Lennox EIM - Duel-Fuel Operations

9
Duel-Fuel Operations
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
discharge 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
13. Dual-Fuel - Conventional Furnace with Conventional Heat Pump
(1 or 2-Stage)” on page 12.
Lennox Communicating
Thermostat
Equipment Interface
Model (EIM)
Furnace
24VAC conventional
Heat Pump
(Outdoor Unit)
Outdoor Sensor
(Included with
Heat Pump)
Defrost Tempering
(Available only if
furnace is variable
Optional
capacity
or multi-stage)
Wiring Legend
4-wire communicating
Lennox
Communicating
Non-Communicating
Figure 7. EIM, Conventional Furnace and Lennox Communicating Heat Pump
Wiring Legend 4-wire communicating
24VAC conventional
24VAC
Conventional Heat
Pump
(Outdoor Unit)
X2658 Outdoor
Sensor Required
Equipment Interface
Model (EIM)
Lennox
Communicating
Thermostat
Lennox
Communicating
Furnance
Figure 8. EIM, Conventional Furnace and Conventional Heat Pump