Service Manual

PRODUCT DESIGN
35
24 Volt Dehumidistat Wiring
The optional usage of a dehumidistat allows the furnace’s
circulator blower to operate at a slightly lower speed (85%
of desired speed) during a combined thermostat call for cool-
ing and dehumidistat call for dehumidification. This can be
done through an independent dehumidistat or through a
thermostat’s DEHUM terminal (if available). This lower blower
speed enhances dehumidification of the conditioned air as
it passes through the AC coil. For proper function, a dehu-
midistat applied to this furnace must operate on 24 VAC
and utilize a switch which opens on humidity rise.
To install/connect a dehumidistat:
1. Turn OFF power to furnace.
2. Secure the dehumidistat neutral wire (typically the white
lead) to the terminal marked “DEHUM” on the furnace
integrated control module.
3. Secure the dehumidistat hot wire (typically the black
lead) to the terminal marked “R” on the furnace inte-
grated control module.
4. Secure the dehumidistat ground wire (typically the green
lead) to the ground screw on the furnace junction box.
NOTE: Ground wire may not be present on all
dehumidistats.
5. Turn ON power to furnace.
To enable the dehumidify function on the integrated control
module, set the dehumidification ENABLE dipswitch from
OFF to ON.
Once the switch is set, the dehumidify function is enabled
during a combination call for cooling (T-Stat) and dehumidi-
fication (DEHUM-Stat).
SWITCH
S5 1
Disabled Off
Enabled On
Dehum
PCBKF103 / PCBKF104 / PCBKF105
Fossil Fuel Applications
Two-Stage furnaces can be used in conjunction with a heat
pump in a fossil fuel application. A fossil fuel application is
where an outdoor temperature sensor determines the most
cost efficient means of heating (heat pump, gas furnace, or
both).
A heat pump thermostat with two stages of heat is required
to properly use the single-stage furnace with a heat pump.
A heat pump thermostat with three stages of heat is re-
quired to properly use the two-stage furnace with a heat
pump. Refer to dual fuel, AFE-18-60A installation manual
(IO-627) for additional wiring instructions.
CONTINUOUS FAN OPERATION
The two stage furnace control will energize ECM blower mo-
tor when the fan switch on the thermostat is turned to the
"ON" position. Continuous fan speed will be of the furnaces
maximum airflow capability. 25%, 50%, 75%, or 100% se-
lectable by DIP switch setting or communicating thermo-
stat.
Example: If the furnace’s maximum airflow capability
is 2000 CFM, the continuous fan speed will be 0.30 x
2000 CFM = 600 CFM.
For the PCBKF103, PCBKF104, and PCBKF105 continu-
ous fan speeds that provide 25, 50, 75 and 100% of the
furnace’s maximum airflow capability are selectable via dip
switches S5- 3, 4.
Example: If the furnace’s maximum airflow capability is
2000 CFM and 25% continuous fan speed
is selected, the continuous fan speed will be
0.25 x 2000 CFM = 500 CFM.
34
25% Off Off
50% On Off
75% Off On
100% On On
Continuous Fan
SWITCH
S5
Once the switch is set, the dehumidify function is enabled
during a combination call for cooling (T-Stat) and dehumidi-
fication (DEHUM-Stat).
SWITCH
S5 1
Disabled Off
Enabled On
Dehum
PCBKF103 / PCBKF104 / PCBKF105
Fossil Fuel Applications
Two-Stage furnaces can be used in conjunction with a heat
pump in a fossil fuel application. A fossil fuel application is
where an outdoor temperature sensor determines the most
cost efficient means of heating (heat pump, gas furnace, or
both).
A heat pump thermostat with two stages of heat is required
to properly use the single-stage furnace with a heat pump.
A heat pump thermostat with three stages of heat is re-
quired to properly use the two-stage furnace with a heat
pump. Refer to dual fuel, AFE-18-60A installation manual
(IO-627) for additional wiring instructions.