Step 7—Gas Piping
Emissions control devices located at heat exchanger inlets
MUST be removed for propane installations. (Refer to gas
conversion kit for instructions.)
Gas piping must be installed in accordance with national and local
codes. Refer to the NFGC. Canadian installations must be installed
in accordance with NSCNGPIC and all authorities having juris-
diction.
The gas supply line should be a separate line running directly from
gas meter to furnace, if possible. Refer to Table 4 for recom-
mended gas pipe size. Risers must be used to connect furnace to
gas meter.
If a flexible connector is required or allowed by the authority
having jurisdiction, black iron pipe shall be installed at the
gas valve and extend a minimum of 2 in. outside the furnace
casing.
Piping should be pressure tested in accordance with local and
national plumbing and gas codes before furnace has been attached.
If test pressure exceeds 0.5 psig (14-in. wc), the gas supply pipe
must be disconnected from the 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 before test. (See Fig. 14.) It is
recommended that the ground joint union be loosened before
pressure testing. After all connections have been made, purge lines
and check for leakage with regulated gas supply pressure.
Install a sediment trap in riser leading to furnace. The trap can be
installed by connecting a tee to riser leading from the furnace.
Connect a capped nipple into lower end of the tee. The capped
nipple should extend below level of gas controls. (See Fig. 14.)
Apply joint compound (pipe dope) sparingly and only to male
threads of each joint. The compound must be resistant to action of
propane gas.
Install an accessible manual shutoff valve upstream of furnace gas
controls and within 72 in. of furnace. A 1/8-in. NPT plugged
tapping is provided on the gas valve for test gage connection.
Installation of an additional 1/8-in. NPT plugged tapping, acces-
sible for test gage connection, installed immediately upstream of
gas supply connection to furnace and downstream of manual
shutoff valve, is not required. Place ground joint union between
gas control manifold and manual shutoff valve.
Use the proper length of pipes to avoid stress on the gas
control manifold. A failure to follow this warning can cause
a gas leak resulting in a fire, explosion, personal injury, or
death.
Use a backup wrench at the furnace gas control when
connecting the gas pipe to the furnace to avoid damaging gas
controls or manifold.
Never purge a line into a combustion chamber. Never use
matches, candles, flame, or other sources of ignition for the
purpose of checking leakage. Use a soap-and-water solution
to check for leakage. A failure to follow this warning can
cause a fire, explosion, personal injury, or death.
Step 8—Electrical Connections
115-V WIRING
Refer to the unit rating plate or Table 5 for equipment electrical
requirements. The control system requires an earth ground for
proper operation.
Fig. 13—Horizontal Application Using Blocks
A95235
Table 4—Maximum Capacity of Gas Pipe*
NOMINAL
IRON PIPE
SIZE (IN.)
INTERNAL
DIAMETER
(IN.)
LENGTH OF PIPE (FT)
10
20
30
40
50
1/2
0.622
175
120
97
82
73
3/4
0.824
360
250
200
170
151
1
1.049
680
465
375
320
285
1-1/4
1.380
1400
950
770
660
580
1-1/2
1.610
2100
1460
1180
990
900
* Cubic ft of gas per hr for gas pressures of 0.5 psig (14-in. wc) or less, and a
supply line pressure drop of 0.5-in. wc (based on a 0.60 specific gravity gas).
Ref: Table 10-2, NFPA 54–1999.
Fig. 14—Typical Gas Pipe Arrangement
A89417
GAS
SUPPLY
MANUAL
SHUTOFF
VALVE
(REQUIRED)
SEDIMENT
TRAP
UNION
10