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Gas Piping
CAUTION
If a flexible gas connector is required or allowed by the
authority that has jurisdiction, black iron pipe shall be
installed at the gas valve and extend outside the furnace
cabinet. The flexible connector can then be added
between the black iron pipe and the gas supply line.
WARNING
Do not over torque (800 in-lbs) or under torque (350 in-
lbs) when attaching the gas piping to the gas valve.
1 - Gas piping may be routed into the unit through either
the left- or right-hand side. Supply piping enters into
the gas valve from the side of the valve as shown in
FIGURE 56. Connect the gas supply piping into the
gas valve. The maximum torque is 800 in lbs and
minimum torque is 350 in lbs when when attaching
the gas piping to the gas valve.
2 - When connecting gas supply, factors such as length
of run, number of fittings and furnace rating must
be considered to avoid excessive pressure drop.
TABLE 11 lists recommended pipe sizes for typical
applications.
NOTE -
Use two wrenches when connecting gas
piping to avoid transferring torque to the manifold.
3 - Gas piping must not run in or through air ducts,
clothes chutes, chimneys or gas vents, dumb waiters
or elevator shafts. Center gas line through piping
hole. Gas line should not touch side of unit. See
4 - Piping should be sloped 1/4 inch per 15 feet (6mm
per 5.6m) upward toward the gas meter from the
furnace. The piping must be supported at proper
intervals, every 8 to 10 feet (2.44 to 3.05m), using
suitable hangers or straps. Install a drip leg in
vertical pipe runs to serve as a trap for sediment or
condensate.
5 - A 1/8” N.P.T. plugged tap or pressure post is located
on the gas valve to facilitate test gauge connection.
6 - In some localities, codes may require installation of
a manual main shut-off valve and union (furnished
by installer) external to the unit. Union must be of the
ground joint type.
IMPORTANT
Compounds used on threaded joints of gas piping must
be resistant to the actions of liquified petroleum gases.
Leak Check
After gas piping is completed, carefully check all field-in
-
stalled piping connections for gas leaks. Use a commer-
cially available leak detecting solution specifically manu
-
factured for leak detection. Never use an open flame to
test for gas leaks
The furnace must be isolated from the gas supply sys
-
tem by closing the individual manual shut-off valve during
any gas supply system at pressures greater than or equal
to ½ psig. (3.48 kPa, 14 inches w.c.). This furnace and
its components are designed, manufactured and inde
-
pendently certified to comply with all applicable ANSI/CSA
standards. A leak check of the furnace and its components
is not required.
MANUAL MAIN SHUT-OFF
VALVE WILL NOT HOLD
NORMAL TEST PRESSURE
CAP
FURNACE
ISOLATE
GAS VALVE
1/8” N.P.T. PLUGGED TAP
FIGURE 55
IMPORTANT
When testing pressure of gas lines, gas valve must be
disconnected and isolated. See FIGURE 55. Gas valves
can be damaged if subjected to pressures greater than
1/2 psig (3.48 kPa).
WARNING
FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly could result
in serious injury, death, or property damage. Never use
an open flame to test for gas leaks. Check all connections
using a commercially available soap solution made
specifically for leak detection. Some soaps used for leak
detection are corrosive to certain metals. Carefully rinse
piping thoroughly after leak test has been completed.
