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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 in upflow applications, and
either the top or bottom in horizontal applications.
Supply piping enters into the gas valve from the
side of the valve as shown in FIGURE 49 and
FIGURE 50. Connect the gas supply piping into the
gas valve. The maximum torque is 800 in lbs and
minimum torque is 350 in lbs 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 FIGURE 49 and FIGURE 50.
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.
See FIGURE 57.
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.
Compounds used on threaded joints of gas piping must
be resistant to the actions of liquified petroleum gases.
MANUAL MAIN SHUT-OFF
VALVE WILL NOT HOLD
NORMAL TEST PRESSURE
1/8" N.P.T. PLUGGED TAP
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.
When testing gas lines using pressures in excess of 1/2
psig (3.48 kPa), gas valve must be disconnected and
isolated. See FIGURE 48. Gas valves can be damaged
if subjected to pressures greater than 1/2 psig (3.48
kPa)..
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.
Page 30
IMPORTANT
CAP
GAS VALVE
FIGURE 48
IMPORTANT
WARNING
FURNACE
ISOLATE
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