The cabinet MUST have an uninterrupted or unbroken ground
according to NEC ANSI/NFPA 70-2002 and Canadian Elec-
trical Code CSA C22.1 or local codes to minimize personal
injury if an electrical fault should occur. This may consist of
electrical wire or conduit approved for electrical ground when
installed in accordance with existing electrical codes. Do not
use gas piping as an electrical ground. Failure to follow this
warning could result in electrical shock, fire, or death.
J-Box Relocation
1. Remove 2 screws holding auxiliary J-box. (See Fig. 29.)
2. Rotate J-box 180° and attach box to left side, using holes
provided.
If manual disconnect switch is to be mounted on furnace,
select a location where a drill or fastener will not contact
electrical or gas components.
Step 2—24-v Wiring
Make field 24-v thermostat connections at 24-v terminal block on
furnace control center. For proper cooling operation, Y wire from
thermostat MUST be connected to Y terminal on furnace control
center, as shown in Fig. 27. The 24-v terminal block is marked for
easy connection of field wiring. (See Fig. 30.) The 24-v circuit
contains a 3-amp, automotive-type fuse located on furnace control
center. (See Fig. 31.) Any electrical shorts of 24-v wiring during
installation, service, or maintenance may cause fuse to blow. If
fuse replacement is required, use only a fuse of identical size (3
amp) and type. The control will flash code 24 when fuse needs
replacement.
NOTE: Use AWG No. 18 color-coded copper thermostat wire for
lengths up to 100 ft. For wire lengths over 100 ft, use AWG No.
16 wire.
Step 3—Accessories
1. Electronic Air Cleaner (EAC)
Two quick-connect terminals marked EAC-1 and EAC-2 are
provided for EAC connection. (See Fig. 31.) These terminals
are energized with 115v (1.0-amp maximum) during blower
motor operation.
DO NOT connect furnace control HUM terminal to HUM
(humidifier) terminal on Thermidistat™, Zone Controller or
similar device. See Thermidistat™, Zone Controller, thermo-
stat, or controller manufacturer’s instructions for proper
connection. A failure to follow this warning could result in
fire.
2. Humidifier (HUM)
A quick-connect terminal (HUM) and screw terminal (C
OM
24v) are provided for 24-v humidifier connection. (See Fig.
31.) HUM terminal is energized with 24v (0.5-amp maximum)
when gas valve is energized.
NOTE: A field-supplied, 115-v controlled relay connected to
EAC terminals may be added if humidifier operation is desired
during blower operation.
DIRECT VENTING
The 58MCA Furnaces require a dedicated (one 58MCA furnace
only) direct-vent system. In a direct-vent system, all air for
combustion is taken directly from outdoor atmosphere, and all flue
products are discharged to outdoor atmosphere.
Fig. 28—Disconnect Switch and Furnace
A93033
COPPER
WIRE ONLY
ELECTRIC
DISCONNECT
SWITCH
ALUMINUM
WIRE
Fig. 29—Relocating J-Box
A00212
FACTORY
INSTALLED
LOCATION
ALTERNATE
FIELD
LOCATION
20
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