Lennox MLA Series Installation & User's Instructions page 12

IMPORTANT
The compressor in
oil (Polyvinylether).
hydrofluorocarbon (HFC) refrigerants, such as HFC-
410A, which this system contains. While it may have
some miscibility properties with mineral-based oil and
POE oil (Polyolester), it is not recommended to mix PVE
oil with any other type of refrigerant oil.
16. Align the threaded
flared refrigerant lines. Tighten the flare nuts
lightly at first to obtain a smooth match as
illustrated in "Figure
(Male to Female Connection)".
Table 3. Refrigerant Piping and Indoor Unit
Connection Sizes
Size Liquid Line
(Btuh)
12000
A
B
Figure 19. Making Connections
(Male to Female Connection)
17. Once snug, continue another half-turn on each nut
which should create a leak-free joint. A torque wrench
may be used to tighten flare nuts using "Table 4. Flare
Nut Torque Recommendations" on page 12. Do
not over-tighten a flared joint. Flared connections
should always be accessible and must be insulated
to prevent condensation.
18. After refrigerant piping has been installed and checked
for leaks, apply insulation over all flared connections.
TORQUE WRENCH
TO INDOOR
UNIT
Figure 20. Tighten Flare Nut
this unit contains
PVE oil is formulated
connections with
19. Making Connections
Gas Line
in. in.
1/4 1/2
CANT ON THE OUTSIDE OF
THE FLARE
MALE FLARE
CONNECTION
BACKUP
WRENCH
TO OUTDOOR UNIT
Table 4. Flare Nut Torque Recommendations
PVE
Outside
for
Diameter
Inches
1/4
1/2
the
12
No torque wrench available
Recommended
Finger tighten and use an
Torque
appropriately sized wrench to
turn an additional:
15 ft.-lb. (20 N)
41 ft.-lb. (56 N)
1/4 turn
7/8 turn