Lennox SL280DFNV Installation Instructions Manual page 20

6 - Electrically ground the unit according to local codes
or, in the absence of local codes, according to the
current National Electric Code (ANSI/NFPA No. 70).
A green ground wire is provided in the field make-up
box.
NOTE - The SL280DFNV furnace contains electronic
components that are polarity sensitive. Make sure that
the furnace is wired correctly and is properly grounded.
7 - One line voltage "ACC" 1/4" spade terminal is
provided on the furnace integrated control. Any
electronic air cleaner or other accessory rated up
to one amp can be connected to this terminal with
the neutral leg of the circuit being connected to the
one of the provided neutral terminals. See figure 25
for control configuration. This terminal is energized
when the indoor blower is operating.
8 - An unpowered, normally open (dry) set of contacts
with a 1/4" spade terminal "HUM" are provided for
humidifier connections and may be connected to
24V or 120V. Any humidifier rated up to one amp can
be connected to these terminals. In 120V humidifier
applications the neutral leg of the circuit can be
connected to one of the provided neutral terminals.
This terminal is energized in the heating mode.
9 - Install the room thermostat according to the
instructions provided with the thermostat. See table
10 for field wiring connections in varying applications.
If the furnace is being matched with a heat pump,
refer to the instruction packaged with the dual fuel
thermostat.
Thermostat Selection
NOTICE
Field wiring for both communicating and non-
communicating applications
diagrams, which begin on the next page.
Non-Communicating
In non-communicating applications the SL280DFNV
is designed to operate in a SINGLE-STAGE mode or
TWOSTAGE mode using a conventional thermostat.
For optimal performance in non-communicating applica-
tions, Lennox recommends use of a ComfortSense® 7500
high quality electronic digital thermostat or any other with
adjustable settings for 1st stage / 2nd stage on / off differ-
entials and adjustable stage timers.
is illustrated in
Page 20
Lennox recommends the following two-stage thermostat
settings:
First heat stage differential set to 1/2 to 1 degree F; sec-
ond heat stage differential set to 1/2 or 1 degree F; second
heat stage upstage timer disabled, or set to maximum (1
hr minimum).
Communicating
In communicating applications a communicating thermo-
stat must be used. Refer to the instructions provided with
the thermostat for installation, set-up and operation. In
communicating system all unused thermostat wire in the
wire bundle needs to be terminated inside and out. The
extra wires can terminate on the 'C" terminal of the com-
munication terminal strip. (RSBus). Using an additional
wire come off "C" terminal and wire nut all the extra wires
together. Termination on the outdoor control must match
the indoor control.
Indoor Blower Speeds
Non-Communicating
1 - When the thermostat is set to "FAN ON," the indoor
blower will run continuously at a field selectable
percentage of the second-stage cooling speed
when there is no cooling or heating demand. The
factory default is setting is 38% of cool speeds. See
table 23 for allowable circulation speeds.
2 - When the SL280DFNV is running in the heating
mode, the indoor blower will run on the heating
speed designated by the positions of DIP switches
11, 12 and 13. First stage heating will run at 91%
heat speed.
3 - When there is a cooling demand, the indoor blower
will run on the cooling speed designated by the
positions of DIP switches 5 and 6. First stage cooling
will run at 70% cool speed.
Communicating
NOTE - When the SL280DFNV is used with a commu-
nicating thermostat, proper indoor blower speed selec-
tions are made by the thermostat.
1 - When the thermostat is set to "FAN ON," the indoor
blower will run at setting determined during system
configuration. See table 23 for allowable circulation
speeds.
2 - When there is a heating demand the fan will run on
heating speeds for firing rate.
3 - When there is a cooling demand, the fan will run on
the first stage and second stage cooling speed set
using the thermostat in the installer setup mode. The
factory default is based upon 400 CFM a ton.