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VMH 09/12/18/24 SD Inverter Mini-Split
Refrigerant Line Set Installation
Refrigerant Line Set Installation
1. Purchase line sets through a Heat Controller
distributor with consideration of the minimum and
maximum line lengths. (Fig, 20)
2. Ductless mini-splits require both-liquid and
suction-lines to be insulated.
3. Connections are made via flare nuts.
4. The number of bends and length of refrigerant
lines determine the pressure drop which affects
capacity and efficiency of the system, as well
as oil return. Minimize the length and number of
bends when possible during installation.
5. Minimum line set length must be maintained,
even if the installation does not require it. Extra
length that is unnecessary can be coiled up near
the outdoor unit (Do not to block air inlets/outlets).
6. Choose a location that places the outdoor unit as
close to the indoor unit as possible to minimize
line set lengths.
7. Use only clean, refrigerant grade tubing suitable
for R-410A.
8. Avoid installing refrigerant lines on wet/rainy
days.
9. Always keep tube ends sealed until the final
connections are to be made.
10. If line sets are being made at the time of
installation, rather than being purchased, be sure
to:
• Remove burrs from cut ends of the tubing
• Use tube benders to prevent kinking.
• Ensure tube cuts are square in relation to the
end of the tube.
• Use the proper diameter tube and flare nut
sizes recommended by the manufacturer.
• Insulate both lines with Amraflex of equivalent
with a wall thickness if at least 3/8". Although
the liquid line does not have to be insulated, it
is recommended.
*Minimum pipe length must not be less that 10 feet.
** Trap rises every 10 feet (5-7m) with a 'p' trap when outdoor unit is mounted above
the indoor unit.
Refrigerant Piping
Liquid Side-Gas Side
Max. Refrigerant Pipe
Length Unit Separation*
Max. Level
Difference/Vertical Lift**
• Use copper tubing suitable to withstand
pressures for R-410A refrigerant. We
recommend a min. wall thickness of 0.027in.
(0.7mm).
11. The tube size should always be the same
diameter as the connections provided at the
service valves of the outdoor unit.
Note: On some models, a reducer or an
expander may be shipped with the indoor unit
in order to adapt the line set connection to
the proper size to mate with the indoor unit's
connection. Be sure to check for this part, should
you discover that the outdoor units service valve
sizes differ from the indoor unit. If this part is
shipped with the indoor unit, then it is required to
be used.
12.Up sizing/downsizing the refrigerant lines/
connections can result in inadequate oil return to
the compressor or excessive refrigerant return
and will void the warranty.
13.Do not over torque the connections, excessive
force can break the flare nut.
14. When routing the line set between the outdoor
and indoor units:
A. Support the tubing adequately to avoid sags
B. Isolate the tubing so it does not transmit
C. Avoid sharp edges that could cut the tubes.
D. Trap rises every 10 ft. (5-7m) with a 'p' trap.
Fig. 20
Model No.
VMH 09
VMH 12/18
Inch
1/4 - 3/8
Ft.
82 (25)
(m)
Ft.
33 (10)
(m)
10
that can trap the oil.
noise from vibration into the structure of the
building.
When outdoor unit mounted above
indoor unit.
VMH 24
1/4 - 1/2
3/8 - 5/8
82 (25)/
98 (30)
98 (30)
33 (10)/
66 (20)
66 (20)
Heat Controller
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