to the DEHUM and R termi
nals. The DEHUM terminal on the control board must be
connected to the normally closed contact of the humidity
control so that the board senses an open circuit on high hu
midity. In this setup, the variable speed motor will operate
at a 30% reduction in the normal cooling airflow rate when
there is a call for dehumidification.
Circulating Airflow Adjustments
Cooling Mod
e
The units are factory set for the highest airflow for each
model. Adjustments can be made to the cooling airflow by
repositioning the jumper plug marked COOL – A, B, C, D
(see Figure 53). To determine what CFM the motor is de
livering at any time, count the number of times the amber
LED on the control board flashes. Each flash signifies 100
CFM; count the flashes and multiply by 100 to determine
the actual CFM delivered (for example: 5 flashes x 100 =
500 CFM).
Heating Mode
These units are factory set to run at the middle of the heat
ing rise range as shown on the unit rating plate. If higher or
lower rise is desired, reposition the jumper plug marked
HEAT - A, B, C, C (see Figure 53) . To determine what CFM
the motor is delivering at any time, count the number of
times the amber LED on the control board flashes. Each
flash signifies 100 CFM; count the flashes and multiply by
100 to determine the actual CFM delivered (for example: 5
flashes x 100 = 500.
Adjust Tap
Airflow amounts may be increased or decreased by 10%
by moving the ADJUST jumper plug (see Figure 53) from
the NORM position to the (+) or (-) position. Changes to the
ADJUST tap will affect both cooling and heating airflows.
The TEST position on the ADJUST tap is not used.
Continuous Blower Operation
The comfort level of the living space can be enhanced
when using this feature by allowing continuous circulation
of air between calls for cooling or heating. The circulation of
air occurs at half the full cooling airflow rate.
To engage the continuous blower operation, place the fan
switch on the thermostat into the ON position. A call for fan
from the thermostat closes R to G on the ignition control
board. The control waits for a 1 second thermostat delay
before responding to the call for fan by ramping the circulat
ing blower up to 50% of the cooling speed. When the call for
continuous fan is satisfied, the control immediately ramps
down the circulating blower.
