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Gas Piping
Gas supply piping should not allow more than 0.5"W.C.
drop in pressure between gas meter and unit. Supply gas
pipe must not be smaller than unit gas connection.
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 the
right-hand side only. Supply piping enters into the
gas valve from the side of the valve as shown in
FIGURE 58. 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 9 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 58 and FIGURE 59.
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 63.
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.
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 system
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 com-
ponents are designed, manufactured and independent-
ly certified to comply with all applicable ANSI/CSA stan-
dards. A leak check of the furnace and its components is
not required.
Isolate Gas Valve
When testing pressure of gas lines, gas valve must be
disconnected and isolated. See FIGURE 57. 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 36
IMPORTANT
Manual Main Shut-Off Valve Will
Not Hold Normal Test Pressure
1/8" N.P.T.
Plugged Tap
Cap
FIGURE 57
IMPORTANT
WARNING
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