Panasonic Mini ECO-i Technical Data Manual

U-36LE1U6

MINI VRF System

U-36LE1U6E

*
U-52LE1U6
U-52LE1U6E

Model No.
Outdoor Unit

Model Name

Refrigerant R410A is used in the outdoor units.
* Salt-Air Damage Resistant Specifications.

Indoor Units

Class 24 36 48 54

U1

4-Way Cassette

4-Way Cassette 60×60

Y1

U-36LE1U6 U-52LE1U6
U-36LE1U6E* U-52LE1U6E*

7 9 12 15 18

*

5236Class

S-12MY1U6 S-18MY1U6

19

Section

1

Section

1

2

2

3

3

4

4

S-24MU1U6 S-36MU1U6S-12MU1U6 S-18MU1U6

5

5

D1

1-Way Cassette

Low Silhouette Ducted

F1

Slim Low Static Ducted

M1

High Static Pressure

E1

Ducted

Ceiling

T1

K1

Wall Mounted

P1

Floor Standing

Concealed Floor

R1

Standing

** Necessary to install the External Electronic Expansion Valve Kit (Optional:CZ-P56SVK1U)

85464869256000

S-07MD1U6 S-09MD1U6 S-12MD1U6

S-07MF1U6 S-09MF1U6 S-12MF1U6 S-15MF1U6 S-18MF1U6

S-07MM1U6 S-09MM1U6 S-12MM1U6

S-12MT1U6 S-18MT1U6 S-24MT1U6

S-07MK1U6 S-09MK1U6 S-12MK1U6

S-07MP1U6 S-09MP1U6 S-12MP1U6 S-15MP1U6 S-18MP1U6 S-24MP1U6

S-07MR1U6 S-09MR1U6 S-12MR1U6 S-15MR1U6 S-18MR1U6 S-24MR1U6

S-15MM1U6 S-18MM1U6

S-18MK1U6

S-19MS1U6**S-24MK1U6

S-24MF1U6

REFERENCE NO.

S-36MF1U6 S-48MF1U6

S-36ME1U6 S-48ME1U6

TD831156-00

S-54MF1U6

6

6

7

7

8

8

IMPORTANT!
Please Read Before Starting

This air conditioning system meets strict safety and oper­ating standards. As the installer or service person, it is an
important part of your job to install or service the system so
it operates safely and efficiently.

For safe installation and trouble-free operation, you must:

Carefully read this instruction booklet before beginning.

Follow each installation or repair step exactly as shown.

Observe all local, state, and national electrical codes.

Pay close attention to all warning and caution notices
given in this manual.

This symbol refers to a hazard or

WARNING

CAUTION

unsafe practice which can result
in severe personal injury or death.

This symbol refers to a hazard or
unsafe practice which can result
in personal injury or product or
property damage.

If Necessary, Get Help

These instructions are all you need for most installation
sites and maintenance conditions. If you require help for a
special problem, contact our sales/service outlet or your
certified dealer for additional instructions.

In Case of Improper Installation

The manufacturer shall in no way be responsible for
improper installation or maintenance service, including fail­ure to follow the instructions in this document.

SPECIAL PRECAUTIONS

WARNING

Do not supply power to the unit until all wiring and tubing

•

are completed or reconnected and checked.

Highly dangerous electrical voltages are used in this

•

system. Carefully refer to the wiring diagram and these
instructions when wiring. Improper connections and inad­equate grounding can cause accidental injury or death.

Ground the unit following local electrical codes.

•

Connect all wiring tightly. Loose wiring may cause over-

•

heating at connection points and a possible fire hazard.

To prevent possible hazards from insulation failure,

•

the unit must be grounded.

When Transporting

Be careful when picking up and moving the indoor and
outdoor units. Get a partner to help, and bend your knees
when lifting to reduce strain on your back. Sharp edges or
thin aluminum fins on the air conditioner can cut your fingers.

When Wiring

ELECTRICAL SHOCK CAN CAUSE
SEVERE PERSONAL INJURY OR DEATH.
ONLY A QUALIFIED, EXPERIENCED
ELECTRICIAN SHOULD ATTEMPT TO
WIRE THIS SYSTEM.

When Installing…

Select an installation location which is rigid and strong
enough to support or hold the unit, and select a location
for easy maintenance.

…In a Room

Properly insulate any tubing run inside a room to prevent
“sweating” that can cause dripping and water damage to
walls and floors.

CAUTION

…In Moist or Uneven Locations

Use a raised concrete pad or concrete blocks to provide a
solid, level foundation for the outdoor unit. This prevents
water damage and abnormal vibration.

…In an Area with High Winds

Securely anchor the outdoor unit down with bolts and a
metal frame. Provide a suitable air baffle.

…In a Snowy Area (for Heat Pump-type Systems)

Install the outdoor unit on a raised platform that is higher
than drifting snow. Provide snow vents.

Keep the fire alarm and the air outlet at
least 5 feet away from the unit.

When Connecting Refrigerant Tubing

• Ventilate the room well, in the event that is refrigerant
gas leaks during the installation. Be careful not to allow
contact of the refrigerant gas with a flame as this will
cause the generation of poisonous gas.

• Keep all tubing runs as short as possible.

• Use the flare method for connecting tubing.

• Apply refrigerant lubricant to the matching surfaces of
the flare and union tubes before connecting them, then
tighten the nut with a torque wrench for a leak-free con­nection.

• Check carefully for leaks before starting the test run.

• When performing piping work
do not mix air except for speci­fied refrigerant (R410A) in
refrigeration cycle. It causes
capacity down, and risk of
explosion and injury due to high

WARNING

• Do not leak refrigerant while piping work for an
installation or re-installation, and while repairing
refrigeration parts.

Handle liquid refrigerant carefully as it may cause

frostbite.

tension inside the refrigerant
cycle.

• Refrigerant gas leakage may
cause fire.

• Do not add or replace refrigerant
other than specified type.
It may cause product damage,
burst and injury etc.

i

When Servicing

• Turn the power OFF at the main power box (mains)
before opening the unit to check or repair electrical
parts and wiring.

•

Keep your fingers and clothing away from any moving
parts.

•

Clean up the site after you finish, remembering to check
that no metal scraps or bits of wiring have been left
inside the unit being serviced.

•

WARNING

Do not clean inside the indoor and
outdoor units by users. Engage
authorized dealer or specialist for
cleaning.

•

In case of malfunction of this
appliance, do not repair by yourself.
Contact to the sales dealer or service
dealer for a repair.

CAUTION

Others

CAUTION

••Do not touch the air inlet or the
sharp aluminum fins of the
outdoor unit. You may get injured.

• Ventilate any enclosed areas when
installing or testing the refrigeration
system. Escaped refrigerant gas, on
contact with fire or heat, can produce
dangerously toxic gas.

Confirm after installation that no
refrigerant gas is leaking. If the gas
comes in contact with a burning stove,
gas water heater, electric room heater
or other heat source, it can cause the
generation of poisonous gas.

•

Do not touch the air inlet or the
sharp aluminum fins of the
outdoor unit. You may get injured.

•

Do not sit or step on the unit,
you may fall down accidentally.

•

Do not stick any object into the
FAN CASE.
You may be injured and the
unit may be damaged.

Check of Density Limit

The room in which the air conditioner is to be
installed requires a design that in the event of refrig­erant gas leaking out, its density will not exceed a set
limit.

The refrigerant (R410A), which is used in the air condition­er, is safe, without the toxicity or combustibility of ammonia,
and is not restricted by laws imposed to protect the ozone
layer. However, since it contains more than air, it poses the
risk of suffocation if its density should rise excessively. Suf­focation from leakage of refrigerant is almost non-existent.
With the recent increase in the number of high density
buildings, however, the installation of multi air conditioner
systems is on the increase because of the need for effec­tive use of floor space, individual control, energy conserva­tion by curtailing heat and carrying power, etc.
Most importantly, the multi air conditioner system is able
to replenish a large amount of refrigerant compared to
conventional individual air conditioners. If a single unit of
the multi air conditioner system is to be installed in a
small room, select a suitable model and installation pro­cedure so that if the refrigerant accidentally leaks out, its
density does not reach the limit (and in the event of an
emergency, measures can be made before injury can
occur).

ASHRAE and the International Mechanical Code of the
ICC as well as CSA provide guidance and define safe­guards related to the use of refrigerants, all of which define
a Refrigerant Concentration Level (RCL) of 25 pounds
per 1,000 cubic feet for R410A refrigerant.
For additional guidance and precautions related to
refrigerant safety, please refer to the following documents:

International Mechanical Code 2009 (IMC-2009)
(or more recently revised)
ASHRAE 15
ASHRAE 34

ii

Precautions for Installation Using New Refrigerant

1.Care regarding tubing

1-1.Process tubing

Material:Use C1220 phosphorous deoxidized copper specified in JIS H3300 “Copper and Copper Alloy Seamless
Pipes and Tubes.”

Tubing size:Be sure to use the sizes indicated in the table below.

Use a tube cutter when cutting the tubing, and be sure to remove any flash.This also applies to distribution joints
(optional).

When bending tubing, use a bending radius that is 4 times the outer diameter of the tubing or larger.

Use sufficient care in handling the tubing.Seal the tubing ends with

CAUTION

Copper tube

Outer diameter 1/4 (6.35) 3/8 (9.52) 1/2 (12.7) 5/8 (15.88) 3/4 (19.05)

Wall thickness 1/32 (0.8) 1/32 (0.8) 1/32 (0.8) 5/128 (1.0) 5/128 (1.0)

1-2. Prevent impurities including water, dust and oxide from entering the tubing.Impurities can cause R410A

refrigerant deterioration and compressor defects. Due to the features of the refrigerant and refrigerating
machine oil, the prevention of water and other impurities becomes more important than ever.

caps or tape to prevent dirt,moisture,or other foreign substances
from entering.These substances can result in system malfunction.

Unit: in. (mm)

OMaterial

2. Be sure to recharge the refrigerant only in liquid form.

2-1. Since R410A is a non-azeotrope, recharging the refrigerant in gas form can lower performance and cause

defects of the unit.

2-2. Since refrigerant composition changes and performance decreases when gas leaks, collect the remaining

refrigerant and recharge the required total amount of new refrigerant after fixing the leak.

3. Different tools required

3-1.Tool specifications have been changed due to the characteristics of R410A.

Some tools for R22- and R407C-type refrigerant systems cannot be used.

New
tool?

Manifold gauge Yes No Types of refrigerant, refrigerating machine oil, and

Charge hose Yes No To resist higher pressure, material must be changed.

Vacuum pump Yes Yes Use a conventional vacuum pump if it is equipped

Leak detector Yes No Leak detectors for CFC and HCFC that

Flaring oil Yes No For systems that use R22, apply mineral oil (Suniso oil)

R407C tools

RemarkscompatibleItem

with R410A?

pressure gauge are different.

with a check valve. If it has no check valve,
purchase and attach a vacuum pump adapter.

react to chlorine do not function because
R410A contains no chlorine. Leak detector
for HFC134a can be used for R410A.

to the flare nuts on the tubing to prevent refrigerant
leakage. For machines that use R407C or R410A, apply
synthetic oil (ether oil) to the flare nuts.

Manifold gauge

Vacuum pump

Outlet
Inlet

* Using tools for R22 and R407C and new tools for R410A together can cause defects.

iii

3-2.Use R410A exclusive cylinder only.

Single-outlet valve

(with siphon tube)
Liquid refrigerant should be recharged
with the cylinder standing on end as
shown.

New refrigerant R410A cannot be used for
earlier models

1.Compressor specifications are different.

If recharging a R22 or R407C compressor with
R410A, durability will significantly decrease since
some of the materials used for compressor parts are
different.

Valve

Liquid

2.Existing tubing cannot be used (especially R22).

Completely cleaning out residual refrigerating

machine oil is impossible, even by flushing.

3.Refrigerating machine oil differs (R22).

Since R22 refrigerating machine oil is mineral oil, it
does not dissolve in R410A.Therefore, refrigerating
machine oil discharged from the compressor can
cause compressor damage.

R22 refrigerating machine oil Mineral oil (Suniso oil)

R407C refrigerating machine oil Synthetic fluid (ether oil)

R410A refrigerating machine oil Synthetic fluid (ether oil)

iv

Contents

Section 1: OUTLINE OF MINI VRF SYSTEM .........................................................................

1. 1-2

Line-up ............................................................................................................

2. 1-4

Salt-Air Damage Resistant Specifications .......................................................

Section 2: DESIGN OF MINI VRF SYSTEM ..........................................................................

1. 2-2

Model Selecting and Capacity Calculator .......................................................

2. 2-13

System Design .............................................................................................

3. 2-22

Electrical Wiring ............................................................................................

4. 2-30

Installation Instructions .................................................................................

5. 2-38HOW TO PROCESS TUBING ......................................................................

6. 2-42AIR PURGING ..............................................................................................

7. 2-45Optional Parts ...............................................................................................

Section 3: CONTROL OF MINI VRF SYSTEM ......................................................................

1.

Main Operating Functions

2.

Wireless Remote Controller

3.

Timer Remote Controller

4.

Simplified Remote Controller

5.

System Controller

6.

Schedule Timer

7.

Intelligent Controller (CZ-256ESMC1U)

8.

Communication Adaptor (CZ-CFUNC1U)

9.

Remote Sensor

10.

LonWorks Interface (CZ-CLNC1U)

Refer to the 2WAY VRF SYSTEM TECHNICAL DATA (TD831157)

*

Section 4: MINI VRF SYSTEM UNIT SPECIFICATIONS .......................................................

1.

Outdoor Unit ..................................................................................................

4-Way Cassette Type (U1 Type)

2.

4-Way Cassette 60×60 Type (Y1 Type)

3.

1-Way Cassette Type (D1 Type)

4.

Low Silhouette Ducted Type (F1 Type)

5.

Slim Low Static Ducted Type (M1 Type)

6.

High Static Pressure Ducted Type (E1 Type)

7.

Ceiling Type (T1 Type)

8.

Wall Mounted Type (K1 Type)

9.

Floor Standing Type (P1 Type)

10.

11. Concealed Floor Standing Type (R1 Type)

12. Intaking Fresh Air of 4-Way Casstte Type and Slim Low Static Ducted Type

Refer to the 2WAY VRF SYSTEM TECHNICAL DATA (TD831157)

*

Section 5: TEST RUN .............................................................................................................

Preparing for Test Run ....................................................................................

1. 5-2

Test Run Procedure ........................................................................................

2. 5-3

Outdoor Unit PCB Setting ..............................................................................

3. 5-4

Auto Address Setting ......................................................................................

4. 5-6

Remote Controller Test Run Settings ...........................................................

5. 5-12

Caution for Pump Down ................................................................................

6. 5-13

Meaning of Alarm Messages ........................................................................

7. 5-13

Section 6: ELECTRICAL DATA ..............................................................................................

Outdoor Unit ...................................................................................................

1. 6-2
Indoor Unit

2.

Refer to the 2WAY VRF SYSTEM TECHNICAL DATA (TD831157)

*

Section 7: PCB AND FUNCTIONS ........................................................................................

Outdoor Unit Control PCB ...............................................................................

1. 7-2
Indoor Unit Control PCB Switches and Functions

2.

Refer to the 2WAY VRF SYSTEM TECHNICAL DATA (TD831157)

*

Section 8: CAPACITY TABLE ................................................................................................

Capacity Ratio of Outdoor Unit ......................................................................

1. 8-2

Cooling Capacity of Indoor Unit ....................................................................

2. 8-10

1-1

2-1

3-1

4-1

4-2

5-1

6-1

7-1

8-1

v

Outline of Mini VRF SYSTEM

4

Contents

1. OUTLINE OF MINI VRF SYSTEM

1. Line-up .................................................................................................................................1-2

2. Salt-Air Damage Resistant Specifications.........................................................................

1-

1

2

3

4

5

6

7

8

1 - 1

1

Outline of Mini VRF SYSTEM

1. Line-up

Indoor units

Type 9 191815127 3624 48 54

4-Way Cassette

(U1 Type)

4-Way Cassette

60 X 60

(Y1 Type)

1-Way Cassette

(D1 Type)

Low Silhouette

Ducted

(F1 Type)

Slim Low Static

Ducted

(M1 Type)

S-07MD1U6 S-09MD1U6 S-12MD1U6

S-07MF1U6 S-12MF1U6 S-15MF1U6 S-18MF1U6S-09MF1U6 S-24MF1U6

S-07MM1U6 S-12MM1U6 S-15MM1U6 S-18MM1U6S-09MM1U6

S-12MU1U6 S-18MU1U6

S-12MY1U6 S-18MY1U6

S-24MU1U6 S-36MU1U6

S-36MF1U6 S-48MF1U6 S-54MF1U6

2

3

4

5

6

High Static

Pressure Ducted

(E1 Type)

Ceiling

(T1 Type)

Wall Mounted

(K1 Type)

Floor Standing

(P1 Type)

Concealed Floor

Standing

(R1 Type)

* Necessary to install the External Electronic Expansion Valve Kit (Optional:CZ-P56SVK1U).

S-07MK1U6 S-09MK1U6 S-12MK1U6

S-07MP1U6 S-12MP1U6 S-15MP1U6 S-18MP1U6S-09MP1U6 S-24MP1U6

S-07MR1U6 S-12MR1U6 S-15MR1U6 S-18MR1U6S-09MR1U6 S-24MR1U6

S-18MT1U6S-12MT1U6 S-24MT1U6

S-19MS1U6

*

S-24MK1U6S-18MK1U6

S-36ME1U6

S-48ME1U6

7

8

1 - 2

1. Line-up

Indoor units

Type

Capacity:
BTU/h (kW)

Cooling /
Heating

38,200 (11.2)

/ 42,700 (12.5)

U-36LE1U6/U-52LE1U6
U-36LE1U6E*/U-52LE1U6E*

Outline of Mini VRF SYSTEM

DC inverter unit

5236

52,900 (15.5)

/ 60,000 (17.6)

Outdoor
Unit

13-3/8

11-21/32

48-7/16

23/32

6-

11/16

2-

3/4

25-31/32

8-5/8

Air intake

1/2

Air
discharge

5-29/32

37

1/2

2/12/1

2-3/8

4-

5/16

25/32

13/32

3-29/32

25/32

2-25/32

13/32

14-31/32

19/32

5-1/2

4-23/32

15-15/16

7-3/4

6-9/16

3-3/16

6-13/16

Air
discharge

23-5/8

22-9/16

5-9/16

1-13/32

2-3/8

4-11/32

5-1/8

Air
intake

4-3/4

2-27/32

1

2

3

4

7-25/32

5

6-5/8

Outdoor unit model name ended with letters "U6E". Refer to the Section 1 "2. Salt-Air Damage Resistant Specifications".

*

1 - 3

6

7

8

2. Salt-Air Damage Resistant Specifications

Specifications

Relevant Parts Material Standard Specifications

Outline of Mini VRF SYSTEM

Salt-Air Damage

Resistant Specifications

Outdoor unit model name ended

with letters "U6E".

1

2

3

Outer box/side plate/
drain pan
between the stud

Base frame

Fan guard

Fin Aluminum No treatment

Tube Copper No treatment Zinc rich treatment (whole)

Tube plate

Heat

Exchanger

Propeller fan

Fan

Installation frame

Electrical component box

Tapping screws

Stud supplementary
bracket

Hot-dip zinc-coated
steel sheet

Hot-dip aluminum-zinc
coated steel sheet

Resin (Polypropylene) No treatment No treatment

Hot-dip zinc-coated
steel sheet

Resin

Aluminum

Hot-dip zinc-coated
steel sheet

--

Hot-dip zinc-coated
steel sheet

Hot-dip zinc-coated
steel sheet

SUS410

Hot-dip zinc-coated
steel sheet

Polyester powder double coating Polyester powder double coating
(both sides) ( 40 m)

No treatment

No treatment

No treatment

No treatment

No treatment

Motor maker's standard spec.Motor

Polyester powder double coating
(both sides) ( 120 m)

No treatment

Hexavalent chromium-free
coating

No treatment

(both sides) ( 120 m)

Polyester powder double coating
(both sides) ( 120 m)

Zinc rich treatment

Zinc rich treatment (whole)

No treatment

Urethane coating ( 30 m)

Urethane coating ( 30 m)

Motor maker's spec. for salt-air
damage resistant (urethane coating)

Polyester powder double coating
(both sides) ( 120 m)

Polyester powder coating ( 120 m)

Hexavalent chromium-free coating +
urethane coating

Polyester powder double coating
( 120 m)

4

5

6

7

8

No treatment

Accumulator
Receiver tank

Welded portion Copper tube No treatment Urethane coating

Outer surface Copper tube No treatment Urethane coating

Refrigeration

cycle tube

Fixing bracket

Notes:

1 Consult us before introducing a salt-air damage resistant model as it requires a special treatment.
2 The specifications are subject to change without notice for development.
3 Contact us for the delivery schedule.

Steel Epoxy coating + alkyd coating

Hot-dip zinc-coated
steel sheet

No treatment

1 - 4

Dessicant coating (PC board 30 m)--

Zinc rich double coating + urethane
coating ( 70 m)

Polyester powder double coating
(both sides) ( 80 m)

Design of Mini VRF SYSTEM

Contents

2. DESIGN OF MINI VRF SYSTEM

1. Model Selecting and Capacity Calculator ......................................................................... 2-2

2-21-1. Operating Range ...........................................................................................................

2-31-2. Procedure for Selecting Models and Calculating Capacity ...........................................

2-41-3. Calculation of Actual Capacity of Indoor Unit ................................................................

2-91-4. Capacity Correction Graph According to Temperature Condition ................................

2-111-5. Capacity Correction Graph According to Tubing Length and Elevation Difference ....

................................................................................................................... 2-132. System Design

2-132-1. Tools Required for Installation (not supplied) ..............................................................

2-13.....................................................................2-2. Accessories Supplied with Outdoor Unit

2-13..............................................................2-3. Type of Copper Tube and Insulation Material

2-132-4. Additional Materials Required for Installation...............................................................

2-14..................................................................................................................2-5. Tubing Size

2-14...........................................................................2-6. Straight Equivalent Length of Joints

2-152-7. Additional Refrigerant Charge .....................................................................................

2-15.......................................................................................................2-8. System Limitations

2-15..............................................................................................................2-9. Tubing Length

2-162-10. Check of Limit Density ...............................................................................................

2-17........................................................................................................2-11. System Example

2-19.........................2-12. Example of Tubing Size Selection and Refrigerant Charge Amount

2-21.........................................................................................2-13. Installing Distribution Joint

2-223. Electrical Wiring.................................................................................................................

2-223-1. General Precautions on Wiring ...................................................................................

Recommended Wire Length and Wire Diameter for Power Supply System .................

Outdoor Unit .................................................................................................................

4-5. 2-32Dimensions of Air-Discharge Chamber........................................................................

4-6. Dimensions of Outdoor Unit with Air-Discharge Chamber (field supply) 2-32

Indoor Unit

Refer to the 2WAY VRF SYSTEM TECHNICAL DATA (TD831157)

*

Air Purging with a Vacuum Pump (for Test Run) Preparation..................................

Distribution Joint Kits

....................................................................................................

2 - 1

....................

..........................4-8. Dimensions of Outdoor Unit with Snow-Proof Ducting (field supply) 2-34

2-223-2.

2-233-3. Wiring System Diagrams .............................................................................................

2-263-4. Important Note When Wiring for Common Type .........................................................

2-293-5. Important Note When Wiring for Y1 Type.....................................................................

2-304. Installation Instructions.....................................................................................................

2-30

2-304-1. Selecting the Installation Site for Outdoor Unit ............................................................

2-314-2. ..................................................................Air Discharge Chamber for Top Discharge

2-314-3. ......................................................................Installing the Unit in Heavy Snow Areas

2-314-4. .......................................................Precautions for Installation in Heavy Snow Areas

2-34Dimensions of Snow Ducting ......................................................................................4-7.

2-37..........................................................................................Installing the Outdoor Unit4-9.

2-374-10. Drainage Work...........................................................................................................

2-374-11. Routing the Tubing and Wiring ...................................................................................

2-385. HOW TO PROCESS TUBING .............................................................................................

2-385-1. Connecting the Refrigerant Tubing ............................................................................

2-395-2. Connecting Tubing Between Indoor and Outdoor Units .............................................

2-405-3. Insulating the Refrigerant Tubing ...............................................................................

2-415-4. Taping the Tubes ........................................................................................................

2-415-5. Finishing the Installation ..............................................................................................

2-426. AIR PURGING ....................................................................................................................

2-42

2-457. Optional Parts .....................................................................................................................

2-457-1.

1

2

3

4

5

6

7

8

1. Model Selecting and Capacity Calculator

1-1. Operating Range

Design of Mini VRF SYSTEM

1

2

Cooling

113

109

104

95

86

77

57

Operating
range

59

68 77 86

68

59

50

41

Outdoor air intake temp. °F (DB)

32

23

14

50

Indoor air intake temp. °F (WB)

Heating

77

68

59

50

41

32

23

14

Outdoor air intake temp. °F (WB)

5

–4

50

Indoor air intake temp. °F (DB)

Operating
range

59 68 77 86 95

3

4

5

6

7

8

2 - 2

Design of Mini VRF SYSTEM

1. Model Selecting and Capacity Calculator

1-2. Procedure for Selecting Models and Calculating Capacity

Model Selection Procedure

■

Select the model and calculate the capacity for each refrigerant system according to the procedure shown below.

Calculation of the indoor air-conditioning load

●

Selection of an air conditioning system

Design of the control system

Preliminary selection of indoor and outdoor units

Check of the tubing length and elevation difference

Calculation of the corrected outdoor unit capacity

Calculation of the corrected capacity for each indoor unit

Calculation of the actual capacity for each indoor unit

Recheck of the actual capacity for each indoor unit

Design of tubing

Calculation of additional refrigerant charge amount

Design of electrical wiring capacity

Calculate the maximum air-conditioning load for each room or zone.

●

Select the ideal air conditioning system for air conditioning of each room or zone.

●

Design a suitable control system for the selected air conditioning system.

●

Make preliminary selections that are within the allowable range for the system.

●

Check that the length of refrigerant tubing and the elevation difference are within the allowable

ranges. ................................................................................................................. 2-4, 2-15 – 2-16

●

Capacity correction coefficient for outdoor temperature conditions .......................... 2-4, 2-6 – 2-7

●

Capacity correction coefficient for tubing length and elevation difference ........................ 2-4, 2-8

●

Heating capacity correction coefficient for frosting/defrosting ............................................ 2-4, 2-7

●

Capacity correction coefficient for indoor temperature conditions ..................................... 2-4, 2-8

●

Capacity distribution ratio based on the tubing length and elevation difference ... 2-4, 2-15 – 2-16

●

Calculate the corrected indoor/outdoor capacity ratio, based on the corrected outdoor unit
capacity and the total corrected capacity of all indoor units in the same system. Use the result to

calculate the capacity correction coefficient for the indoor units. ..................................... 2-4 – 2-8

●

Multiply the corrected capacity of each indoor unit by the capacity correction coefficient to

calculate the actual capacity for each indoor unit. ................................................................... 2-6

●

If the capacity is inadequate, reexamine the unit combinations.

Example 1: Increasing the outdoor unit capacity ........................................................ 2-17 – 2-18

Example 2: Increasing the indoor unit capacity .......................................................... 2-17 – 2-18

●

Create a tubing design which minimizes the amount of additional refrigerant charge as much as

possible. ....................................................................................................................... 2-14 – 2-15

●

If tubing extension is expected in the future, create the tubing design with adequate
consideration for this extension.

●

Select the tubing size for the main tube (LA) up to the No. 1 distribution joint based on the rated
cooling capacity of the outdoor unit. Select tubing sizes after the distribution point based on the
total rated cooling capacity of the connected indoor units.

●

Calculate the additional refrigerant charge from the diameters and lengths of the refrigerant
tubing. Even if the gas tubing diameter was increased, determine the additional refrigerant

charge based only on the liquid tubing size. .......................................................................... 2-21

●

Check the minimum indoor capacity (limit density) with respect to the amount of refrigerant. If the
limit density is exceeded, be sure to install ventilation equipment or take other corrective steps. 2-22

●

Select a wiring capacity according to the method of power supply. ....................................... 2-32

...................

2-2

1

2

3

4

5

6

7

2 - 3

8

1

2

3

4

5

6

7

Design of Mini VRF SYSTEM

1. Model Selecting and Capacity Calculator

1-3. Calculation of Actual Capacity of Indoor Unit

Calculating the actual capacity of each indoor unit

■

Because the capacity of a multi air-conditioner changes according to the temperature conditions, tubing length,
elevation difference and other factors, select the correct model after taking into account the various correction
values. When selecting the model, calculate the corrected capacities of the outdoor unit and each indoor unit. Use
the corrected outdoor unit capacity and the total corrected capacity of all the indoor units to calculate the actual
final capacity of each indoor unit.

1. Outdoor unit capacity correction coefficient

Find the outdoor unit capacity correction coefficient for the following items.

(1) Capacity correction for the outdoor unit temperature conditions

From the graph of capacity characteristics on page 2-6, use the outdoor temperature to find the capacity
correction coefficient.

(2) Capacity correction for the outdoor unit tubing length and elevation difference

From the graph of capacity change characteristics on page 2-7, use the tubing length and elevation difference
to find the capacity correction coefficient.
The outdoor unit correction coefficient is the value which corresponds to the most demanding indoor unit.

(3) Capacity correction for outdoor unit frosting/defrosting during heating

From the table on page 2-7, find the capacity correction coefficient.

2. Indoor unit capacity correction coefficients

Find the indoor unit capacity correction coefficient for the following items.

(1) Capacity correction for the indoor unit temperature conditions

From the graph of capacity characteristics on page 2-8, use the indoor temperature to find the capacity
correction coefficient.

(2) Capacity distribution ratio based on the indoor unit tubing length and elevation difference

First, in the same way as for the outdoor unit, use the tubing length and elevation difference for each indoor unit
to find the correction coefficient from the graph of capacity change characteristics on page 2-8. Then divide the
result by the outdoor unit correction coefficient to find the capacity distribution ratio for each indoor unit.

Capacity distribution ratio for each indoor unit (2) = Correction coefficient for that indoor unit / Correction coefficient for the outdoor uni

3. Calculating the corrected capacities for the outdoor unit and each indoor unit

The corrected capacities for the outdoor unit and each indoor unit are calculated form the formula below.

<Cooling>

●

Outdoor unit corrected cooling capacity (5) = Outdoor unit rated cooling capacity × Correction coefficient for

outdoor temperature conditions ((1) Page 2-6) × Correction
coefficient for tubing length and elevation difference ((2) Page 2-8)

* However, if the outdoor unit corrected cooling capacity [5] is greater than 100%, then the outdoor unit corrected cooling

capacity [5] is considered to be 100%.

●

Corrected cooling capacity of each indoor unit (5) = Rated cooling capacity for that indoor unit × Correction

coefficient for indoor temperature conditions at that indoor unit ((1) Page 2-7) × Distribution ratio based on tubing
length and elevation difference at that indoor unit ((2) Page 2-8)

However, the corrected cooling capacity of each indoor unit is found as shown below.
If (1) < 100% and (1) × (2) > 100%: Corrected cooling capacity for that indoor unit [5] = Rated cooling capacity for that indoor unit
If (1) ≥ 100%: Corrected cooling capacity for that indoor unit (5) = Rated cooling capacity for that indoor unit × (1)

t

8

2 - 4

Design of Mini VRF SYSTEM

1. Model Selecting and Capacity Calculator

<Heating>

●

Outdoor unit corrected heating capacity (5) = Outdoor unit rated heating capacity × Correction coefficient

for outdoor temperature conditions ((1) Page 2-6) × Correction
coefficient for tubing length and elevation difference ((2) Page 2-8)

Correction coefficient for frosting/defrosting ((2) Page 2-7)

×

* However, if the outdoor unit corrected heating capacity [5] is greater than 100%, then the outdoor unit corrected heating

capacity is considered to be 100%.

●

Corrected heating capacity of each indoor unit (5) = Rated heating capacity for that indoor unit × Correction

coefficient for indoor temperature conditions at that indoor unit ((1) Page 2-6) × Distribution ratio based on tubing
length and elevation difference at that indoor unit ((2) Page 2-8).

However, the corrected heating capacity of each indoor unit is found as shown below.

length and elevation difference at that indoor unit ((3) Page 2-72)

If (1) < 100% and (1) × (2) > 100%: Corrected heating capacity for that indoor unit (5) = Rated heating capacity for that indoor unit
If (1) ≥ 100%: Corrected heating capacity for that indoor unit (5) = Rated heating capacity for that indoor unit × (1)

* Characteristic graphs are shown on the pages listed above next to each correction item.

Find each correction coefficient from the appropriate conditions.

4. Calculating the actual indoor unit capacity based on the indoor/outdoor corrected capacity ratio

Calculate the actual capacity of each indoor unit from the values (found in (3)) for the corrected outdoor unit
capacity and the corrected capacity of each indoor unit.

<Cooling capacity>

Corrected indoor/outdoor capacity ratio during cooling (Ruc) = Total corrected cooling capacity of all indoor units in
that system / Corrected outdoor unit cooling capacity

If the corrected outdoor unit cooling capacity is greater than or equal to the total corrected unit cooling capacity of
all indoor units in that system (Ruc ≤ 1), then:

Actual cooling capacity of each indoor unit (7) = Corrected cooling capacity of each indoor unit (5)
(In other words, the correction coefficient (6), based on the corrected indoor/outdoor capacity ratios for each
indoor unit, is 1.)

If the corrected outdoor unit cooling capacity is less than the total corrected unit cooling capacity of all indoor units
in that system (Ruc > 1), then:

(Actual cooling capacity of each indoor unit (7)) = (Corrected cooling capacity of each indoor unit (5)) × (0.25 ×
Ruc + 0.75) / Ruc
(In other words, the correction coefficient (6), based on the corrected indoor/outdoor capacity ratios for each
indoor unit, is the underlined part in the formula above.)

1

2

3

4

<Heating capacity>

Corrected indoor/outdoor capacity ratio during heating (Ruh) = Total corrected heating capacity of all indoor units in
that system / Corrected outdoor unit heating capacity

If the corrected outdoor unit heating capacity is greater than or equal to the total corrected unit heating capacity of
all indoor units in that system (Ruh ≤ 1), then:

Actual heating capacity of each indoor unit (7) = Corrected heating capacity of each indoor unit (5)
(In other words, the correction coefficient (6), based on the corrected indoor/outdoor capacity ratios for each
indoor unit, is 1.)

If the corrected outdoor unit heating capacity is less than the total corrected unit heating capacity of all indoor units
in that system (Ruh > 1), then:

(Actual heating capacity of each indoor unit (7)) = (Corrected heating capacity of each indoor unit (5)) × (0.1 ×
Ruh + 0.9) / Ruh
(In other words, the correction coefficient (6), based on the corrected indoor/outdoor capacity ratios for each
indoor unit, is the underlined part in the formula above.)

2 - 5

5

6

7

8

1. Model Selecting and Capacity Calculator

Refer to the graph below for the correction coefficients for Ruc and Ruh.

Indoor unit capacity correction coefficient for Ruc (cooling)
Indoor unit capacity correction coefficient for Ruh (heating)

1.0

0.9

0.8

0.7

0.6

0.5

Indoor unit capacity correction coefficient

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9
Corrected indoor/outdoor capacity ratio (Ruc or Ruh)

Note:

When Ruc or Ruh is less than or equal to 1.0, the indoor unit capacity correction coefficient for both Ruc and Ruh is 1.0.

5. Graph of capacity correction coefficients

Design of Mini VRF SYSTEM

2.0

1

2

3

4

5

6

Graph of outdoor unit capacity characteristics (1 – (1))

■

Outdoor unit cooling capacity characteristics

120

100

80

Capacity ratio (%)

14

71°F WB

66°F WB

60°F WB

95 100

Outdoor air intake temp. (°F DB)

104
100

109

(1) U-36LE1U6, U-36LE1U6E

(1)
(2)

(1)

90
80

(2) U-52LE1U6, U-52LE1U6E

(2)

7

8

2 - 6

1. Model Selecting and Capacity Calculator

0

–

0

Outdoor unit heating capacity characteristics

Design of Mini VRF SYSTEM

U-36LE1U6, U-36LE1U6E

130
120
110
100

90
80
70
60

Capacity ratio (%)

50
40

4 5 14 23 32 41 50 59

Outdoor air intake temp. (°F DB)

Outdoor unit heating capacity correction coefficient during frosting/defrosting (1 – (2))

■

Outdoor intake air

(°F WB RH 85%)

temp.

Correction

coefficient

* To calculate the heating capacity with consideration for frosting/defrosting operation, multiply the heating capacity

found from the capacity graph by the correction coefficient from the table above.

–4 5 14 17 21 23 24 28 30 32 33 35 37 39 41 42

0.97 0.97 0.97 0.96 0.94 0.91 0.89 0.87 0.87 0.87 0.88 0.89 0.91 0.92 0.95 1.0

(°F DB)

59

68

77

U-52LE1U6, U-52LE1U6E

130
120
110
100

90
80
70
60

Capacity ratio (%)

50
40

–4 5 142332415059

Outdoor air intake temp. (°F DB)

(°F DB)

59

68

77

1

2

3

4

5

6

7

8

2 - 7

1. Model Selecting and Capacity Calculator

Graph of indoor unit capacity characteristics (2 – (1))

■

Indoor unit cooling capacity characteristics Indoor unit heating capacity characteristics

Design of Mini VRF SYSTEM

1

2

3

120

110

100

90

80

57 59 60 62 64 66 68 69 71 73 75 77 59 60 62 64 66 68 69 71 73 75 77 78

Indoor air intake temp. (˚F WB)

Rate of cooling capacity change (%)

Graph of capacity change characteristics resulting from tubing length and elevation difference (1 • 2 – (2))

■

Base capacity
change rate (%)

164

131

98

66

100

33

0

-33

-66

-98

Elevation difference (ft)

-131
0 33 66 98 131 164 197 230 262 295 328 361 394 427 459 492

94

96

98

%

indicates the rating point. indicates the rating point.

<Cooling>

92 90 88 86 84 82 80 78 76

Equivalent length (ft)

110

105

100

95

90

Indoor air intake temp. (˚F DB)

Rate of heating capacity change (%)

<Heating>

Base capacity
change rate (%)

164

131

98

99

66

100

33

%

0

-33

-66

-98

Elevation difference (ft)

-131
0 33 66 98 131 164 197 230 262 295 328 361 394 427 459 492

97 96 95 94 93 92 91

98

Equivalent length (ft)

80

4

5

6

7

8

The positive side for the elevation difference indicates that the outdoor unit is installed at a higher position than the
indoor units. The negative side indicates the opposite.

2 - 8

Design of Mini VRF SYSTEM

1. Model Selecting and Capacity Calculator

1-4. Capacity Correction Graph According to Temperature Condition

Capacity characteristics

■

(The corrected capacity for specific temperature conditions can be found from the graphs below and next page.)

<COOLING>

120

100

80

Capacity ratio (%)

100

50

Capacity ratio (%)

(1) U-36LE1U6, U-36LE1U6E

(1)
(2)

(1)

(2) U-52LE1U6, U-52LE1U6E

(2)

14

71°F WB

66°F WB

60°F WB

95 100

Outdoor air intake temp. (°F DB)

109

104
100

90
80

1

112

92

63

50

33

100104

71°F WB

66°F WB

60°F WB

124
118
114
108
100

(1)
(1)
(2)
(2)
(2)

(1) U-36LE1U6, U-36LE1U6E

(2) U-52LE1U6, U-52LE1U6E

2

3

4

14

95 100 109

Outdoor air intake temp. (°F DB)

5

6

7

8

2 - 9

1. Model Selecting and Capacity Calculator

p. (

)

<HEATING>

Design of Mini VRF SYSTEM

1

U-36LE1U6, U-36LE1U6E

130
120
110
100

90
80
70
60

Capacity ratio (%)Input ratio (%)

50
40

130
120
110
100

90
80
70
60
50

–4 5 142332415059

Outdoor air intake temp. (°F DB)

(°F DB)

59

68

77

59

68

77

U-52LE1U6, U-52LE1U6E

130
120
110
100

90
80
70
60

Capacity ratio (%)Input ratio (%)

50
40

130
120
110
100

90
80
70
60
50

–4 5 142332415059

Outdoor air intake tem

°F DB

(°F DB)

59

68

77

59

68

77

2

3

4

5

6

7

8

2 - 10

1. Model Selecting and Capacity Calculator

●

Inverter model rated performance values

Design of Mini VRF SYSTEM

Item

Cooling

Model

U-36LE1U6, U-36LE1U6E
U-52LE1U6, U-52LE1U6E

Outdoor unit heating capacity correction coefficient during frosting/defrosting (1 – (3))

■

Outdoor intake air

(°F WB RH 85%)

temp.

Correction

coefficient

–4 5 14 17 21 23 24 28 30 32 33 35 37 39 41 42

0.97 0.97 0.97 0.96 0.94 0.91 0.89 0.87 0.87 0.87 0.88 0.89 0.91 0.92 0.95 1.0

capacity

BTU/h(kW)

38,200 (11.2) 9,400 (2.76) 42,700 (12.5) 9,800 (2.88)
52,900 (15.5) 16,600 (4.57) 60,000 (17.6) 15,600 (4.58)

Cooling Heating

Power

consumption

BTU/h(kW)

Heating

capacity

BTU/h(kW)

Power

consumption

BTU/h(kW)

* To calculate the heating capacity with consideration for frosting/defrosting operation, multiply the heating capacity

found from the capacity graph by the correction coefficient from the table above.

1-5. Capacity Correction Graph According to Tubing Length and Elevation Difference

Capacity change characteristics

■

<Cooling>

Base capacity
change rate (%)

164

131

98

66

100

33

0

–33

Elevation difference (ft)

–66

–98

–131

0 33 66 98 131 164 197 230 262 295 328 361

96

98

%

92 90 88 86 84 82 80 78 76

94

*1

Equivalent length (ft)

394 427

459 492

1

2

3

4

<Heating>

Base capacity
change rate (%)

164

131

98

66

33

0

–33

–66

Elevation difference (ft)

–98

–131

99

100

%

0 33 66 98 131 164 197 230 262 295 328 361

97 96 95 94 93 92 91

98

*1

Equivalent length (ft)

394 427

459 492

5

6

7

8

2 - 11

Design of Mini VRF SYSTEM

1. Model Selecting and Capacity Calculator

For U-36LE1U6(E) units

If the maximum tubing length (L1) exceeds 295 ft. (equivalent length), increase the tubing size of the main gas

■

tube (LM) by one rank.

* The size increase is applied to the gas tube only. In addition, for a 6 HP unit it is not necessary to increase the

tubing size.

Increasing the tubing size of the gas tubes can reduce the loss of capacity caused by longer tubing lengths.

■

Refer to Table 2-1 to increase the tubing size. However, the maximum allowable tubing length must not be
exceeded.

* The size increase is applied to the LM gas tube (main tube with the largest diameter) only, and is limited to the

cases shown in Table 2-1. In addition, the amount of additional refrigerant charge is determined from the liquid
tube size only.

* In case of 6pieces, increasing the size of the gas tube is not possible.

Table 2-1 Correction coefficient for equivalent length when the size of the gas tube (LM) is increased

1

2

3

4

Standard tube diameter (gas tube, in. (mm))

Tube diameter after change (gas tube, in. (mm))

Equivalent length correction coefficient

* When increasing the size of the gas tubing (LM), multiply by the correction coefficient from Table 2-1 and calculate the

equivalent length for section LM.

Tubing equivalent length after size increase = Standard tubing equivalent length × Equivalent length correction coefficient

WARNING

The upper limit for tubing size is ø3/4” (ø19.05). Tubing above that size cannot be
used.

ø5/8" (ø15.88)

ø3/4" (ø19.05)

0.4

5

6

7

8

2 - 12

2. System Design

Design of Mini VRF SYSTEM

2-1. Tools Required for Installation (not supplied)

1. Flathead screwdriver

2. Phillips head screwdriver

3. Knife or wire stripper

4. Tape measure

5. Carpenter’s level

6. Sabre saw or key hole saw

7. Hack saw

8. Core bits

9. Hammer

10. Drill

11. Tube cutter

12. Tube flaring tool

13. Torque wrench

14. Adjustable wrench

15. Reamer (for deburring)

2-2. Accessories Supplied with Outdoor Unit

Table 2-2 (Outdoor Unit)

Q'ty

Patr name Figure

Tube Discharge
Assembly

U-36LE1U6

U-36LE1U6E

(4 hp)

U-52LE1U6

U-52LE1U6E

(6 hp)

01

2-3. Type of Copper Tube and Insulation Material

If you wish to purchase these materials separately
from a local source, you will need:

1. Deoxidized annealed copper tube for refrigerant
tubing.

2. Foamed polyethylene insulation for copper tubes as
required to precise length of tubing. Wall thickness
of the insulation should be not less than 5/16".

3. Use insulated copper wire for field wiring. Wire
size varies with the total length of wiring. Refer to

3. Electrical Wiring for details.

CAUTION

2-4. Additional Materials Required for Installation

1. Refrigeration (armored) tape

2. Insulated staples or clamps for connecting wire

(See your local codes.)

3. Putty

4. Refrigeration tubing lubricant

5. Clamps or saddles to secure refrigerant tubing

6. Scale for weighing

Check local electrical codes
and regulations before
obtaining wire. Also, check
any specified instructions
or limitations.

1

2

3

Instruction
manual

paper

11

hp = horsepower

4

5

6

7

8

2 - 13

Design of Mini VRF SYSTEM

p)

ø

5/

8

(

ø

5.

88

)

ø

(

ø

)

ø

3

(

ø

)

ø

3/8

(

ø

)

ø

3/8

(

ø

)

p)

38

p)

47,

8

p)

U/h

Ov

U/h

s

t

u

bi

g

tubi

g

U

2. System Design

2-5. Tubing Size

Table 2-3 Main Tubing Size (LA)

BTU/h (kW)

System horsepower

Gas tubing

Liquid tubing

38,200 (11.2)

4

ø5/8" (ø15.88)

ø 3/8" (ø9.52)

Note: If the system consists of only one indoor unit with an outdoor 6HP (Type 52), the main tube of the unit (LA) should be

ø19.05. Convert ø19.05 to ø15.88 using a reducer (field supply) close to the indoor unit and then make the connection.

Table 2-4 Main Tubing Size After Distribution (LB, LC...)

Total capacity
after distribution

Tubing size

Note: In case the total capacity of connected indoor units exceeds the total capacity of the outdoor units, select the main

tubing size for the total capacity of the outdoor units.

Below BT

er BT

Liquid

n

n

52,900 (15.5)

ø 3/4" (ø19.05)

24,200 (2.5 h

1/2"

12.7

"

9.52

6

Unit: in. (mm)

,200 (4 h

"

00 (5 hp)52,900 (6 h

24,200 (2.5 h

1

"

9.52

/4"

19.05
it: in. (mm)

hp = horsepower

1

2

3

4

5

6

Table 2-5 Indoor Unit Tubing Connection ( 1, 2...

7 9 12 18 3624 48Indoor unit type

Gas tubing

Liquid tubing

ø

1/2" (ø12.7)

ø

1/4" (ø6.35)

n–1

)

5415 19

ø

5/8" (ø15.88)

ø

3/8" (ø9.52)

Unit: in. (mm)

2-6. Straight Equivalent Length of Joints

Design the tubing system by referring to the following table for the straight equivalent length of joints.

1.1

0.9

3.4

9.2

Unit: ft.

3/4" (19.05)

1.4

1

4.1

10.5

Table 2-6 Straight Equivalent Length of Joints

Gas tubing size (in. (mm))

elbow

90°

45°

elbow

U-shape tube bend (R2-3/8" – 4" (60 – 100))

Trap bend

Y-branch distribution joint

Ball valve for ser

vice

1/2" (12.7)

0.8

7.5

Equivalent length conversion not needed.

Equivalent length conversion not needed.

5/8" (15.88)

1

3

Unit: in. (mm)

over 5/128 (1.0)

7

Table 2-7 Required Copper Tubing Dimensions

Material O

Copper tube

Outer diameter 1/4 (6.35) 3/8 (9.52) 1/2 (12.7) 5/8 (15.88) 3/4 (19.05)

Wall thickness 1/32 (0.8) 1/32 (0.8) 1/32 (0.8) 5/128 (1.0)

8

2 - 14

Design of Mini VRF SYSTEM

2. System Design

2-7. Additional Refrigerant Charge

Additional refrigerant charge amount is calculated from the liquid tubing total length as follows.

Table 2-8 Amount of Refrigerant Charge Per Feet, According to Liquid Tubing Size

Liquid tubing size

(in. (mm)) charge (oz/ft.)

ø1/4” (ø6.35) 0.279

ø3/8” (ø9.52) 0.602

Table 2-9 Refrigerant Charge Amount at Shipment (for outdoor unit)

Amount of refrigerant

Required amount of charge = (Amount of refrigerant
charge per ft. of each size of liquid tube × its tube
length) + (...) + (...)

*Always charge accurately using a scale for weighing.

Heat pump unit
(Single-phase)(oz)

2-8. System Limitations

Table 2-10 System Limitations

Outdoor units

Number of max. connectable indoor units 6 9
Max. allowable indoor/outdoor capacity ratio 50 – 130%

2-9. Tubing Length

Select the installation location so that the length and size of refrigerant tubing are within the allowable range shown
in the figure below.

Main tube of unit

U-36LE1U6E

LA

U-36LE1U6

123 123

U-36LE1U6

U-36LE1U6E

L1
L2

LCLB

U-52LE1U6

U-52LE1U6E

LD

U-52LE1U6

U-52LE1U6E

n

H1

1

2

3

4

5

1st branch

1

L3

Unit distribution tube

Note: Do not use commercially available T-joints for the liquid tubing.

* Be sure to use special R410A distribution joints (CZ: purchased separately) for outdoor

unit connections and tubing branches.

23

2 - 15

n-1

H2

R410A distribution joint
CZ-P160BK1U (for indoor unit)

6

7

8

Design of Mini VRF SYSTEM

2. System Design

Table 2-11 Ranges that Apply to Refrigerant Tubing Lengths and to Differences in Installation Heights

Items Marks Contents Length (ft.)

>

>

>

131

>

262

>

>

656

>

>

>

Allowable tubing
length

Allowable elevation
difference

L = Length, H = Height

L1 Max. tubing length

L (L2 – L3)

LA

...

1, 2

n

+2+...

1

n-1

H1

H2 Max. difference between indoor units 49

Difference between max. length and min.
length from the No.1 distribution joint

Max. length of main tubing (at max. diameter)

Max. length of each distribution tube 98

Total max. tubing length including length of

+L1

each distribution tube (only narrow tubing)

When outdoor unit is installed higher than indoor unit 164

When outdoor unit is installed lower than indoor unit 131

Actual length 492

Equivalent length 574

1

2

3

4

5

WARNING

2-10. Check of Limit Density

When installing an air conditioner in a room, it is
necessary to ensure that even if the refrigerant gas
accidentally leaks out, its density does not exceed the
limit level for that room.

CAUTION

Always check the gas den­sity limit for the room in
which the unit is installed.

Pay special attention to any
location, such as a base­ment, etc., where leaking
refrigerant can accumulate,
since refrigerant gas is
heavier than air.

6

7

8

2 - 16

2. System Design

2-11. System Example

(1) Below are the tables created using the “PAC System Diagram Software.”

Details of the calculations are shown in (2).

Outdoor

unit

Design of Mini VRF SYSTEM

131 ft.

Elevation
difference: 33 ft.

Selection conditions

Assumes that installation is in a 60 Hz region.

Outdoor unit

Selected model

Air condition

Cooling

Heating

Actual tubing length

Equivalent length (with
consideration for curves, etc.)

Preliminary selection

Selected model
Load (cooling/heating) (BTU/h)

Rated capacity
(cooling/heating) (BTU/h)

(5) Corrected capacity

(7) Actual capacity

Total corrected capacity of indoor units (cooling/heating) = 32,800 / 39,100
Ruc = 32,800 / 33,200 = 0.988 < 1 Ruh = 39,100 / 33,700 = 1,160 > 1

Outdoor unit changes

During heating, the corrected outdoor unit capacity is less than the total corrected capacity of all indoor units
in the system. As a result, the actual capacity of each indoor unit is less than the maximum load. Therefore
the outdoor unit is increased by one rank.

Selected model

Maximum load
(cooling/heating) (BTU/h)

Rated capacity
(cooling/heating) (BTU/h)

(5) Corrected capacity

(7) Actual capacity

Total corrected capacity of all indoor units (cooling/heating) = 32,800 / 39,100

Ruc = 32,800 / 45,900 = 0.715 < 1 Ruh = 39,100 / 47,300 = 0.827 < 1

(DB/WB)

Max. load (BTU/h)

Air condition
(DB/WB)

Max. load (BTU/h)

(cooling/heating) (BTU/h)

(cooling/heating) (BTU/h)

(cooling/heating) (BTU/h)

(cooling/heating) (BTU/h)

U-36LE1U6 (U-36LE1U6E)

91.0 / 72.0

37.0 / 35.0 69.0 / 55.0 69.0 / 55.0 69.0 / 55.0 69.0 / 55.0

246 ft.

295 ft. 197 ft. 236 ft. 276 ft. 295 ft.

Outdoor unit

U-36LE1U6 (U-36LE1U6E)

38,200 / 42,700

33,200 / 33,700

Outdoor unit

U-52LE1U6 (U-52LE1U6E)

52,900 / 60,000

45,900 / 47,300

Indoor

unit 1

33 ft.

33 ft.

(indoor unit 1)

78.0 / 64.0

(indoor unit 1)

10,000 / 12,000

12,000 / 14,000

11,700 / 14,000

11,700 / 12,200

(indoor unit 1)

10,000 / 12,000

12,000 / 14,000

11,700 / 14,000

11,700 / 14,000

33 ft. 49 ft.

33 ft.

Indoor

unit 2

Room 1

Type 12 Type 7 Type 7 Type 7

10,000 7,000 7,000 7,000

Room 1

Type 12 Type 7 Type 7 Type 7

Room 1

Type 12 Type 7 Type 7 Type 7

2 - 17

33 ft.

Indoor

unit 3

Room 2

(indoor unit 2)

78.0 / 64.0 78.0 / 64.0 78.0 / 64.0

Room 2

(indoor unit 2)

7,000 / 8,400 7,000 / 8,400 7,000 / 8,400

7,500 / 8,500

7,200 / 8,400

7,200 / 7,400 7,000 / 7,300

Room 2

(indoor unit 2)

7,000 / 8,400 7,000 / 8,400 7,000 / 8,400

7,500 / 8,500

7,200 / 8,400

7,200 / 8,400

Indoor

unit 4

Room 3

(indoor unit 3)

Room 3

(indoor unit 3)

7,500 / 8,500

7,000 / 8,400

Room 3

(indoor unit 3)

7,500 / 8,500

7,000 / 8,400

7,000 / 8,400

(indoor unit 4)

(indoor unit 4)

7,500 / 8,500

6,900 / 8,300

6,900 / 7,300

(indoor unit 4)

7,500 / 8,500

6,900 / 8,300

6,900 / 8,300

Room 4

8,4008,4008,40012,000

246 ft.230 ft.197 ft.164 ft.

Room 4

Room 4

1

2

3

4

5

6

7

8

1

2

3

4

5

Design of Mini VRF SYSTEM

2. System Design

Indoor unit changes

The indoor unit in room 4, where the corrected indoor unit capacity is less than the maximum load, is
increased by one rank.

Outdoor unit

Selected model

Maximum load
(cooling/heating) (BTU/h)

Rated capacity
(cooling/heating) (BTU/h)

(5) Corrected capacity

(cooling/heating) (BTU/h)

(7) Actual capacity

(cooling/heating) (BTU/h)

Total corrected capacity of all indoor units (cooling/heating) = 36,900 / 44,500
Ruc = 36,900 / 45,900 = 0.804 < 1 Ruh = 44,500 / 47,300 = 0.941 < 1

•For both cooling and heating in all rooms, actual capacity is now greater than or equal to the maximum
load. Selection is completed.

U-52LE1U6 (U-52LE1U6E)

52,900 / 60,000

45,900 / 47,300

Room 1

(indoor unit 1)

Type 12 Type 7 Type 12Typ e 7

10,000 / 12,000

12,000 / 14,000

11,700 / 14,000

11,700 / 14,000

(2) Calculate the final selection results according to the capacity calculation procedure.

[From calculation of the correction coefficient to calculation of actual capacity] (Cooling/heating)

Outdoor unit

Rated capacity
(cooling/heating) (BTU/h)

(1) Model

(2) Temp. condition

(3) Tubing length,

elevation difference

coefficient

Correction

(4) Frosting • defrosting

Result of (2) × (3)

Correction coefficient
applied to indoor unit *1

(5) Corrected capacity (BTU/h) *2

(6) Correction coefficient

for corrected capacity
ratio

(7) Actual capacity (BTU/h)

*1: This varies depending on the values of (2) and (2) × (Distribution ratio in (3)).
*2: Corrected outdoor unit capacity = Rated outdoor unit capacity × (1) × (2) × (3) × (4)

52,900 / 60,000

1.00 / 1.00

1.020 / 0.937 0.920 / 0.980

0.851 / 0.946 1.000 / 1.0001.062 / 1.020 1.012 / 1.0041.037 / 1.012

— / 0.890

45,900 / 47,300

Room 1

(indoor unit 1)

12,000 / 14,000

0.977 / 1.000 0.954 / 0.992 0.992 / 0.984 0.920 / 0.980

0.977 / 1.000 0.954 / 0.992

11,700 / 14,000

11,700 / 14,000

Room 2

(indoor unit 2)

7,000 / 8,400 7,000 / 8,400 7,000 / 8,400

7,500 / 8,500 7,500 / 8,500

7,200 / 8,400 7,000 / 8,400

7,200 / 8,400 7,000 / 8,400

Room 2

(indoor unit 2)

7,500 / 8,500 7,500 / 8,500

0.920 / 0.980 0.920 / 0.980 0.920 / 0.980

7,200 / 8,400

1.00 / 1.00

7,200 / 8,400 7,000 / 8,400

Room 3

(indoor unit 3)

12,000 / 14,000

11,000 / 13,700

11,000 / 13,700

Room 3

(indoor unit 3)

12,000 / 14,000

0.992 / 0.984 0.920 / 0.980

7,000 / 8,400

11,000 / 13,700

11,000 / 13,700

Room 4

(indoor unit 4)

Room 4

(indoor unit 4)

6

7

8

The actual capacity is calculated as shown below.

Cooling: Ruc = (11,700 + 7,200 + 7,000 + 11,000) / 45,900 = 0.804 < 1
Therefore,
Actual cooling capacity of each indoor unit = Corrected cooling capacity of each indoor unit
(In other words, the correction coefficient [6] for the corrected capacity ratio is 1.)

Heating: Ruh = (14,000 + 8,400 + 8,400 + 13,700) / 47,300 = 0.941 < 1
Therefore,
Actual heating capacity of each indoor unit = Corrected heating capacity of each indoor unit
(In other words, the correction coefficient (6) for the corrected capacity ratio is 1.)

2 - 18

Design of Mini VRF SYSTEM

2. System Design

2-12. Example of Tubing Size Selection and Refrigerant Charge Amount

Additional refrigerant charging

Based on the values in Tables 2-3, 2-4, 2-5 and 2-8, use the liquid tubing size and length, and calculate the amount
of additional refrigerant charge using the formula below.

Required additional
refrigerant charge (oz)

(a): Liquid tubing Total length of ø3/8” (ø9.52) (ft.) (b): Liquid tubing Total length of ø1/4” (ø6.35) (ft.)

●

Charging procedure

Be sure to charge with R410A refrigerant in liquid form.

1. After performing a vacuum, charge with refrigerant from the liquid tubing side. At this time, all valves must be
in the “fully closed” position.

2. If it was not possible to charge the designated amount, operate the system in Cooling mode while charging
with refrigerant from the gas tubing side. (This is performed at the time of the test run. For this, all valves
must be in the “fully open” position.)
Charge with R410A refrigerant in liquid form.
With R410A refrigerant, charge while adjusting the amount being fed a little at a time in order to prevent
liquid refrigerant from backing up.

●

After charging is completed, turn all valves to the “fully open” position.

●

Replace the tubing covers as they were before.

= 0.602 × (a) + 0.279 × (b)

1

2

Tightening torque for valve stem cap: 160 – 180 lbs

Tightening torque: 300 – 360 lbs

1. R410A additional charging absolutely must be done through liquid charging.

CAUTION

2. The R410A refrigerant cylinder has a gray base color, and the top part is pink.

3. The R410A refrigerant cylinder includes a siphon tube. Check that the siphon
tube is present. (This is indicated on the label at the top of the cylinder.)

4. Due to differences in the refrigerant, pressure, and refrigerant oil involved in
installation, it is not possible in some cases to use the same tools for R22 and
for R410A.

3

4

5

Tightening torque: 590 – 710 lbs

4

·

in.

·

in.

3

1

2

Tightening torque for valve stem cap: 240 – 280 lbs

·

in.

·

in.

6

7

8

2 - 19

2. System Design

Example:

Design of Mini VRF SYSTEM

1

2

3

4

LA

Main tube of unit

1st branch

Unit distribution tube

●

Example of each tubing length

Main tubing Distribution joint tubing

LA = 131 ft. Indoor side
LB = 16 ft. 1 = 16 ft. 4 = 20 ft.
LC = 16 ft. 2 = 16 ft. 5 = 16 ft.
LD = 49 ft. 3 = 7 ft.

●

Obtain charge amount for each tubing size
Note that the charge amounts per 3.3 ft. are different for each liquid tubing size.
ø3/8" (ø9.52) → LA + LB + LC + LD : 212 ft. × 0.602 oz/ft. = 127 oz
ø1/4" (ø6.35) → 1 + 2 + 3 + 4 + 5 : 75 ft. × 0.279 oz/ft. = 20 oz

Total 147 oz
Additional refrigerant charge amount is 147 oz.

Be sure to check the limit density

CAUTION

for the room in which the indoor
unit is installed.

1

model 7 model 9 model 12 model 18

L1
L2

LCLB

23

LN

n–1

n

model 18

5

6

7

8

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