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Step 7—Gas Piping
Gas piping must be installed in accordance with national and local
codes. Refer to current edition of NFGC. Canadian installations
must be made in accordance with NSCNGPIC and all authorities
having jurisdiction. Gas supply line should be a separate line
running directly from meter to furnace, if possible. Refer to Table
2 for recommended gas pipe sizing. Risers must be used to connect
to furnace and to meter. Support all gas piping with appropriate
straps, hangers, etc. Use a minimum of 1 hanger every 6 ft. Joint
compound (pipe dope) should be applied sparingly and only to
male threads of joints. Pipe dope must be resistant to propane gas.
Connect gas pipe to furnace using a backup wrench to avoid
damaging gas controls.
Gas valve ON and OFF switch MUST be facing forward or
tilted upward. (See Fig. 40.) Failure to follow this warning
could result in property damage or death.
Never purge a gas line into a combustion chamber. Never use
matches, candles, flame, or other sources of ignition for
purpose of checking leakage. Use a soap-and-water solution
to check for leakage. A failure to follow this warning could
result in fire, explosion, personal injury, or death.
Use proper length of pipe to avoid stress on gas control
manifold. Failure to follow this warning could result in a gas
leak resulting in fire, explosion, personal injury, or death.
Table 2—Maximum Capacity of Pipe
(Cu Ft Per Hr)*
NOMINAL
IRON
INTERNAL
PIPE
DIAMETER
SIZE
(IN.)
(IN.)
1/2
0.622
3/4
0.824
1
1.049
1-1/4
1.380
1400
1-1/2
1.610
2100
* For gas pressures of 0.5 psig (14-in. wc) or less, and a pressure drop of
0.5-in. wc (based on a 0.60 specific gravity gas). Ref: Table 10-2 NFPA
54-1992.
Install a sediment trap in riser leading to furnace. Trap can be
installed by connecting a tee to riser leading to furnace so
straight-through section of tee is vertical. Then connect a capped
nipple into lower end of tee. Capped nipple should extend below
level of gas controls. Place a ground joint union between gas
control manifold and manual gas shutoff valve. (See Fig. 23.)
If a flexible connector is required or allowed by authority
having jurisdiction, black iron pipe shall be installed at gas
valve and extend a minimum of 2 in. outside furnace casing.
LENGTH OF PIPE (FT)
10
20
30
40
175
120
97
82
360
250
200
170
680
465
375
320
950
770
660
1460
1180
990
GAS
SUPPLY
MANUAL
SHUTOFF
VALVE
(REQUIRED)
SEDIMENT
TRAP
Fig. 23—Typical Gas Pipe Arrangement
An accessible manual shutoff valve MUST be installed upstream
of furnace gas controls and within 6 ft of furnace. A 1/8-in. NPT
plugged tapping, accessible for test gage connection, MUST be
installed immediately upstream of gas supply connection to
furnace and downstream of manual shutoff valve.
NOTE: The gas valve inlet press tap connection is suitable to use
as test gage connection providing test pressure DOES NOT exceed
maximum 0.5 psig (14-in. wc) stated on gas valve. (See Fig. 40.)
Piping should be pressure tested in accordance with local and
national plumbing and gas codes before furnace is attached. In
Canada, refer to current edition of NSCNGPIC. If pressure
exceeds 0.5 psig (14-in. wc), gas supply pipe must be disconnected
from furnace and capped before pressure test. If test pressure is
equal to or less than 0.5 psig (14-in. wc), turn off electric shutoff
switch located on gas valve before test. It is recommended that
ground joint union be loosened before pressure testing. After all
connections have been made, purge lines and check for leakage.
See Fig. 24 for field wiring diagram showing typical field 115-v
and 24-v wiring. Check all factory and field electrical connections
for tightness.
50
Blower access panel door switch opens 115-v power to
73
control center. No component operation can occur. Do not
151
bypass or close switch with panel removed. Failure to follow
285
this warning could result in personal injury or death.
580
900
Furnace control must be grounded for proper operation or
control will lock out. Control is grounded through green wire
routed to gas valve and burner box screw.
Step 1—115-v Wiring
Before proceeding with electrical connections, make certain that
voltage, frequency, and phase correspond to that specified on unit
rating plate. Also, check to be sure that service provided by utility
is sufficient to handle load imposed by this equipment. Refer to
rating plate or Table 3 for equipment electrical specifications.
Make all electrical connections in accordance with National
Electrical Code (NEC) ANSI/NFPA 70-1996 and any local codes
or ordinances that might apply. For Canadian installations, all
electrical connections must be made in accordance with Canadian
Electrical Code CSA C22.1 or subauthorities having jurisdiction.
18
UNION
ELECTRICAL CONNECTIONS
A93324
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