shown in Fig. 31. The 24-v terminal block is marked for easy
connection of field wiring. (See Fig. 35.) The 24-v circuit contains
a 3-amp, automotive-type fuse located on furnace control. (See
Fig. 36.) Any electrical shorts of 24-v wiring during installation,
service, or maintenance may cause fuse to blow. If fuse replace-
ment 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.
C.
Accessories
1. Electronic Air Cleaner (EAC)
Two quick-connect terminals marked EAC-1 and EAC-2
are provided for EAC connection. (See Fig. 36.) These
terminals are energized with 115-v (1.0-amp maximum)
during blower motor operation.
CAUTION:
UNIT MAY NOT OPERATE
Failure to follow this caution may result in intermittent
operation or performance satisfaction.
DO NOT connect furnace control HUM terminal to HUM
(humidifier) terminal on Thermidistat™, Zone Controller
or similar device. See Thermidistat™, Zone Controller,
thermostat, or controller manufacturer’s instructions for
proper connection.
2. Humidifier (HUM)
A quick-connect terminal (HUM) and screw terminal (C
OM
24V) are provided for 24-v humidifier connection. (See Fig.
36.) HUM terminal is energized with 24-v (0.5-amp maxi-
mum) 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 all blower operation.
IX.
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.
X.
COMBUSTION AIR AND VENT PIPE SYSTEMS
A.
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-
NGPIC.
The 350A 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.
B.
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
termination kit MUST be used in a direct vent (2-pipe) system.
C.
Non-Direct Vent/1-Pipe System (Sizes 040 Through
120 Only)
In a non-direct vent (1-pipe) system, all air for combustion is taken
from the area adjacent to furnace, and all flue products are
discharged to outdoor atmosphere. A factory-supplied perforated
disk assembly (in loose parts bag) MUST be used in combustion-
air pipe elbow.
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Fig. 34—Relocating J-Box
A05058
FACTORY
INSTALLED
LOCATION
ALTERNATE
FIELD
LOCATION
POWER ENTRY HOLE
FILLER PLUG (FACTORY-
SUPPLIED LOOSE PARTS BAG)
UNUSED 7/8-IN. DIAMETER
POWER ENTRY HOLES
UNUSED 7/8-IN. DIAMETER
POWER ENTRY HOLES
POWER ENTRY HOLE
FILLER PLUG (FACTORY-
SUPPLIED LOOSE PARTS BAG)
—27—
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