Vertiv Liebert DM Series User Manual

Liebert DM S

eries

Precision Air Conditioner

User Manual

Copyright by Vertiv Co. Ltd.

The content in this document is subject to change without notice. All rights, including rights of
translation, reproduced by printing, copying or similar methods, and even of parts, are reserved.
Violators will be liable for damages. All rights, including rights deriving from patent license or
registration of a utility model or design, are reserved. No part of this document may be
reproduced or transmitted in any form or by any means without the prior written consent of
Vertiv Co. Ltd.

Notice

The purchased products, services, and features are stipulated by the contract made between
Vertiv Co., and the customer. All or part of the products, services, and features described in this
document may not be within the purchasing scope or the usage scope. Unless otherwise
specified in the contract, all statements, information, and recommendations in this document are
provided "AS IS" without warranties, guarantees or representations of any kind, either express or
implied. The information in this document is subject to change without notice. Every effort has
been made in the preparation of this document to ensure the accuracy of the contents, but all
statements, information, and recommendations in this document do not constitute a warranty of
any kind, express or implied.

Vertiv Co., Ltd.

• China

Website: www.vertivco.com.

E-mail:

Customer service hotline:

• Asia Pacific

Homepage: www.vertivco.com.

E-mail:

For Technical Support, users may contact the nearest Vertiv Co. local sales office or service
center.

[email protected].

4008876510

[email protected]

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

Purpose of the Document

Situation

Description

The Warning/Danger/Caution note

degradation, or interruption in service.

The Note section indicates additional and

This document applies to the Liebert DM series of precision air conditioners and cooling solutions
which maintain an optimal environmental control mainly for testing laboratories, data center rooms
and similar technological ecosystems at minimal operating costs.

This document explains the product description, installation measures, operational workflow,
maintenance, and detailed aspects from the user perspective. The figures used in this document
are for reference only.

Please read this manual carefully before installing, maintaining, and troubleshooting, especially

the warning information in the manual

Styling used in this Guide

The styles used in the manual will be defined as mentioned in the following table:

indicates a hazardous or potentially

Warning/Danger/Caution

harmful situation that can result in death
or injury. It also indicates instructions that
need to be adhered to, failing which may
result in danger and safety issues thereby
having an adverse effect on the reliability
of the device and security. Even for
practices not related to physical injury, the
content under the Warning heading is
used for precautions which need to be
taken which, otherwise, could result in
equipment damage, performance

Note

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

useful information including tips and
tweaks. It also calls attention to best
practices and industry-best protocols that
are standardized and help make maximum
utilization of the resources at hand.
Helpful information related to the
mainstream stuff also comes under the
Note heading helping the users get to
grips with the definitions, concepts, and
terminologies used in the manual.

Version History

Issue

Revision

Changes

1

1.0

-------

afety Precautions and Measures

S

The important safety precautions and measures that should be followed during the installation and
maintenance of the Liebert DM models are described in the following sections.

Read the manual prior to installation and operation of the unit. Only qualified personnel should
move, install, or service this equipment.

The user reads and takes into account all the precautions, compliance, and safety measures before
working on the equipment. The unit control must be used exclusively for the purpose which it is
intended for; the manufacturer takes no liability for incorrect use or a modification to the unit
control.

Adhere to all the Warnings and Cautionary measures included in the manual.

Please read this manual carefully before installing, maintaining and troubleshooting; especially the
Warning/ Danger/ Caution information in the User Guide. Apart from the User Guide, also pay
attention to the warning labels on the unit and its components.

This manual is retained for the entire service life of the machine. The user must read all the
precautions, danger, warnings, and cautionary measures mentioned in the manual prior to
carrying out any operations on the machine. Each machine is equipped with an electric
insulation which allows the users to work in safe conditions. The main switch is positioned on
the electrical panel cover; Open the right door to access it. Before any maintenance operation,
switch off the machine with this electronic insulation device in order to eliminate risks such as
electrical shocks, burns, automatic restarting, moving parts, and remote control. The panel key,
supplied along with the unit, must be kept by the personnel responsible for the maintenance.
The protective covers can be removed after the electric power has been cut off by opening
the main switch.

In the following section, take a look at the various cautionary measures and warnings that need to be read
carefully prior to installing or operating the system.

 Disconnect the local and remote power supplies prior to working with the unit.

 Prior to the installation process, read all the instructions, verify if all the parts are in place, and check the

nameplate to ensure that the voltage matches the utility power that is available for that unit.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

 The controller doesn’t isolate power from the unit even in the Off mode. Moreover, some internal
components require and receive power even during the Off mode.

 If the unit door is open while the fans are operating, the airflow may result in abrupt slamming of the door
resulting in injury. Another aspect is the presence of small objects in the fans bay which may result in object
ejection during the fan start-up and there is a probable risk of being hit by these objects leading to grievous
injury as well as causing equipment damage.

 The unit contains fluids and gasses under high pressure. Therefore, the pressure should be relieved
before working with the piping.

 Various components such as compressors, refrigerant discharge lines, and humidifiers are extremely hot
during the unit operation. Therefore, allow sufficient time for the unit to cool down before working with the
unit cabinet. Handle the unit with extreme caution and wear safety equipment such as protective gloves,
safety shoes, and arm protection while working with the hot compressors, discharge lines, and reheats.

 There is a risk of leaking water that can cause damage to the equipment as well as the building. There
should be an effective water drain connection and facilities. Installation should be precise. Implementation
of the application and service practices should be suitable and fault-free. Not complying with these norms
will result in water leakage from the unit. Water leakage can result in massive damage and loss of critical
equipment in the hosting ecosystem. Therefore, care should be taken to ensure that the unit must not be
located directly above any equipment that could sustain damage due to water and excessive moisture.
Using a leak detection system for unit and system supply lines are recommended by Vertiv Co.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

TABLE OF CONTENTS

PART I - GENERAL INFORMATION

1 Introduction ......................................................................................................................................................................................... 2

1.1 Model Nomenclature....................................................................................................................................................... 3

1.2 Basic Performance Parameters .............................................................................................................................. 3

1.3 Product Description ........................................................................................................................................................ 4

1.3.1 Compressor ......................................................................................................................................................... 5

1.3.2 Evaporator ........................................................................................................................................................... 6

1.3.3 Thermal expansion valve (TXV) ......................................................................................................... 6

1.3.4 Micro-processing Controller.................................................................................................................. 7

1.3.5 Strainer .................................................................................................................................................................. 7

1.3.6 Filter ......................................................................................................................................................................... 8

1.3.7 Centrifugal Fan................................................................................................................................................. 8

1.3.8 Condenser ........................................................................................................................................................... 8

1.3.9 Sight Glass .......................................................................................................................................................... 9

1.3.10 Infrared Humidifier ..................................................................................................................................... 9

1.4 Optional Components ................................................................................................................................................ 10

1.4.1 Electric Heater ............................................................................................................................................. 10

1.4.2 Remote Monitor ........................................................................................................................................... 10

1.4.3 Energy-Saving Card ...................................................................................................................................11

1.4.4 Power SPD..........................................................................................................................................................11

1.5 Working Conditions................................................................................................................................... 11

1.5.1 Operating Environment ............................................................................................................................ 12

1.5.2 Storage Environment ................................................................................................................................ 13

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

1.5.3 Refrigerant Charging Requirement ................................................................................................ 13

PART II - INSTALLATION

2 Installation .......................................................................................................................................................................................... 15

2.1 Pre-Installation ................................................................................................................................................................. 15

2.1.1 Transportation and Movement ........................................................................................................... 15

2.1.2 Unpacking..........................................................................................................................................................16

2.1.3 Inspection .......................................................................................................................................................... 17

2.2 Installation Preparation (Site Preparation) ................................................................................................. 17

2.2.1 Equipment Room Requirement.......................................................................................................... 17

2.2.2 Installation Space requirements .......................................................................................................18

2.2.3 Installation Tools.........................................................................................................................................20

2.3 Mechanical Installation .............................................................................................................................................. 21

2.3.1 System arrangement during installation..................................................................................... 21

2.3.2 System Installation Mode ..................................................................................................................... 23

2.3.3 Product Dimensions ................................................................................................................................. 24

2.3.4 Outdoor unit ................................................................................................................................................... 25

2.3.5 Indoor Unit Installation ........................................................................................................................... 26

2.3.6 Outdoor Unit Installation ...................................................................................................................... 27

2.3.7 Procedure ......................................................................................................................................................... 27

2.3.8 Piping for AC Unit ...................................................................................................................................... 29

2.3.9 Installation Notes Of Connector ..................................................................................................... 30

2.3.10 Required Pipe Connections............................................................................................................... 31

2.3.11 Connecting Refrigerant Pipe ............................................................................................................. 31

2.3.12 Pipe connector position ...................................................................................................................... 33

2.3.13 Connecting discharge pipe ............................................................................................................... 34

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

2.3.14 Connecting liquid pipe ......................................................................................................................... 34

2.3.15 Connecting Drain Pipe Of Indoor Unit ...................................................................................... 35

2.3.16 Connecting Humidifier Water Supply Pipe (If Applicable) ........................................ 35

2.3.17 Removing Transportation Fastener And Vibration Absorber ................................. 35

2.3.18 Adding Refrigerant For Long Pipe System ........................................................................... 36

2.3.19 Check List ...................................................................................................................................................... 37

2.4 Electrical Installation .................................................................................................................................................. 38

2.4.1 On-site Wire connections ..................................................................................................................... 38

2.4.2 Installation Notes ....................................................................................................................................... 38

2.4.3 Connecting Power Cable Of Indoor Unit ................................................................................... 39

2.4.4 Connecting Power Cable Of Outdoor Unit ............................................................................. 40

2.4.5 Connecting Control Terminals ......................................................................................................... 41

2.4.6 Connecting Monitoring Port Cable ............................................................................................... 45

2.4.7 Connecting Energy-Saving Card .................................................................................................... 45

2.4.8 Checklist ........................................................................................................................................................... 47

PART III - SYSTEM OPERATION & GENERAL MAINTENANCE

3 System Operation ......................................................................................................................................................................... 51

3.1 Start-Up Inspection ....................................................................................................................................................... 51

3.2 Micro-Processing Controller................................................................................................................................. 52

3.2.1 Features ............................................................................................................................................................. 52

3.2.2 Appearance ..................................................................................................................................................... 52

3.2.3 LCD Screen ..................................................................................................................................................... 53

3.2.4 Control Buttons ........................................................................................................................................... 53

3.2.5 Control Buttons Operation Example ............................................................................................ 54

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

3.2.6 ON Screen ........................................................................................................................................................ 55

3.2.7 Language Screen ........................................................................................................................................ 55

3.2.8 Normal Screen .............................................................................................................................................. 56

3.2.9 Password Screen ........................................................................................................................................ 56

3.3 Function Testing ........................................................................................................................................................... 57

3.3.1 Cooling ................................................................................................................................................................ 57

3.3.2 Heating............................................................................................................................................................... 58

3.3.3 Humidifying .................................................................................................................................................... 58

3.3.4 Dehumidifying .............................................................................................................................................. 58

3.3.5 Checking Refrigerant Charge Capacity of Low-Temp Outdoor .............................. 58

3.4 Micro-Processing Controller Menu Options ............................................................................................. 59

3.4.1 Main Menu........................................................................................................................................................ 59

3.4.2 Alarm Menu ................................................................................................................................................... 60

3.4.3 Set Points ......................................................................................................................................................... 63

3.4.4 System Status............................................................................................................................................... 63

3.4.5 System Menu .................................................................................................................................................66

3.4.6 Help Menu ....................................................................................................................................................... 67

3.4.7 Display Set .......................................................................................................................................................68

4 General Maintenance ................................................................................................................................................................69

4.1 Electric Inspection ........................................................................................................................................................ 70

4.2 Indoor Unit Maintenance ........................................................................................................................................ 70

4.2.1 Filter ...................................................................................................................................................................... 70

4.2.2 Fan ......................................................................................................................................................................... 72

4.2.3 Drain Pipe......................................................................................................................................................... 72

4.2.4 Heater ................................................................................................................................................................. 72

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

4.2.5 Humidifier ........................................................................................................................................................ 72

4.2.6 Power SPD ....................................................................................................................................................... 74

4.2.7 Thermal Expansion Valve..................................................................................................................... 76

4.2.8 High-Pressure Switch And Low-Pressure Switch ............................................................. 76

4.2.9 Compressor .................................................................................................................................................... 77

4.3 Outdoor Unit Maintenance .................................................................................................................................... 78

4.3.1 Refrigeration System................................................................................................................................ 78

4.3.2 Air-Cooled Condenser ............................................................................................................................ 78

4.3.3 Low-Temperature Unit Of Low-Temp Outdoor Unit ....................................................... 78

4.4 Maintenance Inspection Checklist .................................................................................................................. 79

4.5 Troubleshooting .............................................................................................................................................................81

APPENDIX 1 - Crcuit Diagrams .................................................................................................................................... 86

APPENDIX 2 Menu Structure ...................................................................................................................................... 87

APPENDIX 3 Parameter Setting Table................................................................................................................... 88

APPENDIX 4 - RDU-Cooling AC Single-Unit Manager Software Introduction ............................91

APPENDIX 5 - Hazardous Substances List........................................................................................................94

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual

PART I

GENERAL INFORMATION

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 1

1 Introduction

The Liebert DM series is the next generation series of small air conditioners that provide precise

environmental control. The Liebert DM models are the latest in the long line of modern enterprise­grade products from the Liebert family. Incorporating the high standards associated with the Liebert
name, the DM series utilizes the latest technology, system components, and a streamlined
manufacturing process.

Liebert DM air conditioners are products that are specifically created and designed for cooling the

electrical devices. It is applicable to equipment rooms, computer rooms, and similar ecosystems
which call for a high degree of accuracy and precision in maintaining the ambient temperature. It
addresses the needs and challenges associated with such applications and setups. It caters to
sensitive applications which need a suitable environment for optimal performance. Therefore, care
should be taken while testing these sensitive products or maintaining a favorable environment for
mission critical equipment, as even a slight deviation may lead to inaccurate results. Precision Air
Conditioning must not only keep room conditions within a specific range but also must have the
precision to react quickly to a drastic change in heat load and prevent wide temperature fluctuations.

The DM air cooled AC unit is packed with features such as high reliability, high sensible heat ratio,

and large airflow. The unit is an air-cooled single cooling system and configured with DC Speed
Regulation back- inclined centrifugal fan.

Packed with a host of features, it lowers the sound emissions significantly and thereby reduces the

noise pollution. It is a top-notch system that adheres to the standard in Precision Air Cooling in
terms of energy-efficiency, space requirements, and reliability.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 2

Figure 1-1 shows the appearance of various models in the Liebert DM series:

Figure 1-1

1.1 Model Nomenclature

The model nomenclature of the Liebert DM AC is shown in Figure 1-2:

Figure 1-1

1.2 Basic Performance Parameters

The basic performance parameters of the Liebert DM AC are given in Table within

Listing 1.1.

Listing 1.1

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 3

Model

Nominal

cooling

capacity

(kW)

Power

(kW)

Annual

energy

efficiency

ratio

Heating

capacity

[1]

(kW)

Humidification

capacity

[2]

(kg/h)

DME07M**5

6.85

2.36

2.9

3.2

1.5

DME12M**5

11.9

4.1

2.9

3.2

1.5

Note:

[1]: The heating capacity is only for the models with heating function;
[2]: The humidification capacity is only for the models with humidification function

1.3 Product Description

The Liebert DM AC unit is a comprehensive system that includes all the main functions fundamental to
precision cooling units such as cooling, humidification, dehumidification, re-heating, air filtration,
condensation management, temperature and humidity control, alarm functions and compatibility with
data communications. Liebert DM AC is designed to comply with mission-critical requirements and
ensure that servers are maintained at the correct temperature and humidity levels.

Figure 1-3 shows the various components and their respective locations:

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 4

Figure 1-2

Item

Description

Item

Description

1

Heater

2

Evaporator

3

Centrifugal Fan

4

Compressor

5

Infrared Humidifier

6

Microcontroller Display

7

Filter

Listing 1.2

In the following sections, take a look at the list of components used in the Liebert DM AC series.

1.3.1 Compressor

The Liebert DM AC series models comprise of a scroll compressor which has a host of promising
features such as low operating noise, less vibration and high reliability. Its compactness, smooth
compression with scroll operation and high energy efficiency ratio makes it an ideal compressor to
bank on for the DM series.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 5

Figure 1-3 shows the image of a compressor.

Figure 1-4

1.3.2 Evaporator

Heat exchanger design and appropriate air distributions are important factors that determine optimum
performance. The Evaporator used in the Liebert DM AC models consists of a fin-tube heat exchanger
for higher efficiency. The sophisticated design of the distributor ensures that the refrigerant is
distributed evenly in each loop, thereby improving the effectiveness of the heat exchanger.

Figure 1-5 shows the image of an Evaporator.

Figure 1-5

1.3.3 Thermal expansion valve (TXV)

The thermal expansion valve controls the amount of refrigerant flow into the evaporator thereby
controlling the superheat at the outlet of the evaporator. Liebert DM consists of a thermal expansion

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 6

valve with external equalizer type. It collects temperature and pressure signals at the same time to
accurately regulate the refrigerant flow.

Figure 1-5 depicts the image for the TXV:

Figure 1-6

1.3.4 Micro-processing Controller

The Controller adheres to the latest and highly advanced PID regulation technology. It provides a
simple operation user interface with multi-level password protection, self-recovery upon power failure,
high-voltage & low-voltage protection, phase loss protection, automatic phase-sequence switching
upon anti-phase and rotate speed control of the outdoor fan. The expert-level fault diagnoses system
can automatically display current fault information to facilitate equipment maintenance by
maintenance personnel.

Figure 1-7 depicts the panel of the Microcontroller:

Figure 1-7

1.3.5 Strainer

The Strainer filters the impurities generated during long-term system operation and ensures normal
system operation.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 7

1.3.6 Filter

Moisture can have an adverse effect on the operation and life of a system in the refrigeration cycle.

To counter that effect, Filter-driers are used to filter out particles, and remove and hold moisture to
prevent it from circulating through the system. The Liebert DM AC consists of nylon filter material
with big mesh. The filter features compact structure and easy maintenance. It can be washed
repeatedly.

1.3.7 Centrifugal Fan

Centrifugal fans are rigid and strong metal fans. Its axial flow blades help in reducing the noise. The
single-phase motor with high performance is customized based on the power grid of base stations, so
it can work over a wide voltage range with high reliability. It features large airflow, long blowing
distance, direct driving and easy maintenance.

Figure 1-8 depicts the image for the Centrifugal Fan:

Figure 1-8

1.3.8 Condenser

The Liebert range of air-cooled condensers offers many advantages, including sharp design, antirust
aluminum cabinets, low sound levels, and reliable operations over a wide range of ambient conditions.

Figure 1-9 depicts the image of a condenser:

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 8

Figure 1-9

1.3.9 Sight Glass

The sight glass is a utility for observing the refrigerant state; specifically the moisture content of the
system. If the moisture content exceeds the levels of defined standards the color changes, thereby,
indicating irregularity in the moisture content.

1.3.10 Infrared Humidifier

The infrared humidifier consists of infrared humidifier lamp, water injection valve, humidifying water
dish, temperature alarm protection devices and water level alarm device.

The infrared humidifier in the Liebert DM series provides quicker and more responsive operation
which is quite important for mission-critical applications. These humidifiers reduce the dependency of
water quality and simultaneously achieve full capacity in quick time using almost any water quality.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 9

Figure 1-10 depicts the image of a Humidifier.

Figure 1-10 Humidifier

1. The electrode humidifier should be installed and tested at the factory.

2. The Liebert DM AC can control the ambient humidity only after a humidifier is installed.

1.4 Optional Components

1.4.1 Electric Heater

T

he PTC electric heaters are used as they have lower running temperatures thereby ensuring

operational safety. PTC heaters are less susceptible to overheating and therefore, are long lasting

due to less wear. Lower maintenance and smooth functioning make it an important utility in Liebert DM

AC models.

Figure 1-11 shows an image of the Electric Heater:

igure 1-11

F

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 10

1.4.2 Remote Monitor

The Liebert DM AC communicates with the host computer through a configured RS485 port and
receives the control of the host software. Select and configure a monitoring card to realize different
monitoring functions. For the descriptions of the host monitoring software RDU-Cooling developed by
Vertiv Co., Refer to Appendix 4 RDU-Cooling Air-Conditioner Single-Unit Manager Software

Introduction.

1.4.3 Energy-Saving Card

The Liebert DM AC can monitor the maximum room temperature with the energy-saving card
located outside the unit cabinet. The card is placed in position with high heat load and temperature.
Up to four cards can be used for an AC unit. When the temperatures measured by all energy-saving
cards are lower than the set-point in ‘Sleep Mod’ and the only indoor fan is running; if the ‘Sleep Mod’
is set to ‘ENAB’, the AC unit will turn off the indoor fan and enter the sleep mode for saving the
energy.

1.4.4 Power SPD

T

he power SPD is used for the second level (C level) lightning over-voltage protection of the AC

power. It can be easily maintained and provides status indicating and alarm function.

1.5 Working Conditions

In

this section, take a look at the environmental conditions including the Operating and Storage

environment.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 11

1.5.1 Operating Environment

The table in Listing 1.3 defines the Operating environment parameters including the Ambient
Temperature, Protection level, Altitude, and Voltage range.

Listing 1.3

Item Requirements

The maximum equivalent horizontal distance between the

Installation position

indoor unit and outdoor unit

Vertical distance ΔH

[2]

[1]

: 50m;

: -5m ≤ ΔH ≤ 20m

Installation mode

Indoor unit: vertical mode, mounting base ≥ 150mm;
outdoor unit: horizontal airflow mode
Indoor: 0°C ~ 40°C

Ambient

Outdoor: standard model, -15°C ~ +45°C; Low-Temp model, -

temperature

34°C ~ +45°C
Ambient humidity 30%RH ~ 80%RH
Protection level Outdoor unit: IPX4
Altitude < 1000m. Derating is required when the altitude exceeds 1000m
Operation voltage
range

380V (-15% ~ +15%), settable according to different

environments, the tolerance is 3%
Note: [1]: For the equivalent lengths of parts, refer to Listing 2.5
[2]: The value is positive if the outdoor unit is installed above the indoor unit; negative
if the indoor unit is installed above the outdoor unit

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 12

1.5.2 Storage Environment

Item

Requirement

Storage environment

Indoor, clean (without dust)

Ambient humidity

5%RH ~ 85%RH

Ambient temperature

-40°C ~ +70°C

Total transportation and storage time should not exceed

Brand

Logo

Note

The DU PONT refrigerant adapts

The following table defines the Storage Environment parameters including the ambient humidity,
ambient temperature, and storage time conditions.

Listing 1.4

Storage time

six months. Otherwise, the performance needs to be re­calibrated

Another essential aspect is the quality and the make of the refrigerant oil. Adding poor quality oil,
counterfeit oil, or oil for a different model will damage the system. The quality issue due to the wrong
refrigerant oil will result in the voiding of warranty.

1.5.3 Refrigerant Charging Requirement

The low quality or counterfeit refrigerant will damage the system severely. Please use the refrigerant
approved by Vertiv Co., Ltd. For the system abnormality or damage caused by using other brands of
refrigerant, Refer the table in listing 1.5 for the refrigerant brands approved by Vertiv Co., Ltd.

Listing 1.5

DU PONT

custom made package

JUHUA

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 13

Part II

INSTALLATION

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 14

2 Installation

2.1 Pre-Installation

Pre-installation contains the following 3 sub-sections, namely –

 Transportation and Movement  Unpacking  Inspection

2.1.1 Transportation and Movement

When transporting the system, Railroad is a preferable choice. However, if railroad transportation is
not possible, then the truck transport option is an optimal choice. One precaution is to choose roads
that do not have too many bumps and if any, avoid it as much as possible.

It is recommended that equipment like an electric forklift is utilized for these heavy duty systems.
Move the equipment to a location which is in the vicinity of the installation site.

If an electric forklift is used, insert the tines of the forklift below the pallet as displayed in Figure 2-1.
Align the tines with the center of gravity to prevent the equipment from falling over. Figure 2-1
depicts the way the tines of the forklift are inserted below the pallet and in the same image; the
graphic to the right indicates that the tines are aligned with the center of gravity to prevent the
equipment from falling over:

Figure 2-1

In the previous Figure 2-1, the air conditioner is lifted using the forklift truck and is aligned with the
center of gravity. While moving the indoor unit, the obliquity has to be maintained at an angle of 75°
to 105°.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 15

Figure 2-2 depicts the 75° to 105° obliquity that is suitable to move the air conditioning package to the
vicinity of the desired location:

Figure 2-2

2.1.2 Unpacking

The cabinet uses a honeycomb cardboard and winding stretch film for packaging purposes. Shift the
product to a location closer to the final installation site prior to unpacking the unit.

Initially, remove the top cover and winding stretch film. Next, remove the honeycomb cardboard as
depicted in Figure 2-3.

Figure 2-3

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 16

The unit is fixed on the packing pallet with M8*20 and M8*80 screws. Use a 17 mm open-end spanner,
ratchet spanner, or sleeve to remove the screws.
Figure 2-4 to shows the schematic diagram:

Figure 2-4

2.1.3 Inspection

Moving forward, check the system fittings and its components against the packing list to ensure that
everything is in place and the assembly is intact. If any parts or components are missing or damaged,
immediately report to the carrier about the same. If hidden damages are observed, then contact the
local offices of that carrier as well as Vertiv Co., at the earliest.

2.2 Installation Preparation (Site Preparation)

The Liebert DM AC series of air conditioners is streamlined for maintaining a favorable environment
for data centers, computer rooms, and similar ecosystems. Strict adherence to the installation
procedures is mandatory in order to ascertain proper installation of the air conditioner.

2.2.1 Equipment Room Requirement

The equipment room must be prepared to ensure a smooth operation flow and obtain accurate
results. The equipment room must meet the standards for appropriate ventilation and heating. The
design specifications for the air conditioners must be ideal and should match the energy-efficient
design standards.

Following are the requirements for maintaining a favorable room environment prior to installation:

 The equipment room should be well insulated and have a sealed damp-proof layer.

 The most important elements for maintaining normal environmental control in the conditioned room

are damp proof and heat preservation.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 17

 The outside air will add to the loads of heating, cooling, humidifying and dehumidifying of the system. It is
recommended that the inhalation of outside air should be kept below 5% of the total indoor airflow.

 All the doors and windows should be properly sealed to minimize the leakage and the seams should be as narrow
as possible.

Vertiv Co. recommends that the site preparation is defined as per the requirements. However, if these

requirements are not met, rectifications must be made on the site so that it complies with the specified

requirements and conditions. However, if the recommended rectifications or modifications are not

implemented, then Vertiv Co. does not guarantee the accuracy and precision of the temperature and

humidity provided by the Liebert DM model. One important aspect to be considered is that the indoor

unit must not be used for the outdoor environment.

2.2.2 Installation Space requirements

Air conditioners in the Liebert DM AC series are advanced precision air cooling units and therefore,
these air conditioners must be installed, preferably in a capacious floor space to ensure its normal
operation.

The Liebert DM AC can generate condensate water. Water leakage can cause damage to other precise

equipment nearby. Do not install the AC units in the vicinity of any precision equipment. The installation

site must provide drainpipes.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 18

The installation location requirements are given as follows:

Not recommended location

location

Recommended

• Avoid locating the indoor unit in confined areas that affect the airflow pattern, shorten cooling cycles and
result in down-draft and air noise.

• Avoid locating the indoor unit in an alcove or at the extreme end of a long, narrow room.

• Avoid locating multiple indoor units close to each other. This can result in crossing air patterns, uneven

loads and compete for operation.

• Do not install additional devices (such as smoke detectors) over the cabinet for facilitating routine
maintenance.

The following Figure 2-5 depicts the installation location of the indoor unit.

Figure 2-5

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 19

2.2.3 Installation Tools

Name

Drawing

Name

Drawing

Slotted

Cross head

Insulated torque

Torque

The following table in listing 2.1 shows the generic toolsets and utilities used in the installation and
maintenance process:

Listing 2.1

Electric hand drill

screwdriver

Stepladder

Drill

Claw hammer

Insulating shoes

Electrician knife

Insulating tape

Adjustable wrench

screwdriver

Forklift

Wire cutting pliers

Diagonal cutting
pliers

Antistatic gloves

Cable ties

Insulating gloves

Crimping pliers

wrench

Multi-meter

tube

screwdriver

Clip-on ammeter

The tools mentioned in listing 2.1 are generic and commonplace; however, depending on various factors
such as site environment, cables, installation equipment, and on-site electrical connections these tools
may vary in a real-time scenario.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 20

Heat shrinkable

Ensure that the tools used in the installation, operation, and maintenance processes are insulated. This

safety measure is important for professionals and service personnel who work with this Liebert DM

range air conditioner.

2.3 Mechanical Installation

Proper installation is important to achieve optimal performance and prolong the product life. In this
section, the mechanical installation will be discussed in detail to help the personnel get to grips with the
installation process.

Before proceeding with the mechanical installation, the following safety precautions need to be taken

into account:

 Prior to installation, ensure that the installation procedures have been read and implemented as per
the requirement. (Refer to section 2.2 for the Installation Site preparation). Check if any modifications
are made to the plumbing, wiring, or ventilation facility before mounting the equipment. Once the
installation preparations are taken into consideration, move on to the next step in the installation
process, and eventually set up the system.

 The Liebert DM cooling units are designed for split-floor installation. The indoor unit must be installed
on the floor of the equipment room or computer room. The outdoor unit must be installed outdoors or
on the floor of the other rooms as per the building architecture.

 Industry-wide standards are followed for the selection, layout, and fixing of pipes.

 Several factors such as pressure drop, compressor oil return, noise reduction, and vibration are

considered during the design and installation process.

 Follow the design drawings strictly when installing the equipment. Reserve space as per the
maintenance and serviceability instructions in the previous chapter on Installation Preparation. The
manufacturer’s engineering dimension drawings must be taken as a reference while installing the
equipment.

2.3.1 System arrangement during installation

The system general arrangement diagram is depicted in Figure 2-6.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 21

Figure 2-6 General arrangement diagram

Actual cooling capacity

Pipe length (m)

Discharge pipe

Liquid pipe

1. : Factory piping

2. : Field piping (by technicians)

The following points should be considered before checking out the overall layout diagram:

The single system is used as an example to describe the entire system.

 Vertiv Co. staff and qualified professionals lay out the piping in the laboratory.

 Piping is done by technicians.

 Components (marked with *) are not supplied by Vertiv Co. but are recommended for proper circuit

operation and maintenance.

 Additional components (marked with +) are required when the equivalent length exceeds 30m.

The standard pipe sizes are shown in Table within Listing 2.2.

Listing 2.2

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 22

OD

OD

Liebert DM

AC series

7.5kW unit

5

1/2” (12mm)

3/8” (10mm)

12.5kW unit

5

5/8” (16mm)

1/2” (12mm)

Outdoor unit

Floor

Isolataion

floor

Max. 20m

1:200

7.5m

1:200

Insulation
material

Trap

Liquid pipe (not be exposed to sun)

Sealed

Protection

tube

Discharge pipe (slope)

Indoor unit

Condensation water
drain pipe (to outdoor)

Humidifier canister water
supply pipe (to water tap)

Humid ifier water supply p ipe
( to water tap )

2.3.2 System Installation Mode

The Liebert DM AC is available in two installation modes:

 Outdoor unit installed higher than Indoor unit

 Indoor unit installed higher than Outdoor unit.

The schematic diagram of Outdoor Unit installed higher than Indoor unit is depicted in Figure 2-7

Figure 2-7 Outdoor unit above indoor unit

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 23

The schematic diagram of Indoor Unit installed higher than Outdoor unit is depicted in Figure 2-8

1850

1975

Figure 2-8 Indoor unit above outdoor unit

2.3.3 Product Dimensions

The dimensions and weight of the indoor unit are displayed in Figure 2-9 and in the table within Listing

2.3

DME07kW DME12kW

Figure 2-9 Dimensions of indoor unit (unit: mm)

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 24

The shadows in Figure 2-10 indicate a reasonable installation and service space. The two sides of the

352

787

829

1240

352

787

352

1037

575

1238

352

1037

575

829

unit need air inlet. Adequate service space must be reserved for the unit to facilitate maintenance.

The AC unit equipped with a heater should be kept a distance of minimum 150 mm from combustible
substance. When testing the AC unit, keep the external static pressure below 150Pa lest the air
volume becomes too low and the heater becomes too hot.

2.3.4 Outdoor unit

The mechanical parameters of the outdoor unit are shown in Figure 2-10, 2-11 and

Table 2.3

2-10 Dimensions of standard outdoor unit (unit: mm)

Figure 2-11 Dimensions of Low-Temp outdoor unit (unit: mm)

Listing 2.3

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 25

Model

Cooling capacity (kW)

Dimensions (W × D × H)

in mm

Net weight

(kg)

Indoor

unit

7.5

510 × 385 × 1850

100

12.5

600 × 500 × 1975

155

7.5

787 × 352 × 829

40

12.5

787 × 352 × 1240

60

7.5

1037 × 352 × 829

55

12.5

1037 × 352 × 1238

90

510

385

Rubber cushion

(8mm ~ 10mm thickness)

Steel plate (60 60 4)

H > 150

Rubber cushion
(8mm thickness)

Angle iron (30 30 3) or
square tube (25 25 3)

×

×

×

×

×

×

600

500

H > 150

Installation hole for

expansion bolt (M6 50)

Rubber cushion

(8mm ~ 10mm thickness)

Steel plate (60 60 4)

Rubber cushion
(8mm thickness)

Angle iron (30 30 3) or

square tube (25 25 2)

×

×

×

×

×

×

×

Outdoor

Standard model

unit

Low-Temp model

2.3.5 Indoor Unit Installation

1. The outline and dimensions of the mounting base are shown in Figure 2-12.

Figure 2-12 Mounting base of DME07kW indoor unit

Figure 2-13 Mounting base of DME12kW indoor unit

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 26

Mounting base (unit: mm)

2. Lay a rubber cushion with 8mm ~ 10mm thickness on the mounting base, as shown in above figure.

Grill

The grilles can be rotated
following the arrow direction

3. Place the indoor unit onto the mounting base and secure it with nuts, spring washers, flat washers
and bolts.

4. Rotate the grilles to regulate the airflow direction of the indoor unit, and the regulating angle is 45°,
as shown in Figure 2-14.

Figure 2-14 Regulating airflow direction

2.3.6 Outdoor Unit Installation

The installation location requirements are mentioned as follows:

 Install the outdoor unit in a place which is secure and easy for maintenance. Do not install it on ground-level sites

with public access and be away from residential areas.

 Do not locate it directly in the environment that requires low noise.

 To ensure heat dissipation effect, locate it in a clean area, which is away from loose dirt and foreign matter to

avoid clogging the heat exchanger.

 Do not locate it in the vicinity of steam, hot air and exhausts.

 Keep a clearance of more than 450 mm between the outdoor unit and the wall, obstruct and adjacent devices.

 Avoid areas where snow will accumulate at the air inlet and outlet side of the outdoor unit.

 Prepare a solid base capable of supporting the outdoor unit weight (refer listing 2.3). The base should be at least

50mm higher than the surrounding ground and 50mm larger than the dimensions of the outdoor unit base, as
depicted in Figure 2-17.

2.3.7 Procedure

 Place the outdoor unit on the base.

 Secure the outdoor unit onto the base with expansion bolts. The installation hole size of the base is shown in

Figure 2-15 and Figure 2-16.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 27

Figure 2-15 Installation hole dimensions of standard outdoor unit base (top view, unit: mm)

787

374

680

R6

394

680

1037

374

394

R6

Figure 2-16 Installation hole dimensions of Low-Temp outdoor unit base (top view, unit: mm)

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 28

If multiple outdoor units are needed to be installed one above the other, refer

Bracket

4m 0.5m

50mm50mm

Min. 50mm

Outdoor unit base

Base

Airflow

Airflow

Out-

door

unit

Out­door

unit

Note:

1. Use 5# angle iron for bracket, when
two units are installed with one above
the other.

2. Use 6.5# channel steel for bracket, when
three units are installed with one above the
other.

Figure 2-17 to install them.

Figure 2-17

2.3.8 Piping for AC Unit

General Principles

 Copper pipes with a quick thread connector should be used to connect to the indoor and the outdoor unit. If the

pipe length exceeds the standard pipe length (refer listing 2.2) and the straight copper pipe is used, piping joints
must be brazed.

 Standard industry procedures must be followed in the selection and placement of pipe, and charging with

refrigerant (only when the pipeline is too long). The standard refrigerant of the AC unit is R407C.

 Considerations must be given to pipeline pressure drop, oil return to the compressor, to avoid oil leakage and

clogging in parts of the system and minimize noise and vibration to the greatest extent.

 Always consult Vertiv Co. before installation on the measures such as, using extended piping kit are needed, if

the equivalent length exceeds 30m, or if the vertical distance between the indoor unit and the outdoor unit
exceeds the values as mentioned in Table within Listing 2.4.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 29

Listing 2.4

Relative position

Value

Outdoor unit installed higher than indoor unit

Maximum: 20m

Outdoor unit installed lower than indoor unit

Maximum: 5m

Liquid pipe OD (inch)

Equivalent length (m)

90° elbow

45° elbow

T-type three way

3/8

0.21

0.10

0.76

1/2

0.24

0.12

0.76

5/8

0.27

0.15

0.76

3/4

0.3

0.18

0.76

7/8

0.44

0.24

1.1

1-1/8

0.56

0.3

1.4

 The equivalent length of each part is given in Table within Listing 2.5. The resistance loss caused by elbows and

valves has been taken into consideration. The installer should confirm if these values are appropriate for site
conditions.

Listing 2.5

2.3.9 Installation Notes Of Connector

Utmost care should be taken while connecting the quick thread connector. Read the following steps

before carrying out the connections:

1. Remove the dust-proof caps.

2. Carefully wipe coupling seats and threaded surface with a clean cloth.

3. Lubricate the male thread with the refrigerant oil.

4. Thread the coupling halves together by hand to ensure that the threads mate properly.

5. Tighten the coupling body’s hexagon nut and union valve until a definite resistance is felt.

6. Use a marking pen to draw a line lengthwise from the coupling union nut to the bulkhead. Tighten
the nuts an additional quarter turn with two wrenches. The misalignment of the lines indicates how
much the coupling has been tightened. The final quarter turn is necessary to ensure that the joint
does not leak. Two wrenches must be used to cooperate with each other during connection
because using one wrench can damage the coupling copper lines easily.

The recommended torque values are mentioned in Table within Listing 2.6.

Listing 2.6

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Coupling size

Torque value (N-m)

5/8”

7 ~ 8

3/4”, 7/8”

25 ~ 32

2.3.10 Required Pipe Connections

Refer Figure 2-7; the required pipe connections are mentioned as follows:

The refrigerant pipe between the indoor unit and the outdoor unit (discharge pipe and liquid pipe).

Drain pipe of the indoor unit.

The following pipe connection is required if a humidifier is selected.

Water supply pipe to the humidifier.

Before starting, ensure that all the pipe connections have been completed without leakage after

engineering installation.

2.3.11 Connecting Refrigerant Pipe

The following notes should be considered while connecting a refrigerant pipe:

1. The indoor unit and outdoor unit should be determined based on the specifications mentioned in
Table within listing 2.7. If longer pipes are required, contact Vertiv Co. or the concerned sales agency.

2. The liquid pipe is the refrigerant liquid pipe of the outdoor unit outlet. Thereby, a reasonable pipe
diameter and length should be selected for the liquid pipe to ensure that the pressure drop of the
refrigerant liquid through the pipe during unit operation does not exceed 40kPa (5psi ~ 6psi).

3. The pipe should be installed and removed with utmost care so that they will not get kinked or
damaged. Ensure to use the tube benders and make all the bends before making connections to
either end.

4. If the joint mode is needed, all refrigerant piping should be connected with silver-brazed joints.

5. Check the piping supports, leakage testing, dehydration of refrigerant pipes and evacuation before
use. A vibration isolating support should be used to isolate the refrigeration pipes from the building.

6. Use a soft and flexible material to pack around the pipes to protect them from damage caused by
going through openings in walls and to reduce vibration transmission.

7. While installing the outdoor unit 7.5m higher than the indoor unit, a trap should be installed on the
discharge pipe. This trap will retain refrigerant oil in the off cycle of the compressor. When the

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 31

compressor starts, oil in the trap will be carried up the vertical riser and return to the compressor

Model

DME07

DME12

Pipe length

D L D

L

10m

12.7

9.52

16

12.7

20m

12.7

9.52

16

12.7

30m

16

9.52

19

12.7

40m*

16

9.52

19

12.7

50m*

19

9.52

22

12.7

Note:

immediately.

Listing 2.7 Recommended pipe sizes (unit: mm)

1. A pipe extension kit is required for ‘Eq.Lgth’ marked with *.

2. D: discharge line, L: liquid line.

3. Consult Vertiv Co. if the pipe length exceeds 50m.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 32

2.4 Pipe connector position

B

处

气侧管

直管

1/2''-12mm

接头3/4

''-20mm

螺纹

液侧管

直管

3/8''-10mm

接头5/8

''-16mm

螺纹

加湿进水管

1/4''

铜螺母

1/4''×1/2''

转换铜螺纹接头

冷凝水排水管

（铜管接头 外径22mm）

B处放大

Liq ui d pipe: straight pipe 3/8″-10mm;
co n nector 5/8″-16mm th read

Co nd ensate water d rain
pip e(O,D,22mm)

A amplified

Humid ifier water supply p ipe
1/4 ″ copp er nut
co n nector 1/4 ″ ×1/2 ″ thread

Discharge pipe:
Straight pipe 1/2 ″-12mm;
Connector 3/4 ″ -20mm thread

A

Liq uid pipe: straight p ipe 1/2″-12mm;
co n nector 3/4″-20mm th read

Humidifier water supply pipe
1/4 ″ copper nut
co n nector 1/4 ″ ×1/2 ″ thread

Cond ensate water d rain
pipe(O,D,22mm)

Discharge pipe:
Straight pipe 5/8″-16mm;
Conn ector 7/8 ″ -22mm thread

B amplified

B

The pipe connectors inside the indoor unit are shown in Figure 2-18.

Pipe connectors inside DME07kW indoor unit

Pipe connectors inside DME12kW indoor unit

Figure 2-18

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 33

2.4.1 Connecting discharge pipe

A

处放大

气侧管 DMC12/ DML12（直管5/8"；接头7/8" －22mm

液侧管 DMC12/ DML12 （直管1/2"

；

3/4" －20mm 螺

气侧管 DMC07/ DML07（直管1/2" ； 3/4" －20mm 螺

液侧管 DMC 07/DML07 （直管3/8" ；接头5/8" －16 mm 螺

B处放大

B处

A处

接头

接头

A amplified

Liq uid pipe DMC 12/DML12 (straight p i pe 1/2″;
co n nector 3/4″-20mm th read)

Dis charge pipe DMC 12/DML12 (straight pipe 5/8″;
co n nector 7/8″-22mm th read)

A

Dis charge pipe DMC 07/DML07(straight pipe 1/2″;
co n nector 3/4″-20mm th read)

Liq uid pipe DMC 07/DML07(straight p i pe 3/8″;
co n nector 5/8″-16mm th read)

B amplified

A

Connect one end of the discharge pipe to the discharge pipe connector of the indoor unit (shown in
Figure 2-18) and the other end to the discharge pipe connector of the outdoor unit (shown in Figure
2-19).

The discharge pipe is the pipe at the compressor discharging side. Its horizontal section should be

sloped downward, away from the compressor, with a slope of at least 1:200 (5mm down for each 1m run).

The discharge pipe should be insulated where it is routed in the conditioned space (including under a

raised floor).

Figure 2-19 Refrigerant pipe connectors of outdoor unit

2.4.2 Connecting liquid pipe

Connect one end of the liquid pipe to the liquid pipe connector of the indoor unit (shown in Figure 2-

18) and the other end to the liquid pipe connector of the outdoor unit. (shown in Figure 2-19).

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 34

2.4.3 Connecting Drain Pipe Of Indoor Unit

The drainage pipe of the indoor unit equipped with a humidifier must be able to endure the hot water
up to 90℃. Use galvanized steel pipe, aluminum-plastic composite pipe with hot water type or PP-R
polypropylene plastic pipe with hot water type as the drainage pipe.

Connect one end of the drain pipe to the connector of condensate water drain pipe (shown in Figure
2-18). Pipe with I.D 22 mm should be used as the indoor unit provides copper pipe of O.D 22 mm to
connect with the drainage pipe. One of the accessories used is a clamp to fix the outdoor drainage
pipe.

2.4.4 Connecting Humidifier Water Supply Pipe (If Applicable)

An isolation valve should be installed on the humidifier water supply pipe for easy maintenance.

Connect the humidifier water supply pipe to the connector of the AC unit shown. The unit provides
the humidifier with copper pipe (O.D 6.35mm). The 1/4” copper nut at the end of the copper pipe and
the 1/4” × 1/2” conversion copper thread connector has been connected to the copper nut to avoid
losing them.

Where the main pipe pressure may rise above 700kPa (The main pipe pressure should be between

100kPa ~ 700kPa), a pressure reducer should be fitted.

Where the main pipe pressure falls below 100kPa, a water tank and pump system should be used.

Some products may include components required by local codes.

2.4.5 Removing Transportation Fastener And Vibration Absorber

To protect partial components from damaging and distorting due to bumping, impact and resonation;
fasteners and vibration absorbers are mounted at certain locations before delivery. Remove the
fasteners and vibration absorbers before the installation and commissioning.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 35

Removing transportation fixing plate of the compressor

To reduce the compressor's operational noise and vibration; the vibration absorbing cushions are
added to the compressor base. However, such a method cannot suitably restrain the equipment
vibration during transportation and would result in loosened connections and wear of certain parts.
To prevent this, three U-shaped fixing plates are added to the compressor base, as shown in Figure
2-20.

Figure 2-20

After the installation and before commissioning, remove the three U-shaped fixing plates, and then
restore the bolts and washers. The fastening torque of the bolts is (12 ± 1) Nm.

2.4.6 Adding Refrigerant For Long Pipe System

The Liebert DM AC has been charged with appropriate refrigerant before delivery. If the connecting
pipe between the indoor unit and the outdoor unit is longer than 10m, add refrigerant to the system
in order to ensure normal system operates based on the following formula:

Adding refrigerant amount (kg) = adding refrigerant amount per meter of liquid pipe (kg/m) × total
length of extended liquid pipe (m)

Refer Table within listing 2.8 for the adding refrigerant amount per meter of liquid pipe with different
OD liquid pipes.

Total length of extended liquid pipe (m) = total length of liquid pipe (m) - 5m.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 36

Listing 2.8

Liquid pipe OD (inch)

Adding refrigerant amount per meter (kg/m)

3/8

0.060

½

0.112

5/8

0.181

¾

0.261

7/8

0.362

1-1/8

0.618

Item

Result

Proper clearance for service access is maintained around the

The equipment is placed vertically and mounting fasteners are

The pipes between the indoor unit and outdoor unit are

Suction pipes should be insulated properly

The drain pipe is connected and insulated

All pipe connectors are tight

After installation, foreign materials in and around the equipment
Rotate the fan blades with the hand; the fan rotates freely

2.4.7 Check List

Confirm the items listed in the table under listing 2.9 on completion of Mechanical Installation.

Listing 2.9

AC unit

fastened

Check compressor mountings to avoid vibration later

completed. The quick connector valves of the indoor unit and
outdoor unit are fully opened

Water supply pipe is connected to the humidifier (if required)

are removed (such as shipping materials, construction
materials, tools, and so on)

without unusual noise

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 37

2.5 Electrical Installation

In this chapter, the electrical installation of the Liebert DM air cooled units is explained in-depth to
help users get to grips with the various tasks which include the task introduction, notes, and cable
connections of the indoor unit apart from the checklist.

The air conditioners in the Liebert DM series are professional devices used in industrial, commercial, or

other professional occasions. It is not tailored for the general public. The total rating power is larger than

1 kW and is in with the IEC61000-3-12 standard. A port of less than a 250 short circuit requires is

required between the user power and the grid. Permission is required from the power supply

department to ensure that the air conditioner is connected to a power no less than 250 circuit ratio.

2.5.1 On-site Wire connections

Following are the wires that have to be connected in/on the site:

 Power cable of the indoor unit: 3P5W (3×L＋N＋PE).

 Power cable of the outdoor unit: standard model (L + N + PE) and Low-Temp model (L + L’ + N + PE).

 Unit monitoring and control cable (if the remote control is applicable).

 Energy-saving card cable (if applicable).

2.5.2 Installation Notes

 The connections of all the power cables, control cables, and ground cables should be in compliance with the local

and national electrical regulations. Power supply cords should not be lighter than ordinary PVC sheathed flexible
cord GB5023.1 (IDT IEC60277) of the No. 53 line.

 Observe the unit nameplate for the full load current. The cables sizes must meet the conditions as specified in

the local wiring protocols and rules.

 Mains supply requirement: 3P5W (380Vac, 50Hz, 3

 The electrical installation must be completed by trained professionals.

 Prior to wiring, a voltmeter must be used to measure the power voltage and ensure that the power has been

switched off.

 An all-pole disconnection device must be configured upstream the device to ensure operation safety.

 If the supply cord is damaged, to avoid danger, a replacement must be made by the manufacturer, the

maintenance department or similar department professional replacement.

×L＋N＋

PE).

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 38

2.5.3 Connecting Power Cable Of Indoor Unit

The recommended cable size is not less than 10AWG (6 mm2).

Use the provided inner hexagon wrench to rotate the indoor unit locks, open the front door. At this
point, the power output terminal of the indoor unit is revealed at the left side panel, as shown in
Figure 2-21.

The Figure 2-21shows the Power connection position of indoor unit:

Figure 2-21

Lead the power cable through the cabling hole, connect it to the power output terminal of the indoor
unit, and fasten it with a cable clamp, as shown in Figure 2-22. Connect the other end to the AC
power outside the AC system.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 39

The Figure 2-22 depicts the input and output power wiring of the indoor unit.

Figure 2-22

 Use copper cables only and ensure that all connections are solid while wiring

 Make sure that the power voltage matches the voltage specified on the unit nameplate.

 Install a disconnect switch before the power input of the indoor unit to isolate the unit for

maintenance. Connect the power cable to the disconnect switch and then to the unit.

 Cut off the power to the unit before maintenance inside the unit because the unit contains high
voltage

2.5.4 Connecting Power Cable Of Outdoor Unit

The standard length of the outdoor unit power cable is 8m, if a longer cable is required, contact
Vertiv Co. The recommended cable size is not less than 18AWG (0.75mm2).

Connect one end of the outdoor unit power cable to the power output terminal of the indoor unit
(shown in Figure 2-22) and the other end to the power connection terminals of the outdoor unit
(shown in Figure 2-23 and Figure 2-24).

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 40

The Figure 2-23 shows the Power connection of standard model outdoor unit

电源线（L＋N＋PE）

PE N N L L'

A

Power cable (L+N+PE+L')

Back side of
outdoor unit

Cable clip

A: Power connection

Slot screwdriver (3mm)

Terminal designation

Figure 2-23

The Figure 2-24 shows the Power connection of Low-Temp model outdoor unit.

Figure 2-24

2.5.5 Connecting Control Terminals

The control terminals are located on the PCB and terminal block of the electrical control box, as
shown in Figure 2-25.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 41

7.5KW single cooling unit 7.5KW humidification unit

control terminals on the terminal block

reactor (EC unit use)

control terminals on the PCB

control terminals on the PCB

control terminals on the terminal block

reactor (EC unit use)

Control terminals on the terminal block

Control terminals on the PCB

12KW cooling unit

Figure 2-25 Control terminal position

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 42

The control terminals on the PCB are shown in Figure 2-26; the control terminals on the terminal
block are shown in Figure 2-27.

Before connecting the control cables, the service personnel must take anti-static measure.

Figure 2-26 Control terminals on the PCB

Figure 2-27 Control terminals on the terminal block

Remote shutdown

The PIN5 and PIN6 of the remote shutdown J19 can be used to remotely control the unit ON/OFF
status, stopping the unit operation depending on the particular time. If the input of remote shutdown
terminal is shorted and the AC unit power is switched on, the AC unit outputs normally. If the terminal
is open, the AC unit will stop outputting. The remote shutdown terminal has been shorted before
delivery. If the control cable of remote shutdown needs to be connected onsite, remove the short
cable and connect the outer controller to the remote shutdown terminal.

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SPD (Customer 1 terminal)

When the PIN1 and PIN2 of the customer 1 terminal (control terminal) J19 are not connected to SPD
signal, they can connect with an alarm signal except for the AC system. Any outer alarm signal with
NO dry contact can be connected to the customer terminal. After the outer alarm signal is connected,
set the corresponding customer alarm information in micro-processing controller. For more details,
refer to Customer Alarm in 3.4.2 Alarm Menu. If there is no alarm signal connected, the input state of
the customer terminal is the same as the settings. If the outer alarm is generated, the input state of
the customer terminal is different from the settings. The AC system will generate an audible alarm
and LCD screen on the micro-processing controller will display the corresponding alarm information.
If a computer using Vertiv Co. host monitoring software is connected, then the alarm will be displayed
on that computer too.

If the power SPD is configured, the PIN1 and PIN2 of the customer 1 terminal J19 has been connected
with alarm signal of power SPD in the factory and the alarm is set to be normally closed (NC).

General alarm terminal

The general alarm relay connected with 19 and 20 on the terminal block (see Figure 6-7) has a set of
NC dry contact, which can be set to normally closed by using the software. When a serious alarm is
generated, the contact is closed. This can be used to send a remote alarm, sending signals to the
building management system or dialing the paging system automatically.

Lead/standby switchover and requirement terminals

The PIN18 and PIN20 of the lead/standby switchover the terminal and the PIN7 and PIN8 of the
requirement terminal J19 (see Figure 2-27) are used to connect two AC units working in master-slave
mode.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 44

Figure 2-28 shows the Connection in master-slave mode.

ERR

COMM

RUN

DME07MC1A2

Front
Plate

Interface

DIP switch

Figure 2-28

2.5.6 Connecting Monitoring Port Cable

The RS485 port of the Liebert DM indoor unit is located on the J39 terminal on the PCB (see Figure
2-26), uses a twisted-pair communication cable to connect it to the upper machine.

Multiple Liebert DM AC's can recognize simultaneous multi-units monitoring through RS485 bus.
Taking RDU-Cooling host monitoring software developed by Vertiv Co. for example, Figure 2-29
introduces to a networking mode of RS485 bus monitoring two AC units simultaneously.

Figure 2-29 Networking mode monitoring two AC units

2.5.7 Connecting Energy-Saving Card

The Figure 2-20 shows the energy-saving card:

Figure 2-20

Use 4-core shielded cables with a recommended cable diameter not less than 20AWG (0.52 mm2) to
connect the energy-saving card. Make sure that the two ends of the shielded layer and the energy-

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 45

saving card are grounded reliably to increase the anti-interference ability. The grounding cable

J8.3

J8.2

J8.1

ON

+12 V GND CA NHCA NL

CANH

CANL

GND

12V

DIP switch

Earth terminal

should not exceed 10 cm, and the cable size should be above 2 mm2. Make sure that all connections
are tight.

Use the energy-saving card according to the following steps:

 Open the front plate of the energy-saving card plastic shell and take out the energy-saving cardboard along with

the card slot inside the plastic shell. The Figure 2-21 shows the energy-saving cardboard.

Figure 2-21

 Short the terminals J8.1 and J8.2 in the furthest energy-saving card and short the terminals J8.2 and J8.3 in other

cards.

 Ground the cards appropriately.

 Put the energy-saving card into the shell along with the card slot and replace the front plate.

 Use 4-core shielded cables to connect the Liebert DM control board on the rear portion of the front door of the

indoor unit to 12V, GND, CANH and CANL interfaces of the energy-saving card; then snap the accessory

magnetic buckle on the shield cable close to the control board end.

 Use 4-core shielded cables to serially connect 12V, GND, CANH and CANL interfaces of other cards (if more than

one card is used).

 Ground the shielded cables appropriately.

 Set bits 1 and 2 of the DIP switch to card address and other bits to 0 (ON: 0, OFF: 1).

 Fix the energy-saving card in position with the heavy room temperature load with screws or the card slot in the

shell.

 Enter Sleep Mod menu to view whether the temperature of the energy-saving card is normal.

 Figure 2-22 and Figure 2-23 indicates the connection modes of a single card and multi-cards respectively.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 46

Figure 2-22 Connection of single card

Item

Result

No open-circuit or short-circuit in the electrical connection

The power voltage is the same as the rated voltage on the

The power cables and earth cables connected to the
The circuit breakers or fuses have the proper ratings for
The control connections are completed.

All wiring and connector connections are tight. The fixing

Figure 2-23 Connection of multi-cards

2.5.8 Checklist

Confirm the items in the table under listing 2.10 on completion of Electrical Installation.

Listing 2.10

exists

unit nameplate

disconnect switch, indoor unit and outdoor unit are
connected properly

equipment installed.

bolts are tight.

After confirming the preceding points, start the start-up inspection & function testing.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 47

Before starting the System Operations and Commissioning, adhere to the following points as

Pre-Commissioning Checklist

Name of Customer:

SL

Indoor Unit positioning & Power cabling, CU piping, GI piping

Remar

1

Indoor units are properly spaced with maintenance point view,
minimum gap of 6" is maintained on back side & in between the

2

Proper leveling of Liebert DM indoor stand with proper grouting

3 Drip tray installed properly with silicon sealant applied on the

4 Units are installed properly with rubber pads in between the unit

5

Proper earthing is provided in the mains power supply as well as
body earthing for PAC unit

6

Power cable is provided with proper sizing of cable to suit the full

7

Power supply is connected to the mains switch with proper lugs &

8

Mains power cable is not routed with low voltage cables

9 Soap leak test on brazing joints & also in Cu piping

10

Pressure holding time

11

Quality of copper piping laying, equidistance in-between two

12

Initial U trap provided near the indoor unit

13

U traps provided after every 7 RMT in vertical length (if require)

14

Inverted U trap provided near the outdoor unit

15

Copper pipe with insulation are tagged properly to indicate the

16

Proper supporting for refrigerant piping is done

17

Copper pipes are painted with proper color code

18

Additional piping kit installed in case vertical distance between

19

Cable trays are used of proper gauges & quality. Ensure supports

20

Dressing & proper routing condenser cable

21

Condenser cable & copper pipes are tagged with unit No & circuit

22

Sufficient fresh air for condenser

23

No hot air short cycling for condenser

mentioned in the checklist:

Listing 2.11

Site Location:
Details:

pipes, Quality of copper piping laying, equidistance in-between

indoor to outdoor is

provided at equal distance to avoid the sag on cable tray

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 48

Pre-Commissioning Checklist

24

Proper earthing is done for condenser

25

Proper supporting given for the condenser in case condensers
are mounted one above

26

Concrete pedestal are provided for the condenser stand

27

Rubber pads are provided in between the condenser & stands

28

Condenser coils & Copper pipes U bends are painted with

29

Proper slope is maintained for drain pipes

30

U traps is provided at end drain pipe

31

Isolating valve provided on inlet of humidifier piping

32

Fresh water head pressure maintained of 21 - 100 PSI & with PPM
level of 80 to 300 (optional)

33

Ensure no leakage in the humidifier & drain piping before

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 49

PART III

SYSTEM OPERATION & GEN

MAINTENANCE

ERAL

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3 System Operation

Item

Inspection requirements

Panel

No damage, well insulated and clean

Filter

Installed in place and reliably, no damage and clean

Measure and record the voltage before the system is powered

The outdoor unit is installed reasonably; the pipes are

Fan

No obstruction material in inlet and outlet area

Humidifier (if

Water supply pipe and drain pipe are connected; water level

Heater (if

Power SPD (if
Controller

The wiring connections are tight

This chapter introduces the system operation, start-up inspection, function testing, general
maintenance and preliminary troubleshooting of the Liebert DM AC.

3.1 Start-Up Inspection

Prior to starting up the system; inspection of the state of the parts is required. The requirements for
start-up inspection are mentioned in the following table within listing 3.1

Listing 3.1

Power supply

Outdoor unit

applicable)

applicable)

applicable)

on. Power cables are connected reliably

supported and sloped down properly; the trap is installed in a
correct position

sensor is secured correctly

Heating components are secured reliably

The module is secured reliably

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After inspecting and confirming the preceding items, power on the AC unit. The inspection

Item

Inspection requirements

The rotation direction is correct; record the rated full load

Heater (if

The rotation direction is correct; record the rated full load

Record the user setpoints, return air temperature, suction

requirements after starting-up are mentioned in the following table within listing 3.2.

Listing 3.2

Fan

current and actual current of the fan motor

Record the heater current

applicable)

Outdoor fan

current and actual current of the fan motor

Others

pressure, discharge pressure, compressor current and discharge
air temperature

3.2 Micro-Processing Controller

The Micro-processing controller for Liebert DM AC comes packed with potential features that help
monitor and manage the AC unit.

3.2.1 Features

The micro-processing controller has the following features:

 Adopt menu operation. It can monitor and display the operation status of precise cooling AC unit to keep the

environment within a setting range.

 Adopt a 128 × 64 dot LCD screen with white backlight. The user interface is easy-to-use.

 Provide three-level password protection to prevent unauthorized operation effectively.

 Provide the functions, including self-recovery upon power failure, high-voltage & low-voltage protection, phase

loss protection and automatic phase-sequence switching upon anti-phase.

 Accurately know the running time of important components through menu operation.

 The expert-level fault diagnoses system can automatically display the current fault information to facilitate

maintenance personnel in equipment maintenance.

 Store up to 200 historical alarm records.

 Configured with an RS485 port.

3.2.2 Appearance

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 52

The micro-processing controller panel is depicted in Figure 3-1.

21 C HEAT SIGL
50% HUM RUN

Hi Hum 4
2012/01/01 00:00

°

Figure 3-1

3.2.3 LCD Screen

The LCD screen displays English menus with white backlight. When the system is operating normally,
it displays the current temperature & humidity (humidity display is optional).

Only the unit configured with a humidifier can display humidity; refer to section Select Options in 3.4.5

System Menu for more details.

It also displays unit output status (cooling, heating, dehumidifying and humidifying), unit mode (single,
lead, standby), unit operation status (running, standby, locked), alarm information and current date &
time, as depicted in Figure 3-2.

Figure 3-2

A detailed operating status of a specific component and alarm information is available on the Main
Menu screen. The selected menu item will be highlighted while browsing. The digit to be changed will
be highlighted while the user is changing the settings.

3.2.4 Control Buttons

The micro-processing controller provides five control buttons, as depicted in Figure 3-3

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 53

Figure 3-3

Control button

Function descriptions

ON/OFF button

Press this button for 3s to turn on or off the unit

Enter button

Enter the selected menu screen. Validate the parameter setting

Exit the current menu and return to the Normal screen or

Move the cursor up or increase the parameter value. For a toggle

Move the cursor down or decrease the parameter value. For a

ON/OFF button

Enter button

Esc button

Down button

Up button

The functions of the control buttons are described in Table within Listing 3.3

Listing 3.3

(ENT)

value

Esc button

previous menu screen. Abort parameter change; silence the

(ESC)

audible alarm

Up button

selection: scroll through the options. For a multi-screen menu:
scroll up the screen

Down button

toggle selection: scroll through the options. For a multi-screen
menu: scroll down the screen

3.2.5 Control Buttons Operation Example

Example 1: Inputting password to enter the Main Menu

This section depicts the process where the password is entered to access the Main Menu. After the
unit is powered on, the unit starts up.

Following are the step-by-step instructions that can need to be adhered and implemented to enter
the Main menu.

 Press the Enter button to enter the Password screen.

 Next, press the Enter button again to highlight the input data field on the Password screen.

 Press the Up and Down button to change the current password number.

 Press the Enter button to confirm the password following which the Main Menu screen is populated on the

controller screen.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 54

Example 2: Changing parameters

Connecting…

通讯中，请稍后

This section depicts the process of changing parameters. In this example, Hi Temp in Alarm Output
screen is used for illustration purposes. Following are the step-by-step instructions for changing
parameters:

 Press the Up or Down button to move the cursor on the Alarm Menu menu in the Main Menu screen.

 Press the Enter button to enter the Alarm Menu menu.

 Press the Up or Down button to move the cursor on Alarm Setting in the Alarm Menu screen.

 Press the Enter button to enter the Alarm Setting screen.

 Press the Up or Down button to move the cursor on Hi-Temp.

 Press the Enter button to highlight the parameter field of Hi-Temp.

 Press the Up or Down button to select the parameter option.

 After selecting, press the Enter button to confirm. The parameter will take effect.

 Press the Esc button to return to the previous menu screen.

On changing the parameters, the Enter button needs to be pressed in order to confirm it. If the Enter

button is not pressed, it means that the confirmation of the parameter change has not taken place.

Therefore, on non-confirmation, the original value of the Hi-Temp will be retained.

3.2.6 ON Screen

After the AC unit is powered on, the LCD screen will display the ON screen, as shown in Figure 3-4.

Figure 3-4

3.2.7 Language Screen

After the AC unit is powered on, the language screen will be displayed after 10 seconds (default) for
choosing the language or through pressing the Enter button directly, as shown in Figure 3-5.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 55

Figure 3-5

Choose Language:

请选择语言：
中文（Chinese）
英文（English）

21 C HEAT SIGL
50% HUM RUN
No alarm 0
2012/01/01 00:00

°

Password: 1***

3.2.8 Normal Screen

After the AC unit is powered on, the Normal screen will be displayed after 20 seconds (default) for
heat startup delay or by pressing the Enter button directly, as shown in Figure 3-6. The Normal
screen displays the following information: the current temperature and humidity, unit operation state
(cooling, heating, dehumidifying, humidifying), unit mode (single, lead, standby), unit operation status
(running, standby, locked, off, sleep), alarm information and current date & time.

Figure 3-6

3.2.9 Password Screen

Press the Enter button on the Normal screen following which the Password screen appears as
depicted in Figure 3-7.

Figure 3-7

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The table in Listing 3.4 depicts the 3 levels of passwords for accessing the menu. The detailed

Password

level

User

Initial

password

Remark

Browse all menu information. Only set

Maintenance

Factory

descriptions are mentioned in Table within Listing 3.4

Listing 3.4

Level 1 General operator 0001

temperature and humidity setpoints
(see Figure 3-13) and cannot change
any values and settings

Level 2

- Set all parameters

personnel

Level 3

- -

technician

For detailed operation on entering the password, refer to section 3.2.5 Operation Example.

On entering an incorrect password, the users cannot change the settings; however, they can view the

menu. To go back to the Normal screen, press the Esc button and then click on the Enter button to get

access to the Password interface again. If the users do not enter a password and press the Enter button,

then similar to the incorrect password example, the users can view the menu settings but cannot change

any parameters.

3.3 Function Testing

The AC unit carries hazardous voltage. Cut off the power before testing the equipment. The test should

be done under the guidance of Vertiv Co.'s professional maintenance personnel or trained service

personnel.

3.3.1 Cooling

The temperature set point should be adjusted based on the Set Points (Refer section 3.4.3) up to 5°C
(10°F) lower than the indoor temperature. Then, the control system should trigger the cooling
demand and the compressor starts working. At least after 3 minutes of cooling, adjust the
temperature set point to 5°C (10°F) higher than the indoor temperature. If the compressor stops
working, it means that the cooling function is normal.

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Restore the temperature set point to the default or the original value after the test

3.3.2 Heating

The temperature set point should be adjusted based on the Set Points (Refer section 3.4.3) up to
5°C (10°F) higher than the indoor temperature. Then the control system should trigger the heating
demand and the heater starts working. Adjust the temperature set point to 5°C (10°F) lower than the
indoor temperature. If the heater stops working, it signifies that the heating function is normal.

Restore the temperature set point to the default or the original value after the test.

3.3.3 Humidifying

The humidity set point should be adjusted based on the Set Points (Refer section 3.4.3) to 10% higher
than the indoor relative humidity. Then, the control system should trigger the humidifying demand
and the humidifier starts working. Adjust the humidity set point to 10% lower than the indoor relative
humidity. If the humidifier stops working, it signifies that the humidifying function is normal.

Restore the humidity set point to the default or the original value after the test.

3.3.4 Dehumidifying

The humidity set point should be adjusted based on the Set Points (Refer section 3.4.3) to 10% lower
than the indoor relative humidity. Then, the control system should trigger the dehumidification
demand and the fan starts running at a low speed. Adjust the humidity set point to 10% higher than
the indoor relative humidity. If the fan automatically starts running at a higher speed, it signifies that
the dehumidification function is normal. Note that during the testing process, if the indoor
temperature is 3°C higher than the temperature set point, the system may enter a forced cooling
mode and the dehumidification demand will not be responded.

Restore the humidity set point to the default or the original value after the test

3.3.5 Checking Refrigerant Charge Capacity of Low-Temp Outdoor

The Low-Temp outdoor unit has been charged with refrigerant before delivery.

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The refrigerant charge capacity should be proper after powering on; it can be verified using the

<Alarm Menu>
<Set Points>
<System Status>
<System Menu>

<Help Menu>
<Display Setting>

following method:

When the high pressure is not lower than 240psig (16.5bar), the liquid level of the refrigerant will
reach the 1/2 point of the tank sight glass. When the ambient temperature is low and the high
pressure cannot meet the requirement, the user can block the part of the upside and downside of the
air intake uniformly to obtain required pressure.

If the liquid level cannot meet the requirement, discharge or refill the refrigerant for a proper liquid
level length. Reclaim the discharged refrigerant according to correlative requirement.

3.4 Micro-Processing Controller Menu Options

3.4.1 Main Menu

On entering the correct credentials for the password and confirming it, the users will gain access to
the Main Menu screen. For more information, refer to the section Appendix - 2 -Menu Structure.
Enter the password in the Password screen and confirm following which the Main Menu screen will
appear, as shown in Figure 3-8.

Remember that the users can change the settings of most of the parameters; however, there are
some parameters that cannot be modified or altered.

For detailed setting procedures, refer to section 3.2.5 Operation Example. For the setting ranges of
the menu items that can be set, refer to Appendix - 3 Parameter Setting Table.

Figure 3-8

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 59

The table under Listing 3.5 describes the different menu items on the Main Menu screen

Listing 3.5

Menu item Descriptions

Alarm Menu

Set alarm parameters; browse alarm historical records and alarm

status records
Set Points Set temperature & humidity setpoints and their sensitivities
System Status Browse ambient temperature & humidity, system output status

and system running records; browse and set system time

Set system parameters and system options; calibrate sensor;
System Menu

change password; output system diagnoses; restore factory

parameters; configure optional function

Browse factory information, product information and maintenance
Help Menu

information
Display Setting Adjust the screen contrast

3.4.2 Alarm Menu

On the Main Menu screen, the users must click on Alarm Menu to gain access to the Alarm Menu
interface. Press the Up and Down button to scroll up or down the menu items.

Figure 3-8 depicts the Alarm Menu screen:

<Alarm Status>
<Alarm History>

<Alarm Setting>

Figure 3-9

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Alarm Status

The Alarm Status menu is used to monitor the present alarm status of the AC unit and prompt No
Alarm or detailed alarm status information.

The detailed alarm status information includes XX/YY, alarm type and alarm start time, as shown in
Figure 3-10. XX is the serial number of alarm status record and YY is the total number of alarm status
record.

Current: 1/8
Hi Temp

2012/01/01 00 :00

Figure 3-10

 The latest alarm SN is the biggest number. Press the Up or Down button to scroll through the alarm
status records if more than one alarm is activated.

 The alarm status records will be automatically cleared upon system power-off.

Alarm History

The Alarm History menu is used to view the historical alarm records of the AC unit, including XX/YY,
alarm type, alarm start time and alarm end time (if the alarm is not ended, the screen displays Not

ed Yet), as shown in Figure 3-11. XX is the screen of the historical alarm record and YY is the total

End
n

umber of the historical alarm records.

History: 1/4
Hi Temp
2012/01/01 00:00
2012/01/01 01:22

Figure 3-11

 Press the Up or Down button to scroll through the historical alarm records if more than one alarm is
activated.

 Up to 200 historical alarm records can be stored. They will not be cleared upon system power-off.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 61

Alarm Setting

The Alarm Setting settings will not be lost when the power fails. The Alarm Setting screen is

depicted in Figure 3-12. For detailed setting range, refer to Appendix - 3 Parameter Setting Table.

It is not recommended to change the defaults. If the change is necessary, change them under the

guidance of the trained professionals.

Hi Temp 30.0 C
Lo Temp 18.0 C
Hi Hum 60.0%
Lo Hum 40.0%

Hum Fail EN
High Water

Temp Snsr

HP LOCK EN

Phase rev EN
Customer 1 EN
T/ H Card EN

Air Loss EN

°

°

EN
EN

AirflowDT 15.0 °C
Hi Press EN

Lo Press EN
Dschg Temp EN

LP LOCK EN

Dschg LOCK EN
Water UF EN
Overvoltage EN

Customer 2 EN

Press Snsr EN

Hum Snsr EN
AirLoss Snsr EN

F

igure 3-12

Hi Temp EN
Lo Temp EN

Hi Hum EN
Lo Hum EN

Power OV EN
Undervoltage EN

Freq offset EN
Phase Loss EN

Customer 1 NC

Customer 2 NC
General Alm NO
ClearAlmHis N

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 62

Listing 3.5

Settings

Alarm history

record

Alarm status

record

Audible alarm

Alarm prompt

EN

Yes

Yes

Yes

Yes

DIS

Yes

Yes

No

No

MSG

No

No

No

No

Temp Set 24.0 C
Temp Band 3.0 C

Hum Set 50.0%
Hum Band 5.0%

°

°

The alarms Hi Press, Lo Press and Hi-Temp are serious fault alarms. So they cannot be set to OFF, but

can only be set to EN and DIS.

Customer Alarm

The AC unit is provided with two customer alarms, including customer 1 and customer 2; it
corresponds to PIN1, 2 of the control terminals J19 and PIN5, 6 of J19 respectively.

The customer alarm can be set to ‘NO’ or ‘NC’. The user can set them according to the actual alarm
signal of the control terminals. If the power SPD is selected, the customer 1 alarm terminal has been
connected with power SPD alarm signal before delivery and the customer 1 has been set to ‘NC’.

3.4.3 Set Points

On the Main Menu screen, the user can select the Set Points option to gain access to the Set points
menu as depicted in Figure 3-13.

The Set Points settings will not be lost when the power fails. For detailed setting ranges, refer to

Appendix - 3 Parameter Setting Table.

Figure 3-13

3.4.4 System Status

On the Main Menu screen, the user can select the System Status option to gain access to the System
Status menu as depicted in Figure 3-14.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 63

Figure 3-14

<Analog>
<Time/Date>

<I/O Status>
<Run Time>

<On/Off Record>

Rtn Temp 24.6 C
Rtn Hum 67.8%

NTC0Temp 25.0 C
Temp Cal 0.0 C

°

°

°

Hum Cal 0.0%
NTC0 Cal 0.0 C

Press1: 15.6Bar
Press2: 0.0Bar

°

Phase A: 220.0V
Phase B: 220.0V
Phase C: 220.0V
Pwr Freq: 0.0Hz

Sw Code 0

Year 2012
Month 1

Day 1
Hour 0

Min 0
Second 0

Analog

The Analog menu displays the indoor temperature & humidity, 3-ph voltage & frequency and
condenser pressure with a decimal in real time, as depicted in

Figure 3-15.

Figure 3-15

Time/Date

The Time/Date screen displays the current time and date of the system in the Year/Month/Date
format and Hour/Minute/Second, as depicted in Figure 3-16.

Figure 3-16

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 64

I/O Status

Evap Fan OFF
Compressor OFF
Heater OFF
Humidifier OFF

Low FanSpeed
Cond Fan OFF
General Alm

OFF

OFF

Fill OFF

EC Output 0.0V
Manual EN N

Hi Press OPEN

Stdby En OFF

Dschg Temp OPEN

Water UF OPEN

Customer 1 OPEN

Lo Press OPEN

Customer 2 OPEN

StdbyReq OPEN

OEM HumFail OPEN

High Water OPEN

Evap Fan 0h
Compressor 0h

Heater 0h
Humidifier 0h

Cond Fan 0h

<Evap Fan>
<Compressor>

<Heater>
<Humidifier>

Evap Fan 1/4
2012/01/01 00:00

2012/01/01 00:00

The I/O Status screen is depicted in Figure 3-17. The user can browse the current input and output
status of the unit on the screen. If Manual Run Enab is set to ‘YES’, the output can be controlled
manually. If the manual output is inner fan output then the rest of the outputs will be closed; if the
manual output is electrical heater output, the inner fans will be started up simultaneously and the rest
of the outputs will be closed. The system will exit the manual mode in an hour automatically if the
user does not exit the manual mode.

Figure 3-17

Run Time

The user can browse the current operation hours of the equipment on the screen. The Run Time
screen is depicted in Figure 5-18.

Figure 3-18

Users can view the start and stop records of important components using this facility. Select the On/Off Record item on the
Run Records screen following to access its menu.

Figure 3-19 depicts the On/Off Record screen:

Figure 3-19

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 65

3.4.5 System Menu

<System Setup>
<Outdoor Unit>

<Optional Func>
<Set Password>

Protocol YDN23
Unit Addr 1

Baud Rate 19200
Overvoltage 15%

Undervoltage 15%
Fq Offset 3Hz

Pwr Freq 60Hz
EvapFanStart 10s

EvapFanStop 30s
CP MinOn 180s

CP MinOff 180s
Cold Start 180s

Hum Ctrl REL

Temp Compens N
Fan Type AC
EC STD 75%

Factory Reset
Run Interval 10h

EC Dehum 65%

Hum Time 30s

Fill Time 8Min

Fill Rate 150%

Prefill Time 7s

On the Main Menu screen, the user can select the System Menu option to gain access to the System
Menu as depicted in Figure 3-20

Figure 3-20

System Setup

The System Setup settings will not be lost in case of the power failure. The menu screen is depicted
in Figure 3-21. For detailed setting ranges, refer to Appendix - 3 Parameter Setting Table.

Figure 3-21

Factory Reset

Use Up or Down button to move the cursor to Reset Factory in the Setup System menu and press
the Enter button. Use Up or Down button to set it to YES or No and press the Enter button to
validate the setting. If Yes is selected, all system set points will be restored to the factory­recommended values, but the operation time and history alarm records will not be cleared.

As the Factory Reset will clear all set points configured by the user and the AC unit will be turned off,

always be cautious to use it.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 66

Outdoor Unit

Min. Volt 30%
Max. Volt 100%
Output Volt 95%
Press Bd 5.0Bar

Start P 13.0Bar

Heater Qty 0
Hum Type IF

Economy Mode OFF
Start at 22:00

End at 7:00
Band Zoom 0.0 C

T/H Card Qty 4
Sleep at 27.0 C

°

°

1#: 0.0 C
2#: 0.0 C

3#: 0.0 C
4#: 0.0 C

°
°
°
°

System Mode SIGL
Switch Mode STDB

Rotate Freq 1d
Rotate at 12:00

Level 1 ****
Level 2 ****

The Outdoor Unit menu screen is depicted in Figure 3-22.

Figure 3-22

Optional Function

The Optional Func will not be lost in case of the power failure. The menu screen is depicted in Figure
3-23. For detailed setting range, refer to Appendix 3 - Parameter Setting Table.

Figure 3-23

Only when the energy-saving card No. is not zero, the Sleep Mod can start. Only the Liebert DM AC

equipped with more than one energy-saving card (dedicated) can enter the Sleep Mod. The lead unit

and standby unit cannot use the same card.

When a lead unit and a standby unit are available, the user must set one of them as the lead unit. If the

user sets both of them as the standby units, they cannot work normally.

Change Password

The Change Password settings will not be affected in case of power failure. The menu screen is
depicted in Figure 3-24.

Figure 3-24

3.4.6 Help Menu

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 67

On the Main Menu screen, the user can select the Help Menu option to gain access to the Help Menu

<Version Info>
<En Activation>

Disp Bd: ACM02D1
Version: 1.01.000.00
Ctrl Bd: ACM02U2
Ver: 1.01.000.00

Contrast 48
Language English

screen as depicted in Figure 3-25. The En Activation is not disclosed to the users.

Figure 3-25

Version Info

The Version Info menu is used to browse the version Info, as depicted in Figure 3-26.

Figure 3-26

3.4.7 Display Set

On the Main Menu screen, the user can select the Display Set option to gain access to the Display
Set screen as depicted in Figure 3-27.

Figure 3-27

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 68

4 General Maintenance

This section deals with the system operation and maintenance of the Liebert DM AC. In this section,
the following points or items will be discussed to help users get to grips with the routine inspections
and checks from a user-perspective. It includes the maintenance of electrical parts and connections,
indoor unit, outdoor unit and inspection checklist. It also discusses the basic troubleshooting which
can be understood from a user perspective.

 Prior to operation and maintenance, lethal voltage may be present in the equipment which can be
fatal. All notes, warnings, and cautionary warnings marked on the equipment as well as the ones
mentioned in the manual must be considered, otherwise, it may lead to injury and fatality.

 Disconnect local and remote power supplies before operating or working with the equipment.

 Qualified and Professional Maintenance personnel are the ones supposed to operate and handle the

equipment. Careful and cautionary measures are conveyed to the professional personnel and therefore,
only those personnel may perform maintenance on these machines.

 Check the label of the components of the unit as well as the manual to ensure all aspects are taken
into account before operation and maintenance.

 Follow all the local codes, protocols, and regulations prior to maintenance.

 Read all the instructions to verify that all the parts are included and check the

nameplate to ensure that the voltage matches the available utility power

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 69

4.1 Electric Inspection

Visual checks need to be carried out to check the correctness of electrical connections and circuit
corrosion of the control board, power detection board, filter board, display board and THS board on a
semi-annual basis.

The micro-processing controller has five circuit boards which jointly complete the system fault
detection, input and output.

Inspect the boards one by one according to the following procedures:

 Conduct the electrical insulation test on the system to find out bad electrical connections and contacts.

Disconnect all the fuses and MCBs of the control part during the test as the high voltage from the insulation test
could damage the components.

 Check the contactors prior to powering on the unit to ensure that the contactors can hold and un-hold freely.

 Clean the electrical and control components off dust with a brush or dry compressed air.

 Check the closing of contactors for arcs or signs of burning. Replace the contactors, if required.

 Fasten all the electrical connection terminals.

 Check that the sockets and plugs are in good condition. Replace the contactors, if required.

 Check if the power cables are damaged; get them replaced by a qualified/certified electrician.

All circuit boards are not hot-pluggable. A Large instant current will be produced if the board is plugged

or unplugged with powering on and it may lead to unrepairable damage to the circuit. The control board

can only be maintained after the micro-processing controller is powered off.

4.2 Indoor Unit Maintenance

4.2.1 Filter

The filter is a consumable part. Its replacement interval is directly related to the cleanliness status of
the equipment room. In order to maintain efficient operation, the filter should be checked monthly
and replaced or washed as recommended. The filters of the indoor unit are installed on the front door
and side panel.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 70

To remove the Filter on the front door:

Filter

A

A amplified

Stator

Fixing screw

(2 pcs)

Front door

 Unscrew the fixing screws on the filter stator;

 Remove the filter stator to take out the filter on the front door, as depicted in Figure 4-1.

Figure 4-1

Filter on the side panel:

 Unscrew (do not remove) the fixing screws on the filter stator and move the stator along the guide rail.

 Take out the filter on the side panel, as depicted in Figure 4-2.

Figure 4-2

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 71

4.2.2 Fan

The monthly inspection items of the fan kit include:

 motor operation status

 impeller status

 fan kit fixation

 clearance between fan and impeller.

Monthly inspection of motor bearing and impeller should be carried out and replace it if any damage
has occurred.

Check whether the impeller is tightly mounted on the rotor of the motor and does not rub against its
neighboring metal components during rotation.

Since the fan kit operates continuously 24 hours a day, any unusual airflow obstruction must be
cleared in time to avoid the damage to the cooling system and other system components caused by
reduced air volume.

4.2.3 Drain Pipe

For normal operation of the drain pipe, inspection of the water tray should be carried out periodically.

Ensure that there are no foreign particles or any leakage present in the drain pipe.

4.2.4 Heater

If the optional heater is used, it should be maintained periodically. Ensure that there is no dust or any
foreign particles collected on its surface; the heater is fixed appropriately and the cable connections.

The heater elements will heat continuously in the normal station. Inspection of the heater should be
carried out bi-annually for its normal operation.

If in case the heater needs to be replaced, please contact the Vertiv Co. maintenance personnel.

The heater cable must be leaded through the thimble socket, and then connected to the heater.

4.2.5 Humidifier

The humidifier kit consists of infrared lamp, water supply solenoid valve, water tray, high temperature
protect device and water high level protect the device.

The micro-processing controller calculates whether the humidification is required based on the
temperature and humidity values from the THS. If a call for humidification is registered, the micro-

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 72

processing controller will send a humidification command and provide 24V power to it. Then the

顶部过温保护开关

加湿器上盖（内含加湿灯管）

注水电磁阀

加湿器水盘与固定支架之间的固定螺丝

加湿器固定支架

加湿器排水管

加湿器进水管

加湿器水盘

Up cov er (lamp in side)

Top over- temperature p rotection switch

Water tray

Brack et

Fixi ng screws between bracket an d water tray

Water supp ly solenoid val ve

Water supp ly pipe o f humidifier

Drai nage p ipe of humidifier

water filling valve will start the humidification operation.

The top temp-switch will act to cut off the lamp power to stop humidifying when abnormal airflow
causes high temperature around humidifier. The temp-switch should be reset manually to light up
the lamp as depicted in figure 4-3.

When the water tray is dry burned, the dry burned protection switch will act to cut off the lamp power
to stop humidifying. The dry burned protection switch should be reset manually to light up the lamp
as depicted in figure 4-4.

As the sediment exists in the water drained from the humidifier, the humidifier water tray should be
cleaned periodically to assure humidifier running efficiently. The cleaning cycle varies with the local
water quality It is recommended to clean (when necessary) the humidifier tray once in a month. Far­infrared humidifier itself automatic flushing function can effectively extend the time interval between
cleanings; however, regular inspection and maintenance are still essential.

The Cleaning steps are mentioned as following:

 Remove the water level standpipe to drain the water tray;

 Disconnect the drainage pipe;

 Disconnect the power of lamp and the signal line of water high-level switch, dry burned protect switch and water

supply solenoid valve;

 Remove the front fixing screws and disassemble humidifier kits;

 Remove fixing screws between bracket and water tray, remove the Up cover kits. Pay attention to protecting the

lamp;

 Remove the fixing screws at the two ends of the water tray, and pull out the water tray. Cleanse the water tray

with water and hard brush;

 Restore the humidifier by reversing the preceding procedures.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 73

Figure 4-3

Figure 4-4

加湿水盘底部防干烧保护开关

Dry burned protection s witch

( at the bottom of water tray)

Before exercising the humidifier water tray cleaning operation, make sure that the power has been

turned off; and also ensure that the water in the water tray is not hot before draining the water from the

infrared humidifier water tray so as to avoid personal injury.

4.2.6 Power SPD

The position of the power SPD is depicted in Figure 4-5.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 74

Figure 4-5

1-ph power SPD

ALARM

L/N

3-ph power SPD

Status indicator
(4 pcs)

ALARM

N N

L1

Status indicator
(4 pcs)

L/N

L2 L3

The power SPD has four status indicators, as depicted in Figure 4-6. The status indicators are green
during normal operation; they turn to red upon failure.

Figure 4-6

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 75

The power SPD does not need special maintenance. It needs a regular check for non-loosening and

Item

psig

MPa

Low pressure

57.5 ~ 99.8

0.397 ~ 0.67

Low-pressure setpoint

20

0.138

Low-pressure recovery point

36.3

0.25

High pressure

180 ~ 275

1.242 ~ 1.895

High-pressure setpoint

400

2.76

High-pressure recovery point

307

2.1

normal status indicating.

If any one of the following phenomena occurs, the power SPD has failed and it needs to be replaced
immediately.

1. Any indicator of the power SPD turns red.

2. The customer alarm 1 is generated (see SPD (Customer 1 terminal) in 6.5.1 Connecting Control
Terminals).

4.2.7 Thermal Expansion Valve

The thermal expansion valve keeps the evaporator supplied with sufficient refrigerant to satisfy load
conditions. Its proper operation can be determined by measuring the superheat level. The correct
superheat setting is 5.6°C to 8.3°C (10°F to 15°F).

4.2.8 High-Pressure Switch And Low-Pressure Switch

The discharge pressure and suction pressure will vary significantly with the AC unit load and ambient
conditions (Refer the table in Listing 4.1) during normal operation. When the discharge pressure rises
to the high-pressure setpoint, the high-pressure switch will activate and the control system will shut
down the compressor after ensuring an abnormal input signal of the high-pressure switch.

When the suction pressure is lower than the low-pressure set point, the low-pressure switch will
activate and the control system will shut down the cooling system after confirming.

Listing 4.1

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 76

4.2.9 Compressor

The compressor fault is mainly classified into two types:

1. Motor faults (such as winding burnout, insulation failure, short-circuit between coils etc.).

2. Mechanical faults (such as compressing failure, relief valve fault, therm-o-disc fault and so on).

If the operation pressure is not built up, it signifies that the compressor has failed. It can be verified if
the suction pressure and discharge pressure are balanced and the motor does not rotate in reverse
direction.

The controller has powerful alarm and protection functions to ensure safe operation of the
compressor. The maintenance personnel should record the high pressure and low pressure and find
out the cause of an alarm protection during periodical maintenance and inspection.

Avoid touching or contacting the residual gas and oils in compressor with exposed skin. Wear long

rubber gloves to handle contaminated parts.

Check the following items before replacing the compressor:

 Check that all fuses and circuit breakers are normal.

 Check the working status of the high and low-pressure switches.

 Check the relevant historical alarm information.

 Check the historical operation records of the compressor.

 Check the motor electric characteristic.

The system contains refrigerant. Reclaim the refrigerant using standard reclaiming equipment before

maintenance

To remove and replace the failed compressor adhere to the following procedure:

 Cut off the power.

 Attach suction and discharge gauges to compressor access fittings.

 Reclaim the residual refrigerant by using standard reclaiming procedures.

Releasing of refrigerant to the atmosphere is harmful to the environment. Refrigerant must be recycled in

accordance with state and local regulations.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 77

 Remove the failed compressor.

 Install replacement compressor and assemble all the connections. Carry out the pressurization and leakage tests

to the system at approximately 150psig (1034kPa).

 Evacuate the system twice to 1500 microns and the third time to 500 microns. Break the vacuum each time with
clean and dry refrigerant to 2psig (13.8kPa).

 Charge the system with refrigerant based on the requirements of the evaporator, condenser and refrigeration
lines.

 Apply power to and operate the AC unit. Check for proper operation. Refer to the circulation suction pressure
and discharge pressure ranges in normal operation, and supplement some refrigerant if necessary.

4.3 Outdoor Unit Maintenance

4.3.1 Refrigeration System

The components of the refrigerant system should be inspected monthly to find out if any abnormal
operations are occurring. Refrigerant pipes must be properly fixed and not allowed to vibrate against
the wall, floor or the unit frame. All the refrigerant pipes should be inspected biannually for any signs
of wear and tear.

4.3.2 Air-Cooled Condenser

When the airflow through the outdoor unit is restricted, use the compressed air or fin cleaner to clean
the condenser off the dust and debris that inhibit airflow. The compressed air should be blown at the
reversed airflow direction. In winter, do not let snow to accumulate on the side or underneath the
condenser. Check for bent or damaged fins and simply repair them if necessary. Check all refrigerant
pipes and capillaries for vibration and support them if necessary. Carefully inspect all refrigerant
pipes for signs of oil leakage, determining the leakage position.

4.3.3 Low-Temperature Unit Of Low-Temp Outdoor Unit

The liquid level of the refrigerant should be checked periodically in the fluid reservoir to ensure that
no refrigerant leakages occur. For detailed operation, refer to section 3.3.5 Checking Refrigerant

Charge Capacity of Low-Temp Outdoor Unit.

Periodically check whether the heating belt of the fluid reservoir works normally. See following for
details:

When the system is powered on and is in the standby mode, the fluid reservoir pressure is lower than

0.85Mpa, the heating belt preheats the fluid reservoir. If there is no heating, check whether the fuse
of the heating belt is blown or if the pressure switch is working normally. After confirming the fault
part(s), replace them.

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 78

The heating belt fuse specifications in Table within listing 4.2.

Manufacturer

Model

Voltage

Rated current

Bussmann

S500-1A

250V

1A

Littelfuse

0217001

250V

1A

Liebert DM AC

Date:

Prepared by:

Model:

Serial Number:

Type

Maintenance

components

Item

Result
Check for restricted airflow

Check the filter

Clean the filter

Check if the water tray is clogged.

Check the humidifier lamp

Check the sediment of water tray

Impellers free of debris and move
Bearings in good condition

Power SPD

Semi­Signs of oil leaks

Vibration isolation

Listing 4.2

4.4 Maintenance Inspection Checklist

Regular inspections are necessary to ensure proper operation of the AC unit.

Listing 4.3

Monthly

annually

Filter

Humidifier
(if applicable)

Indoor unit fan

(if applicable)

Drain system
(including
condensate pump)

Compressor

freely

Check for indicator color

Check and clean out unit drain pipes,
humidifier and tray, condensate
pump and building drain pipes

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 79

Liebert DM AC

Date:

Prepared by:

Model:

Serial Number:

Type

Maintenance

components

Item

Result

Refrigerant system

Suction pressure

Discharge pressure

Superheat

Evaporator in tight and clean
Charging capacity of refrigerant

Evident temperature difference

Condenser coil is clean

Motor mounted tightly

Bearing in good condition

Refrigerant pipes properly supported

Check electrical connections

Check the surface for signs of
Electric heater

Check for signs of corrosion

Check if the water tray is clogged

Check the humidifier lamp

Check the sediment of water tray

Check and fix connectors

Check for the liquid level of the
Check whether the heating belt of

Notes:

Signature:

Air-cooled
condenser

Electric board

Humidifier

condition

between before and after the filter
drier

corrosion

Low-Temp low-

refrigerant in fluid reservoir and leak
of the fluid reservoir fittings

temperature unit

the fluid reservoir works normally

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 80

4.5 Troubleshooting

Fault

phenomenon

Possible cause

Check or remedy
No power to unit

Check unit input voltage

Circuit breaker that

Check jumping cables on the control

Check for 24Vac ± 2Vac at the winding.
High compressor

See ‘High-pressure alarm’ for checking
Plugged strainer

Clean or replace the strainer

Use suction and discharge pressure

Troubleshooting is to be performed by the trained and qualified service personnel. However, the
checklists have been provided just for reference purpose.

 Certain circuits carry lethal voltages. Only professional technicians are allowed to maintain the
machine. Extreme care and caution is required while troubleshooting online.

 If jumpers are used for troubleshooting, remember to remove the jumpers after the troubleshooting,
failing which the connected jumpers may bypass certain control functions and increase the risk to the
equipment.

Listing 4.4

Unit does not
start

No cooling

controls voltage (at the
transformer) is open

Float switch relay has
closed due to high water
level in the condensate
pump sump

Jumping cables not in
place

Compressor contactor
not pulling in

discharge pressure

Locate short circuit and reset circuit
breaker

Check that drain pipes and pipelines are
clogged or that the condensate pump is
damaged

board

If the voltage is right, check the
contactor

and maintenance descriptions

Low refrigerant charge

gauge to check the pressure. View
whether evident bubbles exits through
the sight glass

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 81

Fault

phenomenon

Possible cause

Check or remedy

Insufficient airflow across

Remove debris from coil surface and air

Check that the cable connection from

Set Heat to ‘ON’, refer to Select Options
No heat demand output

Adjust temperature setpoint and

Turn off the power. Check the element

Disconnect the system power, and then

Loose connection

No display,

Disconnection between

No display,

Low power voltage

Check for power voltage

Low-pressure

Refrigerant leakage

Check for leaking place and re-charge

condenser

inlet; check the control board for the fan
speed regulation performance

High-pressure
alarm

Heater does
not operate

Display
abnormal

Condenser fan not
operating

Heat function disabled in
Select Options menu

from the control system

Elements burned out

Static discharge

between display board
and control board

the control board to the terminal block
of outdoor unit is tight; check that the
outdoor unit connections are tight;
check that the condensate pressure
sensor works normally

in

3.4.5 System Menu

sensitivity within the required range

resistance with a multimeter

restart

Tighten the connection after powering
off, and then restart

control buttons

display board and control

board and control board

Check the connection between display

do not respond

board
and equipment
operates

Display board fault Replace the display board
normally

control buttons

Communication between
do not respond

Check the connection between control

control board and display
and equipment

has no output

board interrupted

board and display board

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 82

Fault

phenomenon

Possible cause

Check or remedy

alarm

Outdoor ambient

temperature too low

Low-temperature

Heater operation current
Setpoint unreasonable

Reset the setpoint

Vapor barrier not done in

Low humidity
Check that the water supply is normal

Check that the water supply solenoid

Check the state of the high water-level

Check that the water supply pipe is not
The humidification

Check if the contactor voltage is normal

Contact local maintenance engineer

High­temperature
alarm

Low
temperature
alarm

Outdoor unit fan running

at full speed upon low

outdoor ambient

temperature

High-temperature

setpoint unreasonable

Room load exceeding

unit design ability

setpoint unreasonable

improper

Check that the cable connections of
outdoor unit are normal; check that the
condensate pressure sensor is normal

Reset the setpoint

Check for room seal or make capacity
expansion

Reset the setpoint

Check for heater working operation

High humidity
alarm

Check for the vapor barrier

the room

Setpoint unreasonable Reset the setpoint
alarm

valve is working
Humidification
ineffective

No water in the water tray

switch and water level regulator

clogged

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 83

Fault

phenomenon

Possible cause

Check or remedy

contactor does not close

Check if the safety devices of the

infrared humidifier are opened such as

Check L1, L2 and L3 voltages are normal

Check if the manual reset switch of

Infrared humidifier lamp

the over-temperature protection switch

and dry burned switch.

Humidifier main power
failure

burned

when the contactor is energized.

humidifier is disconnected.

Replace the lamp

Vertiv | Liebert DM Series Precision Air Conditioner | User Manual 84

APPENDIX 1 - Crcuit Diagrams

4

黑

2

黑

6

黑

3

4

1

2

A1

A2

5

6

21

22

31 5

Main switch

PE N

压缩机

控制板

J28

J21

3

4

5

6

7

8

1

2

高压开关/High Pressure Switch

低压开关/Low Pressure Switch

21

21

PTC电加热
PTC Heater

风机

启动电容
Capacitor

压缩机电加热带
Comp.Heater

电源板

滤波板

3

4

1

2

KM1

3

4

5

6

7

821

3

4

5

6

7

821

1

2

1

2

1

3
4
5

2

J13 J31

J1

J3

J02

J01

J03

J29

J30

J18

1

3
4
5

2

6

8
9

10

7

1

3
4
5

2

6

8

7

1

3
4
5

2

6

8

7

J19

J12

J39

2
1
2
1

4

2
1

3

J4

显示板

1

电控盒接地点

GND

排气开关/Exhaust Switch

地板溢水/Water Under FLoor Switch

3 2 1

J23

J34

J14

2
1

备机请求/Lead/standbyrequirement

J36

GND

+12V

CANH
CANL

温湿度检测板

节能卡

压力传感器

Pressure Sensor

23

J2

12

蓝

棕黑 灰

黑黑 黑

线电压线路/Line voltage wiring

现场安装线/Locale wiring

器件自带线/Device own wiring

线体说明/Wire Description：

室外接 线端子
Outdoor Terminal block

N

L

L1

N1

室内端子 排

Indoor Terminal block

电控盒接地点

GND

电控盒接地点

GND

室内外连接电缆
Connection cable

12V

GND

A
B

GND
12V

A
B

端子对插线/Quick disconnect wiring

黄/绿

5

6

A1

A2

室内接线端子TB2
Terminal Block 2

黑

QF-1

QF-3

QF-5

KM1-1

KM1-3

KM1-5

KM1-21

KM1-2

KM1-4

KM1-6

T1T2T3

KM2-1

KM2-3

TB1-1
TB1-3

TB1-7
TB1-9

TB1-13
TB1-15

TB1-N

TB1-2

TB1-8

TB1-14

TB1-N
TB1-N

J1-L

J02-1

J1-N

J01-1

J01-3

J01-5

J01-7

J18-1
J18-2
J18-3

J2-2

J2-1

TB2-25

WV-2

J28-3
J28-4

J28-1
J28-2

TB2-27

KM2-A2
TB2-29

J03

N

PE

J19-7
J19-8

J19-4

J19-3

J19-2

J19-1

J28-4

+5V

VIN

GND

远程开关机/Remote ON/OFF

J28-7
J28-8

J19-5
J19-6

13

14

黑 黑

5

3

1

8

7

KA1-5

45

1

J18-4

蓝黑 白

黄/绿

J28-5
J28-6

KA1-7
TB2-32

KM2-A1

J28-6

KA1-8

BK BK BK BK

灰

灰

黑
黑
蓝
蓝
黑
棕

黑 绿 红

黑

黑

黄/绿

黑

黑
黑
黑

J3-4

J28-9
J28-10

KM1-22

TB1-17
TB1-19
TB1-21
TB1-23

室内接线端子TB1
Terminal Block 1

N
N
N

N
N
N

N N

TB1-17
TB1-19
TB1-21
TB1-23

黑

黑

黑

黑

黑

黑

黑

黑

棕

黑

PE1

J3-2

J3-1

RDU-SIC

DB9

电控盒接地点/GND

L1 N1

PE1

380V/50Hz 3N～

KM2 KA1

J28-3

TB2-25

L1N1

KM1-A1

J3-4

J18-3

KM1-A2

J28-5

TB2-26

棕 棕蓝 蓝

J28-7
J28-8
J28-9

J28-10

黑黑

SPD-NC

SPD-COM

25 2729 31

26 2830 32

TB2-27

TB2-26

TB2-29

TB2-31

TB2-32

J3-1

J3-2

RDU-A

A
B

BKBK BK

BL

Y/G

BKBK

BKBK BK BK BK BK

Compressor

Fan

Display

Y/G

BRBK GR

BLBK WH

BR BRBL BL

BK

BK

BK

BK
BK
BK

Y/G

黑 黑 黑 黑

Power board

Control board

Filter

Temp.and Hum.

detection board

BK
BK
BL
BL
BK
BR

BK

BK

BK

BK

BK

BK

BK

BK

BR

BK

GR

GR

BK G R

接线说明/Wiring Diagram Description：
1、此接线图用于7.5KW和12.5KW机型。/This wir ing diagram for 7.5KW and 12.5KW models.
2、单冷机型无"电加热接触器KM2"、"电加热"、"加湿接触器K M3"、"内风机继电器KA1"、"红外加湿器"及相关电缆。
/Cooling only models without Hea ter contactor KM2,Heater,Humidif ier contactor KM3,Fan relay KA1,

Infrared

Humidifier and relate cables.
3、加热机型无"加湿接触器KM3"、"内风机继电器KA1"、"红 外加湿器"及相关电缆。
/Heating models without Humidifi er contactor KM3,Fan relay KA1,

Infrared

Humidifier and relate cables.
4、单冷机型和加热机型无"内风机继电器KA1"，内风机黑色抽头直 接接到J18-4端子上，蓝色抽头用闭端端子压接后扎于电控盒外。
/Cooling only models and Heating models without Fan relay KA1,Bl ack wire connect to terminal J18 -4,Blue wire tied with a closed- end terminal.
5、变压器T2、接线端子TB2为加热和加湿选配时增加，单冷机型无 变压器T2和接线端子TB2。
/Cooling only models without T2 and TB2.
6、单冷机型变压器T1型号为DME07MCT1T1，加热和加湿选 配时变压器T1型号为KL-LSF24A-T1。
/Transformer T1's type of coolin g only models is DME07MCT1T1,of other models is KL-LSF24A-T1
7、节能卡、监控卡、RDU-A为选配件，如有需求客户现场接线。/ Energy-saving card,SIC and RDU-A are optional.
8、版本代码为T的机组标配电源防雷器；版本代码为P的机组无电源防 雷器及相关电缆，控制板J19-1和J19-2用电缆短接。
/Version code T models with Powe r SPD, Version code P models wit hout Power SPD and relate cables ,connect J19-1 and J19-2 with a short
connection cable.

电源空开

Energy-saving card

到室外机
TO Outdoor
Unit

备机有效Lead/standby
switch over
公共告警
General alarm

配线色 标/Wire color code：

BK-Black/黑色 GR-GRAY/灰 色

R-Red/红色

WH-White/白色

BL-Blue/蓝色
BR-Brown/棕色

Y/G-Yellow green/黄绿 色

YE-Yellow/黄色
G-Green/绿色

黑BK
棕BR

黑BK

BR 棕

黑BK
黑BK

3

4

1

2

5

6

A1

A2

KM3-1

KM3-3

13

14

黑 黑

KM3

白 白

BK BK

WH WH

白

WH

KM3-5

黑

BK

J18-5

黑

KM3-A2

BK

J18-5

J3-3

KM3-A1

TB1-N

高水位告警/High Water Alarm

底盘防干烧开关
TS2

顶部过温开关
TS1

J3-3

红外加湿器
Humidifier

棕BR棕

BR

J28-2

TB2-31

WV-2WV-1

12

J21-5
J21-6

KM3-2

KM3-4

KM3-6

TS2-1TS2-2

TB1-5

TB1-11

HWAHWA

N2 L2 HL3

N1 L1 HL3

11

109

8

7

65

43

21

1413
1615
1817
2019
2221
2423

TB1-4
TB1-6

TB1-12

42

6

变压器T1
Transformer1

变压器T1接线方式详见框内标识

加热加湿机型变压器T1接线方式

黄

BK

黄

R

保险丝/Fuse

YE
G

YE

YE

黑

红
黄
绿

保险丝/Fuse

黄

BK

黄

BK

YE

YE

黑

黑

TB1-14

TB1-16

TB1-14

TB1-16

单冷机型变压器T1接线方式

Vertiv | Liebert DM series Air Conditioner | User Manual 86

APPENDIX 2 Menu Structure

Vertiv | Liebert DM series Air Conditioner | User Manual 87

APPENDIX 3 Parameter Setting

Menu

Parameter

Default

Setting range

Hi Temp

35°C

25°C ~ 50°C

Lo Temp

15°C

5°C ~ 20°C

Hi Hum

65%RH

65%RH ~ 90%RH

Lo Hum

35%RH

10%RH ~ 35%RH

AirflowDT

25°C

30°C

Alarm Setting

Alarm Setting

NC (the unit
Customer 2

Temp Set

24°C

15°C ~ 35°C

Temp Band

3°C

1°C ~ 5°C

Hum Set

50%RH

20%RH ~ 80%RH

Hum Band

5%RH

1%RH ~ 10%RH

Temp Cal

0.0°C

-10°C ~ +10°C

Hum Cal

0.0%

-10% ~ +10%

NTC0 Cal

0.0°C

-10°C ~ +10°C

Manual En

N

Y, N

Evap Fan

OFF

ON, OFF

Compressor

OFF

ON, OFF

Heater

OFF

ON, OFF

Humidifier

OFF

ON, OFF

LowFanSpeed

OFF

ON, OFF

Table

Alarm
Menu

Set Points

Alarm
Setpoint

Analog

(general alarm)

(serious alarm)

Customer 1

(remote
shutdown)

EN MSG, EN, DIS

EN DIS, EN

equipped with

NO, NC

SPD is NC by
default)

NC NO, NC

System
Status

Vertiv | Liebert DM series Air Conditioner | User Manual

I/O Status

88

Menu

Parameter

Default

Setting range

Cond Fan

OFF

ON, OFF

Protocol

1

1 ~ 254

Unit Addr

YDN23

YDN23, MODBUS

Baut Rate

19200

1200 ~ 19200

Overvoltage

15%

10% ~ 30%

Undervoltage

15%

10% ~ 30%

Fq Offset

3Hz

2Hz ~ 5Hz

Pwr Freq

50HZ

50Hz，60Hz

EvapFanStart

10s

10s ~ 600s

EvapFanStop

30s

10s ~ 300s

CP MinOn

180s

60s ~ 300s

CP MinOff

180s

60s ~ 300s

Cold Start

180s

30s ~ 240s

Hum Ctrl

RH

RH, AH

Temp Compens

OFF

ON, OFF

Factory Reset

NO

YES, NO

Fan type

AC

AC, EC

EC STD

75%

50% ~ 100%

EC Dehum

65%

40% ~ 90%

Run Interval

10h

5h~25h

Hum Time

8min

1min~30min

Prefill Time

30s

10s~300s

Fill Time

7s

1s~900s

Fill Rate

150%

100%~500%

Min. Volt

30%

30% ~ 50%

Max. Volt

100%

60% ~ 100%

OutputVolt
Start P

13Bar

11Bar ~ 15Bar

Optional

Heater Qty

0

0, 1

Hum Qty

0

Optional

Economy Mode

OFF

OFF, ON

Start at

22:00

18:00 ~ 3:00

End at

7:00

5:00 ~ 10:00

System
Menu

System
Setup

Outdoor
Unit

Press Bd

5Bar 4Bar ~ 6Bar

System
Menu

Vertiv | Liebert DM series Air Conditioner | User Manual

Func

Func_CostS
ave

0、IF

89

Menu

Parameter

Default

Setting range

Mod_Econo

my Mod

Optional

T/H Card Qty

0

0 ~ 4

System Mode

SIGL

SIGL, HOST, SPAR

Switch Mode

STDB

STDB, ROTA

Rotate Freq

Day

1DAY ~ 7Day

Rotate at

12:00

0:00 ~ 23:00

Set

Func_CostS

Band Zoom 2°C 2°C ~ 10°C

ave
Mod_Sleep
Mod

Optional
Func_Stand
by

Password

Sleep at 27°C 15°C ~ 40°C

Level 1 0001 ~ 9999

Vertiv | Liebert DM series Air Conditioner | User Manual

90