Gas Piping - Lennox ML193UH030XE36B Installation Instructions Manual

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 attaching the
gas piping to the gas valve.
IMPORTANT
When converting the ML193 unit from natural gas to LP/
propane install the field provided low pressure switch.
See FIGURE 54.
switch. See figure 55.
LOW INLET PRESSURE SWITCH
(S145) LOCATION
Orange
White
Gas Valve Shown In Off Position
FIGURE 54
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,
4 - Piping should be sloped 1/4 inch per 15 feet (6mm
5 - A 1/8" N.P.T. plugged tap or pressure post is located
6 - In some localities, codes may require installation of a
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
Orange
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
Yellow
NORMAL TEST PRESSURE
1/8" N.P.T. PLUGGED TAP
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).
Page 33
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 56 and FIGURE 57.
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.
on the gas valve to facilitate test gauge connection.
See FIGURE 61.
manual main shut-off valve and union (furnished by
installer) external to the unit. Union must be of the
ground joint type.
IMPORTANT
VALVE WILL NOT HOLD
FIGURE 55
IMPORTANT
CAP
FURNACE
ISOLATE
GAS VALVE