Bryant 373LAV User Manual
Page 11
WARNING:
The cabinet MUST have an uninterrupted
or unbroken ground according to NEC ANSI/NFPA
70-1999 and Canadian Electrical 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.
B.
24-v Wiring
Make field 24-v connections at the 24-v terminal strip. (See Fig.
14.) Connect terminal Y as shown in Fig. 15 for proper operation
in cooling mode. Use AWG No. 18 color-coded wire only.
The 24-v circuit contains an automotive-type, 3-amp fuse located
on the main control board. Any direct shorts during installation,
service, or maintenance could cause this fuse to blow. If fuse
replacement is required, use ONLY a 3-amp fuse of identical size.
C.
Accessories
1. Electronic air cleaner (EAC)
Two quick-connect terminals, marked EAC-1 and EAC-2,
are provided for EAC connection. (See Fig. 14.) These
terminals are energized with 115v (1.0-amp maximum)
during blower motor operation.
2. Humidifier (HUM)
Quick-connect terminal (HUM) and screw terminal (C
OM
)
are provided for 24-v humidifier connection. The terminals
are energized with 24V (0.5-amp maximum) after inducer
motor prepurge period.
WARNING:
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. A
failure to follow this warning could result in fire.
NOTE:
A field-supplied, 115-v controlled relay connected to
EAC terminals may be added if humidifier operation is desired
during blower operation.
XI.
VENTING
Refer to the national or local installation code such as NFGC in the
United States, or the NSCNGPIC in Canada for proper vent sizing
and installation requirements. Use the enclosed Installation In-
structions (Single-Stage Vent Tables for Category I Fan-Assisted
Furnaces) for a quick, easy reference.
After fully assembling the vent connector to the furnace flue collar,
securely fasten the vent connector to the collar with two field-
supplied, corrosion-resistant, sheet metal screws located 180° apart
and midway up the collar.
The horizontal portion of the venting system shall maintain a
minimum of 1/4-in. upward slope per linear ft and it shall be
rigidly supported every 5 ft or less with hangers or straps to ensure
that there will be no movement after installation.
XII.
START-UP, ADJUSTMENT, AND SAFETY CHECK
A.
General
NOTE:
Proper polarity must be maintained for 115-v wiring. If
polarity is incorrect, control center fault indicator light will flash
rapidly and furnace will not operate.
The furnace must have a 115-v power supply properly connected
and grounded. Proper polarity must be maintained for correct
operation. Thermostat wire connections at R, W, C, and Y must be
made at the 24-v terminal block on the control board. The gas
service pressure must not exceed 0.5 psig (14-in. wc), but must be
no less than 0.16 psig (4.5-in. wc).
Before operating the furnace, check each manual reset switch for
continuity. If necessary, press the button to reset the switch.
The blower compartment door must be in place to complete the
115-v circuit to the furnace.
CAUTION:
This furnace is equipped with 2 manual
reset limit switches in the gas control area. The switches
will open and shut off power to the gas valve if a flame
rollout or an overheating condition occurs in the gas
control area. DO NOT bypass the switches. Correct
inadequate combustion air supply problem and reset the
switches.
B.
Sequence of Operation
CAUTION:
Furnace control must be grounded for
proper operation or control will lockout. Control is
grounded through green wire routed to gas valve and
burner bracket screw.
Using the schematic diagram shown in Fig. 16, follow the
sequence of operation through the different modes. Read and
follow the wiring diagram very carefully.
NOTE:
If there is a power interruption and any thermostat call,
the control will initiate a 90-sec blower only on period before
starting another cycle.
TABLE 6—ELECTRICAL DATA
UNIT SIZE
VOLTS—
HERTZ—
PHASE
OPERATING VOLTAGE RANGE
MAXIMUM
UNIT AMPS
MINIMUM
WIRE GAGE
MAXIMUM WIRE
LENGTH FT‡
MAXIMUM
FUSE OR CKT BKR
AMPS†
Maximum*
Minimum*
024050
115—60—1
127
104
6.6
14
42
15
036050
115—60—1
127
104
8.1
14
34
15
024070
115—60—1
127
104
6.7
14
42
15
036070
115—60—1
127
104
8.4
14
33
15
036095
115—60—1
127
104
9.2
14
30
15
049095
115—60—1
127
104
10.2
14
28
15
048115
115—60—1
127
104
10.1
14
28
15
060115
115—60—1
127
104
13.3
12
33
20
060135
115—60—1
127
104
14.3
12
31
20
* Permissible limits of the voltage range at which the unit will operate satisfactorily.
† Time-delay type is recommended.
‡ Length shown is as measured 1 way along wire path between unit and service panel for maximum 2 percent voltage drop.
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