McQuay ACZ 030B Installation Manual

Installation and Maintenance Manual

Group: Chiller Part Number: 331374201 Effective: July 2007 Supersedes: October 2006

IMM ACZ/AGZ-4

Air-Cooled Scroll Condensing Units

ACZ 030B through 155B

Air-Cooled Scroll Chillers w/ Remote Evaporators

AGZ 026BM through 130BM

60 Hertz, R-22, R 407C

Table of Contents

Introduction.................................................... 3

General Description .....................................................3

Inspection ....................................................................3

Nomenclature ..............................................................3

Installation...................................................... 4

Handling......................................................................4

Location.......................................................................5

Sound Isolation..........................................................12

Vibration Isolators.....................................................12

Ambient Temperature and Water Flow Limitations...14

Water Piping (Model AGZ-BM)................................14

ACZ Staging and Circuiting......................................21

Remote Evaporator Refrigerant Piping .....................22

Chilled Water Flow Switch........................................24

Evaporator Flow and Pressure Drop..........................25

Wind Baffles and Hail Guards...................................26

Physical Data................................................28

Electrical Data Standard Ambient ............. 33

Electrical Data High Ambient.....................43

Dimensional Data......................................... 52

Remote Evaporators ..................................................55

Optional Features......................................... 57

Start-up.........................................................60

Pre Start-up................................................................60

Start-Up.....................................................................60

Shutdown...................................................................61

Water Piping Checkout.............................................. 61

Refrigerant Piping Checkout.....................................61

Electrical Check Out .................................................62

Operation...................................................... 62

Hot Gas Bypass (Optional)........................................62

VFD Low Ambient Control (Optional) .....................63

Filter-Driers (AGZ-BM)............................................63

System Adjustment....................................................63

Liquid Line Sight Glass and Moisture Indicator.......63

Refrigerant Charging.................................................63

Thermostatic Expansion Valve..................................63

Crankcase Heaters.....................................................64

Unit Maintenance......................................... 65

Preventive Maintenance Schedule.............................66

Service...........................................................67

Liquid Line Solenoid Valve.......................................67

Remote Evaporator (AGZ-BM Only) .......................68

Refrigerant Charging.................................................68

Warranty Statement .................................... 69

ACZ/AGZ Troubleshooting Chart ............. 70

Unit controllers are LONMARK certified with an optional LONWORKS communication

Manufactured in an ISO Certified facility

"McQuay" is a registered trademark of McQuay International

Illustrations and data cover McQuay International products at the time of publication and we reserve the right

to make changes in design and construction at anytime without notice.

2 ACZ / AGZ-BM IMM ACZ/AGZ-4

Introduction

General Description

This manual covers two similar product lines: AGZ-BM, Packaged chiller with the evaporator shipped separately for remote installation, field

piping to the outdoor unit, and interconnection of wiring. The refrigeration specialties are shipped from the factory for field installation.

Operating instructions are contained in operating manual OM AGZ. ACZ-BC, Condensing unit with no evaporator included. For use with customer supplied low side

(usually an air-handling unit), field piped and wired to the condensing unit. Operating instructions are contained in operating manual OM ACZ.

These McQuay air-cooled units are complete, self-contained, automatic refrigerating units. Every unit is completely assembled, factory wired, tested and provided with a holding charge. Each unit consists of two air-cooled condenser sections with integral subcooler sections, two tandem or triple scroll compressors, (brazed-plate or replaceable tube, dual circuit shell-and-tube evaporator and liquid line components including manual, sight-glass/moisture indicators, solenoid valves, and thermal expansion valves on AGZ-BM only). Other features include compressor crankcase heaters, an evaporator heater for chilled water freeze protection (on AGZ-BM only), one-time pumpdown during “on” or “off” periods, and automatic compressor lead-lag to alternate the compressor starting sequence.

The electrical control center includes all equipment protection and operating controls necessary for dependable automatic operation. Condenser fan motors are protected in all three phases and started by their own three-pole contactors. Model ACZ condensing units require a field-supplied multi-step thermostat wired to the outdoor unit.

Inspection

Check all items carefully against the bill of lading. Inspect all units for damage upon arrival. Report shipping damage and file a claim with the carrier. Check the unit nameplate before unloading, making certain it agrees with the power supply available. McQuay is not responsible for physical damage after unit leaves the factory.

Note: Unit shipping and operating weights are available in the Physical Data tables beginning on page 28.

Nomenclature

A G Z - XXX B M

C=Condensing Unit

Scroll Compressor

Air-Cooled

G=Global Chiller

Application C= Condensing Unit M= Remote Evaporator

Design Vi ntage Model Size

(Nominal Tons)

IMM ACZ/AGZ-4 ACZ / AGZ-BM 3

Installation

Note: Installation is to be performed by qualified personnel who are familiar with local

codes and regulations.

Sharp edges on unit and coil surfaces are a potential hazard to personal safety. Avoid

Handling

Be careful to avoid rough handling of the unit. Do not push or pull the unit from anything other than the base. Block the pushing vehicle away from the unit to prevent damage to the sheet metal cabinet and end frame (see

To lift the unit, 2 1/2" (64mm) diameter lifting tabs are provided on the base of the unit. Arrange spreader bars and cables to prevent damage to the condenser coils or cabinet (see

Figure 1, Suggested Pushing Arrangement

WARNING

contact with them.

Figure 1).

Figure 2).

Blocking is required across full width

Figure 2, Suggested Lifting Arrangement

Spreader bars

required

(use caution)

Number of fans may vary

from this diagram. The lifting

method will remain the same.

All rigging locations must be used.

4 ACZ / AGZ-BM IMM ACZ/AGZ-4

Location

Unit Placement

ACZ/AGZ units are for outdoor applications and can be mounted either on a roof or at ground level. For

Figure 3, Clearances

SEE TABLE BELOW

DIMENSION “A”

roof mounted applications, install the unit on a steel channel or I-beam frame to support the unit above the roof. For ground level applications, install the unit on a substantial base that will not settle. A one-piece

4 FT. (1220mm) CLEARANCE FOR

SERVICE ACCESS

concrete slab with footings extended below the frost line is recommended. Be sure the foundation is level within 1/2"(13mm) over its length and width. The foundation must be strong enough to support the

SEE TABLE BELOW

DIMENSION “A”

weights listed in the Physical Data Tables beginning on page

28.

Table 1, Recommended Minimum Clearances

ACZ-BC

Model Sizes 030B – 080B 026B – 070B 4 (1.2) 8 (2.4) 6 (1.8) 4 (1.2) 4 (1.2) 090B – 155B 075B – 130B 6 (1.8) 12 (3.6) 8 (2.4) 4 (1.2) 4 (1.2)

AGZ-BM

Model Size

Coil Side “A”

ft (m)

“B”

ft (m)

“C”

ft (m)

End Opposite

Controls ft (m)

Control Panel End

Clearances

Do not block the flow of air to and from the condenser coil. Restricting airflow or allowing air recirculation will result in a decrease in unit performance and efficiency because discharge pressures are increased. There must be no obstruction above the unit that would deflect discharge air downward where it could be recirculated back to the inlet of the condenser coil. The condenser fans are propeller type and will not operate with ductwork.

AIR FLOW AIR FLOW

The recommended minimum side clearance between two units is dimension “B’ in table on this page.

AIR

DISCHARGE

AIR FLOW

“B”

ft. (m)

4 FT. (1220) CLEARANCE FOR

SERVICE ACCESS

AIR

DISCHARGE

Install the unit with enough side clearance for air entrance to the coil

AIR FLOW AIR FLOW

AIR

DISCHARGE

and for servicing. Provide service access to the evaporator, compressors, electrical control panel and piping components.

Do not allow debris to accumulate

“C” “C”

near the unit where it could be drawn into the condenser coil. Keep condenser coils and fan discharge free of snow or other obstructions to permit

The unit must not be installed in a pit or enclosure that is deeper or taller than the height of the unit unless extra space is provided. The minimum clearance on each side of the unit is dimension “C” in table on this page.

adequate airflow for proper operation.

IMM ACZ/AGZ-4 ACZ / AGZ-BM 5

Restricted Air Flow General

The clearances required for design-life operation of ACZ/AGZ air-cooled units are described in the previous section. Occasionally, these clearances cannot be maintained due to site restrictions, such as units being too close together, or a fence or wall restricting airflow, or both.

The McQuay ACZ/AGZ units have several features that can mitigate the problems attributable to restricted airflow.

• The condenser section is configured as shown below. This configuration allows inlet air for

these coils to come in from either side. A vertical coil and its adjacent angled coil are manifolded together to serve one refrigerant circuit.

• The MicroTech II™ control is proactive in response to “off-design conditions”. In the case of

single or compounded influences restricting airflow to the unit, the microprocessor will act to keep the compressor(s) running (possibly at reduced capacity) rather than allowing a shut-off on high discharge pressure.

• The MicroTech II™ control can be programmed to sequence the compressors in the most

advantageous way. For example, in the diagram shown below, it might be desirable to program circuit #1 to be the lag circuit (last circuit to reach full load) during periods of high ambient temperatures.

Figure 4, Coil and Fan Arrangement

Building

Circuit #1 Circuit #2

NOTE: Models ACZ 030 to 045 and AGZ 026 to 035 do not have an interior slanted coil.

The following sections discuss the most common situations of condenser air restriction and give capacity and power adjustment factors for each. Note that in unusually severe conditions, the MicroTech II™ controller would adjust the unit operation to remain online until a less severe condition is reached.

6 ACZ / AGZ-BM IMM ACZ/AGZ-4

Case 1, Building or Wall on One Side of One Unit

The existence of a screening wall, or the wall of a building, in close proximity to an air-cooled unit is common in both rooftop and ground level applications. Hot air recirculation on the coils adjoining the wall will increase compressor discharge pressure, decreasing capacity and increasing power consumption. Only the compressor(s) connected to these coils will be affected.

When close to a wall, place chillers on the north or east-side of them. Have prevailing winds blowing parallel to the unit’s long axis. The worst case is to have wind blowing hot discharge air into the wall.

Figure 5, Unit Adjacent to Wall

Figure 6, Adjustment Factors

3.0

2.0

1.0

ACZ

090-155

AGZ

075-130

4.5 ft.

(1.4m)

6 ft.

(1.8m)

8 ft.

(2.4m)

ACZ

030-080

AGZ

026-070

3.5 ft.

(1.0m)

4 ft.

(1.2m)

6 ft.

(1.8m)

4.0

3.0

2.0

ACZ

030-080

090-155

AGZ

026-070

075-130

4.5 ft.

3.5 ft.

(1.4m)

(1.0m)

6 ft.

8 ft.

4 ft.

(1.2m)

6 ft.

(1.8m)

(2.4m)

IMM ACZ/AGZ-4 ACZ / AGZ-BM 7

Case 2, Two Units Side By Side

Two or more units sited side by side are common. If spaced closer than 12 feet (3.7 meters), or 8 feet (2.5meters), depending on size, it is necessary to adjust the performance of each unit. Circuits adjoining each other are affected. NOTE: This case applies only to two units side by side. See Case 3 for three or more parallel units. If one of the two units also has a wall adjoining it, see Case 1. Add the two adjustment factors together and apply to the unit located between the wall and the other unit.

Mounting units end to end will not necessitate adjusting performance. Depending on the actual arrangement, sufficient space must be left between the units for access to the control panel door opening and/or evaporator tube removal. See “Clearance” section of this guide for requirements for specific units.

Figure 7, Two Units Side by Side

Figure 8, Adjustment Factor

3.0

2.0

1.0

AGZ 075-130

ACZ 090-155

AGZ 026-070

ACZ 030-080

(2.7)

6.5

(2.0)

(3.0)

(2.1)

(3.3)

7.5

(2.2)

(3.6)

(2.4)

AGZ 075-130 ACZ 090-155

AGZ 026-070 ACZ 030-080

6.0

4.0

2.0

(2.7)

6.5

(2.0)

(3.0)

(2.1)

(3.3)

7.5

(2.2)

(3.6)

(2.4)

8 ACZ / AGZ-BM IMM ACZ/AGZ-4

Case 3, Three or More Units Side By Side

When three or more units are side by side, the outside units (1 and 3 in this case) are influenced by the middle unit only on their inside circuits. Their adjustment factors will be the same as Case 2. All inside units (only number 2 in this case) are influenced on both sides and must be adjusted by the factors shown below.

Figure 9, Three or More Units

Chiller 1 Chiller 2 Chiller 3

Figure 10, Adjustment Factor

4.0

3.0

2.0

1.0

AGZ 075-130 ACZ 090-155

AGZ 026-070 ACZ 030-080

(4.6)

(3.3)

(4.9)

(3.7)

(5.2)

(4.0)

(5.5)

(4.3)

AGZ 075-130 ACZ 090-155

AGZ 026-070 ACZ 030-080

8.0

6.0

4.0

2.0

(4.6)

(3.3)

(4.9)

(3.7)

(5.2)

(4.0)

(5.5)

(4.3)

IMM ACZ/AGZ-4 ACZ / AGZ-BM 9

Case 4, Open Screening Walls

Decorative screening walls are often used to help conceal a unit either on grade or on a rooftop. These walls should be designed such that the combination of their open area and distance from the unit do not require performance adjustment. It is assumed that the wall height is equal to or less than the unit height when mounted on its base support. This is usually satisfactory for concealment. If the wall height is greater than the unit height, see Case 5, Pit Installation.

The distance from the ends of the unit to the end walls must be sufficient for service, opening control panel doors, and pulling evaporator tubes, as applicable.

If each side wall is a different distance from the unit, the distances can be averaged, providing either wall is not less than 8 feet (2.4 meters) from the unit. For example, do not average 4 feet and 20 feet to equal 12 feet.

Figure 11, Open Screening Walls

Figure 12, Wall Free Area vs. Distance

AGZ 026-070 ACZ 030-080

(1.2)

3.5

(1.0)

3.0

(0.9)

2.5

(0.7)

AGZ 075-130

ACZ 090-155

(1.8)

(2.0)

(1.2)

(0.9)

01020304050

10 ACZ / AGZ-BM IMM ACZ/AGZ-4

Case 5, Pit/Solid Wall Installation

Pit installations can cause operating problems and great care should be exercised if they are to be used on an installation. Recirculation and restriction can both occur. A solid wall surrounding a unit is substantially the same as a pit and the data presented here should be used.

Steel grating is sometimes used to cover a pit to prevent accidental falls or trips into the pit. The grating material and installation design must be strong enough to prevent such accidents, yet provide abundant open area or serious recirculation problems will occur. Have any pit installation reviewed by McQuay application engineers prior to installation for air-flow characteristics. The installation design engineer must approve the work to avoid an unreasonable risk of accident and is responsible for final design criteria.

Figure 13, Pit Installation

Figure 14, Adjustment Factor

AGZ 026-070

ACZ 030-080 AGZ 075-130

ACZ 090-155

D=4 (1.4)

D=6

(1.8)

D=5 (2.0)

D=8 (2.4)

AGZ

075-130

ACZ

090-155

D=10

(3.1)

AGZ

026-070

ACZ

030-080

D=7 (2.1)

D=4

AGZ 026-070 ACZ 030-080

AGZ 075-130 ACZ 090-155

(1.4) D=6

(1.8)

D=5 (2.0)

D=8 (2.4)

AGZ

075-130

ACZ

090-155

D=10

(3.1)

AGZ

026-070

ACZ

030-080

D=7 (2.1)

IMM ACZ/AGZ-4 ACZ / AGZ-BM 11

Sound Isolation

The low sound level of the ACZ/AGZ units is suitable for most applications. When additional sound reduction is necessary, locate the unit away from sound sensitive areas. Avoid locations beneath windows, or between structures where normal operating sounds can be objectionable. Reduce structurally transmitted sound by isolating refrigerant lines, electrical conduit and the unit itself. Use wall sleeves and rubber isolated piping hangers to reduce transmission of water, refrigerant, or pump noise into occupied spaces. Use flexible electrical conduit to isolate sound transmission through electrical conduit. Spring isolators are effective in reducing the low amplitude sound generated by scroll compressors and for unit isolation in sound sensitive areas.

Vibration Isolators

Vibration isolator springs are recommended for all roof-mounted installations, or wherever vibration transmission is a consideration. Some form of isolator is also recommended for slab installations, primarily to keep the unit base from resting its entire length directly on the slab.

Table 2 and Table 3 list isolator point loads for all unit sizes. Figure 15 and 16 shows isolator locations. See Dimensional Data for detailed mounting hole location.

Isolator Installation

The unit should be initially installed on shims or blocks at the listed free height. When all piping, wiring, flushing, charging, etc., is completed, adjust the springs upward to load them and to provide clearance to remove the shims or blocks.

Installation of spring isolators requires flexible piping connections and at least three feet of conduit flex tie-ins. Piping and conduit must be supported independently of the unit.

Bolting: if the chiller base is to be bolted to the isolators, it is recommended that the short threaded studs usually found on isolators be replaced with eight-inch threaded rod that can extend through the holes on the top of the base and then be bolted. Washers will be required.

Figure 15, RP-4, Neoprene-in-Shear Isolators CP-2, Spring Isolators

Figure 16, Isolator Locations,

4/6 FAN UNIT 8 FAN UNIT

CONTROL

PANEL

12 ACZ / AGZ-BM IMM ACZ/AGZ-4

CONTROL

PANEL

Table 2, Isolator Loads At Each Mounting Location (With Aluminum Fins)

ACZ-B

Model

ACZ 030 AGZ 026

ACZ 035 AGZ 030

ACZ 040 AGZ 035

ACZ 045 AGZ 040

ACZ 050 AGZ 045

ACZ 055 AGZ 050

ACZ 060 AGZ 055

ACZ 065 AGZ 060

ACZ 070 AGZ 065

ACZ 080 AGZ 070

AGZ-BM

Model

Shipping

lbs 3550 3600 1227 901 849 623 3600 72

kg 1608 1631 556 408 385 282 1631 32

lbs 3550 3600 1227 901 849 623 3600 72

kg 1608 1631 556 408 385 282 1631 32

lbs 3550 3600 1227 901 849 623 3600 72

kg 1608 1631 556 408 385 282 1631 32

lbs 3550 3610 1261 872 873 604 3610 72

kg 1608 1635 571 395 395 274 1635 32

lbs 3590 3650 1275 881 883 611 3650 72

kg 1626 1653 578 399 400 277 1653 32

lbs 3730 3800 1295 951 896 658 3800 119

kg 1690 1721 587 431 406 298 1721 54

lbs 3780 3850 1303 1016 860 671 3850 119

kg 1712 1744 590 460 390 304 1744 54

lbs 3820 4040 1367 1066 903 704 4040 142

kg 1730 1830 619 483 409 319 1830 65

lbs 3970 4070 1305 1146 862 757 4070 142

kg 1798 1844 591 519 390 343 1844 65

lbs 4080 4180 1278 1192 885 825 4180 217

kg 1848 1894 579 540 401 374 1894 99

Operating.

Loc. 1 Loc. 2 Loc. 3 Loc. 4 Total

NOTE (1): Additional weight for copper coils is per mounting location.

(1) Add’l for

Copper Fins

Table 3, Isolator Loads At Each Mounting Location (With Aluminum Fins)

ACZ

Model

ACZ090 AGZ 075

ACZ100 AGZ 085

ACZ110 AGZ 090

ACZ120 AGZ 100

ACZ130 AGZ 110

ACZ140 AGZ 120

ACZ155 AGZ 130

NOTE (1): Additional weight for copper coils is per mounting location.

AGZ-BM

Model

Shipping

lbs 5510 5630 1649 1166 1649 1166 - - 5630 217

kg 2496 2550 747 528 747 528 - - 2550 99

lbs 5670 5790 1734 1227 1657 1172 - - 5790 217

kg 2569 2623 786 556 751 531 - - 2623 99

lbs 5830 5950 1770 1205 1770 1205 - - 5950 217

kg 2641 2695 802 546 802 546 - - 2695 99

lbs 6820 6970 1323 1188 1053 1265 1135 1006 6970 289

kg 3089 3157 599 538 477 573 514 456 3157 131

lbs 7080 7230 1396 1205 1014 1396 1205 1014 7230 289

kg 3207 3275 632 546 459 632 546 459 3275 131

lbs 7360 7480 1477 1275 1073 1411 1218 1026 7480 289

kg 3334 3388 669 578 486 639 552 465 3388 131

lbs 7640 7760 1555 1293 1032 1555 1293 1032 7760 289

kg 3461 3515 704 586 467 704 586 467 3515 131

Wt.

Operating

Wt.

Loc 1 Loc 2 Loc 3 Loc 4 Loc 5 Loc 6 TOTAL

Table 4, Isolator Kit Numbers

ACZ-B Model

AGZ-BM Model

Spring Kit Part No.

R-I-S Kit Part No.

030 - 040 045 - 065 070 080 090 - 110 120, 130 140, 155 026 - 035 040 - 060 065 070 075 - 090 100, 110 120, 130

330349601 330349602 330349603 330349604 330349608 330349610 330349611 330349701 330349701 330349703 330349703 330349706 330349707 330349708

(1)

Add’l

for

Copper

Fins

IMM ACZ/AGZ-4 ACZ / AGZ-BM 13

Table 5, Isolator Locations

ACZ-BS, AGZ-BM Less Evaporator Units

ACZ-

AGZ-

Model

NOTE (1): Position #4 is a CP-1, single spring isolator for ACZ 030 to 065 and AGZ 026 to 060. All others are CP-2, two

Model

030 026 035 030 040 035 045 040 050 045 055 050 060 055 065 060 070 065 080 070 090 075 100 085 110 090 120 100 130 110 140 120 155 130

Operating

Weight

lbs kg 1 2 3 4 5 6 1 2 3 4 (1) 5 6

3600 1631 Black Gray Gray Green - - Orange Purple Red Orange 3600 1631 Black Gray Gray Green - - Orange Purple Red Orange - 3600 1631 Black Gray Gray Green - - Orange Purple Red Orange - 3610 1635 Black Gray Gray Green - - Orange Purple Purple Orange - 3650 1653 Black Gray Gray Green - - Orange Purple Purple Orange - 3800 1721 Black Gray Gray Green - - Orange Purple Purple Orange - 3850 1744 Black Gray Gray Green - - Orange Purple Purple Orange - 4040 1830 Black Gray Gray Green - - Orange Purple Purple Orange - 4070 1844 Black Black Gray Gray - - Orange Purple Purple Red - 4180 1894 Black Black Gray Gray - - Orange Orange Purple Red - 5630 2550 Red Black Red Black - - Green Orange Green Orange - 5790 2623 Red Black Red Black - - Green Orange Green Orange - 5950 2695 Red Black Red Black - - Green Orange Green Orange - 6970 3157 Black Black Black Black Black Black Orange Orange Purple Orange Orange Purple 7230 3275 Black Black Black Black Black Black Orange Orange Purple Orange Orange Purple 7480 3388 Red Black Black Red Black Black Green Orange Purple Green Orange Purple 7760 3515 Red Black Black Red Black Black Green Orange Purple Green Orange Purple

spring.

Neoprene-In-Shear Mountings Spring-Flex Mountings

Ambient Temperature and Water Flow Limitations

ACZ/AGZ units are designed to operate in ambient temperatures as shown in the following table.

Table 6, Unit Maximum Operating Ambient Temperature

Unit Model Standard Controls

AGZ 026B – 130B

ACZ 030B – 155B

115°F 105°F 125°F

w/ Low Ambient VFD

Control Option

The VFD Low Ambient Control Option imposes an additional heat load on the control panel limiting operation to 105°F ambient temperature. The addition of the High Ambient Panel Option allows operation to 125°F ambient temperature.

Compressor loading and unloading is adaptively determined by system load, ambient air temperature, and other inputs to the MicroTech control algorithms. An optional low ambient fan VFD option allows operation down to 0°F (-18°C). The minimum ambient temperature is based on still conditions where the wind is not greater than five mph. Greater wind velocities will result in reduced discharge pressure, increasing the minimum operating ambient temperature. Field-installed hail/wind guards are available to allow the chiller to operate effectively down to the ambient temperature for which it was designed.

Evaporator flow rates can be found on page

25. Operation below the minimum values can result in laminar flow causing freeze-up problems, scaling and poor control. Flow rates above the maximum values will result in unacceptable pressure drops and can cause excessive erosion, potentially leading to failure.

w/ Low Ambient VFD Control

Plus High Ambient Panel Option

Water Piping (Model AGZ-BM)

Local authorities can supply the installer with the proper building and safety codes required for safe and proper installation.

Install piping with minimum bends and changes in elevation to minimize pressure drop. The following issues must be considered when designing and installing water piping:

14 ACZ / AGZ-BM IMM ACZ/AGZ-4

1. Vibration eliminators to reduce vibration and noise transmission to the building.

2. Shutoff valves are required to isolate the unit from the piping system during unit servicing.

3. Manual or automatic air vent valves at the high points of the system. Drains must be installed

at the lowest points in the system.

4. Adequate system water pressure must be maintained (expansion tank or regulating valve).

5. Temperature and pressure indicators located at the unit are required to aid in unit servicing.

6. A strainer or other means of removing foreign matter from the water before it enters the pump

be installed. Place the strainer far enough upstream to prevent cavitation at the pump

must inlet (consult pump manufacturer for recommendations). The use of a strainer will prolong pump life and keep system performance up.

7. A strainer must

be installed in the water line before the inlet of the evaporator. This will help

prevent foreign material from entering and decreasing the evaporator performance.

8. If the unit is used as a replacement chiller, flush the system thoroughly before unit

installation. Regular water analysis and chemical water treatment for the evaporator loop is recommended immediately at equipment start-up.

9. The total water volume in the system should be sufficient to prevent frequent “on-off”

cycling. Turnover rate should not be less than 4 minutes for normal variable cooling loads.

10. When glycol is added to the water system for freeze protection, the refrigerant suction

pressure will be lower, cooling performance less, and water side pressure drop greater. If the percentage of glycol is high, or if propylene is used instead of ethylene glycol, the added pressure drop and loss of performance could be substantial. When Glycol or Ice are selected as Unit Mode, the MicroTech controller will automatically reset the available range for the Leaving Water Temperature, Freezestat and Evaporator Pressure settings.

Reset the freezestat setting to approximately 4 to 5 degrees F (2.3 to 2.8 degrees C) below the leaving chilled water setpoint temperature. See the section titled “Glycol Solutions” for additional information concerning glycol.

11. Perform a preliminary leak check before insulating the piping and filling the system.

12. Piping insulation should include a vapor barrier to prevent condensation and possible damage

to the building structure from water dripping.

Figure 17, AGZ 075BM – AGZ 130BM, Typical Field Evaporator Water Piping

THERMOWELL

INLET

IMM ACZ/AGZ-4 ACZ / AGZ-BM 15

Figure 18, AGZ 026BM - AGZ 070BM, Typical Field Evaporator Water Piping

Air

Inlet

Outlet

Thermowell

Vent

Drain

Vibration

Eliminators

Strainer

Isolation

Valves

Flow

Switch

Flow Switch (Model AGZ-BM)

Mount a water flow switch in the leaving water line of the remote water chiller to shut down the unit when water flow is interrupted. A flow switch is an equipment protection control and should never be used to cycle a unit.

A flow switch is available from McQuay (part number 017503300). It is a “paddle” type switch and adaptable to any pipe size from 2” (51 mm) to 6” (152 mm) nominal. Certain minimum flow rates are required to close the switch and are listed in

19. Connect the normally open contacts of the flow switch in the unit control center at terminals 44 and 61. There is also a set of normally closed contacts on the switch that can be used for an indicator light or an alarm to indicate when a “no flow” condition exists. Freeze protect any flow switch that is installed outdoors. Manufacturer’s instructions included with the switch should be followed. NOTE: Differential pressure switches are not recommended for outdoor installation.

Table 7. Installation should be as shown in Figure

Table 7, Flow Switch Minimum/Maximum Flow Rates

Nominal Pipe Size

Inches (mm)

2 (50.8) 13.7 (51.8) 105 (397.4)

2 1/2 (63.50 17.9 (67.8) 149 (564.0)

3 (76.20 24.2 (91.6) 230 (870.6) 4 (101.6) 35.3 (134.0) 397 (1502.7) 5 (127.0) 48.6 (184.0) 654 (2475.4) 6 (152.4) 60.3 (228.0) 900 (3406.5)

Note: See pressure drop table on page 25 for minimum and maximum flow through the evaporator.

Minimum Required Flow To

Activate Switch - gpm (l/m)

Maximum Flow Rate

gpm (l/m)

Figure 19, Flow Switch Installation

Flow direction marked on switch

1" (25mm) NPT flow switch connection

Tee

Water Connections

Bring water piping to the evaporator through the side between the vertical supports. Provide taps for the connection of pressure gauges and thermometers in the inlet and outlet lines. Check the inlet and outlet labels on the unit against the certified drawings supplied on the job and be sure the water piping is hooked up correctly. Contact the McQuay sales office if any discrepancies exist.

16 ACZ / AGZ-BM IMM ACZ/AGZ-4

Variable Speed Pumping

Variable water flow involves lowering the water flow through the evaporator as the load decreases. McQuay chillers are designed for this duty provided that the rate of change in water flow is slow and the minimum and maximum flow rates for the vessel are not exceeded.

The recommended maximum change in water flow is 10 percent of the change per minute. The water flow through the vessel must remain between the minimum and maximum values listed on

25. If flow drops below the minimum allowable, large reductions in heat transfer can occur. If

page the flow exceeds the maximum rate, excessive pressure drop and tube erosion can occur.

System Water Volume Considerations

All chillers need adequate time to recognize a load change, respond to the change and stabilize without short cycling the compressor. The water volume in the system and the size of the piping loop is a critical consideration. Good engineering practice is to have a minimum water volume of four times the flow rate (GPM) for comfort cooling applications. For process applications where the load can change quickly, contact the local McQuay sales office for recommendations. A water storage tank (provided by others) can be required to increase the system water volume in some systems.

Since there are many other factors that can influence performance, systems can successfully operate below these suggestions. However, as the water volume decreases below these suggestions, the possibility of problems increases. We believe that these guidelines should be an industry standard and not just recommendations from McQuay.

Glycol Solutions

The use of a glycol/water mixture in the evaporator to prevent freezing will reduce system capacity and efficiency and increase pressure drop. The system capacity, required glycol solution flow rate, and pressure drop with glycol can be calculated using the following formulas and tables.

1. Capacity – Multiply the capacity based on water by the Capacity correction factor from

through

2. Flow – Multiply the water evaporator flow by the Flow correction factor from

Table 11.

Table 8 through

Table 8

Table 11 to determine the increased evaporator flow due to glycol. If the flow is unknown, it can be calculated from the following equation:

(gpm) Flow Glycol

−

TDelta

3. Pressure drop -- Multiply the water pressure drop from page

factor from

Table 8 through Table 11. High concentrations of propylene glycol at low

)(24

glycolCapacityTons

FactorCorrectionFlow

25 by Pressure Drop correction

temperatures can cause unacceptably high-pressure drops.

4. Power -- Multiply the water system power by Power correction factor from

Table 8 through

Table 11.

Test coolant with a clean, accurate glycol solution hydrometer (similar to that found in service stations) to determine the freezing point. Obtain percent glycol from the freezing point table below. It is recommended that a minimum of 25% solution by weight be used for protection against corrosion or that additional compatible inhibitors be added.

IMM ACZ/AGZ-4 ACZ / AGZ-BM 17

CAUTION

Do not use an automotive grade antifreeze. Industrial grade glycols must be used.

Automotive antifreeze contains inhibitors which will cause plating on the copper tubes

within the chiller evaporator. The type and handling of glycol used must be consistent with

local codes.

Table 8, Ethylene Glycol Factors for Models AGZ 026BM to 070BM

% E.G.

10 20 30 40 50

Freeze Point

26 -3.3 0.998 0.998 1.036 1.097 18 -7.8 0.993 0.997 1.060 1.226

7 -13.9 0.987 0.995 1.092 1.369

-7 -21.7 0.980 0.992 1.132 1.557

-28 -33.3 0.973 0.991 1.182 1.791

Capacity Power Flow PD

Table 9, Propylene Glycol Factors for Models AGZ 026BM to 070BM

% P.G.

10 20 30 40 50

Freeze Point

26 -3.3 0.995 0.997 1.016 1.100 19 -7.2 0.987 0.995 1.032 1.211

9 -12.8 0.978 0.992 1.057 1.380

-5 -20.6 0.964 0.987 1.092 1.703

-27 -32.8 0.952 0.983 1.140 2.251

Capacity Power Flow PD

Table 10, Ethylene Glycol Factors for Models AGZ 075BM to 130BM

% E.G.

10 20 30 40 50

Freeze Point

26 -3.3 0.994 0.998 1.038 1.101 18 -7.8 0.982 0.995 1.063 1.224

7 -13.9 0.970 0.992 1.095 1.358

-7 -21.7 0.955 0.987 1.134 1.536

-28 -33.3 0.939 0.983 1.184 1.755

Capacity Power Flow PD

Table 11, Propylene Glycol Factors for Models AGZ 075BM to 130BM

% P.G.

10 20 30 40 50

Freeze Point

26 -3.3 0.988 0.996 1.019 1.097 19 -7.2 0.972 0.992 1.035 1.201

9 -12.8 0.951 0.987 1.059 1.351

-5 -20.6 0.926 0.979 1.095 1.598

-27 -32.8 0.906 0.974 1.142 2.039

Capacity Power Flow PD

Altitude Correction Factors

Performance tables are based at sea level. Elevations other than sea level affect the performance of the unit. The decreased air density will reduce condenser capacity, consequently reducing the unit's performance. For performance at elevations other than sea level refer to

Table 12 or Table 13.

18 ACZ / AGZ-BM IMM ACZ/AGZ-4

Evaporator Temperature Drop Factors

Performance tables are based on a 10 degree F (5 degree C) temperature drop through the evaporator. Adjustment factors for applications with temperature ranges from 6 degree F to 16 degree F (3.3 degree C to 8.9 degree C) are found in

Table 12 and Table 13. Ranges outside these temperatures

can affect the control system's capability to maintain acceptable control and must not be used. The maximum water temperature that can be circulated through the evaporator in a non-operating

mode is 100°F (37.8°C).

Fouling Factor

Performance tables are based on water with a fouling factor of:

As fouling is increased, performance decreases. For performance at other than 0.0001 (0.0176) fouling factor, refer to

Table 12 and Table 13. Foreign matter in the chilled water system will adversely affect the heat transfer capability of the evaporator and could increase the pressure drop and reduce the water flow. Maintain proper water treatment to provide optimum unit operation.

Table 12, Capacity and Power Derates, Models AGZ 026 to 070

Chilled Water

Altitude

Sea

Level

2000 feet

4000 feet

6000 feet

8000 feet

Delta T

°F °C Cap. Power Cap. Power Cap. Power Cap. Power

6 3.3 0.978 0.993 0.975 0.991 0.963 0.987 0.940 0.980

8 4.4 0.989 0.996 0.986 0.994 0.973 0.990 0.950 0.983 10 5.6 1.000 1.000 0.996 0.999 0.984 0.994 0.961 0.987 12 6.7 1.009 1.003 1.005 1.001 0.993 0.997 0.969 0.990 14 7.7 1.018 1.004 1.014 1.003 1.002 0.999 0.978 0.991 16 8.9 1.025 1.007 1.021 1.006 1.009 1.001 0.985 0.994

6 3.3 0.977 1.001 0.973 1.000 0.961 0.996 0.938 0.989

8 4.4 0.987 1.006 0.984 1.004 0.971 1.000 0.948 0.993 10 5.6 0.998 1.009 0.995 1.007 0.982 1.003 0.959 0.996 12 6.7 1.007 1.011 1.004 1.010 0.991 1.006 0.967 0.998 14 7.7 1.014 1.014 1.011 1.013 0.998 1.009 0.974 1.001 16 8.9 1.022 1.016 1.018 1.014 1.005 1.010 0.981 1.003

6 3.3 0.973 1.011 0.970 1.010 0.957 1.006 0.935 0.998

8 4.4 0.984 1.014 0.980 1.013 0.968 1.009 0.945 1.001 10 5.6 0.995 1.019 0.991 1.017 0.979 1.013 0.955 1.005 12 6.7 1.004 1.021 1.000 1.020 0.987 1.016 0.964 1.008 14 7.7 1.011 1.024 1.007 1.023 0.994 1.018 0.971 1.011 16 8.9 1.018 1.027 1.014 1.026 1.002 1.021 0.978 1.014

6 3.3 0.969 1.021 0.966 1.020 0.954 1.016 0.931 1.008

8 4.4 0.980 1.026 0.977 1.024 0.964 1.020 0.942 1.013 10 5.6 0.989 1.029 0.986 1.027 0.973 1.023 0.950 1.015 12 6.7 0.998 1.033 0.995 1.031 0.982 1.027 0.959 1.020 14 7.7 1.007 1.036 1.004 1.034 0.991 1.030 0.967 1.022 16 8.9 1.014 1.037 1.011 1.036 0.998 1.031 0.974 1.024

6 3.3 0.964 1.034 0.961 1.033 0.949 1.028 0.926 1.021

8 4.4 0.975 1.037 0.971 1.036 0.959 1.031 0.936 1.024 10 5.6 0.986 1.041 0.982 1.040 0.970 1.036 0.947 1.028 12 6.7 0.995 1.044 0.991 1.043 0.979 1.038 0.955 1.031 14 7.7 1.002 1.047 0.998 1.046 0.986 1.041 0.962 1.034 16 8.9 1.009 1.050 1.005 1.049 0.993 1.044 0.969 1.037

0.0001 (0.0176) 0.00025 (0.044) 0.00075 (0.132) 0.00175 (0.308)

)/0176.0(/0001.0

kWCmorBTUFhrft °×°×× per ARI 550/590-98.

Fouling Factor

IMM ACZ/AGZ-4 ACZ / AGZ-BM 19

Table 13, Capacity and Power Derates, Models AGZ 075 to 130

Fouling Factor

Altitude

Sea

Level

2000 feet

4000 feet

6000 feet

8000 feet

Chilled Water

Delta T

°F °C Cap. Power Cap. Power Cap. Power Cap. Power

6 3.3 0.990 0.997 0.976 0.994 0.937 0.983 0.868 0.964

8 4.4 0.994 0.998 0.981 0.995 0.942 0.984 0.872 0.965 10 5.6 1.000 1.000 0.987 0.996 0.947 0.986 0.877 0.967 12 6.7 1.005 1.001 0.991 0.997 0.951 0.986 0.881 0.968 14 7.7 1.009 1.002 0.995 0.998 0.955 0.987 0.884 0.968 16 8.9 1.013 1.004 1.000 1.000 0.960 0.989 0.889 0.970

6 3.3 0.987 1.005 0.974 1.002 0.934 0.991 0.865 0.972

8 4.4 0.992 1.006 0.979 1.003 0.940 0.992 0.870 0.973 10 5.6 0.997 1.008 0.984 1.004 0.944 0.994 0.875 0.975 12 6.7 1.002 1.009 0.989 1.005 0.949 0.994 0.879 0.975 14 7.7 1.007 1.011 0.993 1.007 0.953 0.996 0.883 0.977 16 8.9 1.011 1.012 0.998 1.008 0.958 0.997 0.887 0.978

6 3.3 0.985 1.014 0.972 1.010 0.933 0.999 0.864 0.980

8 4.4 0.991 1.015 0.977 1.012 0.938 1.001 0.869 0.981 10 5.6 0.995 1.016 0.982 1.013 0.943 1.002 0.873 0.982 12 6.7 1.000 1.018 0.987 1.014 0.947 1.003 0.877 0.984 14 6.8 1.005 1.019 0.991 1.015 0.951 1.004 0.881 0.985 16 8.9 1.009 1.021 0.995 1.017 0.955 1.006 0.884 0.987

6 3.3 0.982 1.023 0.969 1.020 0.930 1.009 0.861 0.989

8 4.4 0.988 1.025 0.975 1.022 0.935 1.010 0.866 0.991 10 5.6 0.992 1.026 0.979 1.022 0.940 1.011 0.870 0.992 12 6.7 0.997 1.028 0.984 1.024 0.944 1.013 0.875 0.994 14 7.7 1.002 1.029 0.989 1.025 0.949 1.014 0.879 0.995 16 8.9 1.006 1.031 0.992 1.027 0.952 1.016 0.882 0.996

6 3.3 0.979 1.034 0.966 1.031 0.927 1.019 0.859 1.000

8 4.4 0.984 1.036 0.971 1.032 0.932 1.021 0.863 1.002 10 5.6 0.990 1.037 0.976 1.033 0.937 1.022 0.868 1.002 12 6.7 0.993 1.039 0.980 1.035 0.941 1.024 0.871 1.004 14 7.7 0.998 1.041 0.985 1.037 0.945 1.026 0.875 1.006 16 8.9 1.003 1.041 0.990 1.038 0.950 1.026 0.879 1.007

0.0001 (0.0176) 0.00025 (0.044) 0.00075 (0.132) 0.00175 (0.308)

20 ACZ / AGZ-BM IMM ACZ/AGZ-4

ACZ Staging and Circuiting

All ACZ units have two circuits, each with either two compressors, or three compressors on models ACZ 120 through 155. These circuits must be kept separated throughout the entire refrigerant piping system. Each unit refrigerant circuit must be piped to a separate coil or to a separate air handler (with a single coil).

Temperature control for each evaporator coil is provided by the installer through field-supplied and wired temperature controllers. The field-supplied staging signals are field-wired to the Microtech II controller that correspondingly activates and deactivates the scroll compressors. The MicroTech II controller has a menu screen (See operating manual OM AGZ) that allows selection between “Unit’ and “Circuit”.

Select “Unit” for a single air handler with row control where it does not matter which circuit starts first. When the controller gets a signal to start Stage 1 of cooling, it will start the compressor, on either circuit, with the fewest number of starts, so either circuit can start first. Energizing stage 2 will start the compressor with the fewest starts on the other circuit. Further staging requests will continue to start alternate compressors between the two circuits.

For applications where the staging must be associated with a particular circuit (face-split coils or separate air handlers), select “Circuit”. In this mode, stages 1, 2, and 3 are connected to refrigerant circuit #1 and stages 4, 5,and 6 to refrigerant circuit #2. As the thermostat for coil #1 stages up, the microprocessor will start the compressors on circuit # 1 (compressors 1, 3 and 5). Compressors 5 and 6 are found only on the six compressor units.

The field supplied temperature controller is required to close normally open 24-volt contacts on a demand for cooling. These closure signals are field wired to the terminal strip (TB3) in the condensing unit. Refer to the field wiring diagram (page staging is required:

51) for details. The following control

Condensing Unit Model

ACZ-030B through 110B 4 4 ACZ-120B through 155B 6 6

Number of

Capacity Steps

Number of Required

Contact Closure Signals

In summary:

• Evaporator coil #1 must be piped to the condensing unit circuit #1. See dimension drawings

beginning on page dimension drawings beginning on page

52. Evaporator coil #2 must be piped to the condensing unit circuit #2. See 52 for circuit locations.

• Evaporator staging thermostat for coil #1 must be wired to the unit terminal board TB3, stages 1,

and 2 (and 3 on models 120 through 155). Evaporator staging thermostat for coil #222 must be wired to the unit terminal board TB3, stages 4, and 5 (and 6 on models 120 through 155).

IMM ACZ/AGZ-4 ACZ / AGZ-BM 21

Remote Evaporator Refrigerant Piping

Figure 20, AGZ-BM, Remote Evaporator Piping Schematic

Refrigerant Specialties:

AGZ-BM Remote Evaporator Chillers: Refrigerant specialties including the expansion valves, solenoid valves, filter-drier and sight glasses for use with the AGZ-BM remote evaporator models are supplied by McQuay but require field installation. The remaining components including fittings and Schrader valves are provided and piped by the installer.

The hot gas bypass valve with solenoid valve option can be provided as a field-installed or factory installed option.

ACZ-B Condensing Units: variety of evaporator types, other than a water chiller as shown in the above diagram, may be used. Very often these may be air handlers with multiple-circuited coils. If multiple evaporator circuits and expansion valves are used, they must be piped so that only two circuits end up being piped back to the condensing unit, matching the unit’s two refrigerant circuits. Each circuit must have a solenoid valve with a filter-drier installed ahead of it installed close to the evaporator.

The hot gas bypass valve with solenoid valve option can be provided as a field-installed or factory installed option.

Unit-Mounted Valves: valve and a suction shutoff valve factory mounted as standard.

No Refrigerant specialties are furnished on the ACZ condensing units. A

Both the ACZ-B and the AGZ-BM outdoor sections have a liquid line shutoff

22 ACZ / AGZ-BM IMM ACZ/AGZ-4

Refrigerant Piping

All field piping, wiring, and procedures must be performed in accordance with ASHRAE, EPA, and industry standards. Proper refrigerant piping can make the difference between a reliable system and an inefficient, problematic system.

The primary concerns related to piping are refrigerant pressure drop, a solid liquid feed to the expansion valves, continuous oil return and properly sized refrigerant specialties.

Insulate the suction line to reduce excessive superheat build-up. Insulate the liquid line, where located in areas above ambient temperature, to prevent loss of subcooling and consequent liquid flashing.

A holding charge of R-22 is provided for the evaporator (AGZ-BM) and the outdoor section. The installer must properly evacuate the piping system and provide the operating charge of R22. Refer to the piping schematic drawing on page

The recommended source for refrigerant piping techniques and sizing is the ASHRAE 2002 Refrigeration Handbook, chapter 2.

Although conflicting piping recommendations can be found in different sources, McQuay offers the following recommendations for these controversial issues.

The use of double risers for vertical gas risers is generally not required and should be used only as a last resort to maintain the minimum refrigerant flow to carry oil up the vertical risers. Slightly downsizing the vertical riser is a preferable option to providing double risers.

Slope the refrigerant lines 1” per 10 feet of horizontal run in the direction of refrigerant flow to assist oil return.

22 for additional details.

Resist using hot gas bypass for applications when operation in ambient temperature below 40 degrees is expected. This recommendation helps to maintain adequate condensing pressures and liquid refrigerant at the expansion valve when condenser capacities are at their maximum.

Pressure drops in the refrigerant lines should be maintained at or below the ASHRAE recommendations and line lengths should be made as short as possible. Exceeding these recommendations will decrease performance and could impact reliability.

Small traps should be provided at the base of each major vertical gas riser to assist in the collection of oil. If vertical risers exceed more than 25 feet, install a small trap at the midpoint and at a maximum of 20 foot intervals.

Use caution in sizing the liquid line in applications where the evaporator is above the outdoor section. The weight of the liquid refrigerant in the vertical column will decrease the pressure at the top of the riser (approximately 0.5 psi per foot of vertical rise) allowing some of the refrigerant to flash to a gas. Adequate refrigerant subcooling is needed at the outdoor section to prevent large volumes of refrigerant gas at the expansion valve.

The piping systems should always extend above the highest component in the refrigeration system before dropping down to make the final refrigerant connections to components. This practice will hinder the draining of condensed refrigerant to the lower component when normal shutdown procedures do not occur (such as a power failure).

NOTE: Do not run refrigerant piping underground.

Pumpdown

The pumpdown capacity of ACZ/AGZ units is given in the Physical Data Tables. Care should be exercised to include all equipment and lines when calculating the system charge relative to the unit’s pumpdown capacity. The AGZ-BM remote evaporators have an insignificant operating charge.

IMM ACZ/AGZ-4 ACZ / AGZ-BM 23

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