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VIII. STEP 8 — INSTALL GAS PIPING
Unit is equipped for use with natural gas. Installation must
conform with local building codes or, in the absence of local
codes, with the National Fuel Gas Code, ANSI Z223.1.
Install field-supplied manual gas shutoff valve with a
1
/
8
-in.
NPT pressure tap for test gage connection at unit. Field gas
piping must include sediment trap and union. See Fig. 14.
IMPORTANT: Natural gas pressure at unit gas connection
must not be less than 5.5 in. wg or greater than 13.5 in. wg.
Size gas-supply piping for 0.5-in. wg maximum pressure
drop. Do not use supply pipe smaller than unit gas
connection.
IX. STEP 9 — MAKE ELECTRICAL CONNECTIONS
A. Field Power Supply
Unit is factory wired for voltage shown on unit nameplate.
When installing units, provide a disconnect per NEC
(National Electrical Code) requirements of adequate size
(Table 5).
All field wiring must comply with NEC and local
requirements.
Route power and ground lines through control box end
panel or unit basepan (see Fig. 4-6) to connections as shown
on unit wiring diagram and Fig. 15.
Field wiring must conform to temperature limitations for
type ‘‘T’’ wire. All field wiring must comply with NEC and
local requirements.
Transformer no. 1 is wired for 230-v unit. If 208/230-v unit is
to be run with 208-v power supply, the transformer must be
rewired as follows:
1. Remove cap from red (208 v) wire.
2. Remove cap from orange (230 v) spliced wire.
3. Replace orange wire with red wire.
4. Recap both wires.
IMPORTANT: BE CERTAIN UNUSED WIRES ARE
CAPPED. Failure to do so may damage the transformers.
Operating voltage to compressor must be within voltage
range indicated on unit nameplate. On 3-phase units, volt-
ages between phases must be balanced within 2%.
Unit failure as a result of operation on improper line voltage
or excessive phase imbalance constitutes abuse and may
cause damage to electrical components.
B. Field Control Wiring
Install a Bryant-approved accessory thermostat assembly (or
light commercial Thermidistat™ device for units equipped
with Perfect Humidity™ option) according to the installation
instructions included with accessory. Locate thermostat
assembly on a solid interior wall in the conditioned space to
sense average temperature.
Route thermostat cable or equivalent single leads of colored
wire from subbase terminals through conduit in unit to low-
voltage connections as shown on unit label wiring diagram
and in Fig. 16.
NOTE: For wire runs up to 50 ft, use no. 18 AWG (American
Wire Gage) insulated wire (35 C minimum). For 50 to 75 ft,
use no. 16 AWG insulated wire (35 C minimum). For over
75 ft, use no. 14 AWG insulated wire (35 C minimum). All
wire larger than no. 18 AWG cannot be directly connected at
the thermostat and will require a junction box and splice at
the thermostat.
Set heat anticipator settings as follows:
Settings may be changed slightly to provide a greater degree
of comfort for a particular installation.
C. Optional Non-Fused Disconnect
On units with the optional non-fused disconnect, incoming
power will be wired into the disconnect switch. Refer to
Fig. 17 for wiring for 100 and 200 amp disconnect switches.
Units with an MOCP (maximum overcurrent protection)
under 100 will use the 100 amp disconnect switch. Units
with an MOCP over 100 will use the 200 amp disconnect
switch. Refer to the applicable disconnect wiring diagram.
To prevent breakage during shipping, the disconnect handle
and shaft are shipped and packaged inside the unit control
box. Install the disconnect handle before unit operation. To
install the handle and shaft, perform the following procedure:
1. Open the control box door and remove the handle and
shaft from shipping location.
2. Loosen the Allen bolt located on the disconnect
switch. The bolt is located on the square hole and is
used to hold the shaft in place. The shaft cannot be
inserted until the Allen bolt is moved.
3. Insert the disconnect shaft into the square hole on
the disconnect switch. The end of the shaft is spe-
cially cut and the shaft can only be inserted in the
correct orientation.
WARNING: Do not pressure test gas supply while
connected to unit. Always disconnect union before
servicing.
CAUTION: The correct power phasing is critical in
the operation of the scroll compressors. An incorrect
phasing will cause the compressor to rotate in the
wrong direction. This may lead to premature compres-
sor failure.
WARNING: The unit must be electrically grounded
in accordance with local codes and NEC ANSI/NFPA 70
(National Fire Protection Association).
VOLTAGE W1 W2
208/230 0.98 0.44
460 0.80 0.44
Fig. 14 — Field Gas Piping