Lennox MCA Series Installation Instructions Manual page 11

Figure 23. Cutting Piping
5. Insulate the copper piping.
6. Insert a flare nut onto each pipe before flaring.
7. Use "Table 2. Flaring Pipe" to properly flare the pipe.
Table 2. Flaring Pipe
Flare Dimension
A (mm)
Pipe Diameter
Min
1/4" 8.3
3/8" 12.0
1/2" 15.4
5/8" 18.6
3/4" (22.9) 22.9
8. After flaring the pipe, temporarily sealed pipe ends
with adhesive tape to avoid contaminants from
entering the pipes.
9. The seal on the unit refrigerant piping connections
should remain in place until the last possible moment.
This will prevent dust or water from getting into the
refrigerant piping before it is connected.
10. CAREFULLY adjust refrigerant piping connections to
suit the application.
11. Slowly loosen one of the flare nuts to release the
factory nitrogen charge from the indoor units only.
12. Remove the flare nuts from the connections on the
unit and discard the seal from each of the piping
connections.
13. Slide the flare nuts onto the ends of the field-provided
refrigerant piping before using a suitable flaring tool to
flare the end of the copper pipe.
14. Apply recommended HFC­410A refrigerant lubricant
to the outside of the flared refrigerant lines.
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)".
Lean Crude Burr
Flare Shape
Max
8.7
- +
90 ° 4
12.4
15.8
A
19.1
R0.4~0.8
23.3
connections with
Table 3. Refrigerant Piping and Indoor Unit
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.
IMPORTANT
Always use two wrenches when tightening flare nuts to
avoid twisting refrigerant piping. DO NOT over-tighten
flare nuts.
TO INDOOR
UNIT
Figure 25. Tighten Flare Nut
Table 4. Flare Nut Torque Recommendations
Outside
Recommended
Diameter
Torque
Inches
1/4 15 ft.­lb. (20 N)
3/8 26 ft.­lb. (35 N)
1/2 41 ft.­lb. (56 N)
the
5/8 48 ft.­lb. (65 N)
IMPORTANT
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.
11
Connection Sizes
Liquid Line Suction Line
in.
1/4
1/4
1/4
3/8
CANT ON THE OUTSIDE OF
THE FLARE
MALE FLARE
CONNECTION
TORQUE WRENCH
TO OUTDOOR UNIT
No torque wrench available
Finger tighten and use an
appropriately sized wrench to
turn an additional:
1/4 turn
1/2 turn
7/8 turn
1 full turn
in.
3/8
1/2
1/2
5/8
BACKUP
WRENCH