Lennox MCB Series Installation Instruction page 11

15. Align the threaded
flared refrigerant lines. Tighten the flare nuts
lightly at first to obtain a smooth match as
illustrated in "Figure 24. Making Connections
(Male to Female Connection)".
Table 3. Refrigerant Piping and Indoor Unit
Connection Sizes
Size
(Btuh)
9K
12K
18K
24K
A
B
Figure 24. Making Connections
(Male to Female Connection)
16. Once snug, continue another half-turn on each nut
which should create a leak­free joint. A torque wrench
may be used to tighten flare nuts using "Table 4. Flare
Nut Torque Recommendations".
17. After refrigerant piping has been installed and checked
for leaks, apply insulation over all flared connections.
INDOOR UNIT
Maximum
Elevation -
Outdooor
Unit BELOW
Indoor Unit
Outside Unit BELOW Indoor Unit
connections
Liquid Line Suction Line
in. in.
1/4 3/8
1/4 1/2
1/4 1/2
3/8 5/8
CANT ON THE OUTSIDE OF
THE FLARE
MALE FLARE
CONNECTION
Maximum Line Set
Length
OUTDOOR UNIT
Minimum Line Set
Length - 10 ft. (3m)
Figure 26. Indoor and Outdoor Unit Elevation Relationships
with the
Always use two wrenches when tightening flare nuts to
avoid twisting refrigerant piping. DO NOT over-tighten
flare nuts.
TO INDOOR
UNIT
Table 4. Flare Nut Torque Recommendations
Outside
Diameter
Inches
1/4
3/8
1/2
5/8
Do not allow for excess length of line sets to be left rolled
up as part of the required, or in general. This will also
cause additional performance issues.
Do not over-tighten a flared joint. Flared connections
should always be accessible and must be insulated to
prevent condensation.
Maximum Line Set
Length
INDOOR UNIT
Outside Unit ABOVE Indoor Unit
11
IMPORTANT
TORQUE WRENCH
TO OUTDOOR UNIT
Figure 25. Tighten Flare Nut
Recommended
Torque
sized wrench to turn an
15 ft.­lb. (20 N)
26 ft.-lb. (35 N)
41 ft.-lb. (56 N)
48 ft.-lb. (65 N)
IMPORTANT
IMPORTANT
Minimum Line Set
Length - 10 ft. (3m)
OUTDOOR UNIT
Maximum
Elevation -
Outdooor
Unit ABOVE
Indoor Unit
BACKUP
WRENCH
No torque wrench
available
Finger tighten and
use an appropriately
additional:
1/4 turn
1/2 turn
7/8 turn
1 full turn