25
Thermostat - Two-Stage Hea
ti
ng with Two-Stage Cooling
Y1
C
Y1
C
G
R
W1
Y2
Y/Y1
C
G
R
W/W1
W2
ROOM THERMOSTAT
INTEGRATED FURNACE
CONTROL MODULE
REMOTE COOLING UNIT
(TWO STAGE)
W2
Y2
Y2
Thermostat - Two-Stage Heating with Two-Stage Cooling
Thermostat Wiring Diagrams
Figure 36
Single-Stage Heating Thermostat
Application
A single-stage heating thermostat may be used to control
this furnace, however the furnace is setup by default to use a
two-stage heating thermostat. To use a single stage heating
thermostat the installer must make the desired selections
in the user menus using the push button switches on the
control board.
. When a single stage heating thermostat is used there are
two options for controlling the timed
•
Press the Left or Right menu switch to get to the A H S
menu.
•
The menu will display these options;
no 10 20 30 60 AUt
•
Fixed time options are expressed in minutes on the
display as;
10 20 30 60
.
• If
AUt
(Automatic) is selected, the actual timing for the
transition to 2nd stage heat will be calculated by the
control board based on length of run time of previous
heating cycles (duty cycle).
•
Press the center switch to save the selection.
In Auto mode, the transition to 2nd stage heat will vary be
-
tween 1 to 12 minutes
Duty Cycle %
Timing to 2nd
Stage Gas Heat Demand
0-38
12 minutes
Light
39-50
10 minutes
Light to
Average
51-62
7 minutes
Average
63-75
5 minutes
Average
to Heavy
76-88
3 minutes
Heavy
89-100
1 minutes
Heavy
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
three stages of heat
is required
to properly use a two-stage furnace in conjunction with a heat
pump. Refer to the fossil fuel kit installation instructions for
additional thermostat requirements.
Strictly follow the wiring guidelines in the fossil fuel kit instal
-
lation instructions. All furnace connections must be made
to the furnace two-stage integrated control module and the
“FURNACE” terminal strip on the fossil fuel control board.
Twinning
Two furnaces of the same model may be twinned. The in
-
tegrated control board has a 3/16” terminal labeled “TWIN”
located beside the low voltage thermostat connection strip.
Twinning allows simultaneous operation of two furnaces and
forces the indoor blower motors of each furnace to operate
synchronously into a common duct system. Using the twin
-
ning function will require only field installed wiring with no
external kits or parts.
The staging and speed tap options must be set the same
on both furnaces.
NOTE:
Each furnace must be connected to it’s own 115 VAC
power supply. The L1 connection to each furnace must be
in phase (connected to circuit breakers on the same 115
VAC service panel phase leg). To verify that the furnaces
are in phase, check from L1 to L1 on each furnace with a
voltmeter. If the furnaces are in phase, the voltage between
both furnaces will be
ZERO.
ROOM THERMOSTAT
Y2
Y/Y1
C
G
R
W/W1
W2
Y2
Y/Y1
C
G
R
W/W1
W2
Y2
Y/Y1
C
G
R
W/W1
W2
TWIN
TWIN
COND UNIT
CONTACTOR
COND UNIT
CONTACTOR
FURNACE 1
FURNACE 2
Figure 37
115 Volt Line Connection of Accessories
(Humidifier and Electronic Air Cleaner)
The furnace integrated control module is equipped with line
voltage accessory terminals for controlling power to an op
-
tional field-supplied humidifier and/or electronic air cleaner.
The accessory load specifications are noted in the chart
below:
Humidifier
1.0 Amp maximum at 120 VAC
Electronic Air Cleaner
1.0 Amp maximum at 120 VAC
