37MGHAQ: Installation Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
23
Fig. 20 — Align the center of the two pipes
b. Tighten the flare nut as much as possible by hand.
c. Using a wrench, grip the nut on the unit tubing.
d. While firmly gripping the nut, use a torque wrench to tighten
the flare nut according to the torque values listed in Table 11.
Fig. 21 — Flare Shape
Table 11 — Tightening Torque
NOTE: Use both a backup wrench and a torque wrench when
connecting or disconnecting pipes to or from the unit.
Fig. 22 — Torque wrench with backup wrench
All tubing bends should be performed with a properly sized tubing bender
to prevent kinking or damaging the tubing.
e. After connecting the copper pipes to the indoor unit, wrap the
power cable, signal cable and the piping together with binding
tape.
NOTE: While bundling these items together, DO NOT intertwine or
cross the signal cable with any other wiring.
f. Thread this lineset through the wall and connect it to the
outdoor unit.
g. Insulate all piping, including the outdoor unit valves.
NOTE: DO NOT open the service valves until pressure test is
complete.
7. Pressure Test Piping
NOTE: Use refrigeration gauges that are pressure rated for R454b
refrigerant.
a. Attach low side gauge hose to the 5/16” Schrader valve on the
outdoor unit service valve.
b. Attach the charging hose to the regulator on the dry nitrogen
tank.
c. Preset the nitrogen regulator to 550 psi.
d. Slowly pressurize the line set until the low side gauge reads 500
psi. Do not exceed 550 psi.
e. Close all the valves on the nitrogen tank and gauges.
f. Allow the pressure test to stand for a minimum of 30 minutes.
g. If the pressure holds, release the nitrogen and proceed. Review
“E. AIR EVACUATION” on page 29.
If the pressure goes down in the 30 minute delay, leak check the tubing
and flare fittings to identify the source of the leak. Return to Step C,
above.
BRASS FLARE
SIZES
RECOMMENDED
SEATING TORQUE
FOR BRASS FLARE
NUTS
FLARE DIMENSIONS
(A) (INCH/MM)
In (mm) Ft-Lbs N-M Min Max
Ø1/4 (6.35) 13.3-14.7 18-20 0.33/8.4 0.34/8.7
Ø3/8 (9.52) 23.6-28.8 32-39 0.52/13.2 0.53/13.5
Ø1/2 (12.7) 36.1-42.8 49-59 0.64/16.2 0.65/16.5
Ø5/8 (16) 42-52.4 57-71 0.76/19.2 0.78/19.7
Ø3/4 (19) 49.4-74.5 67-101 0.91/23.2 0.93/23.7
Ø7/8 (22) 62.7-81.1 85-110 1.04/26.4 1.06/26.9
Pipe
Indoor unit tubing
Flare nut
Wrap insulation around the piping. Direct contact with the bare
piping may result in burns or frostbite. Ensure the pipe is properly
connected. Over tightening may damage the bell mouth and under
tightening may lead to leakage.
CAUTION
Only use Dry Nitrogen to pressure test refrigerant systems. Use of
other gases can result in injury, property damage or death.
CAUTION
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