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FIGURE 56
Communicating Thermostat with SL297UHNV
and Non-Communicating Outdoor Unit
COMMUNICATING
ENABLED
SL297UHNV
FURNACE
COMMUNICATING
THERMOSTAT
NON-COMMUNICATING
OUTDOOR AIR
CONDITIONING UNIT -
1 OR 2 STAGE
OPTIONAL
OUTDOOR
AIR SENSOR
OPTIONAL
DISCHARGE
AIR SENSOR
Communicating Thermostat with SL297UHNV
and Communicating Outdoor Unit
COMMUNICATING
ENABLED
SL297UHNV
FURNACE
COMMUNICATING OUT
DOOR AIR CONDITIONING
OR HEAT PUMP UNIT
OPTIONAL
OUTDOOR
AIR SENSOR
OPTIONAL
DISCHARGE
AIR SENSOR
CLIP ON-BOARD LINK
W915 (Y1 TO Y2) FOR
TWO-STAGE OPERATION
COMMUNICATING
THERMOSTAT
Indoor Unit
Controller
Outdoor Unit
Communicating thermostat
Single wire to
terminal C
Single wire to
terminal C
Unused wires
Systems using a communicating thermostat require four thermostat wires
between the thermostat and the furnace/air handler control and four wires
between the outdoor unit and the furnace/air handler control. When a thermo
stat cable with more than four wires is used, the extra wires must be properly
connected to avoid electrical noise. The wires must not be left disconnected.
Use wire nuts to bundle the four unused wires at each end of the cable. A
single wire should then be connected to the indoor unit end of the wire bundle
and attached to the “C” terminals as shown above.
Unused wires