Lennox ML180UHA Installation Instructions Manual page 15

Gas Supply
1 - This unit is shipped standard for left or right side instal­
lation of gas piping (or top entry in horizontal applica­
tions). Connect the gas supply to the piping assembly.
2 - When connecting the gas supply piping, consider fac­
tors such as length of run, number of fittings, and fur­
nace rating to avoid excessive pressure drop.
3 - The gas piping must not run in or through air ducts,
clothes chutes, gas vents or chimneys, dumb waiters,
or elevator shafts.
4 - The piping should be sloped 6.4 mm (1/4 in) per 4.57 m
(15 ft.) upward toward the meter from the furnace. The
piping must be supported at proper intervals every
2.44 to 3.01 m (8 to 10 ft) with suitable hangers or
straps. Install a drip leg in vertical pipe runs to the unit.
MANUAL
MAIN SHUT-OFF
VALVE
(With 1/8 in. NPT
Plugged Tap Shown)
GROUND
JOINT
UNION
DRIP LEG
MANUAL
MAIN SHUT-OFF
VALVE
GROUND
JOINT
UNION
DRIP LEG
Horizontal Application
Right-Side Air Discharge
Left Side Piping
(Standard)
AUTOMATIC
GAS VALVE
NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET
NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET
5 - A 3 mm (1/8") N.P.T. plugged tap or pressure port is lo­
cated on the gas valve to facilitate test gauge connec­
tion. See figure 27.
6 - In some localities, codes may require the installation of
a manual main shut‐off valve and union (furnished by
the installer) external to the unit. The union must be of
the ground joint type.
Compounds used on threaded joints of gas piping
must be resistant to the actions of liquified petro­
leum gases.
NOTE - If emergency shutoff is necessary, shut off the main
manual gas valve and disconnect main power to the fur­
nace. The installer should properly label these devices.
AUTOMATIC
GAS VALVE
FIELD
PROVIDED
AND INSTALLED
FIGURE 22
MANUAL
MAIN SHUT-OFF
VALVE
GROUND
JOINT
UNION
DRIP LEG
FIELD
PROVIDED
AND INSTALLED
FIGURE 23
Page 15
IMPORTANT
MANUAL
MAIN SHUT-OFF
VALVE
(With 1/8 in. NPT
Plugged Tap
Shown)
GROUND
JOINT
UNION
DRIP LEG
Right Side Piping
(Alternate)
Horizontal Application
Left-Side Air Discharge
MANUAL
MAIN SHUT-OFF
VALVE
GROUND
JOINT
UNION
DRIP LEG