Mitsubishi Electric s-AIRME-G02 Service manual

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Installation, use and maintenance manual
English
Air-handling units
s-AIRME-G02/G07
INSTALLATION, USE AND MAINTENANCE MANUAL
Italian is the original language.
The other languages versions are translation of the original.
To ensure safe and correct use, carefully read this manual and make sure to understand all the contained indications
and information.
English
Engsh

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Installation, use and maintenance manual
Keep this manual in a known and easily accessible place to refer to as
necessary during the entire life-span of the machine.
This Manual has been prepared by MEHITS S.p.A.: Reproduction, even partial, of this booklet
is prohibited.
The original copy is kept on file by MEHITS S.p.A.
Any use of the manual other than for personal reference requires the prior authorisation of
MEHITS S.p.A.
In the interest of improving the quality of its products, MEHITS S.p.A. reserves the right to
modify, without notice, the data and content of this Manual.
The information in this document may be modified without prior notice.
The reproduction and/or dissemination of this document, even in part, is prohibited without the written
consent of MEHITS S.p.A.
Before carrying out any operation on the machine, you must
carefully read this manual and make sure you understand all
the instructions and information given.

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Installation, use and maintenance manual
TABLE OF CONTENTS
1......... GENERAL PROVISIONS........................................................................................................... 5
1.1... GENERAL INFORMATION AND SAFETY....................................................................................................................5
1.1.1... Scope of the manual................................................................................................................................................5
2......... SYMBOLS.................................................................................................................................. 6
3......... GLOSSARY AND TERMINOLOGY ........................................................................................... 7
3.1... ATTACHED DOCUMENTATION...................................................................................................................................8
3.1.1... General safety regulations.......................................................................................................................................8
3.1.1.1 PROPER AND IMPROPER USE......................................................................................................................10
3.1.2... Precautions against residual risks.........................................................................................................................10
3.1.3... List of machine internal symbols............................................................................................................................13
MINIMUM INSTALLATION AREA FOR UNITS WITH R32 ..................................................................................................16
3.1.4... Procedure for requesting support..........................................................................................................................22
3.2... MACHINE IDENTIFICATION.......................................................................................................................................22
3.2.1... Designation and identification plate.......................................................................................................................22
3.3... STORAGE TEMPERATURE ....................................................................................................................................... 23
3.4... OPERATING LIMITS ...................................................................................................................................................23
3.4.1... Operating limits in start-up.....................................................................................................................................23
3.4.2... Operating limits......................................................................................................................................................23
3.4.3... Characteristics of machines with R410A refrigerant..............................................................................................23
3.4.4... Characteristics of machines with R32 refrigerant ..................................................................................................29
3.5... GENERAL DESCRIPTION .......................................................................................................................................... 35
3.5.1... General description ...............................................................................................................................................35
3.5.2... AR Function = All Recirculation.............................................................................................................................35
3.5.3... MF function –Mixing and Free cooling..................................................................................................................36
3.5.4... Heat Recovery Plate Function (Plate heat recovery and return fan)......................................................................36
3.5.5... Unit configuration...................................................................................................................................................37
3.6... DESCRIPTION OF THE MAIN COMPONENTS..........................................................................................................40
3.6.1... Structure................................................................................................................................................................40
3.6.2... Electrical panel......................................................................................................................................................41
3.6.3... Direct expansion coil .............................................................................................................................................41
3.6.4... Ventilation..............................................................................................................................................................41
3.6.5... Air filter..................................................................................................................................................................41
PACKAGING OF STANDARD UNITS..................................................................................................................................42
3.6.6... Information on the packaging ................................................................................................................................42
4......... TRANSPORT, STORAGE AND INSTALLATION.....................................................................44
4.1... TRANSPORT AND MOVING.......................................................................................................................................44
4.1.1... General transport, handling and storage information.............................................................................................44
Temperature and humidity limits for transportation and storage........................................................................................44
4.1.2... Transport...............................................................................................................................................................44
4.1.3... Discharge..............................................................................................................................................................44
4.1.4... Receipt and inspection..........................................................................................................................................46
4.1.5... Handling................................................................................................................................................................47
4.1.6... Loading and unloading from containers.................................................................................................................49
4.2... INSTALLATION...........................................................................................................................................................50
4.2.1... Installation of the standard machiine.....................................................................................................................50
4.2.2... Machine positioning...............................................................................................................................................53
4.2.3... Joining the sections...............................................................................................................................................54
2.2.4 CONNECTION OF THE COOLING CIRCUIT BETWEEN S-AIRME-G02/G07 AND MR. SLIM UNIT........................56
4.3... HYDRAULIC CONNECTIONS.....................................................................................................................................58
4.3.1... Hydraulic connection to water coils .......................................................................................................................58
4.3.2... Installation technical notes ....................................................................................................................................58
4.3.3... Cleaning and filling the hydraulic circuit.................................................................................................................58
4.3.4... Water quality..........................................................................................................................................................59
4.3.5... Anti-freeze solutions..............................................................................................................................................60
4.4... HYDRAULIC CONNECTION OF THE CONDENSATE DRAIN...................................................................................60
4.5... ELECTRICAL CONNECTIONS...................................................................................................................................61
4.5.1... Power supply for packaged machine.....................................................................................................................61
4.5.2... Control circuit interlocking .....................................................................................................................................62
4.6... AIR CONNECTIONS....................................................................................................................................................65
4.7... OPTIONS.....................................................................................................................................................................67
5......... DISCLOSURE REQUIREMENT (EU) NO. 1253/2014...............................................................76
6......... PRE-COMMISSIONING............................................................................................................86
7......... START......................................................................................................................................91
7.1... CALIBRATION AND FINE-TUNING............................................................................................................................91

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Installation, use and maintenance manual
7.2... MACHINE START-UP .................................................................................................................................................91
8......... METHOD OF USE.....................................................................................................................92
8.1... PROVISIONS AND WARNINGS FOR USE ................................................................................................................92
8.2... DESCRIPTION OF CONTROLS..................................................................................................................................92
8.3... EMERGENCY STOP ................................................................................................................................................... 92
8.4... PROLONGED SHUTDOWNS OF THE MACHINE......................................................................................................92
8.5... START-UP AFTER EXTENDED MACHINE INACTIVITY ...........................................................................................93
9......... FIRST DIAGNOSTICS ..............................................................................................................93
9.1... TROUBLESHOOTING … ............................................................................................................................................93
10....... MAINTENANCE........................................................................................................................95
10.1. MAINTENANCE INSTRUCTIONS...............................................................................................................................95
10.2. SCHEDULED MAINTENANCE....................................................................................................................................97
10.3. TABLE OF GENERAL MAINTENANCE JOBS...........................................................................................................98
10.4. STRUCTURE CHECK .................................................................................................................................................99
10.5. CHECKING OF THE WATER FLOW AND CLEANING OF THE EXCHANGERS......................................................99
10.6. CHECK THAT THE COILS ARE CLEAN....................................................................................................................99
10.7. AIR FILTER MAINTENANCE/REPLACEMENT........................................................................................................ 100
10.8. STEAM HUMIDIFIER CHECK...................................................................................................................................101
10.9. ELECTRIC HEATER MAINTENANCE ......................................................................................................................101
10.10EXTRAORDINARY MAINTENANCE.........................................................................................................................101
11....... DISPOSAL OF THE MACHINE...............................................................................................106

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Installation, use and maintenance manual
1 GENERAL PROVISIONS
1.1 General information and safety
1.1.1 Scope of the manual
This manual, which is an integral part of the machine (1), wasprepared by the Manufacturer to provide the necessary information
to all those who are authorised to interact with it during its life span: Buyers, System Designers, Carriers, Handling Operators,
Installers, Expert Operators, Specialist Technicians and Users.
As well as adopting a code of good practice, the recipients of the manual must read the information with care and apply it
scrupulously. Taking a little time to read this information can help avoid risks to the health and safety of persons as well as
prevent financial losses.
The information was written by the Manufacturer in the manufacturer's native language (Italian) and is referred to as the
"ORIGINAL INSTRUCTIONS". This information is also available into other languages as "TRANSLATION OF THE ORIGINAL
INSTRUCTIONS" to meet legislative and/or commercial requirements. The information is valid even if the machine in your
possession is not exactly the same as the one referred to.
Keep this manual in a known and easily accessible place to refer to as necessary.
The Manufacturer reserves the right to modify the product without prior notice.
A number of symbols are used to highlight some parts of the text that are of particular importance. These are described below.
(1) in the interest of clarity, this term is used as defined in the Machinery Directive.

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Installation, use and maintenance manual
2 SYMBOLS
DANGER:
Indicates an imminently hazardous situation which, if not avoided, will result in death or serious
injury.
WARNING:
Warning indicates a potentially hazardous situation which, if not avoided, could result in death or
serious injury.
ATTENTION:
Attention indicates a potentially hazardous situation which, if not avoided, could cause minor or
moderate damage.
PROHIBITION:
Prohibition to perform certain movements or activities.
OBLIGATION:
This indicates mandatory actions and behaviours to ensure product reliability and safety.
INFORMATION:
Indicates technical information of particular importance which should not be neglected.
NOTICE:
This is used to address practices not connected with possible physical injury.

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Installation, use and maintenance manual
3 GLOSSARY AND TERMINOLOGY
There are some recurring terms in the manual which are described below in more detail.
Manufacturer: this is the company that has designed and built the machine in line with current laws, implementing all the good
construction rules, and paying attention to the health and safety of people interacting with the machine.
Buyer: the person responsible for making the purchase whomust supervise the organisation and assignment of duties to ensure
that everything is done in compliance with the applicable laws.
Owner: Legal representative of the company, a body, or a natural person who owns the plant where the machine is installed
and is responsible for checking compliance with all the safety rules in this manual and the national regulations in force.
Designer: a competent specialist person duly appointed and authorised to draw up a project that takes into account all the
legislative and regulatory aspects and code of good practice that apply to the system as a whole. In any case, as well as comply
with the instructions provided by the machine Manufacturer, the designer must consider all the safety aspects for all those
persons who will have to interact with the system during its expected life span.
Installer: specialist competent person duly appointed and authorised to set up the machine or system according to the project
specifications and the recommendations of the machine Manufacturer and in compliance with the laws on safety at work.
User: person authorised to manage use of the machine in compliance with the "instructions for use" and the laws in force
concerning safety at work.
Carriers: the persons who take the machine to the destination in a suitable means of transport. They must stow and position
the machine in a suitable way to ensure that it cannot move suddenly during transfer. When using devices for loading and
unloading, they must observe the instructions that can be found on the machine to ensure their own safety and that of those
people with whom they interact in the process.
Handling operators: those who duly set up the machine and implement all the applicable measures so that it can be handled
in a safe and correct manner. They are also those persons who, upon receipt of the machine, move it to the place of installation
according to the instructions which can be found on the machine. All the above employees must have adequate skills and
observe the instructions to ensure their own safety and that of those people with whom they interact in the process.
Maintenance person: The person authorised by the owner tocarry out on the machine all operations of regulation and checking
expressly indicated in this manual, and which must be strictly followed. His/her work will be limited only to what is clearly allowed.
Expert operator: person appointed and authorised by the User or the Buyer to use the machine and carry out the routine
maintenance according to the instructions provided by the Manufacturer. In the event of failures not considered in this manual,
the expert operator must request the assistance of a specialist technician.
Specialist technician: The person authorised directly by the Manufacturer to carry out all operations of ordinary and
extraordinary maintenance. He/she will also carry out all regulations, checks, repairs and replacement of parts that should
become necessary during the life of the machine itself. Outside Italy and those countries where the Manufacturer is not directly
present, the Agent is personally responsible for acquiring a suitable number of Technicians, proportional to the area and the
business.
Routine maintenance: all the operations that help to ensure the good performance and efficiency of the machine. These
operations are planned by the Manufacturer who defines the skills required and the procedures to be implemented.
Extraordinary maintenance: all the operations that help to ensure the good performance and efficiency of the machine.
These operations, which are not foreseeable, are not planned by the Manufacturer and must only be carried out by the
specialist technician.

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Installation, use and maintenance manual
3.1 Attached documentation
The following documents are delivered with the unit:
•Installation, use and maintenance manual (multilingual): this manual accompanies the unit and contains the main
installation, use and maintenance information.
•Installation, use and maintenance manual (extended): in electronic format and available on the manufacturer's
website, it offers detailed information on the installation, use and maintenance steps set out in the multilingual
manual supplied with the machine.
•Refrigeration system diagrams (paper and electronic format).
•Hydraulic diagrams (paper and electronic format).
•Wiring diagram: it is specific to the machine in question. It is useful for the persons who will have to carry out work
on the electrical system, as it shows the various components and connections.
•Dimensional drawings: with handling, lifting and transport information.
•EC declaration of conformity: indicates that the machines comply with current European directives.
•Installation, use and maintenance manual: it contains the list of operations to carry out.
•Wiring diagram: it is specific to the machine in question. It is useful for the persons who will have to carry out work
on the electrical system, as it shows the various components and connections.
•Dimensional and lifting drawings
•Assembly instructions for optional items: they describe the procedures for their installation on the machine.
•EC declaration of conformity: indicates that the machines comply with current European directives.
•Manual of the electronic controller
The instructions are also available in electronic format on the website https://www.melcohit.com/EN/download/
3.1.1 General safety regulations
The Manufacturer, during design and construction, has paid particular attention to aspects that may pose a risk to the safety
and health of people interacting with the machine. The manufacturer has complied with the applicable laws as well as the code
of good manufacturing practice. The purpose of this manual is to encourage users to take all due care and thereby avoid any
risks. In any case, prudence is required at all times. Safety is also the responsibility of alloperators who interact with the machine.
Carefully read the instructions in this manual and those applied directly on the machine, and respect those concerning safety in
particular.
The inclusion of these machines in a system requires an overall project that must take into account all the “good practice”
requirements, as well as the legislative and regulatory provisions. Particular attention must be paid to all the recommendations
and technological information provided by the Manufacturer. Do not tamper with, avoid, remove or bypass the safety devices
installed on the machine. Failure to observe this requirement could result in serious risks to the health and safety of the persons
involved.
The personnel who carry out any kind of work during the entire life span of the machine must have precise technical knowledge,
special skills and recognised experience in the specific sector. Non-fulfilment of these requirements could endanger people's
health and safety.
Keep the area around the machine in a good state in order to avoid risks to the health and safety of persons during normal use
and maintenance of the machine.
Some processes may require the assistance of one or more helpers. In which case, these helpers must be duly trained and
informed of the type of work to be carried out in order to avoid risks to their health and safety.
When moving the machine, refer to the information provided on the instructions for use supplied by the manufacturer.
The personnel who carry out loading, unloading and handling of the equipment must have recognised skills and experience in
the specific sector and must have absolute command of the lifting equipment to be used.
During installation, observe the clearances indicated by the Manufacturer and take into account all the work activities carried
out in the vicinity. Installation must also be carried out in compliance with the laws in force on safety at work.
The machine must be installed and connected in accordance with the Manufacturer's instructions. The person in charge must
also take into account all regulatory and legislative requirements, carrying out all installation and connection operations in a
workmanlike manner.
After installation and before commissioning the machine, he must perform a general check to make sure that these requirements
have been met.
Check that any means of transport to be used for transfer of the machine are suitable for the purpose, and that the machine is
loaded and unloaded with care to ensure the safety of the operator and of any other persons who are directly involved. Before
transfer, make sure that the machine and its components are duly anchored to the vehicle and do not exceed the maximum

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Installation, use and maintenance manual
permitted dimensions for transport on the vehicle. Apply any necessary signs.
The operator must have read and understood the information on use of the machine, and have suitable skills and experience
for carrying out the work in hand.
Put the machine only to the uses foreseen by the manufacturer. Improper use of the machine may pose risks to the health and
safety of the persons and cause financial losses.
The machine has been designed and constructed to meet all the operating conditions indicated by the Manufacturer. Tampering
with any of the devices to change the performance can expose the persons to health and safety risks and cause financiallosses.
Only use the machine with the safety devices properly installed and in perfect working order.Failure to observe this requirement
could result in serious risks to the health and safety of the persons involved.
Keep the machine in perfect working order and perform the routine maintenance recommended by the Manufacturer. Good
maintenance can help to ensure the best possible performance, a long useful life and constant compliance with the safety
requirements.
Before maintenance and adjustments, activate all the applicable safety devices and provide the personnel and any other people
in the vicinity with all necessary information. In particular, cordon off the area and prevent access to all the devices that could,
if activated, inadvertently cause danger and pose risks to health and safety.
Maintenance and adjustments must be carried out by authorised persons who must implement all the necessary safety
measures according to the procedures set down by the Manufacturer.
All maintenance operations that require specific technical expertise or skills must only be carried out by qualified personnel with
recognised experience in the field.
In the case of maintenance in areas that are awkward or dangerous to access, implement appropriate measures to ensure the
safety of oneself and of other people, in compliance with the laws in force on safety at work.
This device is not intended foruse by people (including children) withreduced physical, sensoryor mental capabilities, or without
experience and not duly informed, unless they are given adequate supervision and training regarding its use by an experienced
operator or specialist technician.
Children should be supervised to make sure that they don't play with the machine.
WARNING:
During the periodic maintenance activities, or in the event of a fault, replace faulty parts with original
spare parts. Use the components recommended by the manufacturer, so as to ensure the machine
performance and the expected safety level.
PROHIBITION:
The user is strictly prohibited to perform activities such as commissioning, regular/extraordinary
maintenance, modifications or anything else not provided for in this Manual.

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Installation, use and maintenance manual
3.1.1.1 Proper and improper use
Use the unit only for the intended purposes for which it was designed. Any other use relieves Mehits of all liability arising from
improper use of the unit.
Air-handling units are designed for civil and industrial air handling.
In case of corrosive and/or explosive operating environments, during the design stage it is essential to make the machine
suitable for handling particular flows.
The use of the unit must always and in all cases comply with the design parameters set during the contract negotiations in
agreement with the customer. Any other use must be considered improper and dangerous.
Mehits shall not be liable for damage caused by different and unintended uses of the materials provided.
It is forbidden to use the unit:
•In explosive atmosphere
•In a flammable atmosphere
•In a corrosive atmosphere
•In excessively dusty environments
•By untrained personnel
•Not in accordance with current legislation
•If incorrectly installed
•With supply defects
•Without fully or partially following the instructions
•If not properly maintained and/or if non-original spare parts are installed
•With inefficient safety components.
3.1.2 Precautions against residual risks
Prevention of residual mechanical risks
•The unit must be installed outdoors;
•Install the unit according to the instructions set out in this manual;
•Regularly carry out all the maintenance operations foreseen in this manual;
•Wear protective equipment (gloves, eye protection, hard hat, etc.) appropriate for the work being carried out. Do not
wear clothing or accessories that can get entangled or sucked in by the air flow. Collect and tie hair to the head before
entering the unit;
•Before opening the machine panelling make sure that it is firmly hinged to the machine;
•The fins on heat exchangers and the edges of metal components and panels can cause cuts;
•Do not remove the guards from mobile components while the unit is operating;
•Make sure that mobile component guards are fitted correctly before restarting the unit;
•Fans, motors and belt drives might be running: before accessing these, always wait for them to stop and take
appropriate measures to prevent them from starting up;
•Fans, motors and transmissions may be running: before starting the machine make sure to install the appropriate
protections to prevent contact with the components during operation;
•The surfaces of the machine and pipes can get very hot or cold and cause the risk of scalding;
•Never exceed the maximum pressure limit (PS) of the water circuit of the unit indicated;
•Before removing parts on the pressurised water circuits, close the section of the piping concerned and drain the fluid
gradually to stabilise the pressure at the atmospheric level;
•Do not use your hands to check possible refrigerant leaks.
PROHIBITION:
It is strictly forbidden to connect the unit to rooms with naked flames (e.g. smoking rooms or
kitchens).
OBLIGATION:
The unit can only be connected to rooms with naked flames (e.g. smoking rooms or kitchens) if it is
equipped with the safety damper accessory.

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Installation, use and maintenance manual
Prevention of residual electrical risks
•The unit contains live parts that could cause serious injury or death. Only personnel trained in electrical hazards
should work on electrical and electronic components, such as electrical panels, motors, wiring. Personnel must wear
the appropriate personal protective equipment for the activities at all times, including, for example, gloves, dielectric
shoes and face shield, and use dielectric tools;
•Before opening the electrical panel and any other electrical and electronic components, disconnect the unit from the
mains using the external switch on the machine;
•Check that the unit has been grounded correctly before starting it;
•Install the machine in a suitable area; in particular, do not install it outdoors if it is intended for use indoors;
•Do not use cables of inadequate cross-section or loose connections. Not even in an emergency, or for limited periods;
•For units with power correction capacitors, wait 3 minutes after removing the electric power supply before accessing
the inside of the electrical panel;
•If the unit is equipped with frequency converters (inverters), disconnect it from the mains and wait a minimum of 15
minutes before accessing it to carry out maintenance: the internal components remain live during this period and
therefore pose the risk of electric shock.
Prevention of environmental risks
•The machine contains substances and components that are dangerous for the environment, such as refrigerant
gases and lubricant.
•The units may only be serviced and disposed of by qualified technicians.
Refrigerant gas:
The cooling circuit contains fluorinated greenhouse gases covered by the Kyoto Protocol.
The units may only be serviced and disposed of by qualified technicians.
The fluorinated greenhouse gases contained in the cooling circuit must not be disposed of in the atmosphere.
Refrigerant gases must be recovered in accordance with current laws.
Refrigerant
R32
GWP100
675
Lubricant oil:
The cooling compressors and the cooling circuit contain lubricant oil.
The oil must be recovered in accordance with current laws.
Do not disperse the oil in the environment.
For the level of machine noise emissions refer to the Technical Data Sheet of the unit. For the PPE required and any
operations/components for the reduction of noise see the table.
Prevention of other residual risks
•Considering the use of R32 refrigerant, it will be necessary to take into account its LFL (Low Flammable Level), equal
to 0.307 kg/m3. To reduce the risk of flame, avoid areas with a gas concentration greater than 0.077 kg/m3 (25% LFL).
•To ensured safety with units charged with R32 refrigerant, make sure to observe the minimum area constraints for
installation as outlined in Section 1.1.5.1
•Units using R32 refrigerant may only be installed outdoors.
•In order to ensure adequate ventilation to units with R32 charge, it is important that ducts are as indicated in chapter
2.2.15.
•The unit contains pressurised refrigerant gas: the pressurised equipment must not be touched except during
maintenance, which must be entrusted to qualified and authorised personnel;
•Connect up the utilities to the unit following the indications set out in this manual and in the pictograms on the panelling
of the unit itself;
•The water circuit contains harmful and bio-hazardous substances (e.g. legionella). Do not drink from the hydraulic
circuit and make sure the material contained in it does not touch your skin, eyes or clothing.
•In order to avoid an environmental risk, make sure that any leaking fluid is collected in suitable devices in accordance
with local regulations;
•If a part needs to be dismantled, make sure it is correctly re-assembled before starting the unit;
•When the rules in force require the installation of fire-fighting systems near the machine, check that these are suitable
for extinguishing fires on electrical equipment and on the lubricating oil of the compressor and the refrigerant, as
specified on the safety data sheets of these fluids (for example, a CO2extinguisher);
•For units equipped with pressure relief valves (safety valves): when these valves are triggered, the refrigerant gas is
released at a high temperature/speed; prevent the release of gas from harming people or damaging objects; if
necessary, discharge the gas according to the provisions of EN 378-3 and the local regulations in force, particularly
making sure to discharge fluids that belong to a safety class other than A1 into safe, open areas (see Tab.3);
•Keep all the safety devices in good working order and check them periodically according to the regulations in force;
•Keep all lubricants in suitably marked containers;

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Installation, use and maintenance manual
•Do not store inflammable liquids near the unit;
•Solder or braze only empty pipes after removing all traces of lubricant oil; do not use flames or other heat sources in
the vicinity of pipes containing cooling fluid;
•Do not use naked flames near the unit;
•The machinery must be installed in structures protected against atmospheric discharge according to the applicable
laws and technical standards;
•Do not bend or hit pipes containing pressurised fluids;
•It is not permitted to walk or rest other objects on the machines;
•The user is responsible for overall evaluation of the risk of fire in the place of installation (for example, calculation of
the fire load);
•During transport, always secure the unit to the bed of the vehicle to prevent it from moving about and overturning;
•The machine must be transported according to the regulations in force taking into account the characteristics of the
fluids in the machine and the description of these on the safety data sheet;
•Inappropriate transport can cause damage to the machine and leaking of the cooling fluid. Before start-up, the machine
must be checked for leaks and repaired accordingly;
•The accidental discharge of refrigerant in a closed area can cause a lack of oxygen and, therefore, the risk of
asphyxiation: install the machinery in a well ventilated environment according to EN 378-3 and the local regulations in
force;
•The installation must comply with the requirements of EN 378-3 and the local regulations in force; in the case of
installations indoors, good ventilation must be guaranteed and refrigerant detectors must be fitted when necessary;
•Unless arranged otherwise with MEHITS, the machine be installed in environments where there is no risk of explosion
(SAFE AREA).
•The structure of the unit is not designed to withstand the stresses (accelerations) caused by an earthquake
In accordance with the standard EN 60204-1, the handle of the circuit breaker must be easy to accessand at a height of between
0.6 and 1.9 metres above the floor. The positioning of the machine in the place of installation must be considered, as if the unit
is placed on a raised platform, the height of the switch might no longer be in compliance with the standards. In which case the
installer must arrange for a walkway or a similar solution that can allow operators to access the safety device with ease.
Residual risks
Mandatory personal protective equipment
Residual mechanical
risks
Residual electrical risks
Other residual risks
Residual risks for
maintenance
Table 1: Correspondence between residual risk and corresponding PPE.
As far as the required PPE and its use, reference should be made to Italian Legislative Decree. 81/08 and IEC 82078-
1:2012

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Installation, use and maintenance manual
3.1.3 List of machine internal symbols
The unit is fitted with the necessary safety signs; here are some examples:
3.1.3.1 Precautions against residual risks
GENERAL
This chapter contains information on the correct handling of units containing flammable fluid R32, with reference to European
regulations and directives. National laws and local building codes of each country shall in any case always be respected and
applied with priority.
The following information helps the installer to operate in a proper and safe way but cannot replace a comprehensive risk
assessment for the installation of the unit. Risk assessment is necessary to determine if there is a direct risk of injury or damage
to property in relation to hazards identified at the installation site.
Commissioning, start-up, service, decommissioning and other operations on the unit shall be undertaken by trained and fully
qualified personnel, in accordance with applicable local standards and codes of practice.
Cylinders and equipment containing R32 refrigerant require compliance with proper storage and handling procedures in
accordance with EN 378-3:2021. Any person operating on the refrigeration circuit must have complete knowledge of the
flammable refrigerants and the related risks.
NOTE: the leak detector supplied on request with the unit cannot be considered a safety device. It is to be used only as a means
of testing for leaks.
REFRIGERANT PROPERTIES
The R32 refrigerant is classified as mildly flammable and non-toxic (A2L according to ISO/ASHRAE). Mildly flammable means
that, under the three conditions shown below, there is a possibility the refrigerant could slowly burn. Removing one of the three
conditions does not pose the danger of fire, and can therefore be considered safe.
In any case, most refrigerants emit a toxic gas when a naked flame comes into contact with them.
All flammable refrigerants (class A2L and above) will not ignite if the concentration level stays below the lower flammability limit
(LFL).
The flammability risk of MEHITS units with R32 refrigerant is minimal. However, a site risk analysis may need to be carried out
depending on the local regulations.
Concentration
Leakage
Source
of ignition
Ignition

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Installation, use and maintenance manual
Some of the properties of R32 are listed below:
ASHRAE/ ISO817 Name
R32
PED Group
1
ASHRAE Safety Classification
A2L
ODP (Ozone Depletion Potential) (R11 = 1)
0
GWP (Global Warming Potential) AR5 (AR4) (CO2 = 1)
677 (675)
Saturated Liquid Temperature(1) @ 1 atm
-51.65
Practical Limit (kg/m3)
0061
Lower between the acute toxicity exposure limit (ATEL) and the oxygen
deprivation limit (ODL) (kg/m3)
0.30
LFL (Lower Flammability Limit) @ 23 °C, 50% RH (% v/v)
14.4
LFL (kg/m3)
0307
UFL (Upper Flammability Limit) @ 23 °C, 50% RH (% v/v)
29.3
UFL (kg/m3)
0559
Density (1) @ 21 °C, 1atm (kg/m3)
2.13
Burning rate (cm/s)
6.7
Minimum ignition energy (mJ) (ASTM E582-13)
30-100
Molecular mass
52
Auto-ignition temperature (°C) (ASTM E659-15)
648
Surface switching on temperature (°C)
(ASTM E659-18)
>800

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Installation, use and maintenance manual
INSTALLATION
•The units can be installed both inside machinery rooms and outdoors.
For indoor installations such as semi-basements, basements or machinery rooms, these must comply with EN 378-3:2021 -
par. 5 requirements (gas detection, ventilation, alarm system, etc.).
•The refrigerant is heavier than air and can stagnate, e.g. below the ground or near the floor, and could reach a flammable
concentration. To avoid ignition, maintain a safe work environment by ensuring appropriate ventilation.
•For R32 units where a release of refrigerant can stagnate e.g. below ground, installation must comply with the requirements
of EN 378-3:2021 on gas detection, ventilation and alarm systems.
•R32 units located outside must be positioned to avoid the refrigerant from flowing into a building or otherwise endangering
people, animals and property, in the event of a leak. Ensure that in the event of leaks no refrigerant penetrates through
vents, doors, hatches or similar. When installing units outdoors with shelter, ensure adequate forced or natural ventilation.
The installation site must meet the requirements of EN 378-3:2021.
In addition to arc, spark, hot surfaces, flames, etc. there are other ignition sources that must be taken into consideration:
oElectric currents and cathodic corrosion protection: take care when the unit is installed near railways, electromagnetic
induction ovens, large welding systems or other apparatus that can induce stray currents in order to avoid source of
ignition.
Stray currents can flow in electrically conductive systems or parts of systems as:
➢return currents in power generating systems - especially in the vicinity of electric railways and large welding
systems - when, for example, conductive electrical system components such as rails and cable sheathing laid
underground lower the resistance of this return current path;
➢a result of a short-circuit or of a short-circuit to earth owing to faults in the electrical installations;
➢result of magnetic induction (e.g. near electrical installations with high currents or radio frequencies).
If parts of a system able to carry stray currents are disconnected, connected or bridged (even in thecase of slight potential
differences) an explosive atmosphere can be ignited as a result of electric sparks and/or arcs. Moreover, ignition can
also occur due to the heating up of these current paths.
When impressed current cathodic corrosion protection is used, the above mentioned ignition risks are also possible.
However, if sacrificial anodes are used, ignition risks due to electric sparks are unlikely, unless the anodes are aluminum
or magnesium.
oGenerated sparks: due to an imbalance or damage to the bearings, the blades of a fan can crawl or impact against grids
and nozzles; friction or impact or abrasion can lead to overheating or detachment of solid particles at high temperature,
which could represent a potential source of ignition. Make sure that the fans have no abnormal vibrations or noises; in
this case stop the machine and inform the service department.
•The R32 unit is provided with some parts of the refrigerant circuit inside an enclosure: a potentially flammable zone may
extend beyond the boundary of the equipment, especially when doors or panels of the unit are opened following a leak. A
risk assessment shall be conducted to determine the requirements of the location of the unit to be installed.
•The installer shall provide adequately protected documentation that shall be kept near the operating site of the unit and be
clearly readable. It shall, at a minimum, contain details of the flammability of the flammable refrigerant (see EN 378-2,
6.4.3.3).

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Installation, use and maintenance manual
MINIMUM INSTALLATION AREA FOR UNITS WITH R32
The unit must be selected according to the minimum square footage given in the table below, referring to the smallest room
served by the unit at the installation site.
The unit itself cannot be intended as a safety feature for the indoor environment.
The responsibility for proper installation and safety of the environments served by the unit rests entirely with the installer.
For installations that do not comply with the table, the environment must be adapted in accordance with the chapters on
additional safety of the EN378-3 standard and the applicable local regulations.
The installer is fully responsible for the sizing activities and the implementation of these additional safety measures.
The minimum surface areas to be respected, referring to the smallest room served by the unit at the installation site, are those
corresponding to the external unit with the largest capacity listed in Chapter 3.5.5.
The table below shows the minimum surface area values for each external unit. These are indicated depending on the "h0”
reference height, which must be considered starting from the height from the floor of the lowest vent in the room.
SAFETY DEVICE FOR THE USE OF A2L GAS
The units are always equipped with an R32 refrigerant presence sensor at the delivery fan compartment in order to detect
possible refrigerant leaks.
Once the leak has been detected, the unit maintains a minimum level of ventilation in order to prevent an excessive accumulation
of gas in the conditioned environment, diluting it with the treated air flow.
If the leak occurs when the machine is switched off, the alarm does not allow the unit to start.
The unit is also equipped with a “sensor fault” alarm, which triggers the same actions as described above should a fault be
detected in the sensor itself.
SAFETY DAMPER ACCESSORY
When the unit has to serve rooms with naked flames (e.g. smoking rooms, kitchens, etc.), in order to guarantee a greater level
of safety, the unit is equipped with class 4 dampers (according to EN 751) on the air supply and return, in order to isolate the
served environment in the event of a leakage of refrigerant gas.
Once the leakage is detected, the unit is turned OFF and the dampers connecting the unit to the indoor environment are closed,
ventilation is stopped and natural ventilation is ensured by opening the external air intake damper and the counter-rotating blade
on the supply damper to evacuate the possible refrigerant leakage from the unit.
If the leak occurs when the machine is switched off, the alarm does not allow the unit to start.
The unit is also equipped with a “sensor fault” alarm, which triggers the same actions as described above should a fault be
detected in the sensor itself.
In this case, ventilation is stopped and natural ventilation is ensured by opening the external air intake damper and the counter-
rotating blade on the supply damper to evacuate the remaining refrigerant leakage.
In the case of the AR machine, where there is no external air intake damper, the supply damper is equipped with a counter-
rotating blade, which opens outwards when the machine is not in operation.
Height of the appliance's ports
(h0in EN 378-1, Annex C.2)
Minimum indoor installation areas
PUZ-
ZM / M
100
PUZ-
ZM / M
125
PUZ-
ZM / M
140
PUZ-
ZM / M
200
PUZ-
ZM / M
250
[m]
[m²]
[m²]
[m²]
[m²]
[m²]
0.6
306
306
306
338
394
1
110
110
110
122
142
1.8
34
34
34
38
44
2.2
23
23
23
25
29

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Installation, use and maintenance manual
This damper keeps the unit in communication with the outside environment, ensuring the evacuation of any refrigerant
leakage.
For further information refer to the dedicated chapter 4.6.
MAINTENANCE
The following precautions must be taken before working on the refrigerant circuit:
•Obtain a permit for work on hot parts (if required);
•Ensure that no flammable materials are stored in the work area and that no ignition sources are present anywhere in the
work area;
•Ensure that suitable fire extinguishing equipment (CO2 or dry-powder type) is available within the immediate area;
•Ensure that the work area is properly ventilated before working on the refrigerant circuit or before welding, brazing or
soldering work. Use auxiliary ventilation, rated for R32 refrigerant, such as blowers or fans, if necessary, to disperse
refrigerant vapours, especially in confined areas. (This recommendation applies, in any case, to all refrigerants);
•Ensure that suitable flammable gas detectors are present and operating to warn workers of a dangerous concentration of
refrigerants, especially during any work on hot parts;
•Ensure that the leak detection equipment being used is non-sparking, adequately sealed or intrinsically safe;
•Display appropriate warning signs. For example, “no smoking” and “no entry”;
•Verify that all appropriate and necessary tools and Personal Protective Equipment (PPE) are available;
•Ensure that all maintenance staff have been instructed.
NOTE: When installation permits, it is recommended to remove the equipment from the existing position to a controlled
workshop environment where work can be carried out safely.
The following procedure must be followed before working on the refrigerant circuit:
•Remove the refrigerant (specify the residual pressure);
•Purge the circuit with inert gas (e.g. nitrogen);
•Evacuate at a pressure of 30 kPa absolute (or 0.03 MPa);
•Purge again with inert gas (e.g. nitrogen);
•Open the circuit.
•Do not braze pipe and components which contain refrigerant. Before opening the circuit, the refrigerant must be recovered
or pumped down. To open the pipelines, use only pipe cutters. Do not use naked flames. Before brazing, check with a
refrigerant detector the absence of a potential flammable atmosphere. Refrain from using flames until the work environment
is adequately ventilated.
•If compressors or compressor oils are to be removed, evacuate to an acceptable level to ensure that there is no flammable
refrigerant remaining within the lubricant.
•Only refrigerant recovery equipment designed for use with flammable refrigerants must be employed. HFC refrigerant
recovery machines may not have been assessed for use with flammable refrigerants. If the national rules or regulations
permit the refrigerant to be drained, this should be done safely, using a hose, for example, to discharge the refrigerant into
the outside atmosphere in a safe area. It should be ensured that an inflammable explosive refrigerant concentration cannot
occur near an ignition source or penetrate into a building under any circumstance.
•After any repair work, the safety devices, e.g. refrigerant detectors and mechanical ventilation systems, shall be checked
and the results recorded.
•It shall be ensured that any missing or illegible labels on components of the refrigerant circuit are replaced.
•Sources of ignition shall not be used when searching for a refrigerant leak.
•Maintenance and repair requiring the assistance of other skilled personnel shall be carried out under the supervision of the
person competent in the use of flammable refrigerants. Any person conducting servicing or maintenance on a system or
associated parts of the equipment shall be competent according to EN 13313.

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Installation, use and maintenance manual
Persons working on the unit shall have competence in the safety aspects of handling flammable refrigerants, supported by
evidence of appropriate training. This will include the following requirements:
•Knowledge of legislation, regulations and standards relating to flammable refrigerants;
•Detailed knowledge of and skill in handling flammable refrigerants, personal protective equipment, refrigerant leakage
prevention, handling of cylinders, charging, leak detection, recovery and disposal.
3.1.3.2 Gas presence sensor for units with R32
The sensitive layer of the sensor reacts chemically to the presence of R32, changing its conductivity. The oxidation process
changes its resistance and thus the measurement, so regular calibrations are necessary. Carry out regular maintenance
according to the instructions.
Certain substances and gases in the air monitored by the sensor can change the sensitivity of the sensor element or damage
it completely.
The currently known substances are:
•Polymerising substances such as ethylene oxide, acrylonitrile, butadiene, styrene, silicone.
•Corrosive substances, such as halogenated hydrocarbons.
•Catalytic poisons, such as sulphur and phosphorus compounds, silicon compounds, metal vapours.
•Organic solvents
•Oils and lubricants
OPERATING CONDITIONS
Permissible temperature
from -30°C to +60°C
Allowed humidity
from 15 to 90% relative humidity, non-condensing
Permissible pressure
from 0.9 to 1.1 bar
Storage temperature
from 0°C to +50°C
Storage
Up to 12 months
Calibration interval
12 months
Useful life
> 60 months
Type of gas
MSR Unit
MSR
Calibration
gas
Measurement
range
Relative
density
R32
FR08
2080-02
R407c
20-2000 ppm
1.8
NOTICE:
Fire and smoke safety takes priority over leakage detection.
The gas presence sensor consists of a sensing element (sensor head) and a control board. Both are
located in the delivery fan compartment.
WARNING:
Do not change the position of the sensor elements.
WARNING:
Do not generate electrostatic charges.
WARNING:
Connecting the 24 V fieldbus voltage to the X7 terminal of the local bus may damage the board.

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Installation, use and maintenance manual
Description of the LEDs
The sensor board has a status LED and two relays.
Open the casing housing the sensor to check the status of the LED.
The two relays detect the presence of gas (alarm) and the presence of faults in the sensor (fault).
The status of the analogue output, relays and signalling LEDs are shown in the following tables:
Start-up and normal operation:
Service instrument LED
Analogue
output
Relay
LED on the
board
Power
Alarm
Fault
Alarm
Fault
Start up
Diagnostics (0,5s)
<2 mA
OFF
Fault 4
Preheating (300s)
2s
2s
2s
<2 mA
OFF
Fault 4
2s
2s
2s
Normal operation
6
2
4-20 mA1
3
OK5
Alarms and other modes:
Service instrument LED
Analogue
output
Relay
LED on
the board
Power
Alarm
Fault
Alarm
Fault
Maintenance message
2
4-20 mA1
3
OK5
2s
2s
2s
Special mode
6
7
2 mA8
7
Fault 4
Fault detected
6
7
2 mA
7
Fault 4
Processor fault
< 1 mA
OFF
Fault 4
1 The status depends on the concentration of the measured gas.
2 The status depends on the concentration of the measured gas and the alarm threshold.
3 The status depends on the concentration of the measured gas, alarm threshold and operating mode.
4 Relay off, contact open.
5 Relay on, contact closed.
6 The LED flashes cyclically while sending a message.
7 The previous status remains unchanged.
8 No influence on the analogue signal if the special mode was initiated by the user.

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Installation, use and maintenance manual
Commissioning
Commissioning must only be carried out by authorised Mitsubishi Electric personnel.
Remove the sensor head cap when commissioning the unit.
Perform a documented functional test without gas.
After the functional test has been completed, record the maintenance carried out in the controller of the Rooftop unit. The next
maintenance should be performed within 12 months.
Inspection
Gas sensors must be checked regularly by a competent person. Check the following:
•That the calibration/maintenance interval has not been exceeded, that is, there is no alarm on the
unit's keypad.
•Visually inspect sensor, wiring etc.
•Remove dust deposits, especially in the gas inlet.
•Replace the filter at the gas inlet if extremely dirty.
Maintenance and calibration
The Rooftop unit is equipped with two warnings, of impending maintenance and required sensor maintenance.
During maintenance, as well as inspection, perform calibration and the functional test (see below).
Material required
•Calibration adapter C2-Z4 to be connected to the cylinder to supply calibration gas to the sensor head.
•Service-Tool STL06 for calibration/configuration of the sensor: STL06-PGX2.
•Alternative to STL06: PCE06-PGX2 software kit for calibration/configuration of the sensor via PC.
•Calibrated gas with specific concentration (50% of measurement range).
•Flow and pressure regulator ensuring a gas flow rate of 150 ml/min (pressure: 1 bar ± 10%).
•Multimeter.
Calibration procedure
1. Make sure there is no gas present and power the sensor, if not already powered. Pay attention to the preheating time
of 300 seconds before taking action.
2. Open the sensor housing.
3. Connect the cable from the Service Tool or PCE06 kit to the dedicated connector on the board (for use of PCE06
connect the USB side to the PC first).