Lennox 22X18 Assembly instructions

507240-04
11/2022
Supersedes 9/2022
Equipment Interface Module (EIM) (22X18)
Installation and Setup Guide

2
Shipping and Packing List..............................................................................2
Indoor Transformer Requirements ................................................................2
Overview...........................................................................................................2
Equipment Interface Module Control Layout................................................3
Jumpers Pins, DIP Switch, Connections and LEDs.....................................4
Unit Type Jumper Pin Settings ................................................................................... 4
Heat Stages Jumper Pin Settings .............................................................................. 4
Heat Pump Capacity Jumper Pin Settings ................................................................. 5
Others / Vent DIP Switch Settings.............................................................................. 5
Sensor Connections ................................................................................................... 5
Dual-Fuel Terminal Connections ................................................................................ 6
Conventional Terminal Connections and Wiring Requirement ................................... 6
LED Indicators............................................................................................................ 7
Soft Disable ................................................................................................................ 7
Lennox Communicating Thermostat Commissioning (Conventional Outdoor Unit) ... 8
Operating Environment Specications .........................................................8
Unit Dimensions ..............................................................................................8
Most Common Congurations.......................................................................9
Lennox Communicating Thermostat, EIM, Non-communicating Furnace,
Non-communicating Air Conditioner or Heat Pump.................................................... 9
Lennox Communicating Thermostat, EIM, Non-communicating Air Handler,
Non-communicating Air Conditioner or Heat Pump.................................................... 9
Lennox S40 Smart Thermostat Only, EIM and Ventilation Only................................. 9
Duel-Fuel Congurations..............................................................................10
Lennox Communicating Thermostat, EIM, Lennox Communicating Furnace and
Non-communicating Heat Pump .............................................................................. 10
Lennox Communicating Thermostat, EIM, Non-Communicating Furnace and
Communicating Heat Pump ..................................................................................... 10
Lennox S40 Smart Thermostat Only, EIM (2), Lennox Communicating
Furnace, 24VAC Heat Pump and Ventilation (ERV/HRV) .........................................11
Thermostat Terminal Information ................................................................11
Field Wiring Diagrams...................................................................................12
Communicating Wiring Diagrams............................................................................. 13
Minimizing Electrical Noise....................................................................................... 14
Alert Codes and Troubleshooting................................................................22
Alert Code Types ...................................................................................................... 22
Alert Codes............................................................................................................... 23
Applications (Ventilation and Zoning) ........................................................31
ERV/HRV Applications ............................................................................................. 31
Fresh Air Damper Application................................................................................... 31
Ventilation Zoning Application .................................................................................. 31
Ventilation Control Modes ........................................................................................ 32
Thermostat Ventilation Parameters .......................................................................... 33
TABLE OF CONTENTS WARNING
Improper installation, adjustment, alteration, service or maintenance can
cause property damage, personal injury or loss of life.
Installation and service must be performed by a licensed professional
HVAC installer (or equivalent) or a service agency.
Shipping and Packing List
Quantity Description
1 Equipment Interface Module.
1 Installation and setup guide
1Warranty certicate
Indoor Transformer Requirements
The following lists the required indoor unit transformer rating (VA) for spe-
cic congurations.
Table 1. System VA Loading Chart
Conguration Minimum Transformer Rating (VA)
2-Stage HP, 3-Stage Electric heat and Fresh Air 70
2-Stage HP, 2-Stage Furnace (with tempering) 70
2-Stage HP, 2-Stage Furnace (without tempering) 50
2-Stage AC, 2-Stage Furnace 40
Single stage fresh air damper 6 to 12VA
Overview
The Equipment Interface Module (EIM) is used with an Lennox commu-
nicating thermostat using the R, i+, i-, and C terminals. The EIM is the
interface between non-communicating HVAC equipment and Lennox com-
municating HVAC equipment.
NOTE: EIM will support single-stage outdoor units with single-stage or
variable-stage indoor furnaces.
For ventilation or zoning applications, see “Applications (Ventilation and
Zoning)” on page 31.

3
Equipment Interface Module Control Layout
OUTDOOR AIR SENSOR
CONNECTIONS
DISCHARGE AIR
SENSOR CONNECTIONS
COMMUNICATION AND
POWER TERMINALS
NON-COMMUNICATING TERMINALS
STATUS LED
ACTIVE COMMUNICATION
STATUS LED
DUAL-FUEL TERMINAL
CONNECTIONS
UNIT TYPE JUMPER
PINS
HEAT STAGES
JUMPER PINS HEAT PUMP CAPACITY
JUMPER PINS
3 AMP FUSE
OTHERS / VENTILATION
DIP SWITCH
Figure 1. Connections, Jumpers, Fuse and LEDs

4
CAUTION
Electrostatic discharge can a󰀨ect electronic components. Take
precautions during unit installation and service to protect the unit’s
electronic controls. Precautions will help to avoid control exposure to
electrostatic discharge by putting the unit, the control and the technician
at the same electrostatic potential. Neutralize electrostatic charge
by touching hand and all tools on an unpainted unit surface before
performing any service procedure
WARNING
Controls in this module are sensitive to moisture. Do NOT secure this
module to the sheet metal cabinet where moisture may condense during
periods of high humidity. Secure the module to a nearby wooden stud, if
possible.
Jumpers Pins, DIP Switch, Connections and LEDs
IMPORTANT
The Lennox communicating thermostat paired with the Equipment
Interface Module (EIM) will work with most 24VAC furnaces, air handlers,
air conditioners and heat pumps (up to 2-stages of cooling and 3-stages
of heat).
The Lennox communicating thermostat without the Equipment Interface
Module (EIM) will work with Lennox communicating HVAC equipment.
1. Remove the module cover.
2. Mount the Equipment Interface Module (EIM) near the indoor unit.
3. Use the wiring diagrams reference in the section titled “Field Wiring
Diagrams” on page 12 to complete the wiring connections for the
specic application and conguration.
Unit Type Jumper Pin Settings
Set the unit type jumper for the type of indoor unit, Use the following table
and gure as a guide. The factory default setting is IFC. If jumper is miss-
ing from the jumper pins, then alarm 130 is activated.
Table 2. Unit Type Jumper Pin Settings
Jumper
Position Indoor Unit Outdoor Unit
VENT ERV, HRV or Fresh Air Damper
Not supported. Second EIM would be
required for non-communicating heat
pump or air conditioner.
HP Lennox Communicating Furnace Non-communicating heat pump.
IFC
(Default) Conventional furnace Non-communicating heat pump or air
conditioner.
AHC Conventional air handler
UNIT TYPE JUMPER POSITIONS
HP IFC AHCVENT
VENTILATION HEAT PUMP FURNANCE AIR HANDLER
Figure 2. Unit Type Jumper Terminal Settings
Heat Stages Jumper Pin Settings
The factory default setting is position 2 (two heat stages). If jumper is miss-
ing from the jumper pins, then alarm 130 is activated. Depending on the
type of equipment and system set up being used:
• Set the number of stages of electric heat (air handler) when jumper pin
selection is AHC selection.
• Set the number of stage of gas heat (Furnace) when jumper pin selection
is IFC.
• Set the number of stages of the compressor when jumper pin selection
is HP.
HEAT STAGES JUMPER POSITIONS
0123
HP or IFC:
AHC:
1 STG 1 STG
1 STG
2 STG
2 STG
2 STG
3 STGNO ELEC. HEAT
Figure 3. Heat Stage Jumper Positions

5
Table 3. Heat Stage Jumper Pin Settings
Label
(Position)
Air Handler Heat
Stages Furnace Heat Stages Heat Pump Stages
Number of
Electric Heat
Stages
Stage
Percentage
Number of
Gas Stages
Stage
Percentage
Number of
Compressors
Stages
Stage
Percentage
0
No
Electric
Heat
0 1 100% 1 100%
1 1 100% 1 100% 1 100%
2 (default) 2 50%,
100% 270%. 100% 270%. 100%
3 3
33.5%,
66.5%,
100%
270%,
100% 270%. 100%
NOTE: If jumper is missing, setting defaults to single stage. Changing jumper position
after power-up requires recommission for the change to be recognized.
Heat Pump Capacity Jumper Pin Settings
Heat pump size must be congured when using a non-communicating heat
pump using the Heat Pump Size jumper (see gure 4 and table 5). Factory
default setting is for 3.0 (3-ton). If jumper is missing from jumper pins then
alarm 130 is activated.
1.5 TON
HEAT PUMP SIZE
JUMPER POSITIONS
2.5 TON
3 TON
3.5 TON
4 TON
5 TON
2 TON
Figure 4. Conventional Heap Pump Capacity Jumper Setting
Others / Vent DIP Switch Settings
• Ventilation Only Operation (ERV/HRV) - Set the unit type jumper to
VENT and the DIP switch set to OFF (VENT).
• Ventilation Only Operation (FRESH AIR DAMPER) - Set the unit type
jumper to VENT and the DIP switch set to OFF (VENT).
• IFC/AHC/HP Operation - Set the unit type jumper to the desire component
and the DIP switch must be set on ON (OTHERS) position.
NOTE: Factory default for this switch is ON.
Figure 5. OTHERS/VENT DIP Switch Settings
Sensor Connections
Refer to “Figure 1. Connections, Jumpers, Fuse and LEDs” on page 3
for various terminal locations.
Table 4. Outdoor Air and Discharge Air Sensors
Label Function / Description
Outdoor Air
Sensor
Show ambient temperatures (optional if weather feed is acceptable or
outdoor unit is a communicating unit; use X2658 Outdoor Sensor - two
terminals).
NOTE: Wiring distance between the EIM and the outdoor tempera-
ture sensor can not exceed 150 feet (45 meters) when wired
with minimum 18 - 22 AWG dedicated two-conductor thermo-
stat cable.

6
Table 4. Outdoor Air and Discharge Air Sensors
Label Function / Description
Discharge Air
Sensor
This sensor is optional for diagnostics of indoor air. Recommend using
use discharge air sensor (88K38).
Dual-Fuel Terminal Connections
Table 5. Dual-Fuel Terminals
Label Description Function
DFTS Not Used Not Used
W1-DEF Defrost signal
input
• This input is used in systems with non-communicating
heat pumps for defrost indication.
• The input provides a nominal load of 50 mA, 24 VAC.
O
Heat Pump Re-
versing Valve.
(Power for cool-
ing)
• In systems with communicating IFC, the EIM (HP) O
output is connected to a non-communicating heat pump
compatible with Osignal for reversing valve operation.
• A 24VAC signal is generated on Ofor cooling operation,
while the terminal is open for heating operation.
B
Heat Pump Re-
serving Valve
(Power for heat-
ing)
• In systems with communicating IFC, the EIM (HP) B
output is connected to a non-communicating heat pump
compatible with Bsignal for reversing valve operation.
• A 24VAC signal is generated on Bfor heat pump opera-
tion, while the terminal is open for cooling operation.
Conventional Terminal Connections and Wiring Requirement
Table 6. Conventional Terminals
Label Description Function
NOTE: 18AWG unshielded thermostat cable (eld-provided) for all non-communicat-
ing connections.
W1/Vent 1
• Set the unit type jumper to IFC and the DIP switch to ON (OTHERS),
then there is a rst-stage gas heat output
• Set the unit type jumper to AHC, and the DIP switch to ON (OTHERS),
then there is rst stage electric heat output.
• When unit type jumper is set to VENT and the DIP switch is set to OFF
(VENT), then there is single-speed ventilation.
• When unit type jumper is set to VENT and the DIP switch is set to OFF
(VENT), then there is single-speed fresh air damper output.
W2/Vent 2
• Set the unit type jumper to IFC and the DIP switch to ON (OTHERS),
then there is second stage gas heat output.
• Set the unit type jumper to IFC and the DIP switch to ON (OTHERS),
then there is second stage electric heat output.
• Set the unit type jumper to VENT and the DIP switch to OFF (VENT),
then this terminal can be used for two-speed ventilation only.
W3/Vent C
• Set the unit type jumper to IFC and the DIP switch to ON (OTHERS),
then there is third stage gas heat output.
• Set the unit type jumper to IFC and the DIP switch to ON (OTHERS),
then there is third stage electric heat output.
• Set the unit type jumper to VENT and the DIP switch to OFF (VENT), then
this terminal can be used as common for single or two speed ventilation.
• Set the unit type jumper to VENT and the DIP switch to OFF (VENT),
then this terminal can be used when installed wire jumpered between
W3/Vent C and terminal R, can provide 24VAC in a fresh air damper
application.
GIndoor blower control (continuous fan) (monitoring only).
Y2 2nd - stage compressor output
Y1 1st - stage compressor output
DS • 24VAC dehumidication signal output.
• The DS terminal is powered when there is not a dehumidication call.
CClass II, 24VAC trans-
former common
• Rand Cterminals are used to receive
power from the indoor unit and capable of
providing the power to the EIM and all the
associated loads.
• The Rpower input uses a 3A fuse (Lennox
catalog number 25J49.
RClass II. 24VAC trans-
former power
H24VAC humidier signal output.

7
Table 6. Conventional Terminals
Label Description Function
NOTE: 18AWG unshielded thermostat cable (eld-provided) for all non-communicat-
ing connections.
O
Heat pump reversing
valve
(24VAC = cool)
• Used as reversing valve output for heat
pumps.
• The EIM uses a single-pole dual throw relay
to generate Oand Bsignals.
• Normally the Ooutput is open and Boutput
at 24VAC during heating calls.
• During cooling calls Ois 24VAC and Bopen.
• With relay de-energized then 24VAC is
present on Oterminal.
• When power o󰀨/ or control reset, 24VAC
power shall not be present on the O terminal.
B
Heat pump reversing
valve
(24 VAC = heat)
LED Indicators
This control has two green LED to indicate status and communication activ-
ity One LED is labeled Status and the other is labeled RSBUS.
RSBUS LED
The RSBus LED ashes when information is being communicated over the
RSBus.
Status LED
The following table lists all status LED information.
Table 7. Status LED (Green)
Green LED Function / Description
Steady On Remains steady ON until the device sends its start-up mes-
sage.
Blinks 1 second ON
and 3 seconds OFF Soft disable state
Blinks 2 seconds ON
and 2 second OFF
Service is being provided (W, Yor Grelay is ON, or Ginput
ON
Blinks 1 second ON
and 1 second OFF
When alarms are present, you may review alarm(s) listed either
on the homeowner notication screen or notications under
Dealer Service Center. Information will be listed in either location
on how to clear the alert code(s).
Table 7. Status LED (Green)
Green LED Function / Description
Blink 3 seconds ON
and 1 second OFF.
• OTHERS/VENT switch mis-match. Unit type jumper is set to
VENT but the OTHERS/VENT DIP switch is set to ON.
• Other switch mis-match. Unit type switch is set to IFC, AHC or
HP, but the OTHERS/VENT DIP switch is set to OFF.
NOTE: This notication will only appear when there is a de-
mand being called.
Soft Disable
• Soft disabling is when the thermostat detects an unknown control such
as a indoor or outdoor unit control, Lennox Smart Zoning (iHarmony) or
EIM on the system communication bus.
• The thermostat sends the unknown control a message to go into soft
disable mode until component is properly congured.
• The thermostat will display (--) symbols for a soft disabled control.
• When soft disabling occurs only the control that has been disabled will
display the blinking LED status. In this case, the control blinks three
seconds OFF and one second ON.
Use the following procedure if the equipment interface module is displaying
the soft disable code.
1. Conrm proper wiring between all devices such as thermostat, EIM,
indoor and outdoor unit).
2. Cycle power to the control that is displaying the soft disable code.
3. Touch the Lennox icon on the thermostat home screen and hold until
the installer warning screen appears.
4. Touch yes to continue.
5. Touch Setup and then conrm to continue.
6. Use this Thermostat? Touch press here to continue.
7. Touch the next button to continue past the next three screens.
8. From the System Devices list, touch reset ALL to reset all devices.
9. Touch the conrm button.
The thermostat will reboot and start through the setup process again.

8
IMPORTANT
If any jumpers were set incorrectly AFTER commissioning was
completed, then reposition jumpers to correct positions. Re-running the
commissioning procedure will be required at the Lennox communicating
thermostat.
This completes the conguring of the conventional outdoor unit.
Lennox Communicating Thermostat Commissioning (Conventional
Outdoor Unit)
Both unit capacity and number of compressor stages are required to be
congured through the Lennox communicating thermostat. Once the out-
door unit has been installed and connected to the equipment interface
module, go to the thermostat and start the conguration process.
1. From the equipment found screen, touch the non-communication
equipment location to add non-communicating equipment.
2. A add/remove equipment screen will appear. Under Outdoor Unit
Type, select the applicable 1 or 2-stage unit.
3. Touch either the plus or minus buttons to selected the applicable
Outdoor Unit Capacity. Valid options are 18, 24, 30, 36, 42, 48 and
60.
4. Touch save to continue.
Operating Environment Specications
The Equipment Interface Module is designed to operate in the following
environmental conditions.
• Operating Temperature Range: 40°F to 176°F (40° C to 80°C).
• Shipping and Storage Temperature Range: 40° F to 185°F (40°C to
85°C).
• Operating Humidity Range: 10% to 90% non-condensing at 104°F.
Unit Dimensions
8” (203mm)
6” (152mm)
1-5/8” (42mm)
Figure 6. Unit Dimensions

9
Most Common Congurations
How the EIM is congured is determined by the system components.
NOTE: Changing jumper positions after the control has been powered-up
requires recommissioning for the change to be recognized.
NOTE: When the Equipment Interface Module is replaced, recommissioning
the Lennox communicating thermostat will also need to be re-
accomplished. See the Lennox communicating thermostat Setup
Guide for recommissioning procedure.
The following examples are three typical congurations used with the EIM.
There are other applications as well and are address in the wiring diagrams
section titled “Field Wiring Diagrams” on page 12. Those diagrams will
indicate all required jumper settings on the EIM and wiring connections.
Lennox Communicating Thermostat, EIM, Non-communicating
Furnace, Non-communicating Air Conditioner or Heat Pump
Lennox
Communicating
Thermostat
Equipment Interface
Model (EIM)
Non-communicating
Furnace
Non-Communicating
Air Conditioner or
Heat Pump
Wiring Legend
4−wire communicating
24VAC conventional
Outdoor Unit: Non-communicating Air Conditioner or Heat Pump
Indoor Units: Lennox Communicating Thermostat, EIM and non-communicating Furnace
Figure 7. Lennox Communicating Thermostat, EIM, Non-Comm Furnace and
Non-Communicating AC or HP
1. Set the EIM Unit Type Jumper to IFC.
2. Set the EIM Heat Stage Jumper (see “Table 3. Heat Stage Jumper
Pin Settings” on page 5) to the applicable number of furnace heat
stages or number of electric heat stages.
3. Set the OTHERS/VENT DIP switch to the OTHERS (ON) position.
Lennox Communicating Thermostat, EIM, Non-communicating Air
Handler, Non-communicating Air Conditioner or Heat Pump
Lennox S40
Communicating
Thermostat
Equipment Interface
Model (EIM)
Non-communicating
Air Handler
Non-Communicating
Air Conditioner or
Heat Pump
Wiring Legend
4−wire communicating
24VAC conventional
Outdoor Unit: Non-communicating Air Conditioner or Heat Pump
Indoor Units: Lennox Communicating Thermostat, EIM and non-communicating Air Handler
Figure 8. Lennox Communicating Thermostat, EIM, Non-Comm Air Handler and
Non-Communicating AC or HP
1. Set the EIM Unit Type Jumper to AHC.
2. Set the EIM Heat Stage Jumper (see “Table 3. Heat Stage Jumper Pin
Settings” on page 5) to the applicable number of HP heat stages or
number of electric heat stages.
3. Set the OTHERS/VENT DIP switch to the OTHERS (ON) position.
4. Use the Lennox communicating thermostat to complete the
commissioning procedure.
Lennox S40 Smart Thermostat Only, EIM and Ventilation Only
Lennox Communicating
Thermostat
Equipment Interface
Model (EIM)
Ventilation - ERV/HRV
or Fresh Air Damper
Wiring Legend
4−wire communicating
24VAC conventional
Outdoor Unit: None
Indoor Units: S40, EIM and Ventilation
Figure 9. System View - Ventilation Only

10
1. Set the Unit Type Jumper to VENT.
2. Set the OTHERS/VENT DIP switch to the VENT (OFF).
3. Use the Lennox communicating thermostat to complete the
commissioning procedure.
Duel-Fuel Congurations
To use the EIM in dual-fuel mode, the following equipment combinations
and conguration is required.
Defrost Air Tempering Kit (67M41) will be required. The included DT1 dis-
charge temperature probe is inserted in the furnace air outlet between the
furnace and the indoor coil to keep the furnace from overheating the coil
which would cause heat pump high pressure tripping during the defrost
cycling. The DT1 is only needed with non-communicating furnaces and is
not required for air handlers.
Wiring example for the DT1 Discharge Temperature Probe is in “Figure
20. Dual-Fuel - Conventional Furnace with Conventional Heat Pump
(1 or 2-Stage)” on page 16.
Lennox Communicating Thermostat, EIM, Lennox Communicating
Furnace and Non-communicating Heat Pump
Lennox
Communicating
Thermostat
Equipment Interface
Model (EIM)
Communicating
Furnace
Wiring Legend
4−wire communicating
24VAC conventional
Non-Communicating
Heat Pump
Outdoor Unit: Non-communicating Heat Pump
Indoor Units: Lennox Communicating Thermostat, Communicating Furnace and EIM
X2658 Outdoor
Sensor Required
Figure 10. Duel Fuel - Lennox Communicating Thermostat, IFC, EIM
and Non-Comm HP
1. Set the EIM Unit Type Jumper to HP.
2. Set the EIM Heat Stage Jumper (see “Table 3. Heat Stage Jumper
Pin Settings” on page 5) to the applicable number of heat pump
heating stages.
3. Set the OTHERS/VENT DIP switch to the OTHERS (ON) position.
4. Use the Lennox communicating thermostat to complete the
commissioning procedure.
NOTE: For two-stage heat pump go to the heat pump defrost control,
locate P3 - low ambient thermostat pins and disable this function
by removing the installed jumper and relocating it to one pin only.
Lennox Communicating Thermostat, EIM, Non-Communicating
Furnace and Communicating Heat Pump
Lennox
Communicating
Thermostat
Equipment Interface
Model (EIM)
Non-communicating
Furnace
Communicating
Heat Pump
Wiring Legend
4−wire communicating
24VAC conventional
Outdoor Unit: Communicating Heat Pump
Indoor Units: Lennox Communicating Thermostat, EIM and non-communicating -
Furnace
Outdoor Sensor
(Included with
Heat Pump)
Defrost Tempering
(Available only if
furnace is variable
Optional
capacity
or multi-stage)
Figure 11. Lennox Communicating Thermostat, EIM, Non-Comm Furnace/Air
Handler and Communicating AC or HP
1. Set the EIM Unit Type Jumper to IFC.
2. Set the EIM Heat Stage Jumper (see “Table 3. Heat Stage Jumper
Pin Settings” on page 5) to the applicable number of furnace heat
stages or number of electric heat stages.

11
3. Set the OTHERS/VENT DIP switch to the OTHERS (ON) position.
4. Use the Lennox communicating thermostat to complete the
commissioning procedure.
Lennox S40 Smart Thermostat Only, EIM (2), Lennox
Communicating Furnace, 24VAC Heat Pump and Ventilation (ERV/
HRV)
Lennox S40
Communicating
Thermostat
Equipment Interface
Model (EIM)
Communicating
Furnace
Wiring Legend
4−wire communicating
24VAC conventional
Non-communicating
Heat Pump
Equipment Interface
Model (EIM)
Ventilation - ERV/HRV
or Fresh Air Damper
Outdoor Unit: Non-communicating Heat Pump
Indoor Units: S40, Communicating Furnace, EIM (2) and Ventilation (ERV/HRV)
X2658 Outdoor
Sensor Required
Figure 12. Duel Fuel - Lennox Communicating Thermostat, IFC, EIM (2) No-Comm
HP and Ventilation
1. Set the EIM 1 Unit Type Jumper to HP.
2. Set the EIM 1 Heat Stage Jumper (see “Table 3. Heat Stage Jumper
Pin Settings” on page 5) to the applicable number of heat pump
heating stages.
3. Set the OTHERS/VENT DIP switch to the OTHERS (ON) position.
NOTE: For two-stage heat pump go to the heat pump defrost control,
locate P3 - low ambient thermostat pins and disable this function
by removing the installed jumper and relocating it to one pin only.
4. Set the EIM 2 Unit Type Jumper to VENT.
5. Set the EIM 2 OTHERS/VENT DIP switch to the VENT (OFF) position.
6. Use the Lennox communicating thermostat to complete the
commissioning procedure.
Thermostat Terminal Information
Table 8. Terminal Designations and Wiring Recommendations
Terminal
Designation Description Thermostat Wiring
R24VAC input 18AWG unshielded
I+ RS-BUS I+ 18 - 22AWG unshielded or shielded
NOTE: Shielded wiring may be required in some
rare situations. Use two-conductor shield-
ed cabling.
I- RS-BUS I-
C24VAC return 18AWG unshielded

12
Field Wiring Diagrams
Table 9. Wiring Diagrams
System Type Lennox Indoor
Unit
Lennox Outdoor
Unit
EIM 1 Jumper Settings EIM 2 Jumper Settings
Diagram
Unit Type Heat Stages OTHER/VENT
DIP Setting
Unit
Type
Heat
Stages
OTHER/VENT
DIP Setting
Air Conditioner Conventional
Furnace
Conventional Air
Conditioner IFC Set to number of furnace stages. ON N/A N/A N/A
Figure 16 on page
15.
Air Conditioner Conventional Air
Handler
Conventional Air
Conditioner AHC
Set to number
of air handler
electric heat
stages.
ON N/A N/A N/A
Heat Pump Conventional Air
Handler Conventional Heat Pump HP
Set to number
of heat pump
compressor
stages.
ON N/A N/A N/A
Figure 17 on page
15.
Dual Fuel Conventional
Furnace Communicating Heat Pump IFC Figure 19 on page
16.
Dual Fuel Communicating
Furnace Conventional Heat Pump HP Figure 18 on page
15.
Dual Fuel Conventional
Furnace Conventional Heat Pump IFC Figure 20 on page
16.
Dual Fuel with iHarmony Communicating
Furnace Conventional Heat Pump HP Figure 23 on page
18.
Duel Fuel with Ventilation Communicating
Furnace Conventional Heat Pump HP
Set to number
of heat pump
compressor
stages.
ON VENT N/A OFF Figure 26 on page
21.
Baseboard Heat Conventional Air
Handler*
Communicating Air
Conditioner or Heat Pump IFC Set to the number
of heat pump
compressor
stages or air
handler electric
heat stages.
ON N/A N/A N/A
Figure 21 on page
16.
Hot Water Coil with Aquastat Blower
Control
Conventional Air
Handler*
Communicating Air
Conditioner or Heat Pump IFC
Accessories - Dehumidiers, humidi-
ers, HEPA Bypass Filter
Conventional Air
Handler or Furnace
Conventional Air
Conditioner or Heat Pump IFC Figure 22 on page
17
Accessory - Ventilation (ERV/HRV or
Fresh Air Damper
Conventional or
Communicating
Thermostat
None VENT N/A OFF N/A N/A N/A Figure 25 on page
20.
Accessory - EDA Conventional Conventional IFC or
AHC
Set to the number
of heat pump
compressor
stages or air
handler electric
heat stages.
ON N/A N/A N/A Figure 24 on page
19.
* 24VAC conventional air handler or CBA38MV setup as 24VAC conventional.

13
Communicating Wiring Diagrams
OPTION 1
Lennox Communicating
Thermostat
Cut shield off at
this end
EIM (Using Shielded Wiring for Communication Lines)
18AWG
unshielded **
Shield (drain) wire MUST
be connected to EIM
common terminal.
OPTION 2
18 or 22AWG
shielded
18 or 22AWG
Standard Thermostat
Cable (4-Conductor)
EIM (Using Non-Shielded Wiring)
Lennox Communicating
Thermostat
Figure 13. EIM Wiring Connections (Options 1 and 2)
There may be situations where alternate wirings methods may need to be employed. Two options are available to address an inductive voltage issue.
If Alert Code 105 (see “Alert Codes and Troubleshooting” on page 22) is still present after following troubleshooting Steps 1 and 2 then proceed to
Step 3 wiring options 2 or 3.
• Option 2 - Using shielded 2-conductor cable between the indoor, outdoor and thermostat -i and +i terminals may be required.
• Option 3 - Using unshielded 2-conductor cable between the indoor, outdoor and thermostat -i and +i terminals may be required.
NOTE: When using multi-conductor unshielded thermostat cable, refer to “Figure 15. Minimizing Electrical Noise” on page 14.

14
Lennox
Communicating
Thermostat
Equipment Interface Module (EIM) (Using 2-conductor Unshielded Cable for Communication Lines and
Separate 2-conductor Unshielded Cable for R and C)
OPTION 3
18/2 Brown Solid CU CL2 Thermostat Wire
Figure 14. EIM Connections using Separate Unshielded Cable
(Option 3)
Minimizing Electrical Noise
When using multi-conductor unshielded thermostat cable, to minimize
electrical noise, cap unused wires as illustrated below and run to indoor
unit C terminal.
Single wire
to indoor unit
terminal “C”.
Unused
wires
Single wire directly to
C terminal or
to second bundle.
.
Indoor Unit Controller
Outdoor Unit
Thermostat
R i+ I- C
Unused
wires
Figure 15. Minimizing Electrical Noise

15
Component Wiring
The following diagrams are for specic component applications.
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
LENNOX
COMMUNICATING
THERMOSTAT
Y2
Out
BL
VENT
1
VENT
2
VENT
C
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
DIP SWITCH MUST BE SET TO ON
POSITION.
5
5

5
5

See Lennox Communicating
System Wiring Connections
diagram
Figure 16. Conventional Furnace or Air Hander with Conventional Air Conditioner
(1 or 2-Stage)
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
Y2 OUT
BL
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
VENT
1
VENT
2
VENT
C
LENNOX
COMMUNICATING
THERMOSTAT
DIP SWITCH MUST BE SET TO ON
POSITION.
5
5

5
5

See Lennox Communicating
System Wiring Connections
diagram
Figure 17. Conventional Air Hander with Conventional Heat Pump (1 or 2-Stage)
Y2
Y2 OUT
BL Y2 OUT IS FOR TWO-STAGE
OUTDOOR UNITS ONLY
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
LENNOX
COMMUNICATING
THERMOSTAT
VENT
1
VENT
2
VENT
C
DIP SWITCH MUST BE
SET TO ON POSITION.
4
4
See Lennox Communicating
System Wiring Connections
diagram
Figure 18. Dual-Fuel - Lennox Communicating Furnace with Conventional Heat
Pump (1 or 2-Stage)

16
REMOVE JUMPER BETWEEN R AND W2 IF
PRESENT. IT MAY CAUSE ERRONEOUS ALERT
CODE 125.
NOTE: NOT APPLICABLE FOR
VARIABLE CAPACITY
OUTDOOR UNITS.
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
VENT
1
VENT
2
VENT
C
LENNOX
COMMUNICATING
THERMOSTAT
DIP SWITCH MUST BE SET TO ON
POSITION.
7
7

7
7

LENNOX
COMMUNICATING
LENNOX COMMUNICATING
See Lennox Communicating
System Wiring Connections
diagram
Figure 19. Dual-Fuel - Conventional Furnace with Lennox Communicating
Heat Pump (1 or 2-Stage)
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
Y2 OUT
BL
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
VENT
1
VENT
2
VENT
C
LENNOX
COMMUNICATING
THERMOSTAT
DIP SWITCH MUST BE SET TO ON
POSITION.
5
5

5
5

See Lennox Communicating
System Wiring Connections
diagram
Figure 20. Dual-Fuel - Conventional Furnace with Conventional Heat Pump
(1 or 2-Stage)
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
VENT
1
VENT
2
VENT
C
LENNOX
COMMUNICATING
THERMOSTAT
4
4

DIP SWITCH MUST BE SET TO ON
POSITION.
4
4

LENNOX
COMMUNICATING
See Lennox Communicating
System Wiring Connections
diagram
Figure 21. Hot Water or Baseboard Heat - Conventional or Communicating Air
Handler in Non-Communicating Setup with either a Lennox Communicating AC
Conditioner or HP

17
REMOVE JUMPER
BETWEEN R AND
W2 IF PRESENT.
IT MAY CAUSE
ERRONEOUS ALERT
CODE 125.
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
SET UNIT TYPE TO EITHER IFC OR AHC
48100/130
2
2
DIP SWITCH MUST BE SET TO ON
POSITION.
2
2
LENNOX
COMMUNICATING
THERMOSTAT
See Lennox Communicating
System Wiring Connections
diagram
Figure 22. Optional Accessories with Conventional Indoor Unit (HEPA Bypass Filter,
24VAC Humidier and HCWHD4 Dehumidier)

18
Y2 OUT
BL
3
2
LENNOX
COMMUNICATING
THERMOSTAT
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
VENT
1
VENT
2
VENT
C
DIP SWITCH MUST BE SET TO ON
POSITION.
4
4
LENNOX
COMMUNICATING
FURNACE
See Lennox Communicating
System Wiring Connections
diagram
Figure 23. Dual-Fuel - Lennox Communicating Furnace, Smart Zoning and Conventional Heat Pump

19
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
Y2 OUT
BL
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
SET UNIT TYPE TO EITHER IFC OR AHC
LENNOX
COMMUNICATING
THERMOSTAT
CBA27UHE, CBA25UHV AND CBA25UH
VENT
1
VENT
2
VENT
C
4
4

DIP SWITCH MUST BE SET TO ON
POSITION.
4
4

1
1

1
1

2
2
See Lennox Communicating
System Wiring Connections
diagram
Figure 24. Conventional Indoor and Outdoor Units (EDA Humiditrol)

20
FRESH AIR DAMPER MOTOR
VENT
1
VENT
2
VENT
C
S40 SMART
THERMOSTAT
TWO-WIRE CONTROL
EQUIPMENT INTERFACE MODULE (EIM)
6” ROUND POWER OPEN / SPRING
CLOSED AND REQUIRES 24VAC
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
VENT
1
VENT
2
VENT
C
S40 SMART
THERMOSTAT
WIRE JUMPER REQUIRED BETWEEN ON AND RED TERMINALS.
LOW
ON
RED
YEL
GRN
HI
COM
NO
NC
BLK
HRV/ERV
TERMINAL BLOCK
1
1
LOW-STAGE
HIGH-STAGE
DIP SWITCH MUST BE SET TO OFF.
2
2
2
2
3
3
1
1
EQUIPMENT INTERFACE MODULE (EIM)
4
DIP SWITCH MUST BE SET TO OFF.
UNIT TYPE JUMPER POSITIONS
HP IFC AHC
VENT
VENTILATION HEAT PUMP FURNACE AIR HANDLER
5
4
LENNOX
LENNOX
5
120VAC
CONTINUOUS POWERED
24VAC TRANSFORMER
(FIELD-PROVIDED)
See Lennox Communicating
System Wiring Connections
diagram
Figure 25. Lennox S40 Smart Thermostat, EIM and Ventilation (ERV/HRV or Fresh Air Damper) -