Installation Guide

21
Figure15.LowVoltageField,Four-wire
Heating/CoolingApplications
RCYGW
STATUS
FLAME
GREEN
RED
180
COOL
HEAT
120
90
60
YELLOW
BLOWER
OFF
DELAY
LOW
ML
MH
HIGH
EAC
L1
XFMR
HUM
COM
SPEED
SELECT
3 AMP
FUSE
24V
5
NEUTRALS
ROOM
THERMOSTAT
A/C CONDENSING UNIT
CONDENSING UNIT
CONTROL BOX
EXPANSION PORT
(MOTOR CONNECTION)
FIELD WIRING
LOW VOLTAGE
CONNECTION
R
C
Y
G
W
NOTE: The “Y” terminal
on the control board
must be connected to the
thermostat for proper
cooling mode operation.
Connect
R & W
For Heating
Only
2
ELECTRONIC AIR CLEANER
MOTOR SPEED TAPS
(NOT USED)
HUMIDIFIER TAP
NEUTRAL LEADS
6 3
4
1
7
8
9
5
2
63
4
1
FAN
Thermostat/LowVoltageConnections
• Thefurnaceisdesignedtobecontrolledbya24VAC
thermostat. The thermostat’s wiring must comply with
the current provisions of the NEC (ANSI/NFPA 70) and
with applicable local codes having jurisdiction.
• The thermostat must be installed according to the
instructions supplied by the thermostat manufacturer.
Low voltage connections (24 VAC) from the thermostat
are wired to the terminal strip on the integrated control in
the furnace. Figure 15 contains the proper connections
for heating only (two-wire) and heating/cooling (four-wire)
applications. Recommended minimum wire gauge for
thermostat wiring is shown in Table 2 (page 20).
• Thethermostatshouldbemountedabout5feetabove
the floor on an inside wall. DO NOT install the thermostat
on an outside wall or any other location where its
operation may be adversely affected by radiant heat from
fireplaces, sunlight, or lighting fixtures, and convective
heat from warm air registers or electrical appliances.
Refer to the thermostat manufacturer’s instruction sheet
for detailed mounting information.
• Thesixpinterminalmarked“ExpansionPort”(Figure
15) is not used in the single stage furnace as shipped
from the factory. It is used for the furnace control board
to communicate to a fixed speed or variable speed high
efficiency motor that may be optionally installed. Please
contact your distributor for the proper upgrade motor
kit.
Heat Anticipator
Set the heat anticipator according to the instructions
supplied by the thermostat manufacturer. To determine
the heat anticipator setting:
1. Add the current draw of the system components; or
2. Measure the current flow on the thermostat R-W circuit
after the circulating blower motor has started.
Twinning
Single stage furnaces are not supplied with a built-
in twinning capability. Other valuable features and
enhancements were made to the new control that made it
necessary to remove the twinning capability. For twinning
of single stage furnaces with PSC motors, a twinning kit
(920919) is available for purchase. Pleasefollowthe
instructionsprovidedwiththekit.
If both single stage furnaces are upgraded to the fixed
speed iSEER ™ blower, the twin terminal on the blower
control boards (Figure 16) may be used to twin the single
stage furnaces only if the following criteria are met:
• Bothfurnacesandmotorsmustbethesamesize.
• Bothmotorsmustbeonthesamespeedforcooling
and heating.
• Bothfurnacesmusthaveacommonreturnductand
common supply plenum.
• Both furnaces must be the same phase and on the
same leg of power.
IMPORTANTNOTE:Furnacesequippedwithvariable
speediSEER™motorsmaynotbetwinnedunder
anycircumstances.
wARNING:
Whenservicingeithertwinnedfurnace,power
mustbeturnedoffonbothfurnaces.Failureto
complymayresultinimproperoperationleading
todamagetothefurnacesorpersonalinjury!
For twinning of single stage furnaces equipped with fixed
speed iSEER ™ blowers, refer to Figure 16 and the
following instructions:
1. Turn off all power to both furnaces.
2. Attach a wire between the two twin terminals on the
twinning control boards. Use field supplied wire and
two 3/16” wire terminals.
TWIN TERMINAL
FURNACE 1
6-Pin Wiring
Harness
TWINNING
CONTROL
BOARD
FURNACE
BOARD
FURNACE 2
TWIN TERMINAL
TWINNING
CONTROL
BOARD
FURNACE
BOARD
Expansion Port
6-Pin Wiring
Harness
Expansion Port
Expansion Port
Expansion Port
W
G
Y
C
R
THERMOSTAT
WG
YR
A/C
UNIT
W
G
Y
C
R
Figure16.SingleStageTwinning