McQuay AC 40A Instructions for use

AM - MAC

Contents

Introduction .............................................................................................................. 1 - 3

1. Chiller Mounting ................................................................................................... 4 - 8

2. Water Pipe Circuit............................................................................................... 9 - 27

3. Water Pipe and Fittings ................................................................................... 28 - 66

4. Pipe and Fitting Size ....................................................................................... 67 - 72

5. Water Pump ..................................................................................................... 73 - 86

6. Water Storage Tank and Expansion Tank ..................................................... 87 - 93

7. Insulation Material ......................................................................................... 94 - 106

8. Pipe Support ......................................................................................................... 107

9. Water Side Treatment .................................................................................. 108 - 114

10. Heating Operation ...................................................................................... 115 - 120

11. Electrical Wiring Control ............................................................................ 121 - 140

12. Flow Switch................................................................................................. 141 - 145

13. System Balancing....................................................................................... 146 - 148

14. Chiller Shut Down....................................................................................... 149 - 150

Appendix (Appendix 1-19) ...............................................................................37 Pages

is meant for DISTRIBUTORS of McQuay International only. No part of this publication may bereproduced

or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior

written permission of McQuay International.

Introduction

The air-cooled mini chillers form part of a complete integrated water hydronic system with the

chiller water fan coil units. The range of capacity from 30,000 Btu/hr to 150,000 Btu/hr (8.79 –

43.96 KW) makes them suitable for various applications:

-Office Rooms

-Private Houses

-Business Rooms

-Club, Pubs, Coffee Houses

-Hotels

-Restaurants

-Process Cooling

The advantages of using these chillers are:

1. Due to its compact design, the mini-chillers require a smaller space for installation.

The design also allows for flexibility in design to meet various types of application

requirements.

2. The amount of refrigerant used is small compared with other split and multi-split direct

expansion systems, i.e. they are more environmental friendly.

3. There is no necessity to use cooling towers.

4. No refrigerant is used in the occupied space.

5. The usage of water as the cooling medium allows for excellent load variability with minimal

system complexity as against equivalent VRV systems.

6. Ability to have long piping distances.

A water hydronic system can be classified as a close or open system.

Definition: A close water system is one with no more than one point of interface with a

compressible gas or surface. [ASHRAE handbook: 1996 System & Equip.]

The basic design of the mini-chiller is for a close system. However, a modification for an open

system is possible.

The close hydronic system will consist of the following fundamental components:

a. Source

b. Load

c. Expansion Tank

d. Pump

e. Distribution System

Introduction Page 1

Schematic diagram of the basic close hydronic system:

Expansion

tank

Heat Pump Heat

Distribution system

SOURCE LOAD

In the mini chiller, the source will comprise of the refrigeration circuit, i.e. compressor, expansion

device, condenser and evaporator. A brazed plate heat exchanger (BPHE) is used as the

evaporator to produce the chilled water.

A built-in water tank is also provided in the mini chiller to act as a buffer storage. See next page.

For integration, both the expansion tank and pump are incorporated together into the mini chiller.

Hence, the schematic diagram of the system becomes as follows:

Introduction Page 2

If both chilled water and hot water are required in the system, a mini chiller with a reverse

cycle operation will be used. The unit will have an additional 4-way valve and accumulator for

this purpose.

It is by such integration of components of the hydronic system that the mini chiller becomes

compact. Installation of the chiller will thus only involve:

1. The chiller mounting

2. Indoor fan coil unit installation

3. Water piping installation between the chiller and fan coil unit

4. Electrical wiring connection

This manual is written with the purpose of providing guidelines as to the installation and operation

of the hydronic system; i.e. both the chiller and fan coil unit. Application design guidelines will also

be discussed. Selection criteria of piping, valve, pump and other equipment are also given.

Examples of such complete installations are as shown in the following pages. This manual will

give some technical information and details on how such installations are designed and done

at site.

In general, there are three series of mini chillers available:

a) A series (from 30,000 Btu/hr [8.79 kW] to 50,000 Btu/hr [14.65 kW])

- double stack design, with built-in buffer tank

b) B series (from 75,000 Btu/hr [21.98 kW] to 125,000 Btu/hr [36.64 kW])

- double stack design, with built-in buffer tank

c) C series (from 80,000 Btu/hr [23.45 kW] to 150,000 Btu/hr [43.96 kW])

- monoblock design, without buffer tank

This manual must be used in conjunction with the Technical Manual and Installation and

Operation Manual (IOM) of the mini chillers and chilled water fan coil units.

Introduction Page 3

Section 1: Chiller Mounting

Care must be taken to locate the air-cooled chiller at the proper place. Ensure sufficient

clearance around the unit to allow proper air flow and to facilitate access for maintenance.

Location of the units must also prevent short-circuiting of the discharge air. Do not block any air

passage in and out of the units.

Please refer to the corresponding Technical Manual for further information.

The chiller unit must be placed on a firm surface, e.g. concrete flooring, slab or plinth. Due

to space consideration, the chiller may be mounted onto a steel bracket which is secured to

a firm surface, e.g. brick wall, concrete wall or a steel structure.

concrete flooring

Series B Chiller

Plinth

Wall

Steel bracket

Plinth

Section 1 Page 4

Such brackets must have sufficient strength to carry the weight of the chiller unit. It is

recommended that angle bars (e.g. 38mm*38mm*3mmt) or hollow section bars (e.g. 25mm*

50m*2mmt) to be used for fabricating these brackets.

These brackets must also allow clearance for removal of service panels for maintenance

purposes.

In any case, it is vital that the chiller unit is secured firmly onto the concrete floor/slab or steel

bracket by using studs, wall plugs or bolts/nuts at the four (4) mounting holes located at the base

plate of the chiller. The weight of the chiller unit and the water pipe connections are not sufficient

to prevent unit movement should any sudden impact or strong vibrations occur in the unit. Failure

to do so may cause the water pipes to deform and break.

It is further recommended that rubber isolation pads (1/2" thick) to be placed beneath each

mounting hole to prevent excessive vibration and noise. If necessary, isolating springs can

also be mounted.

The following pages are examples of these isolation pads and springs.

Section 1 Page 5

Special installation:

The A and B series mini chiller units have been designed with the refrigerant circuit located in the

top compartment and the hydraulic kit in the bottom compartment:

A-series B-series

Hydraulic kit

Piping

connection

Refri

erant

Water

B-series

-series

In some special installations whereby the available space (especially the height) is not

sufficient to install the chiller, it is possible to to detach these two compartments and install

them side by side. This is especially useful when there are multiple units which are stacked

together with a steel bracket.

Bracket

Hydraulic kit

Water

Refrigerant pipe

connection

Hydraulic kit

Water pipes

Section 1 Page 6

For the A-series type of mini chiller, the inter-connecting pipes between the two

compartments are the refrigerant pipes. For the B-series type, there is a water pipe in

between the two compartments.

Therefore, the detached installation of the A-series mini chillers is very similar to the

installation of a split type air-conditioning unit.

Note:

Gas line to be insulated with

tube insulation. Use the

correct size for each pipe, thickness

¼”

Refrig. Pipe size

Liquid Gas

AC 040A 3/8” ¾”

AC 050A 3/8” ¾”

AC 058A ½” ¾”

Take care of the following items [for detached A-series installations]:

Maximum pipe length,m

AC 040C 20

AC 050C 20

AC 058C 20

a) Do not allow excessive refrigerant pipe

length between the two compartments.

Always choose the shortest path.

Long piping will cause high pressure

drops and reduces the capacity of the

system. Use the following

recommendations:

Maximum elevation, m

AC 040A 10

AC 050A 10

AC 058A 10

b) It is possible to have the hydraulic kit

higher or lower than the refrigerant

compartment. Do not allow excessive

elevation between these two

compartments. Use the following

recommendations:

If the elevation exceeds the above recommendations, care must be taken to ensure sufficient oil

return to the compressor. Use oil traps (one every 30ft height interval) or oil separators, if

necessary.

c) The longer pipe lengths will require more refrigerant charge for optimum

performance.

Recommendation: Additional 50g (R-22) for every 1 meter of connecting pipe length.

Similarly, additional refrigerant oil charge may be required.

Section 1 Page 7

d) Use as few bends as possible in the pipe run. Each bend will cause extra pressure drop and

reduces the capacity of the system. Do not use more than 10 bends. For both A and B-

series chillers, locating the hydraulic kit at a far distance will also mean having a longer

water pipe length. This will incur a higher pressure head to the water pump in the chiller

unit. If not careful, this will reduce the water flow rate through the system and may cause

system failure, e.g. water freezing, compressor tripping.

Furthermore, the longer pipe will increase the cost of installation.

Always look for the closest possible locations for these two compartments.

External drain pan

In some instances, it is necessary to install an external drain pan beneath the unit to collect

any condensate water from the chiller unit. This is especially so for the heat pump versions

,where water will condense on the heat exchanger coil during the heating mode. Further more,

a lot of water will flow out during the defrost cycle.

Such external drain pans are needed when the chiller units are installed inside a plant

room where it is not appropriate for the floor to be wet. (Note A)

It is recommended that the drain pan to be fabricated out of galvanised iron (GI) sheet

metal, at least 0.8 mm in thickness. Allow the drain pan depth of about 20mm.

This external drain pan should be laid out on the floor first before placing the entire chiller

unit on top of it. It is recommended that the chiller unit to be raised up by 20 - 30mm from

the drain pan so as to prevent rusting of the chiller base pan.

Note A: Caution! Please ensure adequate ventilation in the plant room else the

chiller unit may trip.

Section 1 Page 8

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