Daikin VRV Service Manual
Si30-408
Basic Training Manual
PREFACE
The latest technological innovations of air conditioners make remarkable progress. We are not able to perform our duty
without mastering the proper basic theory and knowledge in service skills and techniques.
The field of VRV system particularly
shows such a rising tendency. The techniques on trouble shooting and trouble removing corresponding to the
computerized and systematized products are required. Based on these requests, therefore, we have prepared this
manual, emphasizing the understanding on VRV system.
We wish that you would use this manual as a guidebook for the service of VRV system or as a reference book for
education of service personnel, which leads to the development of skills in whole service group of Daikin.
DEC.2004
DAIKIN INDUSTRIES, LTD.
After Sales Service Division
Si30-408
General Contents i
General Contents
General ContentsGeneral Contents
General Contents
A. Introduction................................................................................1
B. Basic Information..................................................................... 21
C. Field Settings from Remote Controller.................................... 41
D. Troubleshooting ....................................................................... 67
E. Cases for Examination ...........................................................109
F. Service Checker Type3 Application Edition ..........................127
G. Appendix ................................................................................ 191
Index ................................................................................................i
Drawings & Flow Charts ...............................................................iii
Si30-408
ii General Contents
Si30-408
Introduction 1
A. Introduction
A. IntroductionA. Introduction
A. Introduction
1. What is a VRV System?..........................................................................2
2. List of VRV Unit Models ..........................................................................3
2.1 List of Outdoor Unit Models ......................................................................3
2.2 Nomenclature ...........................................................................................5
3. System Basic Configuration..................................................................11
3.1 Cooling / Heating Selection -Standard- System .....................................11
3.2 Heat Recovery (Cooling / Heating Individual Operating) System...........14
4. Super Wiring System ............................................................................15
4.1 Points of Super Wiring System...............................................................15
4.2 Wiring Length .........................................................................................16
5. REFNET Piping.....................................................................................17
5.1 Allowable Length of Refrigerant Piping ..................................................17
5.2 For Refrigerant Piping ............................................................................19
What is a VRV System? Si30-408
2 Introduction
1. What is a VRV System?
VRV System
Thirty or more indoor units can be connected to single system.
There are "cooling / heating selection -standard- type" and "individual operating system of
cooling and heating" according to type of the system.
One of the biggest characteristics is mounting of expansion valves ⊗ to the indoor unit as
well as to the outdoor unit.
SkyAir, Residential Air Conditioner
Pair Type
Single indoor unit is connected to single outdoor unit.
(The expansion valve is mounted to the outdoor unit only.)
SKY AIR System for Simultaneous Operation (Twin, Triple, and Double-Twin)
These series are included in SkyAir. These types can be connected to two to four indoor
units to single system. However, the individual operation is not available, only the
simultaneous operation.
(The expansion valve is mounted to the outdoor unit only.)
Multi System for Individual Operation
Each indoor unit can be operated individually.
However, refrigerant piping is connected to each indoor unit using separate connecting
piping, not using halfway branch piping.
(The expansion valve is mounted to outdoor unit by each indoor unit.)
: Position of expansion valve
Si30-408 List of VRV Unit Models
Introduction 3
2. List of VRV Unit Models
2.1 List of Outdoor Unit Models
Type R22 C to H series R22 K series
Standarad Comp. Type
VRV Standard C series VRV for High outdoor temp (with unloader comp.)
Model Type
Service manual
Model Type
Service manual
—
RSC10,15C—Cooling only
—
(ES20-2)
RSNY8KTAL
Heat-pump Si-06
VRV Standard D series
Model Type
Service manual
RSCY10,15D
—
Heat-pump—Si-46A
—
VRV Standard G series
Model Type
Service manual
RSCY5,10
G
RSC5,10G
Heat-pump
Cooling only
Si-45F
Si-45F
VRV Standard F series
Model Type
Service manual
RSCY10,15F
RSC10,15F
Heat-pump
Cooling only
Si-46A
Si-46A
Small Capacity Inverter Type
VRV Inverter G series VRV Inverter K series
Model Type
Service manual
Model Type
Service manual
RSXY5-10G(J)
RSX8,10G(J)
RSEY8,10G(J)
Heat-pump
Cooling only
Heat recovery
Si-45F
Si-45F
Si-45F
RSXY5-10K
RSX5-10K
RSEY8,10K
Heat-pump
Cooling only
Heat recovery
Si-05C
Si-05C
—
VRV Inverter H series VRV Inverter KU series
Model Type
Service manual
Model Type
Service manual
RSXY5-10H(J)
RSX5-10H(J)
Heat-pump
Cooling only
Si-46C
Si-46C
RSX5-10KU Cooling only
Si-91
VRV Inverter KA series
Model Type
Service manual
RSX5-10KA Cooling only
Si-92
VRV Inverter K series (H/R with Scroll Comp.)
Model Type
Service manual
RSEY8-10KLY1
Heat recovery
Si-95
High COP
Inverter Type
Large Capacity Inverter Type
VRV Plus series
Model
Function unit
Inverter
Cnstant Speed
Type
Service manual
RXY16-30K
RX16-30K
REY16-30K
BL2 or 3K
BC2 or 3K
BR2 or 3K
RXY8 or 10K
RX8 or 10K
RXY8 or 10K
RNY8 or 10K
RN8 or 10K
RNY8 or 10K
Heat-pump
Cooling only
Heat recovery
Si-05C
Si-05C
Si-11
VRV Plus series for High outdoor temp
Model
Function unit
Inverter
Cnstant Speed
Condenser Type
Service manual
RXY16-30K-K
RX16-30K-K
BL2 or 3K
BC2 or 3K
RXY8 or 10K
RX8 or 10K
RNY8 or 10K
RN8 or 10K
RXE2 or 3K
RXE2 or 3K
Heat-pump
Cooling only
Si-94
Si-94
VRV R22 Plus series
Model Main unit Sub unit Type
Service manual
RSXY16-30KA RXY8 or 10KA RXE8 or 10KA
Heat-pump Si33-101
VRV II series
Model Module Type
Service manual
RXY5-48M
RX5-48M
RXY8-16M
RX8-16M
Heat-pump
Cooling only
Si38-304
Si38-304
List of VRV Unit Models Si30-408
4 Introduction
Type R-407C R410A
Standarad Comp. TypeSmall Capacity Inverter Type
VRV Inverter K series
Model Type
Service manual
RSXYP5-10KJY1
RSXP5-10KY1
Heat-pump
Cooling only
Si-90A
Si33-106
VRV Inverter K series (H/R with Scroll Comp.)
Model Type
Service manual
RSEYP8, 10KJY1
HeatRecovery
Si-96
High COP
Inverter Type
VRV High COP type L series
Model Type
Service manual
RSXYP5-10L
Heat-pump Si33-201
Large Capacity Inverter Type
VRV Plus series
Model Main unit Sub unit Type
Service manual
RSXYP16-30KJ
RSXP16-30K
RSEYP16-30KJ
RXYP8 or 10KJ
RXP8 to 20K
REYP8 or 20KJ
RXEP8 or 10KJ
RXEP8 to 10K
RXEP8 or 10KJ
Heat-pump
Cooling only
Heat recovery
Si33-002
Si33-103
Si33-105
VRV II series
Model Module Type
Service manual
RXYQ5-48M
REYQ5-48M
RXYQ5-16M
REYQ5-16M
Heat-pump
Heat recovery
Si39-302
Si39-404
Si39-306
Si30-408 List of VRV Unit Models
Introduction 5
2.2 Nomenclature
2.2.1 Nomenclature (Previous indication)
Indoor Unit
Power supply symbol
V1 : Single phase 220 to 240V, 50Hz
VE : Single phase 220 to 240V, 50Hz : 220V, 60Hz
VAL : Single phase 220V, 60Hz
Indicates major design category
KA : Models for ceiling mounted low silhouette duct type
Models for ceiling suspended type
KB : Models for super cassette
KJ : Models applied for EC regulation
KF : Outdoor air processing unit
Capacity Indication
Conversion to horsepower:
20 : 0.8 HP 50 : 2.0 HP 125 : 5 HP
25 : 1 HP 63 : 2.5 HP 200 : 8 HP
32 : 1.25 HP 80 : 3.2 HP 250 : 10 HP
40 : 1.6 HP 100 : 4 HP
Refrigerant type
No indication : R22
P : R407C
Type of unit
C : Ceiling mounted cassette type (Double flow)
F : Ceiling mounted cassette type (Multi flow) – Super cassette –
K : Ceiling mounted cassette corner type
D : Ceiling mounted low silhouette duct type (Low static pressure)
S : Ceiling mounted built-in type
B : Ceiling mounted built-in (Rear suction)
M : Ceiling mounted duct type or outdoor air processing unit
H : Ceiling suspended type
A : Wall mounted type
L : Floor standing type
LM : Concealed floor standing type
N : Concealed floor standing type
Indicates that this is a INVERTER SERIES indoor unit.
FX : Cooling Only
FXY : Heat Pump
C 40V1KP
FXY
(V1217)
List of VRV Unit Models Si30-408
6 Introduction
Indoor Unit
Power supply symbol
V1 : Single phase 220 to 240V, 50Hz
Indicates major design category
B: New ceiling suspended cassette
K: Wall mounted type 40-63
Capacity Indication
Conversion to horsepower:
40 : 1.6HP 50 : 2.0HP 63 : 2.5HP
71 : 3 HP 100 : 4 HP 125 : 5 HP
Refrigerant : R407C
Type of unit
FUY : New ceiling suspended cassette type
FXYA : Wall mounted type 40-63
P 71V1B
FUY
(V2863)
Si30-408 List of VRV Unit Models
Introduction 7
Connection Unit (Only Necessary for FUYP Indoor Units)
BS Unit (Only Necessary for Heat Recovery System)
Power supply symbol
VE : Single phase 220 to 240V, 50Hz : 220V, 60Hz
Indicates major design category
Capacity Indication
Conversion to horsepower:
71 : 3HP
140 : 6HP
Type of Unit
Connection Unit.
BEV K VE71
(V2864)
V1 : Single phase 220 to 240V, 50Hz
Indicates major design category
Capacity Indication (Connectable total indoor unit capacity)
100 : Total indoor unit capacity less than 100
160 : Total indoor unit capacity 100 or more but less than 160
250 : Total indoor unit capacity 160 or more but less than 250
Refrigerant type
No indication : R22
P : R407C
Q : R410A
Indicates that this is a BS unit.
BSV KJ V1P 100
(V2287)
List of VRV Unit Models Si30-408
8 Introduction
Outdoor Unit (Combination Model Name)
Outdoor Unit (Modular Model Name)
Y1K
The unit with anti-corrosion treatment
Power supply symbol
Y1 : 3 phase 380 to 415V, 50Hz TAL : 3 phase 220V, 60Hz
YAL : 3 phase 380V, 60Hz
Indicates major design category
L : Heat Pump (5, 8, 10HP) KL : Heat Recovery
KJ : Heat Pump, Heat Recovery KU : Cooling Only, 50Hz
K : Cooling Only KA : Cooling Only, 50Hz
(internal company symbol)
5 : 5HP 16 : 16 HP 24 : 24 HP 30 : 30 HP
8 : 8 HP 18 : 18 HP 26 : 26 HP
10 : 10 HP 20 : 20 HP 28 : 28 HP
Refrigerant : R407C
No indication : R22
Indicates that this is a
RSXY : Heat Pump
RSEY :Heat Recovery
RSX : Cooling Only
16 EP
RSX
(V2288)
The unit with anti-corrosion treatment
Power supply
Y1 : 3 phase 380 to 415V, 50Hz
Indicates major design category
KJ : Indicates that this is a Heat Pump or Heat Recovery type
K : Indicates that this is a Cooling Only type
8 : 8 HP 16 : 16 HP
10 : 10 HP 20 : 20 HP
Refrigerant : R407C
RXY : Indicates that this is a main unit (Heat Pump)
REY : Indicates that this is a main unit (Heat Recovery)
RX : Indicates that this is a main unit (Cooling Only)
RXE : Indicates that this is a sub unit
E
Y1
8
K
RX
P
(V2289)
Si30-408 List of VRV Unit Models
Introduction 9
2.2.2 Nomenclature (New indication)
Indoor Unit
BS Unit (Only Necessary for Heat Recovery System)
Power supply symbol
VE : Single phase 220 to 240V, 50Hz : 220V, 60Hz
V1 : Single phase 220 to 240V, 50Hz
Indicates major design category
Capacity Indication
Conversion to horsepower:
20 : 0.8 HP 50 : 2.0 HP 125 : 5 HP
25 : 1 HP 63 : 2.5 HP 200 : 8 HP
32 : 1.25 HP 80 : 3.2 HP 250 : 10 HP
40 : 1.6 HP 100 : 4 HP
Refrigerant : R410A
No indication : R22
Type of unit
C : Ceiling mounted cassette type (Double flow)
Z : Ceiling mounted cassette type (600×600 Multi flow)
F : Ceiling mounted cassette type (Multi flow)
K : Ceiling mounted cassette corner type
S : Ceiling mounted built-in type
M : Ceiling mounted duct type
H : Ceiling suspended type
A : Wall mounted type
L : Floor standing type
N : Concealed floor standing type
D : Slim ceiling mounted duct type
U : Ceiling suspended cassette type (Connection unit series)
Indicates that this is VRV system indoor unit.
C 40VEMQ
FX
(V2286)
V1 : Single phase 220 to 240V, 50Hz
Indicates major design category
Capacity Indication (Connectable total indoor unit capacity)
100 : Total indoor unit capacity less than 100
160 : Total indoor unit capacity 100 or more but less than 160
250 : Total indoor unit capacity 160 or more but less than 250
Refrigerant : R410A
No indication : R22
Indicates that this is a BS unit.
BSV M V1Q 100
(V2287)
List of VRV Unit Models Si30-408
10 Introduction
Outdoor Unit
Connection Unit (Only Necessary for FXUQ Indoor Units)
Y1
B : The unit is for European Standards
E : Unit with anti corrosion treatment
Power supply symbol
Y1 : 3 phase 380 to 415V, 50Hz YL : 3 phase 380V 60Hz
TL : 3 phase 220V, 60Hz
Indicates major design category
5 : 5HP 14 : 14 HP 22 : 22 HP 30 : 30 HP 40 : 40 HP
8 : 8 HP 16 : 16 HP 24 : 24 HP 32 : 32 HP 42 : 42 HP
10 : 10 HP 18 : 18 HP 26 : 26 HP 34 : 34 HP 44 : 44 HP
12 : 12 HP 20 : 20 HP 28 : 28 HP 36 : 36 HP 46 : 46 HP
38 : 38 HP 48 : 48 HP
Refrigerant: R410A
No indication : R22
Indicates that this is a
RX : Cooling Only
RXY : Heat Pump
REY : Heat Recovery
MB
48Q
RXY
(V2288)
Power supply symbol
VE : Single phase 220 to 240V, 50Hz : 220V, 60Hz
Indicates major design category
Capacity Indication
Conversion to horsepower:
71 : 3HP
140 : 6HP
Type of refrigerant
Q : R410A
Type of Unit
Connection Unit.
BEV M VEQ 71
(V2864)
Si30-408 System Basic Configuration
Introduction 11
3. System Basic Configuration
3.1 Cooling / Heating Selection -Standard- System
3.1.1 Type A
z R(S)XY(P) ~
Outdoor unit
Cooling Mode
Cooling Mode
R22 / R407C
Two pieces of piping for liquid and gas
Normal motorized valve
(SH) control
Normal motorized valve (SH) control
Master Slave
Slave
• Controls operation mode by using four way valve
• Changing of outdoor heat exchanger to
condenser or evaporator
• Selection for cooling / heating is possible only by master
remote controller (not displaying "selection under control")
which has been set.
• Slave remote controllers have following selection function
only.
(1) Cooling, dry and fan only at Master unit cooling
(2) Heating and fan only at Master unit heating
System Basic Configuration Si30-408
12 Introduction
3.1.2 Type B
z BL 2 ~ 3K (A) : Functional unit
RXY ~ K (A) : Inverter unit
RNY ~ K (A) : STD unit
Functional unit
STD unit
Inverter unit
Enter to functional unit
from each outdoor unit.
Among outdoor units: three pieces of piping for liquid,
gas, and oil equalizer
To indoor units : Two pieces of piping for liquid and gas
Cooling Mode
Cooling Mode
Normal motorized valve (SH) control
Normal motorized valve (SH) control
Master Slave
Slave
R22 R22
• Selection for cooling / heating is possible only by master remote
controller (not displaying "selection under control") which has
been set.
• Slave remote controllers have following selection function only.
(1) Cooling, dry and fan only at Master unit cooling
(2) Heating and fan only at Master unit heating
Si30-408 System Basic Configuration
Introduction 13
3.1.3 Type C
z RX(Y)(Q) ~ M
Outdoor unit
Outdoor unit
Cooling Mode
Outdoor unit
R410A or R22
R410A or R22
R410A or R22
Three pieces of piping for liquid, gas, and oil equalizer
Oil equalizer is installed only when outdoor VRV system is connected.
Cooling Mode
Normal motorized valve
(SH) control
Normal motorized valve (SH) control
Master
Slave
Slave
• Controls operation mode by using
four way valve
• Changing of outdoor heat
exchanger to condenser or
evaporator
• Selection for cooling / heating is possible only by master
remote controller (not displaying "selection under control")
which has been set.
• Slave remote controllers have following selection function only.
(1) Cooling, dry and fan only at Master unit cooling
(2) Heating and fan only at Master unit heating
System Basic Configuration Si30-408
14 Introduction
3.2 Heat Recovery (Cooling / Heating Individual Operating)
System
z R(S)EYP(Q) ~
Outdoor unit
Selection to cooling and heating in the BS unit.
Cooling Mode
Heating Mode
R22 / R407C
/ R410A
BS unit
BS unit
Three pieces of piping for discharge, liquid,
and gas
Normal motorized valve
(SH) control
Normal motorized valve (SC) control
Master
Slave
Master
Controls cooling and heating by selection the inside
solenoid valve
• Control operation mode by using plural four way valves
• Outdoor heat exchanger is divided and changed to condenser
/ evaporator based on the load
• Selection for cooling / heating is possible only by master
remote controller (not displaying "selection under control")
which has been set in each BS unit.
• Slave remote controllers have following selection function only.
(1) Cooling, dry and fan only at Master unit cooling
(2) Heating and fan only at Master unit heating
Si30-408 Super Wiring System
Introduction 15
4. Super Wiring System
4.1 Points of Super Wiring System
Point
Q
All control wires shall be of
no polarity and two core type.
Point
T
Point
R
O-O connection wiring
·
Connection wiring between
refrigerant piping systems
·
Maximum ten refrigerant piping
systems can be installed.
·
In order to connecting to system
including conventional system
wiring, connect centralized
transmission lines with this part.
ABC
Cooling / heating selection
remote controller
F1F2
O· O
F1F2
I· O
F1F2
I· O
F1
F2
F1F2 F1F2
Outdoor unit
(Master unit)
Outdoor unit
(Slave unit)
Power supply
Centralized control
device
Point
S
NNPP
Indoor unit
Power supply
Single phase, 220 ~ 240 V
Remote controller
F1F2
I· O
NNPP
F1F2
I· O
NP
F1
I· O
N
NP
Indoor unit
Power supply
Single phase, 200 V
Remote controller
Power supply
3-phase, 220 V
or 380 ~ 415 V
ABC
Cooling / heating selection
remote controller
O· O I· O
Outdoor unit A
(Master unit)
Outdoor unit B
(Slave unit)
F1F2
I· O
Outdoor unit C
(Slave unit)
Power supply 3-phase, 200 V
Power supply
3-phase, 200 V
F1F2F2
I· O
NNPPP
F1F2
I· O
N
System
Q
To other system
Remote controller Remote controller Remote controller
·
Wire from terminal unit of
O-O connection wiring to
avoid three wires clamping
on terminal block. (Use
relay terminal for halfway
branch)
I-O connection wiring
· Wire by refrigerant piping
system
· This time, in super wiring
system, centralized
transmission line is
integrated to I-O
connection wiring.
Wiring between indoor
units beyond the system is
not available. (Otherwise,
operation with temperature
control will not be
available.)
Remote controller Remote controller
Remote controller
System
R
Super Wiring System Si30-408
16 Introduction
4.2 Wiring Length
In super wiring system, limit the wire length within the following number except the wiring of
remote controller, due to standardization of wiring for connection between outdoor and
indoor unit and centralized transmission lines.
The farthest length: 1000m or less,
the total wiring length: 2000m or less
(When using sheathed wire, the total wiring length can be 1500m or less)
Example of System
Note: Be sure to check the farthest length and the total wiring length in designing.
If the sum of lengths exceeds the restricted limits, divide the system, or install more DIII-NET
expander adapters as countermeasures.
In the above system, the farthest connecting distance is 900m between (A) and (C), conforming the condition of the
farthest length of 1000m or less, and the total wiring length is 1100m, the sum of 900m between (A) and (C) plus
200m between (B) and (D), also conforming the condition of 2000m or less.
Thus, as long as both the farthest length and the total wiring length stay within the limits, the system operates
without any trouble.
Si30-408 REFNET Piping
Introduction 17
5. REFNET Piping
5.1 Allowable Length of Refrigerant Piping
5.1.1 For RSXY(P) ~ KA(L)
Allowable Length of Refrigerant Piping (Actual length)
Allowable Level Difference
Notes: 1. Be sure to use REFNET piping materials for piping branch part.
2. Do not make branch part after branching with REFNET header.
Outdoor unit (master) to
Outdoor unit (slave) [a]
#1 branch kit to Indoor unit [c] Outdoor unit to Indoor unit (b + c)
Allowable length (m) 5m or less 40m or less 120m or less
Between outdoor unit and indoor unit [H
1]
Between indoor
units [H
2]
Between outdoor units
(master and slave units) [H3]
Allowable level
difference (m)
50m or less
If outdoor unit is located lower than indoor unit: 40m or less
15m or less 5m or less
H1
H
3
H2
c
b
a
Outdoor unit (Master unit)
Outdoor unit (Slave unit)
Indoor units
Indoor units
Indoor units
#1 refrigerant branch kit
REFNET header
REFNET Piping Si30-408
18 Introduction
5.1.2 For RX(Y)(Q) ~ M
Allowable Length of Refrigerant Piping (Actual Length)
Allowable Level Difference
Notes: 1. Be sure to use REFNET piping materials for piping branch part.
2. Do not make branch part after branching with REFNET header.
H1
H3
H2
c
a
Outdoor unit 1
Outdoor unit 2
Indoor units
Indoor units
Indoor units
#1 refrigerant branch kit
Outdoor branch kit
b
REFNET header
Outdoor branch to Outdoor
unit [a]
#1 branch kit to idoor unit [c] Outdoor branch to Indoor unit [b + c]
Allowable length (m) 10m or less 40m or less 150m or less
Between outdoor unit and indoor unit [H
1]
Between indoor
units [H
2]
Between outdoor units [H
3]
Allowable level
difference (m)
50m or less
If outdoor unit is located lower than indoor unit: 40m or less
15m or less 5m or less
Si30-408 REFNET Piping
Introduction 19
5.2 For Refrigerant Piping
Guideline for Tightening Flare Nut (When No Torque Wrench is Available.)
Notes: 1. When pipe jointing with flare nut, use both open-ended spanner and a torque wrench.
2. If no torque wrench is available, refer to the following item 3 as a guide.
3. In the work of tightening flare nut, there should be a spot where the tightening torque
suddenly increases. Thereafter, tighten further with tightening angle shown in above list.
Bending Radius in Pipe and Flare Tightening Torque
Processing Dimension for Flare Section
Calculation List on Equivalent Length of Joint (For Reference)
Unit: m
Piping size Tightening angle (guideline) Recommended arm length of tool
φ6.4 60º ~ 90º Approximately 150mm
φ9.5 60º ~ 90º Approximately 200mm
φ12.7 30º ~ 60º Approximately 250mm
φ15.9 30º ~ 60º Approximately 300mm
φ19.1 20º ~ 35º Approximately 450mm
Piping size Bending radius Tightening torque (N·cm)
φ6.4 30 to 40 mm 1420 ~ 1720
φ9.5 30 to 40 mm 3270 ~ 3990
φ12.7 40 to 60 mm 4950 ~ 6030
φ15.9 40 to 60 mm 6180 ~ 7540
φ19.1 — 9720 ~ 11860
Piping size
Dimension-A
Flared shape
R22, R407C For R410A
φ6.4 8.6 ~ 9.0 8.7 ~ 9.1
φ9.5 12.6 ~ 13.0 12.8 ~ 13.2
φ12.7 15.8 ~ 16.2 16.2 ~ 16.6
φ15.9 19.0 ~ 19.4 19.3 ~ 19.7
φ19.1 23.3 ~ 23.7 (24)
Pipe diameter
Type
φ6.4 φ9.5 φ12.7 φ15.9 φ19.1 φ25.4 φ31.8
L joint
0.16 0.18 0.20 0.25 0.35 0.45 0.55
Trap bend
1.41.31.52.02.43.44.0
REFNET joint
0.5
REFNET header
1.0
REFNET Piping Si30-408
20 Introduction
Si30-408
Basic Information 21
B. Basic Information
B. Basic InformationB. Basic Information
B. Basic Information
1. Explanations on P-H Diagram (Refrigerant Characteristics Table).......22
2. Concept of Basic Refrigeration Cycle ...................................................23
3. Points of Refrigerant Control of VRV System .......................................24
3.1 Cooling Operation ..................................................................................24
3.2 Heating Operation ..................................................................................25
3.3 Compressor Capacity Control ................................................................26
3.4 Control of Electronic Expansion Valve ...................................................27
4. Control of Indoor Unit............................................................................28
4.1 Thermostat-control .................................................................................28
4.2 Drain Pump Control ................................................................................30
4.3 Freeze-up Prevention Control ................................................................31
4.4 Heater Control ........................................................................................32
4.5 Thermostat Control in Cooling / Heating Automatic Operation ..............33
5. Other Functional Operations.................................................................35
5.1 Explanations on Main Functional Control...............................................35
5.2 Explanations on Electric and Functional Components ...........................36
Explanations on P-H Diagram (Refrigerant Characteristics Table) Si30-408
22 Basic Information
1. Explanations on P-H Diagram (Refrigerant
Characteristics Table)
P-H diagram shows characteristics of various refrigerants with pressure on vertical axis and
enthalpy on horizontal axis.
Change of state change from gas to liquid is said condensation and that from liquid to gas
said evaporation. The boundary state of each change is said saturation, and the temperature
generating saturation is said saturation temperature.
Saturation temperature depends on kinds of refrigerant and pressure. The characteristics of
saturation temperature are shown on P-H diagrams of various refrigerants, which is called
saturation curve.
The characteristics of temperature gradients for pressure and enthalpy are shown on P-H
diagrams, which is called "isothermal lines". By knowing the zone divided with saturation
curve in which the intersection point of pressure and isothermal line is included, the
information on the state of refrigerant can be provided. The intersection above can be
obtained by measuring pressure and temperature of refrigerant at a certain point.
As to single refrigerants (R22, R134A etc.), isothermal line has no gradient in the saturated
area ,that is, the saturation temperature under certain pressure is same at both liquid side
and gas side. As to mixed refrigerants (R407C, R410A etc.), in which plural refrigerants with
different boiling points are mixed, their isothermal lines have gradients in the saturated area,
so the saturation temperatures under certain pressure are different at liquid side and gas
side. They are called zeotropic refrigerants, with the exception that R410A is called false
azeotropic refrigerant.
States of refrigerants are classified following 3 categories.
Superheated vapor: state that refrigerant is existing as gas
Saturated vapor: state that is mixture of liquid and gas (this is also called wet vapor)
Subcooled liquid: state that refrigerant is existing as liquid
Subcooled area
(Subcooled liquid)
Saturated area
(Saturated vapor)
Superheated area
(Superheated vapor)
Isothermal line
Saturation curve
Enthalpy h (KJ .kg
-1
)
Pressure P(MPa)
Zeotropic refrigerant R407C has different saturation points at
liquid side and gas side. (gas side is higher than liquid side)
Si30-408 Concept of Basic Refrigeration Cycle
Basic Information 23
2. Concept of Basic Refrigeration Cycle
The refrigeration cycle is composed of repetition of the following process.
"Compression
→ Condensation → Expansion → Evaporation"
The refrigerating machine conducts above cycle with compressor, condenser, expansion valve
and evaporator.
Theoretic refrigeration cycle neglecting pressure loss, etc. drawn on P-H diagram is shown as
above.
The difference between "temperature" and "pressure equivalent saturation temperature" is
called superheated degree.
The difference between discharging pipe temperature and condensation temperature is
called discharging superheated degree(DSH).
The difference between suction pipe temperature and evaporating temperature is called
suction superheated degree (SH).
(Generally, superheated degree means suction superheated degree)
The difference between "temperature" and "pressure equivalent saturation temperature" in
subcooled liquid is called subcooled degree (SC).
In order to prevent wet operation (*), the superheated degree is made at evaporator outlet and
refrigerant flow rate into evaporator is regulated with expansion valve, so that the superheated
vapor can be sucked by compressor.
* Wet operation is a state of operation, where wet vapor due to the vapor not completely
vaporized in the evaporator, wet vapor is sucked by compressor.
(Wet operation may cause damage of compressor due to liquid compression, dilution of
refrigeration oil, etc..)
Condenser
Hot air
Cold air
P
Pc
Pe
Tcl
Tcg
h
Tel
Teg
High pressure liquid
Low pressure liquid
Subcooled degree
(SC)
Discharge superheated degree
(DSH)
Discharge pipe temperature
Suction superheated degree (SH)
Suction pipe temperature
Cooling effect (Evaporating capacity)
GasLiquid
Heating effect (Condensing capacity)
High
Low
High pressure
Low pressure
Temperature
Low pressure gas
Compressor
High pressure gas
Evaporator
Expansion valve
Points of Refrigerant Control of VRV System Si30-408
24 Basic Information
3. Points of Refrigerant Control of VRV System
3.1 Cooling Operation
Subject to change of the number of operation (thermostat-on) units, capacity, air flow rate,
suction temperature, humidity change of indoor units
Load on total system changes.
Loads on every indoor machine are different.
Compressor
Capacity Control
In order to maintain the cooling capacity corresponding to the capacity of evaporator and load
fluctuation, based on the pressure detected by low pressure sensor of outdoor unit (Pe), the
compressor capacity is so controlled to put the low pressure equivalent saturation temperatures
(evaporation temperature = Te) close to target value.
Superheated
Degree Control of
Indoor Electronic
Expansion Valve
In order to maintain the superheated degree in evaporator and to distribute proper refrigerant
flow rate in spite of different loads on every indoor unit, based on the temperature detected by
thermistors of liquid pipes and gas pipes, indoor electronic expansion valve is so regulated as to
put superheated degree at evaporator outlet close to target value.
• Superheated degree SH = (indoor gas pipe temperature – indoor liquid pipe temperature)
Superheated degree control
Outdoor electronic expansion valve is fully opened.
Cooling
Compressor
Receiver
Low pressure sensor
Gas pipe themistor
Liquid pipe themistor
Operation
Operation Stop
As to stopping unit and thermostat-off unit, motorized
valve should be closed completely not to send
refrigerant into indoor heat exchanger.
Si30-408 Points of Refrigerant Control of VRV System
Basic Information 25
3.2 Heating Operation
Subject to change of the number of operation (thermostat-on) units, capacity, air flow rate,
suction temperature, of indoor units
Load on total system changes.
Loads on every indoor unit are different.
Compressor
Capacity Control
In order to maintain the heating capacity against condenser capacity and load fluctuation, based
on the pressure detected by high-pressure sensor control (Pc), compressor capacity is so
controlled to put the high pressure equivalent saturation temperature (condensing temperature
= Tc) close to target value.
Superheated
Degree Control of
Outdoor
Electronic
Expansion Valve
In order to maintain the superheated degree in evaporator, based on the pressure detected by
the low pressure sensor (Te) and the temperature detected by the thermistor of suction pipe,
outdoor electronic expansion valve is so controlled as to put superheated degree at evaporator
outlet close to target value.
• Superheated degree SH = (outdoor suction pipe temperature – outdoor evaporating
temperature)
Subcooled
Degree Control of
Indoor Electronic
Expansion Valve
In order to distribute proper refrigerant flow rate in spite of different loads on every indoor unit,
based on the pressure detected by the high pressure sensor of outdoor unit (Tc) and the
temperature detected by the thermistor of indoor liquid pipes, indoor electronic expansion valve
is so controlled as to put subcooled degree at condenser outlet close to target value.
• Subcooled degree SC = (outdoor condensing temperature – indoor liquid pipe
temperature)
Subcooled degree control
Superheated degree control
Suction pipe thermistor
Heating
Compressor
Low pressure sensor
Receiver
High pressure sensor
Gas pipe thermistor
Liquid pipe thermistor
As to stopping unit and thermostat-off unit, electronic
expansion valve should be minute-closed (approx.
200 pls) in order to prevent refrigerant from collection
in indoor heat exchanger.
Operation
Operation Stop
Points of Refrigerant Control of VRV System Si30-408
26 Basic Information
3.3 Compressor Capacity Control
In the compressor capacity controller of VRV system, the pressure detected (Pe or Pc) by
pressure sensor installed in outdoor unit is converted into equivalent saturation temperature,
and the evaporation temperature (Te) while cooling or the condensation temperature (Tc) while
heating are so controlled with PI control as to put them close to the target value in order to
maintain stable capacity in spite of incessantly varying load. (Refer target value below table.)
*Above all target temperatures mean saturation temperatures on gas sides.
The pressure loss in piping increases depending on connecting piping length and operation
capacity of compressor. In order to compensate capacity lowering caused by the pressure loss
in piping, the following correction are made.
Correction of Target Evaporation Temperature by ∆P.
Target value adjustment can be made through field setting.
Long connection piping at the installation site may increase pressure loss in piping and an
inverse installation (outdoor unit is placed lower than indoor unit) may increase liquid pipe
inside resistance. In such case, "lower" setting of target evaporation temperature by using
field setting will give stable operation.
On the other hand for short connection piping, higher setting will make stable operation
easy.
In addition, samplings of evaporation temperature and condensation temperature are so made
that pressure detected by every pressure sensors of high/low pressure are read every 20
seconds and calculated. And every time the compressor capacity (INV frequency or STD ON/
OFF) is controlled to eliminate deviation from target value.
P(MPa)
Target condensing temperature
Target evaporating temperature
Discharge pressure Pc :
Detected by high-pressure sensor
Suction pressure Pe :
detected by low-pressure sensor
h (KJ .kg
-1
)
∆P = pressure loss
(caused by compressor operation capacity and
piping length)
Target condensation temperature /
High pressure
Target evaporation temperature /
Low pressure
R22 46°C 1.8MPa 5.5°C 0.59MPa
R407C 48°C 1.9MPa 7.5°C 0.58MPa
R410A 46°C 2.8MPa 6.0°C 0.96MPa
Target evaporation temperature
Target evaporation
temperature setting
Compressor operation capacity
: "Higher" setting
: "Normal" setting
(factory setting)
: "Lower" setting
Max
Min
+
3Cº
–3Cº
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