24-V Wiring; Accessories; Removal Of Existing Furnaces From Common Vent Systems; Combustion-Air And Vent Pipe Systems - Carrier 58MCB Installation, Start-Up, And Operating Instructions Manual

Use a separate, fused branch electrical circuit containing a properly
sized fuse or circuit breaker for this furnace. See Table 6 for wire
size and fuse specifications. A disconnecting means must be
located within sight from and readily accessible to furnace.
NOTE: Proper polarity must be maintained for 115-v wiring. If
polarity is incorrect or the furnace is not grounded, control center
LED status indicator light will flash rapidly and furnace will NOT
operate.
ELECTRICAL SHOCK AND FIRE HAZARD
Failure to follow this warning could result in serious injury,
death, or property damage.
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.
J-Box Relocation
1. Remove 2 screws holding auxiliary J-box. (See Fig. 32.)
2. Rotate J-box 180° and attach box to left side, using holes
provided.
ELECTRICAL SHOCK AND FIRE HAZARD
Failure to follow this warning could result in serious injury,
death, or property damage.
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.

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. 30. The 24-v terminal block is marked for
easy connection of field wiring. (See Fig. 33.) The 24-v circuit
contains a 3-amp, automotive-type fuse located on furnace control
center. (See Fig. 34.) Any electrical shorts of 24-v wiring during
ALTERNATE
FIELD
LOCATION
Fig. 32—Relocating J-Box
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.

ACCESSORIES

1. Electronic Air Cleaner (EAC)
Two quick-connect terminals marked EAC-1 and EAC-2 are
provided for EAC connection. (See Fig. 34.) These terminals
are energized with 115v (1.0-amp maximum) during blower
motor operation.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit component
damage.
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.
2. Humidifier (HUM)
A quick-connect terminal (HUM) and screw terminal (C
24v) are provided for 24v humidifier connection. (See Fig.
34.) 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.
Step 9—Removal of Existing Furnaces from
Common Vent Systems
When an existing Category I furnace is removed or replaced, the
original venting system may no longer be sized to properly vent
the remaining attached appliances. An improperly sized Category
I venting system could cause the formation of condensate in the
furnace and vent, leakage of condensate and combustion products,
spillage of combustion products into the living space, etc.
Step 10—Combustion Air and Vent Pipe Systems
GENERAL
Vent system or vent connectors may need to be resized. For any
other appliances when resizing vent systems or vent connectors,
system or connector must be sized to approach minimum size as
determined using appropriate table found in the NFGC or NSC-
FACTORY
NGPIC.
INSTALLED
→
LOCATION
The 58MCB can be vented as either a direct vent (all sizes) or as
a non-direct vent (except for 140 size) application. A direct vent
system shall be installed in accordance with the direct vent
(2-pipe) procedures in the following Combustion Air and Vent
Pipe Systems section. For non-direct vent (1-pipe) applications,
refer to the non-direct vent (1-pipe) procedures in the same section.
→
Multistory and common venting are prohibited.
DIRECT VENT/2-PIPE SYSTEM (ALL SIZES)
In a direct-vent (2-pipe) system, all air for combustion is taken
directly from outdoor atmosphere, and all flue products are
discharged to outdoor atmosphere. A factory accessory vent
A00212
termination kit MUST be used in a direct vent (2-pipe) system.
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OM