Lennox EIM - Air Temperature Sensor Connections; Lennox Communicating Terminal Connections and Wiring Recommendations; Dual-Fuel Terminal Connections; Conventional Terminal Connections and Wiring Requirement

6
Air Temperature Sensor Connections
Refer to “Figure 1. Terminals 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 - 2
terminals).
NOTE: Wiring distance between the EIM and the outdoor temperature
sensor can not exceed 150 feet (45 meters) when wired with
minimum 22AWG (Recommend) 18AWG dedicated two-
conductor thermostat cable.
Discharge Air
Sensor
Optional for diagnostics of indoor air; use 88K38 Discharge Air Sensor -
2 terminals.
Lennox Communicating Terminal Connections and Wiring
Recommendations
Table 5. Communicating Terminals
Label Function / Description Thermostat Wiring
R 24VAC communication power Input 18AWG unshielded
i+ Communication high – data line
18 - 22AWG shielded
(recommended)
i- Communication low – data line
C
24VAC communication common
power Input
18AWG unshielded
IMPORTANT
Use 18AWG unshielded thermostat cable (eld-provided) for power
terminals (R and C) and all non-communicating terminals. Highly
recommend using 18 - 22AWG shielded thermostat cable for
communications terminals ( i+ and i-) which will help eliminate any noise
interference.
Dual-Fuel Terminal Connections
Table 6. Dual-Fuel Terminals
Label Description Function
DFTS
Pre-coil discharge
air temperature (2
terminals)
The pre -coil discharge air sensor should be
installed downstream of the gas heat exchanger
and before the in door coil when a heat pump is
used and defrost tempering is required.
It must be placed in free airow, where other
accessories (such as humidiers, UV lights, etc.)
will not interfere with its accuracy. Wiring distance
between the EIM and the discharge air sensor
should not exceed 10 feet when using 18AWG
thermostat wire.
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.
0
Heat Pump Reversing
Valve (Powered for
cooling)
In systems with communicating IFC, the EIM (HP)
O output is connected to a non-communicating
heat pump compatible with O signal for reversing
valve operation. A 24VAC signal is generated on
O for cooling operation, while the terminal is open
for heating operation.
B
Heat Pump Reserving
Valve
(Powered for
heating)
In systems with communicating IFC, the EIM (HP)
B output is connected to a non-communicating
heat pump compatible with B signal for reversing
valve operation. A 24VAC signal is generated on
B for heat pump opera tion, while the terminal is
open for cooling operation.
Conventional Terminal Connections and Wiring Requirement
Table 7. Conventional Terminals
Label Description Function
18AWG unshielded thermostat cable (eld-provided) for
all non-communicating connections
W1
1st - stage heat output (1st stage gas heat output when congured as IFC
and 1st stage electric heat output when congured as AHC.
W2
2nd - stage heat output (2nd stage gas heat output when congured as
IFC and 2nd stage electric heat output when congured as AHC.
W3
3rd - stage heat output (3nd stage electric heat output when congured as
AHC)