Connect gas pipe to furnace using a backup wrench to avoid
damaging gas controls. Failure to follow this caution will
result in intermittent unit operation or performance satisfac-
tion.
Gas valve shutoff switch MUST be facing forward or tilted
upward. Failure to follow this warning could result in
property damage or death.
Never purge a gas line into a combustion chamber. Never test
for gas leaks with an open flame. Use a commercially
available soap solution made specifically for the detection of
leaks to check all connections. 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.
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. 27.)
If a flexible connector is required or allowed by authority
having jurisdiction, black iron pipe shall be installed at
furnace gas control valve and extend a minimum of 2 in.
outside furnace casing. Failure to follow this caution will
result in potential chaffing of flexible gas connection.
An accessible manual shutoff valve MUST be installed external to
furnace casing and within 6 ft of furnace. A 1/8-in. NPT plugged
tapping, accessible for test gauge connection, MUST be installed
immediately upstream of gas supply connection to furnace and
downstream of manual shutoff valve.
NOTE: The gas valve inlet pressure tap connection is suitable to
use as test gauge connection providing test pressure DOES NOT
exceed maximum 0.5 psig (14-in. wc) stated on gas valve. (See
Fig. 62.)
Fig. 25—Bottom Filter Arrangement
A00290
WASHABLE
FILTER
FILTER
SUPPORT
FILTER
RETAINER
17
1
⁄2-IN. WIDE
CASINGS ONLY:
INSTALL FIELD-SUPPLIED
FILTER FILLER STRIP
UNDER FILTER.
1″
24
1
/
2
″
3″
21-IN. WIDE
CASINGS ONLY:
SUPPORT RODS (3)
EXTEND 1/4" ON EACH
SIDE OF FILTER AND
REST ON CASING FLANGE
Fig. 26—Removing Bottom Closure Panel
A93047
BOTTOM
CLOSURE
PANEL
FRONT FILLER
PANEL
Table 3—Maximum Capacity of 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 pressure drop of 0.5-in. wc (based on a 0.60 specific gravity gas). Ref:
Table 9-2 NFPA 54-2002.
19
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