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 2-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 stepping up can be set at either a fixed
5-minute transition time or a load based variable time between
1 and 12 minutes (Auto transition). If the Auto transition mode is
selected, the control averages the cycle times of the previous
3 cycles and uses the average to determine the time to transition
from low stage to high stage.
To use a single-stage thermostat:
1. Turn off power to the furnace.
2. Move the thermostat selection DIP switch to the Off
3. Set the desired transition time by setting the Stage Delay DIP
switch to On for Auto transition, or Off for 5-minute transition
4. Turn on power. Refer to the following illustration.
Heat OFF Delay
24-Volt Dehumidistat Wiring
The optional usage of a dehumidistat allows the furnace's
circulator blower to operate at a slightly lower speed (82% of
desired speed) during a combined thermostat call for cooling 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 dehumidistat 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
3. Secure the dehumidistat hot wire (typically the black lead) to
the terminal marked R on the furnace integrated control
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 DEHUM DIP switch from Off to
Once the switch is set, the dehumidify function is enabled during
a combination call for cooling (T-Stat) and dehumidification
Fossil Fuel Applications
This furnace can be used in conjunction with a heat pump in a
fossil fuel application. A fossil fuel application refers to a
combined gas furnace and heat pump installation which uses an
outdoor temperature sensor to determine the most cost efficient
means of heating (heat pump or gas furnace).
A heat pump thermostat with 3 stages of heat is required to
properly use a 2-stage furnace in conjunction with a heat pump.
Refer to the fossil fuel kit installation instructions for additional
Strictly follow the wiring guidelines in the fossil fuel kit installation
instructions. All furnace connections must be made to the
furnace 2-stage integrated control module and the FURNACE
terminal strip on the fossil fuel control board.
115-Volt Line Connection of Accessories (Humidifier
and Electronic Air Cleaner)
To avoid personal injury or death due to
electrical shock, disconnect electrical
power before servicing or changing any
The furnace integrated control module is equipped with line
voltage accessory terminals for controlling power to an optional
field-supplied humidifier and/or electronic air cleaner.
The accessory load specifications are as follows:
Electronic Air Cleaner
Turn off power to the furnace before installing any
Follow the humidifier or air cleaner manufacturers'
instructions for locating, mounting, grounding and controlling
Accessory wiring connections are to be made through the ¹⁄₄"
quick connect terminals provided on the furnace integrated
The humidifier and electronic air cleaner hot terminals are
identified as HUM and EAC.
The humidifier and electronic air cleaner neutral terminals are
identified as NEUTRAL.
All field wiring must conform to applicable codes.
Connections should be made as shown in the "Optional
Accessories Wiring" illustration.
1.0 Amp maximum at 120 VAC
1.0 Amp maximum at 120 VAC