McQuay MDS030A User manual

Design & Installation Guide For McQuay MDS Multi System
Engineered for flexibility and performance.TM

©2004 McQuay International. All Rights Reserved.
is a registered trademark of McQuay in the United States and other countries, licensed and recognized
all over the world. Without prior written consent of McQuay, use of the above-named trademark for business
purposes may constitute a violation of the federal and state laws in the Unites states and laws of related countries,
and remain subject to a charge of trademark infringement and unfair competition.
This manual is prepared by the Market Department of McQuay ’sShenzhen-based factory. Pursuant to the
copyright law, this manual may not be reproduced or otherwise distributed in whole or in part without prior
written permission of McQuay.
We have used our best endeavor to make sure the information contained in this manual is accurate. As we are
always committed to technological improvement, any change in the units and specifications is subject to further
notice. In addition, to meet local criteria and customer requirements, we may modify the units and specifications.
Please also take notice that not all the models suit every market.
Discussed in this manual is a product made in China in compliance with the national standard –GB/T18837-2002.

CONTENTS
Foreword
1. Overview
1.1 General Information………………………………………………………………………………4
1.2 Working Principle & System Principle…………………………………………………………4
1.3 Main Features……………………………………………………………………………………11
1.4 Nomenclature……………………………………………………………………………………13
1.5 Products Series…………………………………………………………………………………15
1.6 Performance Parameter…………………………………………………………………………16
1.7 Operating Range…………………………………………………………………………………20
1.8 Refnet………………………………………………………………………………………………20
1.9 Outline of Indoor Units…………………………………………………………………………22
1.10 Outline of Outdoor Units………………………………………………………………………28
2. Unit Control
2.1 Introduction of the Controller……………………………………………………………………34
2.2 Main Functions……………………………………………………………………………………34
2.3 Operation of the Controller………………………………………………………………………35
2.4 Software Management System…………………………………………………………………39
2.5 Network Central Control…………………………………………………………………………41
2.6 Wiring Diagram……………………………………………………………………………………42
2.7 Electric Connection………………………………………………………………………………56
2.8 Electric Data……………………………………………………………………………………58
3. Selection
3.1 Load Calculation…………………………………………………………………………………59
3.2 Selection of Indoor Units………………………………………………………………………61
3.3 Selection of Outdoor Units……………………………………………………………………63
3.4 Design of Air System……………………………………………………………………………66
3.5 Selection of Refnet Joint………………………………………………………………………71
4. Installation
4.1 Installation of Indoor Units………………………………………………………………………75
4.2 Installation of Outdoor Units……………………………………………………………………82
4.3 Refrigerant Pipe & Installation…………………………………………………………………87
4.4 Design, Processing and Installation of Condensate Pipe…………………………………102
5. Testing
5.1Hardware Diagram and Equipment………………………………………………… 106
5.2 Running……………………………………………………………………………………………113
6. Servicing and Maintenance
6.1 Notice to the Customer…………………………………………………………………………114
6.2 Maintenance………………………………………………………………………………………115
7. Troubleshooting…………………………………………………………………………………119
Annexes…………………………………………………………………………………………………121

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Design & installation Guide For McQuay MDS Multi System
The MDS(Multi Digital Scroll) air conditioning system is operated by a digital compressor and is
accommodated by multiple evaporators (indoor units). It is touted as the next-generation modular
system in the world of high-efficiency air conditioning. lt has undoubtedly changed the face of cooling
associated with high-storied buildings. It provides a broad range of different applications for settings
such as offices, hotels and schools. With its easy installation and simple controlling system, the MDS
will more than meet the demands of the air conditioning market.
C H A P T E R
1
Overview
1.1 General information
1.2 Working principle & system principle
1.2.1Working principle
The beauty of this technology is its inherent simplicity. The standard digital scroll compressor has
a unique feature called axial compliance. This allows the fixed scroll to move in the axial direction, by
very small amounts, to ensure that the fixed and orbiting scrolls are always loaded together with the
optimal force.
This optimal force holding the 2 scrolls to-
gether at all operating condi tions ensure the
high efficiency of Copeland scrolls. The Digital
Scroll operation builds on this principle.
The Digital Scroll operates in two stages -
the "loaded state", when the solenoid valve is
normally closed and "unloaded state", when
the solenoid valve is open. During the loaded
state the compressor operates like a standard
scroll and delivers full capacity and mass flow.
However, during the unloaded state, there is no capacity and no mass flow through the compressor.
At this stage, let us introduce the concept of a cycle time. A cycle time consists of a "Loaded State"
time and "Unloaded State" time. The duration of these 2-time segments determine the capacity
modulation of the compressor. Example: In a 20 seconds cycle time, if the loaded state time is 10 seconds
and the unloaded state time is 10 seconds, the compressor modulation is (10 seconds x 100% + 10
seconds x 0%)/ 20 = 50% (Figure 3). If for the same cycle time, the loaded state time is 15 seconds
and the unloaded state time is 5 seconds, the compressor modulation is 75%. The capacity is a time
averaged summation of the loaded state and unloaded state. By varying the loaded state time and
unloaded state time, any capacity (10%-100%) can be delivered by the compressor.
fixed scroll
(movable in axial direction)
PWM vale
Orbiting scroll
(Rotatable in radial direction)

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Design & installation Guide For McQuay MDS Multi System
■ PWM valve power off
■ Valve close
■ Fixed scroll move downwards
■ Two scrolls gather together
■ Loading
■ PWM valve power on
■ Valve open
■ Fixed scroll moves upwards
■ Two scrolls separate
■ Unloading
Resident system Commerce system
1.2.2 Installation sketch map

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Design & installation Guide For McQuay MDS Multi System
MDS030AR、MDS040AR、MDS050AR、MDS060AR
1.2.3 System principle
MDS030A、MDS040A、MDS050A、MDS060A
Note: MDS030AR unit excludes the reservoir.
Note: MDS030A unit excludes the reservoir.

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Design & installation Guide For McQuay MDS Multi System
MDS080R、MDS100BR、MDS120BR
MDS150BR

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Design & installation Guide For McQuay MDS Multi System
MDS200BR、MDS220BR、MDS240BR
MDS180BR

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Design & installation Guide For McQuay MDS Multi System
MDS280BR、MDS300BR
MDS260BR

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Design & installation Guide For McQuay MDS Multi System
1.3 Main features
1.3.1 Wide range and stepless capacity modulation
■Wide capacity modulation range（10%-100%)；
■According to changing the ratio of “loading time”and “unloading time, MDS can modulate
the capacity steplessly；
■Lower the energy consumption and running cost.
1.3.2 Accurate temperature control and quick response.
■The cooling/heating capacity of the indoor units is controlled by the EXV,
which ensure the low temperature fluctuation of ±0.3℃;
■Stepless capacity modulation;
■Quick response to output the capacity (40s).
1.3.3 Simple, reliable and long life
■The PWM valve has the longevity of 40 million times
■Wide range of capacity modulation makes sure
the start/stop times reduces
■Less components
■No complicate inverter controller
■The compressor has an excellent oil return
performance, there is no need for the oil return
circuit
■Even the units run in 10% part load, the MDS
system can be in good stage.