Service Manual

26
SYSTEM OPERATION
Use a separate fused branch electrical circuit containing
properly sized wire, and fuse or circuit breaker. The fuse or
circuit breaker must be sized in accordance with the maxi-
mum overcurrent protection specified on the unit rating plate.
An electrical disconnect must be provided at the furnace
location.
NOTE: Line polarity must be observed when making field
connections.
W
A
R
N I N G
IN 90% FURNACE UPRIGHT UPFLOW INSTALLATIONS, THE DRAIN TRAP MUST
BE MOUNTED ON THE OPPOSITE SIDE OF THE UNIT FROM THE JUNCTION
BOX. THIS WILL REDUCE THE RISK OF WATER REACHING THE JUNCTION
BOX IN THE EVENT OF A BLOCKED DRAIN CONDITION.
Connect hot, neutral, and ground wires as shown in the wir-
ing diagram located on the unit’s blower door. Line polarity
must be observed when making field connections. Line volt-
age connections can be made through either the right or left
side panel.
The furnace is shipped configured for a right side (left side
for counterflow) electrical connection with the junction box
located inside the burner compartment. To make electrical
connections through the opposite side of the furnace, the
junction box must be relocated to the other side of the burner
compartment prior to making electrical connections.
NOTE: Wire routing must not interfere with circulator
blower operation, filter removal, or routine maintenance.
WARNING
TO AVOID THE RISK OF ELECTRICAL SHOCK, INJURY, OR DEATH, THE
FURNACE MUST BE ELECTRICALLY GROUNDED IN ACCORDANCE WITH LOCAL
CODES OR, IN THEIR ABSENCE, WITH THE LATEST EDITION OF THE
NATIONAL ELECTRIC CODE.
115 VOLT LINE CONNECTION OF ACCESSORIES
(ELECTRONIC AIR CLEANER)
WARNING
HIGH VOLTAGE
DISCONNECT ALL POWER BEFORE SERVICING OR
CHANGING ANY ELECTRICAL WIRING. MULTIPLE POWER
SOURCES MAY BE PRESENT. FAILURE TO DO SO MAY CAUSE
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
Ele ctr onic
Air Cleaner
1.0 Amp maximum at 120 VAC
Humidifie r
1.0 Amp maximum at 120 VAC
ACCESSORY LOAD SPECIFICATIONS
Turn OFF power to the furnace before installing any acces-
sories. Follow the humidifier or air cleaner manufacturers’
instructions for locating, mounting, grounding, and control-
ling these accessories.
If it is necessary for the installer to supply additional line
voltage wiring to the inside of the furnace, the wiring must
conform to all local codes, and have a minimum tempera-
ture rating of 105°C. All line voltage wire splices must be
made inside the furnace junction box.
The integrated control module electronic air cleaner termi-
nals (EAC) are energized with 115 volts whenever the circu-
lator blower is energized.
24 VOLT THERMOSTAT WIRING
NOTE: Low voltage connections can be made through ei-
ther the right or left side panel. Wire routing must not inter-
fere with circulator blower operation, filter removal, or routine
maintenance.
A 40 V.A. transformer and an integrated electronic control
are built into the furnace to allow use with most cooling equip-
ment. Consult the wiring diagram located in this manual,
the installation manual, or on the blower door for further de-
tails of 115 Volt and 24 Volt wiring.
THERMOSTAT WIRING
The *MEC96 furnace has W1 & W2 terminals for connec-
tion of a two stage heating thermostat. If desired, a thermo-
stat with only one stage of heat may be used. As shipped,
the furnace S1-1 switch is OFF; S1-2 switch is ON. This is
the correct position to use a single stage heating thermo-
stat with auto timing transition to high fire.
R
Y C
Furnace
Integrated
Cont r ol
Module
Remot e Condensing Unit
(Singl e-St age Cooling)
R
Thermostat - Single -Stage Heating with Single-Stage Cooling
NOTE: To apply a single-stage Heating Thermostat, the
thermostat selector switch on the Integrated Control Module
must be set on single-stage.