PRODUCT DESIGN
31
1
2
DEHUM
TRIM ENABLE
Move to the ON position
to enable dehumidification
ON
OFF
S5
PCBKF103 / PCBKF104 / PCBKF105
24 Volt Dehumidistat Wiring - Two-Stage Variable
Speed ComfortNet™ Furnaces (WR50C51)
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 dehumi-
distats.
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).
Y
Two-Stage Heating with Single-Stage Cooling
R
R
Y
C
Furnace Integrated
Control Module
Thermostat
Two-Stage Heating
with
Single-Stage Cooling
Remote
Condensing Unit
(Single-Stage Cooling)
Dehumidistat
[Optional]
NEU
Place Jumper Between Y1
and O For Proper
Dehumidification Operation
and Proper Ramping
Profile Operation
Two-Stage Heating with Two-Stage Cooling
W1
W2
Y2
Furnace Integrated
Control Module
Thermostat
Two-Stage Heating
with
Two-Stage Cooling
(
)
Remote
Condensing Unit
(Two-Stage Cooling)
Dehumidistat
[Optional]
Y2
Y2
W2
W1
NEU
Place Jumper Between Y1
and O For Proper
Dehumidification Operation
and Proper Ramping
Profile Operation
Thermostat Wiring Diagrams
Single-Stage Thermostat Application - Two-Stage
Variable Speed ComfortNet™ Furnaces (WR 50C51)
A single-stage thermostat with only one heating stage may
be used to control this furnace. The application of a single-
stage thermostat does not offer “true” thermostat-driven two-
stage operation, but provides a
timed
transition from low to
high fire. The furnace will run on low stage for a fixed period
of time before stepping up to high stage to satisfy the
thermostat’s call for heat. The delay period prior to step-
ping up can be set at either a fixed 5 minute time delay or a
load based variable time between 1 and 12 minutes (AUTO
mode). If the AUTOmode is selected, the control averages
the cycle times of the previous three cycles and uses the
average to determine the time to transition from low stage to
high stage.
To use a single-stage thermostat, turn off power to the fur-
nace, move the thermostat selection DIP switch to the OFF
position. Set the desired transition time by setting the tran-
sition delay DIP switch to the desired ON/OFF position.
Turn power back on. Refer to the following figure.
