Mitsubishi Heavy Industries AHU-KIT-SP User manual

Manual No.'21・AHU-T-393
TECHNICAL MANUAL
AIR HANDLING UNIT INTERFACE
AHU-KIT-SP

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'21 • AHU-T-393
CONTENTS
1. AHU-KIT-SP - Overall composition....................................................................4
1.1 Product description.......................................................................................4
(1) What is Air Handling Unit?..........................................................................4
(2) What is AHU-KIT-SP? ................................................................................5
(3) Systems based on AHU Interface...............................................................6
(a) Single refrigerant line system................................................................6
(b) Multiple refrigerant line system .............................................................7
(c) AHU Interface input/output/in-output circuit .........................................8
(4) AHU Interface check sheet.........................................................................8
(5) Range of use..............................................................................................8
1.2 How to use .....................................................................................................9
1.2.1 AIR HANDLING UNIT INTERFACE check sheet .........................................9
(1) Confirmation of design conditions (Air capacity,
suction air temperature/humidity, target temperature/humidity).................10
(a) Design air condition............................................................................10
(b) Air capacity condition.........................................................................10
(c) Total heat exchanger ..........................................................................10
(d) Humidifier, Heater...............................................................................10
(e) Design requirement capacity condition...............................................10
(f) Piping length ......................................................................................10
(g) Height difference between in-/outdoor units .......................................10
(2) Confirmation of heat exchanger specifications..........................................11
(a) Heat exchanger calculating conditions ...............................................11
(b) Connecting pipe size..........................................................................11
(c) Recommended number of heat exchanger circuits.............................11
(d) Recommended number of heat exchanger columns ..........................11
(e) Design pressure of heat exchanger ....................................................11
(f) Allowable volume and minimum air capacity standard
for heat exchanger .............................................................................11
(3) Outdoor unit selection..............................................................................12
(a) Confirmation of the range of use ........................................................12
(b) Correction coefficient A ......................................................................12
(c) Correction coefficient B ......................................................................12

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(d) Correction coefficient C......................................................................12
(e) Correction coefficient D......................................................................12
(f) Calculation of total correction coefficient ............................................12
(g) Calculation of rated capacity of outdoor unit ......................................13
(h) Confirmation of volume of internal heat exchanger .............................13
(4) Select control method and settings..........................................................14
(a) Capacity Control SW7-4: OFF............................................................14
(b) Temperature Control SW7-4: ON .......................................................15
1.2.2 Sensor installation guidelines ...................................................................17
2. Single cooling line system................................................................................23
2.1 Single cooling line system - Outline ..........................................................23
2.2 Specifications ..............................................................................................23
(1) AHU Interface Master input switch ...........................................................23
(2) External in-/output terminals ....................................................................26
(3) Analog input circuit: X3 connector............................................................27
(4) Digital input circuit: X2 connector .............................................................27
(5) Digital output circuit .................................................................................28
(6) In-/output circuits.....................................................................................29
2.3 Basic control................................................................................................30
(1) Operation stop command to AHU system................................................30
(2) Operation mode selection ........................................................................31
(3) Outdoor unit (Compressor) control means selection .................................31
(3-1) Capacity Control...............................................................................31
(3-2) Temperature Control .........................................................................32
3. Multiple refrigerant line system: Cascade control .........................................33
3.1 Cascade control – Outline ..........................................................................33
3.2 Difference of specifications/setting with cascade control
single refrigerant system ............................................................................34
(1) Input switch .............................................................................................34
(a) Address setting: SW1..........................................................................34
(b) Sensor connection ..............................................................................34
(2) Master/slave in-/output functions in cascade control................................34

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3.3 Basic control................................................................................................35
(1) Capacity distribution control by multiple unit connection ..........................35
(2) Rotation control .......................................................................................39
(3) Fault backup control ................................................................................40
4. Modbus communication ...................................................................................41
4.1 Communication specifications ..................................................................41
4.2 Function........................................................................................................41
4.3 Data information..........................................................................................41
4.4 Communication – Outline ...........................................................................42
4.5 Input register................................................................................................43
4.6 Retention register........................................................................................50
5. Protection control..............................................................................................51
5-1 Cooling frost protection .............................................................................51
5-2 Heating overload protection ......................................................................51
5.3 Compressor inching protection control ....................................................52
5.4 Fan control during defrost control.............................................................52
5.5 Forced compressor OFF control by suction temperature .......................52
6. Error display.......................................................................................................53
6.1 Abnormal temperature sensor (return air/heat exchanger)
broken wire/short-circuit detection...........................................................53
6.2 Trouble/error detection ...............................................................................53
6.3 Trouble/error display ...................................................................................54
6.4 Error mode reset (Error reset) ....................................................................54

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1. AHU-KIT-SP Overall composition
1.1 Product description
(1) What is Air Handling Unit?
This system controls air-conditioning by means of a direct expansion air-heat exchanger, which uses the same
refrigerant as for air-conditioning as the heat transferring media.
<MHI AHU system (example)>
Example of cooling
AHU
I/F
(Option)
Remote
c
ontrol
Ventilation
Fan(IN)
Cooling air
Noise reduction
Outside
Fan(OUT)
AHU-KIT-SP
(AHU Interface)
AHU
control
Total heat exchange
Heat exchanger
Outdoor unit

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(2) What is AHU-KIT-SP?
AHU-KIT-SP is the control kit (hereafter AHU Interface), which provides a refrigerant control for Air Handling Unit
(hereafter AHU) equipped with a direct expansion heat exchanger to be connected to an outdoor unit for use at a
shop.
AHU Interface has an analog input circuit for 0 – 10V, 4 – 20mA as the basic capacity control means for
connected outdoor unit. Air conditioning control by remote control may be used as other control method.
AHU Interface can communicate also on Modbus protocol and control the capacity (0 – 100%) and setting
temperature, if necessary. For details, refer to related sections.
Item Air Handling Unit Interface (AHU Interface)
Type AHU-KIT-SP
Connectable outdoor unit See list below. (*1)
Environment for use Temperature: -20 to 60°C, RH: 85% or less (Dewing not allowed)
Environment for storage Temperature: -20 to 70°C, RH: 40 to 90% (Dewing not allowed)
Power source Single phase 220 to 240V +10%/-15%, 50Hz, single phase 220V +10%/-15%, 60Hz
Power consumption 5W
Dimensions (HxWxD) 109.5mm x 290mm x 57mm
Weight 0.55kg
Installed on DIN rail TS 35 mm x 7.5 mm (DIN rail to be provided)
Cascade connection Max. 16 outdoor units can be combined by cascade control.
(16 interface units are required.)
Power failure
compensation
This interface has no battery circuit for recovery after power failure.
Condition to continue operation: Power-out duration – Less than 30 msec.
Accessory
Heat exchanger temperature sensor (Thi-R1, Thi-R2, Thi-R3) x 1
Suction temperature sensor (Thi-A) x 1
Spare sensor x 1
Heat exchanger spring leaf x 3
Ferrite core x 1 (for function earth connection)
Installation manual
Caution label
(*1) Connectable outdoor units
Model capacity Outdoor unit
R410A R32
40/50/60 SRC40/50/60ZSX-S, -SA SRC40/50/60ZSX-W1, -W2, -WA
71 FDC71VNX FDC71VNX-W
100/125/140 FDC100/125/140VN(S)A FDC100/125/140VN(S)A-W
FDC100/125/140VN(S)X FDC100/125/140VN(S)X-W
200/250 FDC200/250VSA FDC200/250VSA-W
280 FDC280VSA-W
AHU Interface outline

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(3) Systems based on AHU Interface
(a) Single refrigerant line system
・
Single refrigerant line system is a system composed of single refrigerant line, which is controlled with one unit
of AHU Interface (Master).
* Leakage breaker of the leakage category III must be used.
* ： Leakage breaker
Fan
ＡＨＵ
AHU
control
AHU Interface
(Master)
Remote
control
Modbus
Heat exchanger
Heat exchanger temperature sensors
Refrigerant pipe
Return air
temperature
sensor
Outdoor
unit
Analog input
Digital input
Digital output
E
E

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(b) Multiple refrigerant line system (Cascade control)
・Multiple refrigerant line system is a system which installs multiple refrigerant lines on AHU.
・Since multiple outdoor units can be connected in a system, it is adaptable to a large capacity.
・To this control, a combination of Master and Slave, a combination of maximum 16 units of AHU Interface and
outdoor units, including Master, can be connected.
・Number of units can be controlled from AHU Interface (Master) according to the air-conditioning load.
*3 ：
Leakage breaker
Fan
ＡＨＵ
AHU
control
AHU Interface
(Master)
Remote
control
Modbus
Master
AHU
Interface
Slave➀
Slave➀
Slave⑮
Heat exchanger
…
Heat exchanger temperature sensors
Return air
temperature
sensor
Outdoor
unit
Outdoor
unit
Outdoor
unit
Analog input
Digital input
Digital output
E E E
E
AHU
Interface
Slave⑮
Heat exchanger temperature sensors
Heat
exchanger
temperature
sensors
*1
*2
*1 Remote control cannot be connected to Slave.
*2 Modbus cannot be connected to Slave.
*3 Leakage breaker of the leakage category Ⅲmust be connected.

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(c) AHU Interface input/output/in-output circuit
In-/output function of each connector is as follows.
Remote control
communication
Analog input
Thi-A
Return air
temperature sensor
Cascade
Digital input
Common Digital output
Outdoor unit
AC220–240V 50Hz
AC220V 60Hz
Thi-R1
Thi-R3
Thi-R2
Heat exchange
temperature sensor
Functional
ground wire
Modbus
(RS-485)
GND
B A
X2* X4*
Cascade
spare
Enclosure
plate
2N
13
1N
+
-
* : X2 and X4 are of reinforced insulation specification, which
inputs or outputs the power source level at primary side.
Handle with care because there is risk of electric shock.
(4) AHU Interface check sheet
・Although the heat exchanger is designed according to users’ requirements, it needs to be used within the range
of use for MHI outdoor unit at the same time.
・In order to check if the heat exchanger designed according the users’ requirements falls within the range of use
for air-conditioner, including air condition, utilize the check sheet referred to in 1.2.
・To design a heat exchanger, it is necessary to use the technical data for the outdoor unit to be connected.
Design and select the heat exchanger according to the check sheet in 1.2 and the technical data of outdoor
unit.
・AHU Interface is one of components for the air handling system, and the product assurance responsibility for
entire air handling system is not covered by the assurance by MHI.
(5) Range of use
Confirm that the air condition, limitation of pipe length, or other, fall within the range of use for the air-conditioner.
For practical range of use, refer to the technical data for the outdoor unit to be connected.

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1.2 How to use
1.2.1 AIR HANDLING UNIT INTERFACE check sheet
Flow to select the outdoor unit and design the heat exchanger is as shown below.
◇ Refer to the following figure for the definition of design air condition and air capacity.
EX Exhaust air
OA Outdoor air
DA Discharge air
CA Circulating air
SA Supply air
List of abbreviations
OA
DA
CA
EX
SA
Air handling
system*
Total heat exchanger
Heat exchanger
unit
(1) Confirmation of design conditions
(2) Confirmation of heat exchanger specifications
(3) Outdoor unit selection
(4) Confirmation of control means and contents of setting
* Due to the system’s complexity, the illustration schematic and simplified.

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(1) Confirmation of design conditions (Air capacity, suction air temperature/humidity, target temperature/
humidity)
(a) Design air condition
Exhaust air (EX) Cooling °CDB °CWB
Heating °CDB °CWB
Outdoor air (OA) Cooling °CDB °CWB
Heating °CDB °CWB
(b) Air capacity condition
Supply air(SA) m3/h
Circulating air(CA) m3/h
Outdoor air(OA) m3/h
(c) Total heat exchanger
Total
heat exchanger
with( ) without( )
If with, fill in following items
Exchange efficiency
Outdoor air volume m3/h
Discharge air volume m3/h
(d) Humidifier, Heater
Humidifier Humidifying volume kg/h
Heater Heater capacity kW
(e) Design requirement capacity condition
Requirement
capacity
Cooling kW
Heating kW
Heat exchanger inlet
air condition
Cooling °CDB °CWB
Heating °CDB °CWB
(f) Piping length
Piping length ｍ
(g) Height difference between in-/outdoor units [*1]
Hight difference ｍ
Fan
Fan -5m
+5m
0m
[*1 ]Example of hight difference

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(2) Confirmation of heat exchanger specifications
Design the heat exchangers according to following conditions.
(a) Heat exchanger calculating conditions
Cooling evaporator outlet
superheat degree 3deg.C Target evaporation
temperature 5－12deg.C
Heating condenser outlet
subcool degree 1deg.C
Target
condensation
temperature
30 －47deg.C
Calculate the heat exchanger capacity based on the design conditions of (1) and the above temperature
condition.
(b) Connecting pipe size
Refer to the technical data of connected outdoor unit.
(c) Recommended number of heat exchanger circuits
When the pipe size of heat exchanger is φ9.52, following number of circuits is recommended.
Recommended circuit number for φ9.52 tube
Outdoor unit model capacity 40 50 60 71 100 125 140 200 250 280
Recommended circuit 2 －4 4 －6 6 －10
(d) Recommended number of heat exchanger columns
Maximum 3 columns is the standard design for heat exchanger.
If it has 4 or more columns, the heat exchanger efficiency will not be good.
Larger number of columns for heat exchanger increases its volume so that it becomes impossible to
accommodate in the standard.
(e) Design pressure of heat exchanger
Limit the design pressure at ≧4.15 MPa. This is common to R32 and R410A refrigerants.
(f) Allowable volume and minimum air capacity standard for heat exchanger
Limit the volume of heat exchanger within the range listed below for the volume of each outdoor unit.
Air capacity for heat exchanger must be larger than the minimum air capacity in the following list.
Outdoor unit
model capacity
Allowable heat exchanger volume
[L] Minimum air volume
Min Max [m3/h] [m3/min]
SRC40 0.3 0.8 420 7
SRC50 0.3 0.9 420 7
SRC60 0.5 1.1 480 8
FDC71 0.7 1.6 600 10
FDC100 0.7 2.1 840 14
FDC125 1.0 2.2 960 16
FDC140 1.0 2.8 1080 18
FDC200 1.2 4.2 1680 28
FDC250 2.0 4.4 1920 32
FDC280 2.0 4.4 2160 36

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(3) Outdoor unit selection
Select correct outdoor unit by applying the correction value adequate for the condition of use.
Select the outdoor unit according to the following flow.
(a) Confirmation of the range of use
Confirm that the air condition, limit of pipe length, or other, fall within the range of use for air-conditioner.
(b) Correction coefficient A
Capacity correction according to air condition
Calculate the capacity correction coefficient according to the operation mode.
(c) Correction coefficient B
Correction for pipe length
Calculate the capacity correction coefficient.
(d) Correction coefficient C
Correction for height difference between in-/outdoor units
Calculate the capacity correction coefficient.
Make this correction only when the outdoor unit is positioned at the bottom during cooling and at the top
during heating.
(e) Correction coefficient D
Calculate the correction coefficient for frosting on outdoor heat exchanger during heating (heating only)
Some models may have no correction coefficient D.
For the confirmation of the range of use and calculation of correction coefficients A to D, refer to the technical
data of outdoor unit.
( f ) Calculation of total correction coefficient
Calculate total correction coefficient by multiplying coefficient A to D.
Correction
coefficient Cooling Heating
A
B
C
D
Total
α β
Operation mode Total correction coefficient
Cooling Correction coefficient α= A x B x C
Heating Correction coefficient β= A x B x C x D

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(g) Calculation of rated capacity of outdoor unit
Confirm that the result of multiplying the rated capacity of selected outdoor unit by the total correction
coefficient is larger than the required capacity.
Calculate for the heating and the cooling respectively.
When the capacity is insufficient, reselect the outdoor unit.
Outdoor unit model Cooling(rated) Heating(rated) Number of units
kW kW pcs.
Operation mode
①Rated capacity
of selected
outdoor unit
②
①x Number of outdoor units x
Total correction coefficient
③Required
capacity
(Necessary
capacity)
Judgment
②≧③ :OK
Cooling kW pcs. kW kW
Heating kW pcs. kW kW
(h) Confirmation of volume of internal heat exchanger
Check ( f ) Allowable volume for heat exchanger of (2) Heat exchanger calculating conditions to see if
the internal volume of AHU heat exchange is adequate for the selected outdoor unit.
Outdoor unit model Number of units AHU heat exchanger volume
to be used(per outdoor unit)
pcs.
If it does not satisfy the conditions, set conditions once more.
(Resetting of indoor heat exchanger volume, resetting of outdoor unit volume, etc.)

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(4) Select control method and settings
The outdoor units can be controlled by one of two methods (Capacity Control or Temperature Control).
Select the suitable control combination (No.1 －No.4) based on the equipment to be installed.
Correct Master/Slave settings are required when using cascading control.
Check each setting by referring to table 1-1, 1-2 in this section.
(a) Capacity Control SW7-4：OFF (External input:0—10V / 4—20mA / 0—100%)
System diagram
AHU
control
AHU Interface
Master
AHU Interface
Slave1
AHU Interface
Slave15
Analog Input
0－10V or 4－20mA
Compressor
speed
Compressor
speed
Compressor
speed
Modbus
control
Modbus
0－100%
Digital
Input/Output
Master Slave15
Slave1
The following control combinations are to be used for Capacity Control.
Table 1-1
No. Analog input
(0 －10V/4 －20mA)
Modbus
(0 －100%)
Remote control
(Include SL adaptor)
AHU system
How to Run/Stop
1★ △ (*1) Monitoring only(*2) Digital input
or Modbus(*3)
2 × ★Monitoring only(*2) Digital input
or Modbus(*3)
★：Main control for Capacity Control
△：Option control
×
：Not available
(*1) Analog input will be invalidated once 0 －100% command is sent from the Modbus control.
Power reset is required to restore analog input function.
(*2) Monitoring purpose only. Operation from remote control is not possible.
(*3) Select either of the following ways to Run/Stop the AHU system:
- Digital input (ON/OFF)
- Modbus command (Run/Stop)

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(b) Temperature Control SW7-4：ON (Set temperature control:18°C—30°C)
System diagram
AHU
control
AHU Interface
Master
AHU Interface
Slave1
AHU Interface
Slave15
Set temperature
Modbus
control
Digital
Input/Output Analog input not available
Master Slave15
Slave1
Compressor
speed
Compressor
speed
Comp
ressor
speed
The following control system can be used for Temperature Control.
Table 1-2
No. Analog input
(0 －10V/4 －20mA) Modbus Remote control
(Include SL adaptor)
AHU system
How to Run/Stop
3 × ★(*4) ○(*4) Digital input,
RC or Modbus(*5)
4 × ○(*4) ★(*4) Digital input,
RC or Modbus(*5)
★：Main control
△：Option control
×
：Not available
(*4) Last received operation command has priority.
(*5) Select one of the following ways to Run/Stop the AHU system:
- Digital input (ON/OFF)
- Modbus command (Run/Stop)
- Remote control command (Run/Stop)

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<Confirmation of peripheral equipment and setting contents>
①Selected control system
No.
②Confirmation of peripheral equipment to be connected to AHU Interface
Item Model
AHU control
Remote control
Modbus
Option
③Input/Output setting on AHU Interface
Check functions to use.
Connector Input setting Check Connector Output setting Check
X2-1 Run/Stop X4a Outdoor unit error interface error
X2-2 Cooling/Heating X4b Compressor ON
X2-3 Emergency stop X4c Defrost ON
X2-4 Reserve - X4d Run/Stop -
④AHU Interface Master setting
Item Setting
SW1(Interface address)
SW2(Reserve) -
SW3(Reserve) -
SW4(Reserve) -
SW5(Modbus address：ones)
SW6(Modbus address：tens)
SW7-1(Analog input switching)
SW7-2(Modbus bps)
SW7-3(Modbus parity setting)
SW7-4(Compressor control)
SW8-1(Digital output:X4d)
SW8-2(Reserve) -
SW8-3(Reserve) -
SW8-4(Reserve) -
JX1(Termination of Modbus)
JX2(Analog input switching)
⑤AHU Interface slave setting
Only SW1 and JX1 setting is required for the Slave Interface.
AHU Interface No. SW1(Interface address) JX1(Termination of Modbus)
Slave1
Slave2
Slave3
Slave4
Slave5
Slave6
Slave7
Slave8
Slave9
Slave10
Slave11
Slave12
Slave13
Slave14
Slave15

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<Confirmation of peripheral equipment and setting contents>
①Selected control system
No.
②Confirmation of peripheral equipment to be connected to AHU Interface
Item Model
AHU control
Remote control
Modbus
Option
③Input/Output setting on AHU Interface
Check functions to use.
Connector Input setting Check Connector Output setting Check
X2-1 Run/Stop X4a Outdoor unit error interface error
X2-2 Cooling/Heating X4b Compressor ON
X2-3 Emergency stop X4c Defrost ON
X2-4 Reserve - X4d Run/Stop -
④AHU Interface Master setting
Item Setting
SW1(Interface address)
SW2(Reserve) -
SW3(Reserve) -
SW4(Reserve) -
SW5(Modbus address：ones)
SW6(Modbus address：tens)
SW7-1(Analog input switching)
SW7-2(Modbus bps)
SW7-3(Modbus parity setting)
SW7-4(Compressor control)
SW8-1(Digital output:X4d)
SW8-2(Reserve) -
SW8-3(Reserve) -
SW8-4(Reserve) -
JX1(Termination of Modbus)
JX2(Analog input switching)
⑤AHU Interface slave setting
Only SW1 and JX1 setting is required for the Slave Interface.
AHU Interface No. SW1(Interface address) JX1(Termination of Modbus)
Slave1
Slave2
Slave3
Slave4
Slave5
Slave6
Slave7
Slave8
Slave9
Slave10
Slave11
Slave12
Slave13
Slave14
Slave15
1.2.2 Sensor installation guidelines
●
Install all sensors correctly.
Each sensor has particular function so that it must be installed correctly. Otherwise, the system will not function
correctly.
●
Correct method for installation of temperature sensor (Example)
When installing the temperature sensor, confirm that it optimally touches the face to measure.
Fix it with a wide hose clamp.
If a cable tie is used, it may break down or crush the temperature sensor. Fix it with a wide hose clamp.
Black Color tape for identification
Thi-A
CNH
No. Designation
1 Temperature sensor cable
2 Temperature sensor
3 Fastener
Thi-R1
(
Φ
5)
Red
Yellow
Black
Black
Gray
CNN(PCB)
(R9)
6P,Yellow
Thi-R2
(
Φ
5)
Thi-R3
(
Φ
6)
Leaf spring
Sensor holder
Heat exchanger
temperature sensor
Mounting method of
heat exchanger temperature sensor
* Sensor holder : Provided locally
Identification
With/Without
tape
Sensor φMaterial
For Thi-R3
φ9.52 x t 0.6
For Thi-R1 and -R2
φ8.0 x t 0.6
Copper tube
Sensor part Connector part
Color tape for identification
Return air temperature sensor
Heat exchanger temperature sensor
Temperature detection range
●Suction temperature sensor (Thi-A) can detect temperatures accurately in the range of 14 – 33 (±1.2)°C.
●Range of use for suction temperature sensor is -10 to 50°C.

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• Installation locations of the heat exchanger sensor
●Each heat exchanger requires 3 pieces of heat exchanger sensor.
●
Connect heat exchanger sensor connectors to AHU Interface.
●
Install each heat exchanger sensor correctly according to the following table.
Heat exchanger
temperature
sensor
Mounting
position
Detected temperature Purpose
Cooling Heating
Thi-R1 U-bend Evaporating temperature Condensing temperature Anti-freezing protection
Thi-R2 Capillary Evaporating temperature Outlet temperature Anti-freezing protection
Thi-R3 Header Outlet temperature Inlet gas temperature EEV-control
Mounting position of temperature sensors (example)
Sensor on header
（Thi-R3）
Distributor
Return air
temperature
sensor
（Thi-A）
U-bend sensor
（Thi-R1）
AIR AIR
[Recommendation]
Gas header to avoid
Capillary tube or liquid pipe
sensor（Thi-R2）
liquid drop during
stopping.
Refrigerant temperature in heat exchanger
Subcool
Thi-R1Thi-R2 Thi-R3
Thi-R1Thi-R2 Thi-R3
Refrigerant in heat exchanger
Gas
Liquid
Gas
Heating
Liquid
Superheat
Mixed
Cooling
Flow
Flow
Flow
Flow
Enthalpy
Pressure
Thi-R2
on capillary
Thi-R1
on U-bend
Thi-R3
on header
Thi-R2
on capillary
Thi-R1
on U-bend
Thi-R3
on header
Heating
Cooling
Flow
Flow
Flow Flow
Temperature
Temperature
Thi-R1
Thi-R3
Thi-R2
Thi-R1 Thi-R3
Thi-R2
Temperature detection range
●
Heat exchanger temperature sensors (Thi-R1, -R2, -R3) can detect temperatures accurately in the range
of 0 – 63 (±2)°C.
●Range of use for heat exchanger temperature sensor is -30 to 72°C.

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'21 • AHU-T-393
Heat exchanger
Thi-R3
Thi-R1
Thi-R2
Each sensor has unique function, Important to fix to
correct location.
If fixed to incorrect location, the system will not
be controlled correctly, double check during
commissioning.
The Thi-R3 sensor diameter is larger than the others to
avoid mistakes.
• Items to be checked
1. Thi-R1 : On U-bend section (with RED tape)
a) Considering the frost of the heat exchanger in cooling, mount the sensor on the circuit with the lowest temperature
among all circuits (Avoid mounting on the lowest position of the circuit). However the circuit in which the liquid
refrigerant is not held in heating operation is better.
b) Mounting the sensor at the middle point of the circuit pass is recommended. If it is mounted near to the header side
or the distributor side, it will detect the temperature at the superheat or subcool area, so it cannot detect the actual
condensing/evaporating temperature correctly.
Be sure to check whether the refrigerant is in 2-phase flow in the circuit by testing the actual unit.
Sensor on U-bend
（Thi-R１）
2. Thi-R2 : on capillary tube section of distributor (with YELLOW tape)
a) It should be mounted on the capillary tube section to detect the evaporating temperature under conditions
enabling a good response.
b) It should be mounted in a position that detects the average outlet temperature and not to hold the liquid refrigerant
during heating.
Sensor on capillary tube
（Thi-R2）