Midea MUE-18FNXD0 User manual

CEILING & FLOOR TYPE AIR CONDITIONER
Installation Manual
Ceiling & Floor Type
IMPORTANT NOTE:
Read this manual carefully before
installing or operating your new air
conditioning unit. Make sure to save
this manual for future reference.
MUE-36FNXD0 MOU-36FN8-RD0
MUE-48FNXD0 MOU-48FN8-RD0
MUE-55FNXD0 MOU-55FN8-RD0
MUE-36FNXD0 MOU-36FN8-QD0
MUE-18FNXD0 MOU-18FN8-QD0
MUE-24FNXD0 MOU-24FN8-QD0
MUE-30FN1D0
MOU-30FN1-QD0

Accessories .................................................... 04
a. Indoor Unit Parts ........................................ 09
b. Indoor Unit Installation Instructions ....... 10
Safety Precautions ..................................... 05
Outdoor Unit Installation ......................... 11
a. Outdoor Unit Installation Instructions ..... 14
b. Outdoor Unit Types and Specifications ... 15
c. Notes on Drilling Hole in Wall .................... 16
Drainpipe Installation ............................... 17
Table of Contents
Installation Manual
Indoor Unit Installation ........................... 09
Installation Overview ............................... 08
1
2
5
3
4
6
Indoor Unit Installation ........................... 07

Page 3 
Refrigerant Piping Connection...................... 19
A. Notes on Pipe Length and Elevation ............... 19
B. Refrigerant Piping Connection Instructions ... 21
Wiring................................................. 23
a. Outdoor Unit Wiring ................... 23
b. Indoor Unit Wiring ...................... 24
c. Power Specifications .................... 25
Air Evacuation ................................................ 27
a. Evacuation Instructions ............................... 27
b. Note on Adding Refrigerant ...................... 28
Test Run.......................................................................................... 29
30
MC MC
7
8
9
10
L N
(R32/R290 refrigerant )
C au t i o n: Risk of fire
European Disposal Guidelines .......................................................
11
Information servicing...................................................................... 31
12

Page 4 
Accessories 1
The air conditioning system comes with the following accessories. Use all of the installation parts
and accessories to install the air conditioner. Improper installation may result in water leakage,
electrical shock and re, or equipment failure.
Name Shape Quantity
Refrigeration
Fittings Soundproof/insulation sheath (some models)
1
Drainpipe
Fittings
Outlet pipe sheath (some
models)
1
Outlet pipe clasp (some
models)
1
Drain joint (some models) 1
Seal ring (some models) 1
EMC Magnetic
Ring (some
models)
Remote
controller & Its
Frame (some
models)
Magnetic ring (wrap the
electric wires S1 & S2
( P & Q & E ) around
the magnetic ring twice)
Magnetic ring (Hitch it on
the connective cable
between indoor unit and
outdoor unit after
installation.)
1
1
1
2
1
1
1
1
2
Remote controller
Fixing screw for remote
controller holder ST2.9 x 10
Remote controller holder
Dry battery AAA
Owner’s manual
Installation manual
Remote controller illustration
S1&S2(P&Q&E)

Page 5 
Safety Precautions 2
Read Safety Precautions Before Installation
Incorrect installation due to ignoring instructions can cause serious damage or injury.
The seriousness of potential damage or injuries is classified as either a WARNING or CAUTION.
Failure to observe a warning may result in death. The appliance must be installed in
accordance with national regulations.
Failure to observe a caution may result in injury or equipment damage.
WARNING
CAUTION
WARNING
• Carefully read the Safety Precautions before installation.
• In certain functional environments, such as kitchens, server rooms, etc., the use of specially
designed air-conditioning units is highly recommended.
• This appliance can be used by children aged from 8 years and above and persons with reduced
physical, sensory or mental capabilities or lack of experience and knowledge if they have been
given supervision or instruction concerning use of the appliance in a safe way and understand
the hazards involved. Children shall not play with the appliance. Cleaning and user
maintenance shall not be made by children without supervision.
• Do not use means to accelerate the defrosting process or to clean, other than those
recommended by the manufacturer.
• Only trained and certified technicians should install, repair and service this air
conditioning unit.
Improper installation may result in electrical shock, short circuit, leaks, fire or other damage to
the equipment and personal property.
• Strictly follow the installation instructions set forth in this manual.
Improper installation may result in electrical shock, short circuit, leaks, fire or other damage to
the equipment.
•Before you install the unit, consider strong winds, typhoons and earthquakes that might aect
your unit and locate it accordingly. Failure to do so could cause the equipment to fail.
•After installation, ensure there are no refrigerant leaks and that the unit is operating properly.
Refrigerant is both toxic and flammable and poses a serious health and safety risk.
An all-pole disconnection device which has at least 3mm clearances in all poles , and have a
leakage current that may exceed 10mA, the residual current device (RCD) having a rated residual
operating current not exceeding 30mA, and disconnection must be incorporated in the xed
wiring in accordance with the wiring rules.

Page 6  Page 6 
Amount of refrigerant
to be charged (kg) maximum installation
height (m) Minimum room area (m²)
≤2.048 1.8m 4
≤2.048 0.6m 35
2.048-3.0 1.8m 8
2.048-3.0 0.6m 80
>3.0 1.8m 9
>3.0
Model
(Btu/h)
≤30000
≤30000
30000-48000
30000-48000
>48000
>48000 0.6m 80
WARNING
• Appliance shall be installed, operated and stored in a room with a oor area larger than X m²,
installation of pipe-work shall be kept to a minimum X m²(Please see the following form ).
The appliance shall not be installed in an unventilated space, if that space is smaller than X m²
(Please see the following form ).Spaces where refrigerant pipes shall be compliance with
national gas regulations.
• Any person who is involved with working on or breaking into a refrigerant circuit should hold a
current valid certicate from an industry-accredited assessment authority, which authorises their
competence to handle refrigerants safely in accordance with an industry recognised assessment
specication.
• Servicing shall only be performed as recommended by the equipment manufacturer.
Maintenance and repair requiring the assistance of other skilled personnel shall be carried out
under the supervision of the person competent in the use of ammable refrigerants.
• Appliance shall be stored in a well-ventilated area where the room size corresponds to the room
area as specied for operation.
• Appliance shall be stored in a room without continuously operating open ames (for example
an operating gas appliance) and ignition sources (for example an operating electric heater).
• The appliance shall be stored in a room without continuously operating ignition sources
(for example: open ames, an operating gas appliance or an operating electric heater).
• Do not pierce or burn.
• The appliance shall be stored so as to prevent mechanical damage from occurring.
•
• Be aware that the refrigerants may not contain an odour.
• Keep ventilation openings clear of obstruction.
Compliance with national gas regulations shall be observed.
• A warning that the appliance shall be stored in a well-ventilated area where the room size
corresponds to the room area as specied for operation.

Note about Fluorinated Gases
1. This air-conditioning unit contains fluorinated gases. For specific information on the type of gas
and the amount, please refer to the relevant label on the unit itself.
2.
Installation, service, maintenance and repair of this unit must be performed by a certified technician.
3. Product uninstallation and recycling must be performed by a certified technician.
4. If the system has a leak-detection system installed, it must be checked for leaks at least every 12
months.
5.
When the unit is checked for leaks, proper record-keeping of all checks is strongly recommended.
CAUTION
CAUTION
CAUTION
This symbol shows that a service personnel should be handling this
equipment with reference to the installation manual.
This symbol shows that information is available such as the operating
manual or installation manual.
This symbol shows that this appliance uses a ammable refrigerant. If the
refrigerant is leaked and exposed to an external ignition source, there is a
risk of re.
This symbol shows that the operation manual should be read carefully.
WARNING
CAUTION
Explanation of symbols displayed on the indoor unit or outdoor unia
(applicable to the unit adopts R32/R290 Refrigerant only):
Page 7  

Page 8 
Unit Installation Overview
Installation Overview 3
L N
123
4
5
MC MC
6
7
Install the indoor unit
(Page 10)
INSTALLATION ORDER
Install the outdoor unit
(Page 14) Install the drainpipe (Page 17)
Evacuate the refrigeration
system (Page 27) Connect the wires
(Page 24) Connect the refrigerant
pipes (Page 19)
Perform a test run
(Page 29)

Page 9 
Indoor Unit
Installation
Air inlet Display panel
Air outlet
grille
Louver
Installation part
Indoor Unit Installation 4
Indoor Unit Parts
Fig. 4.1
Safety Precautions
WARNING
•Securely install the indoor unit on a
structure that can sustain its weight. If the
structure is too weak, the unit may fall and
cause personal injury, unit and property
damage, or death.
• DO NOT install the indoor unit in a
bathroom or laundry room as excessive
moisture can short the unit and corrode the
wiring.
CAUTION
•Install the indoor and outdoor units, cables,
and wires at least 1m (3.2’) from televisions
and radios to prevent static or image
distortion. Depending on the appliances,
a 1m (3.2’) distance may not be sucient.
•If the indoor unit is installed on metal,
it must be electrically grounded.

Page 10
Indoor Unit
Installation
Indoor Unit Installation Instructions
NOTE: Panel installation should be performed
after piping and wiring have been completed.
Step 1:Select installation location
The indoor unit should be installed in a location
that meets the following requirements:
Enough room exists for installation and
maintenance.
Enough room exists for the connecting the
pipe and drainpipe.
The ceiling is horizontal and its structure can
sustain the weight of the indoor unit.
The air inlet and outlet are not blocked.
The airflow can fill the entire room.
There is no direct radiation from heaters.
CAUTION
DO NOT install the unit in the following
Areas with oil drilling or fracking
Coastal areas with high salt content in the
air
Areas with caustic gases in the air, such as
hot springs
Areas that experience power uctuations,
such as factories
Enclosed spaces, such as cabinets
Kitchens that use natural gas
Areas with strong electromagnetic waves
Areas that store flammable materials or gas
Rooms with high humidity, such as
bathrooms or laundry rooms
RECOMMENDED DISTANCES BETWEEN THE INDOOR UNIT
The distance between the mounted indoor unit should meet the specications illlustrated in the
following diagram. (See Fig. 4.2)
Fig. 4.2
≥35mm
≥1000mm
≥ 35mm ≥ 35mm
locations:

Page 11 
Indoor Unit
Installation
Fig. 4.3
Refrigerant pipe
connection
(D. gas side)
Refrigerant pipe
connection
(E. Liquid side)
Drain point
Hook
A
C
D
E
B
Table 4.1: Indoor parts installation size
MODEL(Btu/h) Length of A (mm/inch) Length of B (mm/inch)
18K~24K 1068/42 675/26.6
30K~48K 1285/50.6 675/26.6
36K~48K 1650/65 675/26.6
60K 1650/65 675/26.6
Length of C (mm/inch) Length of D (mm/inch) Length of E (mm/inch)
235/9.3 983/38.7 220/8.7
235/9.3 1200/47.2 220/8.7
235/9.3 1565/61.6 220/8.7
235/9.3 1565/61.6 220/8.7

Page 12 
Indoor Unit
Installation
Cut o the roof beam.
Strengthen the area at which the cut was
made and consolidate the roof beam.
Fig. 4.6
Fig. 4.7
Fig. 4.8
Original concrete bricks
Steel roof beam structure
Install and use the supporting angle steel
directly. (See Fig.4.8)
Fig. 4.4
Wood
Place the square timber traversely over the roof
beam, then install the hanging screw bolts.
(See Fig.4.4)
Timber over the beam
Roof beam
Hanging screw bolts
Ceiling
Fig. 4.5
New concrete bricks
Inlaying or embedding the screw bolts.
(Blade shape insertion) (Slide insertion)
Steel bar
Embedding screw bolt
(Pipe hanging and embedding screw bolt)
Hanging screw bolt
Hanging
bolts
Supporting
angle steel
CAUTION
The unit body should align perfectly with the
hole. Ensure that the unit and the hole are the
same size before moving on.
2. Install the pipes and lines in the ceiling after
installing the main body. When choosing
where to start the, determine the direction of
the pipes to be drawn out. In cases where
there is a ceiling, position the refrigerant pipes,
drain pipes, and indoor and outdoor lines to
the connection points before mounting the
machine.
3. The installation of hanging screw bolts.
4. After the selection of installation location,
position the refrigerant pipes, drain pipes,
and indoor and outdoor wires to the
connection points before mounting the
machine.
5.
Drill 4 holes 10cm (4”) deep at the ceiling
hook positions in the internal ceiling. Be sure
to hold the drill at a 90° angle to the ceiling.
6. Secure the bolt using the included washers
and nuts.
7. Install the four suspension bolts.
8. Mount the indoor unit. You will need two
people to lift andsecure it. Insert suspension
bolts into the unit’s hanging holes. Fasten
them using the included washers and nuts.
(See Fig. 4.9).
Fig. 4.9
Step 2:Hang indoor unit
Install the hanging hook with expansible
bolt into the concrete to a depth of
45~50mm to prevent loosening.

Page 13 
Indoor Unit
Installation
Fig. 4.10
Fig. 4.12
Fig. 4.13
Fig. 4.14
9. Remove the side board and the grille.
(See Fig. 4.10).
Fig. 4.11
Screw nut
Washer
Hanging screw bolt
Overhang part
Shockproof cushion
NOTE: Conrm the minimum drain tilt is 1/100 or
more.
10. Mount the indoor unit onto the hanging
screw bolts with a block.
Position the indoor unit on a at level by
using a level to prevent leaks.
(See Fig. 4.11).
Wall Mounting Installtion
Ceiling Installation
20mm
D. Refrigerant pipe
connection
(D.gas side)
Drain point
Downward slope between(1-2)/100
E. Refrigerant pipe
connection
(E. Liquid side)
Side board
Grille
Hanging arm
Hanging
screw bolt

Page 14 
Outdoor Unit
Installation
Outdoor Unit Installation
Outdoor Unit Installation Instructions
Step 1: Select installation location.
The outdoor unit should be installed in the
location that meets the following requirements:
Place the outdoor unit as close to the indoor
unit as possible.
Ensure that there is enough room for
installation and maintenance.
The air inlet and outlet must not be
obstructed or exposed to strong wind.
Ensure the location of the unit will not be
subject to snowdrifts, accumulation of leaves
or other seasonal debris. If possible, provide
an awning for the unit. Ensure the awning
does not obstruct airflow.
The installation area must be dry and well
ventilated.
There must be enough room to install the
connecting pipes and cables and to access
them for maintenance.
The area must be free of combustible gases
and chemicals.
The pipe length between the outdoor and
indoor unit may not exceed the maximum
allowable pipe length.
If possible, DO NOT install the unit where it
is exposed to direct sunlight.
If possible, make sure the unit is located far
away from your neighbors’ property so that
the noise from the unit will not disturb them.
If the location is exposed to strong winds (for
example: near a seaside), the unit must be
placed against the wall to shelter it from the
wind. If necessary, use an awning.
(See Fig. 5.1 & 5.2)
Install the indoor and outdoor units, cables
and wires at least 1 meter from televisions or
radios to prevent static or image distortion.
Depending on the radio waves, a 1 meter
distance may not be enough to eliminate all
interference.
Strong wind
Strong wind
Strong wind
Fig. 5.1 Fig. 5.2
Step 2: Install outdoor unit.
Fix the outdoor unit with anchor bolts (M10)
>60cm / 23.6”
Fix with bolts
CAUTION
• Be sure to remove any obstacles that
may block air circulation.
• Make sure you refer to Length
Specifications to ensure there is
enough room for installation and
maintenance.
Fig. 5.3
5
√
√
√
√
√
√
√
√
√
√
√
√

Page 15 
Outdoor Unit
Installation
>120cm / 47”
Air Outlet
(Wall or obstacle)
H
D
W
>30cm / 11.8”
Air inlet
Air inlet Air inlet
Air inlet
(Wall or obstacle)
>30cm / 11.8”
>30cm / 11.8”
>30cm / 11.8”
Table 5.1: Length Specifications of Split Type
Outdoor Unit (unit: mm/inch)
Table 5.2: Length Specifications of Vertical
Discharge Outdoor Unit (unit: mm/inch)
MODEL DIMENSIONS
W H D
18 633/25 554/21.8554/21.8
24 633/25 554/21.8554/21.8
36 759/29.8 554/21.8554/21.8
36 633/25 600/23.6600/23.6
48 759/29.8 710/28710/28
60 843/33 710/28710/28
Split Type Outdoor Unit
(Refer to Fig 5.4, 5.5, 5.6, 5.10 and Table 5.1)
Vertical Discharge Type Outdoor Unit
(Refer to Fig 5.7, 5.8, 5.9 and Table 5.2)
Fig. 5.7
Fig. 5.8
Fig. 5.9
Fig. 5.6
Fig. 5.5
A
B
D
W
H
W
H
Fig. 5.4
Outdoor Unit Dimensions
W x H x D
Mounting Dimensions
Distance A Distance B
760x590x285 (29.9x23.2x11.2) 530 (20.85) 290 (11.4)
810x558x310 (31.9x22x12.2) 549 (21.6) 325 (12.8)
845x700x320 (33.27x27.5x12.6) 560 (22) 335 (13.2)
900x860x315 (35.4x33.85x12.4) 590 (23.2) 333 (13.1)
945x810x395 (37.2x31.9x15.55) 640 (25.2) 405 (15.95)
990x965x345 (38.98x38x13.58) 624 (24.58) 366 (14.4)
946x810x420 (37.24x31.9x16.53) 673 (26.5) 403 (15.87)
946x810x410 (37.24x31.9x16.14) 673 (26.5) 403 (15.87)
952x1333x410 (37.5x52.5x16.14) 634 (24.96) 404 (15.9)
952x1333x415 (37.5x52.5x16.34) 634 (24.96) 404 (15.9)
845x702x363 (33.27x27.6x14.3) 540 (21.26) 350 (13.8)
938x1369x392 (36.93x53.9x15.43) 634 (24.96) 404 (15.9)
900x1170x350 (35.4x46x13.8) 590 (23.2) 378 (14.88)
800x554x333 (31.5x21.8x13.1) 514 (20.24) 340 (13.39)

Page 16 
Outdoor Unit
Installation
NOTE: The minimum distance between the
outdoor unit and walls described in the
installation guide does not apply to airtight
rooms. Be sure to keep the unit unobstructed
in at least two of the three directions (M, N, P)
(See Fig. 5.10)
M
N
P
30 cm / 11.8” from back wall
60 cm / 23.6” on right
60 cm / 23.6” above
30 cm / 11.8” on left
200 cm / 78” in front
Fig. 5.10
Drain Joint Installation
NOTE: Make sure the water drains to a safe
location where it will not cause water damage
or a slipping hazard.
Seal
Drain joint
(A) (B)
Base pan hole of
outdoor unit
Seal
Fig. 5.12
Notes On Drilling Hole In Wall
You must drill a hole in the wall for the
refrigerant piping, and the signal cable that will
connect the indoor and outdoor units.
1. Determine the location of the wall hole
based on the location of the outdoor unit.
2. Using a 65-mm (2.5”) core drill, drill a hole
in the wall.
NOTE: When drilling the wall hole, make
sure to avoid wires, plumbing, and other
sensitive components.
3.
Place the protective wall cu in the hole.
This protects the edges of the hole and will
help seal it when you nish the installation
process.
Fig. 5.11
L
H
300 cm / 118” or more
A
60 cm / 23.6”
or more
150 cm / 59”
or more
25 cm / 9.8”
or more
25 cm / 9.8”
or more
Rows of series installation
L ≤H L ≤1/2H
L A
25 cm / 9.8” or more
1/2H < L ≤H 30 cm / 11.8” or more
L >H Can not be installed
Table 5.3 The relations between H, A and L
are as follows.
If the drain joint comes with a rubber seal
(see Fig. 5.12 - A ), do the following:
1. Fit the rubber seal on the end of the drain joint
that will connect to the outdoor unit.
2. Insert the drain joint into the hole in the base
pan of the unit.
3. Rotate the drain joint 90° until it clicks in place
facing the front of the unit.
4. Connect a drain hose extension (not included)
to the drain joint to redirect water from the
unit during heating mode.
If the drain joint doesn’t come with a rubber
seal (see Fig. 5.12 - B ), do the following:
1. Insert the drain joint into the hole in the base
pan of the unit. The drain joint will click in
place.
2. Connect a drain hose extension (not included)
to the drain joint to redirect water from the
unit during heating mode.

Page 17 
Drainpipe Installation
NOTE ON DRAINPIPE INSTALLATION
• When using an extended drainpipe, tighten
the indoor connection with an additional
protection tube to prevent it from pulling
loose.
• The drainpipe should slope downward at a
gradient of at least 1/100 to prevent water
from flowing back into the air conditioner.
• To prevent the pipe from sagging, space
hanging wires every 1-1.5m (39-59”).
• Incorrect installation could cause water to
flow back into the unit and flood it.
The drainpipe is used to drain water from the
unit. Improper installation may cause unit and
property damage.
CAUTION
• Insulate all piping to prevent condensation
and water damage.
• If the drainpipe is bent or installed
incorrectly, water may leak and cause a
malfunction of the water-level switch.
• In HEAT mode, the outdoor unit will
discharge water. Ensure that the drain hose
is placed in an appropriate area to avoid
water damage and slippage due to frozen
drain water.
• DO NOTpull the drainpipe forcefully as this
could cause it to disconnect.
NOTE ON PURCHASING PIPES
This installation requires a polyethylene tube
(outside diameter = 3.7-3.9cm, inside diameter
= 3.2cm), which can be obtained at your local
hardware store or dealer.
Indoor Drainpipe Installation
Install the drainpipe as shown in Figure 6.2.
1.
2.
Drainpipe
connecting port
Drain hose
Pipe clasp Insulation
Fig. 6.1
Drainpipe Installation
Fig. 6.2
6
Cover the drainpipe with heat insulation to
prevent condensation and leakage.
Attach the mouth of the drain hose to the
unit’s outlet pipe. Sheath the mouth of the
hose and clip it rmly with a pipe clasp.
(Fig 6.1)
Downward slope
1/100
1-1.5m
(39-59”)
NOTE: When connecting multiple drainpipes,
install the pipes as shown in Fig 6.3.
≥10cm
(4”)
Fig. 6.3

Drainpipe Installation
Page 18 
3. Using a 65-mm (2.5”) core drill, drill a hole in
the wall. Make sure that the hole is drilled at
a slight downward angle, so that the outdoor
end of the hole is lower than the indoor end
by about 12mm (0.5”). This will ensure proper
water drainage (See Fig. 6.4). Place the
protective wall cu in the hole. This protects
the edges of the hole and will help seal it
when you nish the installation process.
Wall
IndoorOutdoor
≈ 12mm / 0.5 inch
Fig. 6.4
NOTE: When drilling the hole in the wall, make
sure to avoid wires, plumbing, and other
sensitive components.
4. Pass the drain hose through the hole.
Make sure the water drains to a safe location
where it will not cause water damage or a
slippage.
NOTE: The drainpipe outlet should be at least
5cm (1.9”) above the ground. If it touches the
ground, the unit may become blocked and
malfunction. If you discharge the water directly
into a sewer, make sure that the drain has a U
or S pipe to prevent unwanted odors from
entering the house.

Page 19 
Refrigerant Piping
Connection
Safety Precautions
WARNING
•All eld piping must be completed by a
licensed technician and must comply with
the local and national regulations.
•When the air conditioner is installed in a
small room, measures must be taken to
prevent the refrigerant concentration in
the room from exceeding the safety limit
in the event of refrigerant leakage. If the
refrigerant leaks and its concentration
exceeds its proper limit, hazards due to
lack of oxygen may result.
•When installing the refrigeration system,
ensure that air, dust, moisture or foreign
substances do not enter the refrigerant
circuit. Contamination in the system may
cause poor operating capacity, high
pressure in the refrigeration cycle,
explosion or injury.
•Ventilate the area immediately if there is
refrigerant leakage during the installation.
Leaked refrigerant gas is both toxic and
flammable. Ensure there is no refrigerant
leakage after completing the installation
work.
Notes On Pipe Length and Elevation
Ensure that the length of the refrigerant pipe, the
number of bends, and the drop height between
the indoor and outdoor units meets the
requirements shown in Table 7.1:
Table 7.1: The Maximum Length And Drop
Height Based on Models. (Unit: m/ft.)
Type of model Capacity
(Btu/h) Length of
piping Maximum drop height
North America,
Australia and the
eu frequency
conversion Split
Type
<15K 25/82 10/32.8
≥15K - <24K 30/98.4 20/65.6
≥24K - <36K 50/164 25/82
≥36K - ≤60K 65/213 30/98.4
Other Split Type
12K 15/49 8/26
18K-24K 25/82 15/49
30K-36K 30/98.4 20/65.6
42K-60K 50/164 30/98.4
Refrigerant Piping with Twin Indoor Units
When installing multiple indoor units with a
single outdoor unit, ensure that the length of
the refrigerant pipe and the drop height between
the indoor and outdoor units meet the
requirements illustrated in the following diagram
(See Fig. 7.1) :
LL1
L2
H2
The line branch pipe
Indoor unit
Outdoor unit
H1
Indoor unit
The drop height
between two
indoor units
must be less
than or equal to
50cm (19.6”)
The drop height
between indoor
unit
and outdoor unit
must be less than
or equal to 20m
(65.6’)
Fig. 7.1
Refrigerant Piping Connection 7

Page 20 
Refrigerant Piping
Connection
Fig. 7.2 Fig. 7.3
Oil traps
CAUTION
•
If the indoor unit is installed higher than the
outdoor unit:
An oil trap should be installed every 10m
(32.8ft) of vertical suction line riser.
(See Fig. 7.2)
-If oil flows back into the outdoor unit’s
compressor, this might cause liquid
compression or deterioration of oil return.
Oil traps in the rising gas piping can prevent
this.
CAUTION
The indoor unit is installed higher than the
outdoor unit
If the outdoor unit is installed higher than the
indoor unit:
-It is recommended that vertical suction risers
not be upsized. Proper oil return to the
compressor should be maintained with suction
gas velocity. If velocities drop below7.62m/s
(1500fpm (feet per minute)), oil return will be
decreased. An oil trap should be installed every
6m(20ft) of vertical suction line riser.
(See Fig. 7.3)
The outdoor unit is installed higher than the
indoor unit