6
6. REFRIGERANT PIPING WORK
6-1
GENERAL INSTRUCTIONS
• For refrigerant piping of outdoor units, see the installation
manual attached to the outdoor unit.
• Before refrigerant piping work, check which type of refriger-
ant is used. Proper operation is not possible if the types of
refrigerant are not the same.
• The outdoor unit is charged with refrigerant.
NOTE
• Use a pipe cutter and flare suitable for the type of refrigerant.
• To prevent dust, moisuture or other foreign matter from infiltrating
the tube, either pinch the end or cover it with tape.
• Do not allow anything other than the designated refrigerant
to get mixed into the refrigerant circuit, such as air, etc. If any
refrigerant gas leaks while working on the unit, ventilate the
room thoroughly right away.
6-2
Connecting the refrigerant piping
• When connecting the flare nut, coat the flare both inside and
outside with ester
oil
or
ether
oil and initially tighten by hand 3
or 4 turns before tightening firmly.
• To prevent flare nut cracking and gas leaks, be sure to use
both a spanner and torque wrench together, as shown in the
drawing below, when connecting or disconnecting pipes to/
from the unit.
• Refer to the Table 2 for the dimensions of flare nut spaces.
• Refer to the Table 2 to determine the proper tightening torque.
Table 2
NOTE
• Apply ester oil or ether oil around the flare portions before
connecting.
• The flare nuts used must be those included with the main
body.
• Over-tightening may damage the flare and cause a refriger-
ant leakage.
Not recommendable but in case of emergency
You must use a torque wrench but if you are obliged to
install the unit without a torque wrench, you may
follow the installation method mentioned below.
After the work is finished, make sure to check that
there is no gas leak.
When you keep on tightening the flare nut with a spanner,
there is a point where the tightening torque
suddenly increases. From that position, further tighten the
flare nut the angle shown below:
Table 3
6-3
Piping insulation
• Execute heat insulation work completely on both sides of the
gas piping and the liquid piping. Otherwise, a water leakage
can result sometimes.
• When using a heat pump, the temperature of the gas piping
can reach up to approximately 250°F, so use insulation
which is sufficiently resistant.
• Also, in cases where the temperature and humidity of the refrig-
erant piping sections might exceed 86°F or RH80%, reinforce
the refrigerant insulation. (13/16” or thicker) Condensation may
form on the surface of the insulating material.
• Check the pipe connector for gas leaks, then insulate it as
shown in the drawing below.
• Make absolutely sure to execute heat insulation works on the
pipe-connecting section after checking gas leakage by thor-
oughly studying the following figure and using the attached
heat insulating materials for fitting. (Fasten both ends with
the clamps (accessory).)
• Wrap the sealing pad (accessory) only around the insulation
for the joints on the gas piping side.
CAUTION
Be sure to insulate any field piping all the way to the piping
connection inside the unit. Any exposed piping may cause
condensation or burns if touched.
Pipe
size
Tightening torque
(ft.lbf)
Flare
dimensions
A (in.)
Flare shape (in.)
φ
1/4”
10.4 – 12.7
0.342-0.358
φ
3/8”
24.1 – 29.4
0.504-0.520
φ
1/2”
36.5 – 44.5
0.638-0.654
φ
5/8”
45.6 – 55.6
0.760-0.776
Pipe size
Further tightening
angle
Recommended arm length of
tool (in.)
φ
1/4”
60 to 90 degrees
Approx. 5 7/8
φ
3/8”
60 to 90 degrees
Approx. 7 7/8
φ
1/2”
30 to 60 degrees
Approx. 9 13/16
φ
5/8”
30 to 60 degrees
Approx. 11 13/16
