Electrical - Lennox ML193UH Installation Instructions Manual

Electrical

ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect elec­
tronic components. Take precautions
to neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
INTERIOR MAKE-UP BOX INSTALLATION
MAKE-UP
BOX
FIGURE 59
The unit is equipped with a field make-up box. The make-
up box may be moved to the right side of the furnace to fa­
cilitate installation. Seal unused openings on left side with
plugs removed from right side. Secure the excess wire to
the existing harness to protect it from damage.
Refer to figure 60 for schematic wiring diagram and trou­
bleshooting.
The power supply wiring must meet Class I restrictions.
Protected by either a fuse or circuit breaker, select circuit
protection and wire size according to unit nameplate.
NOTE - Unit nameplate states maximum current draw.
Maximum Over-Current Protection allowed is 15 AMP.
Holes are on both sides of the furnace cabinet to facilitate
wiring.
Install a separate (properly sized) disconnect switch near
the furnace so that power can be turned off for servicing.
Before connecting the thermostat check to make sure the
wires will be long enough for servicing at a later date. Make
sure that thermostat wire is long enough to facilitate future
removal of blower for service.
remove and relocate
plug to unused
opening on left side
Right Side
Complete the wiring connections to the equipment. Use the
provided unit wiring diagram and the field wiring shown in
figure 60. Use 18-gauge wire or larger that is suitable for
Class II rating for thermostat connections.
Electrically ground the unit according to local codes or, in
the absence of local codes, according to the current Na­
tional Electric Code (ANSI/NFPA No. 70) for the USA and
current Canadian Electric Code part 1 (CSA standard
C22.1) for Canada. A green ground wire is provided in the
field make-up box.
NOTE - The ML193UH furnace contains electronic compo­
nents that are polarity sensitive. Make sure that the furnace
is wired correctly and is properly grounded.
Accessory Terminals
One line voltage "EAC" 1/4" spade terminal is provided on
the furnace integrated control. See figure 1 for integrated
control configuration. This terminal is energized when the
indoor blower is operating. Any accessory rated up to one
amp can be connected to this terminal with the neutral leg
of the circuit being connected to one of the provided neutral
terminals. If an accessory rated at greater than one amp is
connected to this terminal, it is necessary to use an exter­
nal relay.
One line voltage "HUM" 1/4" spade terminal is provided on
the furnace integrated control. See figure 1 for integrated
control configuration. This terminal is energized in the
heating mode when the combustion air inducer is operat­
ing. Any humidifier rated up to one amp can be connected
to this terminal with the neutral leg of the circuit being con­
nected to one of the provided neutral terminals. If a humidi­
fier rated at greater than one amp is connected to this termi­
nal, it is necessary to use an external relay relay.
Thermostat
Install the room thermostat according to the instructions
provided with the thermostat. See figure 60 for thermostat
designations. If the furnace is being matched with a heat
pump, refer to the FM21 installation instruction or appropri­
ate dual fuel thermostat instructions.
Indoor Blower Speeds
1 - When the thermostat is set to "FAN ON," the indoor
blower will run continuously on the heating speed
when there is no cooling or heating demand.
2 - When the ML193UH is running in the heating mode,
the indoor blower will run on the heating speed.
3 - When there is a cooling demand, the indoor blower will
run on the cooling speed.
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