Lennox SL280UHNV Series Unit Information page 42

Communicating Enabled Furnace and
Non-Communicating Outdoor Unit
COMMUNICATING
FURNACE
OPTIONAL
DISCHARGE
AIR SENSOR
COMMUNICATING
THERMOSTAT
CLIP ON-BOARD LINK
W915 (Y1 TO Y2) FOR
TWO-STAGE OPERATION
Outdoor Unit
OPTIONAL
OUTDOOR
AIR SENSOR
NON-COMMUNICATING
OUTDOOR AIR
CONDITIONING UNIT -
1 OR 2 STAGE
Communicating systems require four thermostat wires between the thermostat and
the furnace/air handler control and four wires between the outdoor unit and the fur­
nace/air handler control. When a thermostat 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 below.
Communicating Enabled Control
Single wire
to terminal C
Unused wires
Communicating Enabled Furnace and
Communicating Enabled Outdoor Unit
COMMUNICATING
FURNACE
OPTIONAL
DISCHARGE
AIR SENSOR
OPTIONAL
OUTDOOR
AIR SENSOR
COMMUNICATING
THERMOSTAT
Single wire
to terminal C
Unused wires
Page 42
COMMUNICATING ENABLED
OUTDOOR UNIT