McQuay ACZ 045A Installation Manual

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Page 1

Installation, Operation and Maintenance Manual

IOMM ACZ/AGZ-2

Group: Chiller Part Number: 074644102 Effective: June 2002

Supersedes: IOM M ACZ/AGZ-1

AIR-COOLED, SCROLL COMPRESSOR, SPLIT SYSTEMS

Chiller w/ Remote Evaporator, AGZ 035AM-050AM Condensing Units, ACZ 045A-055A DX Evaporators, CDE

60 Hertz, R-22 Global Chiller Line

Page 2

Table of Contents

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

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

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

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

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

Service Access............................................. 5

Vibration Isolators....................................... 7

Water Piping................................................ 8

Flow Switch................................................. 9

Glycol Solutions........................................ 10

Evaporator Flow and Pressure Drop.......... 12

Refrigerant Piping ..................................... 13

Physical Data ...................................18

Electrical Data................................. 21

Field Wiring............................................... 21

Electrical Data AGZ-AM........................... 22

Electrical Data ACZ................................... 22

Electrical Notes ......................................... 23

Wiring Diagrams ....................................... 25

Dimensional Data............................ 36

Startup.............................................. 38

Pre Start-up................................................ 38

Start-Up..................................................... 38

Shutdown................................................... 38

Water Piping Checkout.............................. 39

Refrigerant Piping Checkout ..................... 39

Refrigerant Charging................................. 40

Electrical Check Out.................................. 41

Operation .........................................42

System A djustment .................................... 44

Liquid Sightglass and Moisture Indicator.. 44

Thermostatic Expansion Valve...................44

Crankcase Heaters......................................45

Water Cooler..............................................45

Global UNT Controller, AGZ-AM. 46

General Description................................... 46

Optional Sensors........................................ 46

Controller Inputs /Outputs......................... 48

Additional UNT Features...........................51

Alarms........................................................53

ZONE TERMINAL (optional)...................54

Zone Terminal Glossary............................. 58

Global UNT Controller Troubleshooting

Chart.......................................................... 60

MicroTech Controller, AGZ-AM....61

General Description................................... 61

Optional Sensor Packages..........................61

Installation.................................................61

Sequence of Operation............................... 70

Start-Up and Shutdown .............................. 72

Keypad / Display ....................................... 73

Menu Descriptions..................................... 76

Trouble Analysis for the AGZ MicroTech

Controller................................................... 87

Test Procedures..........................................90

Unit Maintenance............................97

Preventative Maintenance Schedule.......... 98

Service ..............................................99

Liquid Line Solenoid Valve....................... 99

Evaporator ............................................... 100

Refrigerant Charging................................100

Troubleshooting Chart............................. 102

Sequence of Operation .............................. 42

Hot Gas Bypass (Optional)........................ 43

Filter Driers ............................................... 44

Our facility is ISO9002 Certified

"McQuay" is a registered trademark of McQuay International

"Information represents 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 IOMM ACZ/AGZ-2



2002 McQuay International

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Introduction

This Installation and Operating Manual contains information on three different McQuay product lines

• Model AGZ-AM This is a split packaged chiller consisting of an outdoor unit

• Model ACZ This is an air-cooled condensing unit for use with a remote

• Model CDE This is a DX water chiller that can be used in conjunction with the

IMPORTANT INFORMATION

and an evaporator shipped loose for remote mounting. Liquid line specialties are field supplied and mounted. Capacity control is either Johnson UNT or McQuay’s MicroTech Control. The outdoor unit is basically the same as an ACZ condensing unit, the difference being in how it is packaged and in the control furnished.

evaporator, typically a water chiller or DX coil. No capacity control is supplied, nor are any liquid line specialties nor evaporator.

Model ACZ condensing unit. No controls or specialties are included.

Nomenclature

A G/C Z - XXX A S/M

Air-Cooled

G=Chiller

C=Cond. Unit

Scroll Compressor

Application S=Standard Cooling M=Remote Evaporator

Design Vintage

Model Size

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 name plate 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 18.

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Installation

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

and regulations.

WARNING

Sharp edges and coil surfaces are a potential hazard. Avoid contact with them.

Handling

Be careful to avoid rough handling of the unit. Do not push or pull the unit from anything other t han the base. Block the pushing vehicle away from the unit to prevent damage to the sheet metal cabinet and end frame (see Figure 1).

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

Figure 1, Suggested Pushing Arrangement

Blocking is required

across full width

Figure 2, Suggested Lifting Arrangement

Number of fans may vary

Spreader Bars

Recommended

(use caution)

4 IOMM ACZ/AGZ-2

from this diagram. The

lifting method will remain

the same.

These rigging holes

must be used.

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Location

Unit Placement

AGZ-AM and ACZ units are for outdoor applications and can be mounted on a roof or ground level. Set units on a solid and level foundation. For 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 concrete slab with footings extended below the frost line is recommended. Be sure the foundation is level (within 1/2” [13 mm] over its length and width). The foundation must support the operating weights listed in the Physical Data Tables.

On ground level applications protect the unit against vandalism by using the optional fin and base guards or by erecting a screen fence. The fence must allow free flow of air to the condenser coil for proper unit operation.

The remote evaporator on the AGZ-AM can be mounted indoors, or if precautions against freeze-up are taken where subjected to below freezing temperatures, can be mounted outdoors It is equipped with a heating element.

Clearances

The flow of air to and from the condenser coil must not be limited. Restricting air flow or allowing air recirculation will result in a decrease in unit performance and efficiency. 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 on the fan outlet.

Install the unit with enough si de clearance for air entranc e to the coil and for servicing. Provide service access to the evaporator, compressors, electrical control panel and piping components as shown in Figure 3.

Do not allow debris to accumulate near the unit. Air movement may draw debris into the condenser coil causing air starvation. Give special consideration to low ambient operation where snow can accumulate. Keep condenser coils and fan discharge free of snow or other obstructions to permit adequate airflow.

Sound Isolation

The ultra-low sound levels of the AGZ outdoor unit and the ACZ condensing unit 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 may be objectionable. Reduce structurally transmitted sound by isolating water lines, electrical conduit and the unit itself. Use wall sleeves and rubber isolated piping hangers to reduce transmission of water or pump noise into occupied spaces. Use flexible electrical conduit to isolate sound transmission through electrical c onduit. Spring isolators are effective in reducing the low amplitude sound generated by scroll compressors and for unit isolation in sound sensitive areas.

Service A ccess

Each end of the unit must be accessible after installation for periodic service. Compressors, filterdriers, and manual liquid line shutoff valves are accessible. The high pressure control is located in the control panel when using the Global UNT controller, and on the compressor when using the MicroTech controller. Low pressure, and motor protector controls are on the compressor. Most other operational, safety and starting controls are located in the unit control box.

The condenser fan and motors can be removed from the top of the unit.

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Figure 3, Clearance Requirements

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Vibration Isolators

Vibration isolators are recommended for all roof mounted installations or wherever vibration transmission is a consideration.

Table 1 and Table 2 list isolator point loads for all unit sizes, Figure 4 shows isolator locations. See Dimensional Data for detailed dimensions required to secure each isolator to the mounting surface.

The spring flex isolators are white type CP2-32, McQuay part number 047792932. A total of four per unit is required.

Figure 4, Isolator Locations Spring Isolator Dimensions

Table 1 , Isolator Loads At Each Mounting Location With Aluminum Fins

ACZ AGZ-AM 1 2 3 4 Total Unit

Size Size lb kg lb kg lb kg lb kg lb kg 030A - 838 380 944 428 773 351 870 395 3425 1554 035A 030AM 838 380 944 428 773 351 870 395 3425 1554 040A 035AM 850 386 960 435 785 356 885 401 3480 1579 045A 040AM 864 392 974 442 797 362 900 408 3535 1603 050A 045AM 928 421 1048 475 858 389 966 438 3800 1724 055A 050AM 940 426 1062 482 868 394 980 445 3850 1746

Table 2, Isolator Loads At Each Mounting Location With Copper Fins

ACZ

Size 030A - 946 429 1066 484 873 396 985 447 3870 1755

035A 030AM 946 429 1066 484 873 396 985 447 3870 1755 040A 035AM 960 435 1082 491 886 402 997 452 3925 1780 045A 040AM 973 441 1096 497 899 408 1012 459 3980 1805 050A 045AM 1038 471 1170 531 958 435 1079 489 4245 1926 055A 050AM 1050 476 1184 537 970 440 1091 495 4295 1948

AGZ-

Size lb kg lb kg lb kg lb kg lb kg

1234Total Unit

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Water Piping

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. Consider the following when installing water piping:

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

2. Shutoff valves 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. Install drains at the lowest

points in the system.

4. A means of maintaining adequate system water pressure ( expansion tank or r egulating valve).

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

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

Place the strainer far enough upstream to prevent cavitation at the p ump inlet (consult p ump manufacturer for recommendations). The use of a strainer will prolong pump life and keep system performance up.

7. Place a strainer in the water line just before the inlet of the evaporator. This will help prevent

foreign material from entering and decreasing the performance of the evaporator.

8. The remote shell-and-tube evaporator has a thermostat and heating cable to prevent freeze-up down to -20°F (-29°C). It is suggested that the heati ng cable be used a nd wired to a separate 110V supply circuit should the evaporator be located in an area subject to freezing temperatures. If used, all water piping to the unit must also be protected to prevent freezing.

9. If the unit is used as a replacement chiller on a previously existing piping system, flush the system thoroughly before unit installation. Regul ar water analysis and chemica l wate r treatment for the evaporator loop is recommended immediately at equipment start-up.

10. The total water volume in the system should be sufficient to prevent frequent “on-off” cycling. Turnover rate should not be less than 15 minutes for normal variable cooling loads. Turnover rate for process cooling or a constant load, should not be less than 6 minutes.

11. 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. Reset the freezestat and low leaving water alarm temperatures. The freezestat is factory set to default at 36°F (2.2°C). 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.

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

13. Piping insulation should include a vapor barrier to prevent condensation and possible damage to the building structure.

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Figure 5, Typical Evaporator Field Water Piping

Flow Switch

Mount a water flow switch in either the entering or leaving water line to shut down the unit when water flow is interrupted.

A flow switch is available from McQuay (part number 017503300). It is a “paddle” type switch and adaptable to any pipe size from 3” (76mm) to 8” (203mm) nominal. Certain minimum flow rates are required to close the switch and are listed in Table 3. Installation should be as shown in Figure 6. Connect the normally open contacts of the flow switch in the unit control center at terminals 5 and 6. 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.

NOTE: Differential pressure switches are not recommended for outdoor installation.

Table 3, Flow Switch Minimum Flow Rates

NOMINAL PIPE SIZE

INCHES (mm)

1 (25.4) 6.00 (0.38) 1 1/4 (31.8) 9.80 (0.62) 1 1/2 (38.1) 12.70 (0.80)

2 (50.8) 18.80 (1.20)

2 1/2 (63.50 24.30 (1.50)

3 (76.20 30.00 (1.90) 4 (101.6) 39.70 (2.50) 5 (127.0) 58.70 (3.70) 6 (152.4) 79.20 (5.00)

MINIMUM REQUIRED FLOW TO ACTIVATE SWITCH - GPM (L/S)

Figure 6, Flow Switch Installation

Flow direction marked

on switch

1" (25mm) NPT flow

switch connection

Tee

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Note: The procedure does not specify the type of glycol. Use the derate factors found in Table 4 for corrections when using ethylene glycol and those in Table 5 for propylene glycol.

Glycol Solutions

The use of a glycol/water mixture in the CDE 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 may be calculated using the following formulas and Table 4 and Table 5.

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

4 and Table 5 to

2. Flow – Multiply the water evaporator flow by the Flow correction factor from and Table 4 or

Table 5 determine the increased evaporator flow due to glycol If the flow is unknown, it can be calculated from the following equation:

(gpm) Flow Glycol ×

For Metric Applications – Use the following equation for metric applications:

(l/s) Flow Glycol

Pressure drop -- Multiply the water pressure drop from Figure 7 by Pressure Drop correction

CapacitykW

elta

−×=18.4

factor from Table 4 or Table 5 to obtain corrected glycol pressure drop. High concentrations of propylene glycol at low temperatures may cause unacceptably high pressure drops.

Power -- Multiply the water system power by Power correction factor from Table 4 or Table 5.

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.

glycolCapacityTons

)(24

TDelta

−

FactorCorrectionFlow

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 4, Ethylene Glycol Correction Factors

E.G.

10 26 -3 0.991 0.996 1.013 1.070 20 18 -8 0.982 0.992 1.040 1.129 30 7 -14 0.972 0.986 1.074 1.181 40 -7 -22 0.961 0.976 1.121 1.263 50 -28 -33 0.946 0.966 1.178 1.308

Table 5, Propylene Glycol Correction Factors

P.G.

10 26 -3 0.987 0.992 1.010 1.068 20 19 -7 0.975 0.985 1.028 1.147 30 9 -13 0.962 0.978 1.050 1.248 40 -5 -21 0.946 0.971 1.078 1.366 50 -27 -33 0.929 0.965 1.116 1.481

Freeze Point °F °C

Capacity Power Flow Pressure Drop

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Table 6, Capacity and Power Derates

Chilled Water

ALTITUDE

SEA

LEVEL

2000 ft.

610 m

4000 ft. 1220 m

6000 ft. 1830 m

Delta-T

°F °C Cap. kW Cap. kW Cap. kW

6 3.3 0.992 0.995 0.996 0.982 0.911 0.935

8 4.4 0.995 0.997 0.969 0.984 0.914 0.937 10 5.6 1.000 1.000 0.975 0.986 0.919 0.939 12 6.7 1.005 1.002 0.980 0.989 0.923 0.941 14 6.8 1.010 1.005 0.985 0.991 0.928 0.943 16 8.9 1.014 1.007 0.989 0.993 0.930 0.944

6 3.3 0.978 1.005 0.957 0.990 0.903 0.943

8 4.4 0.982 1.007 0.961 0.993 0.905 0.945 10 5.6 0.986 1.009 0.965 0.995 0.909 0.947 12 6.7 0.992 1.011 0.970 0.998 0.914 0.949 14 6.8 0.997 1.014 0.973 1.001 0.919 0.952 16 8.9 1.000 1.016 0.975 1.002 0.921 0.953

6 3.3 0.966 1.016 0.944 0.999 0.894 0.951

8 4.4 0.969 1.018 0.947 1.001 0.896 0.953 10 5.6 0.973 1.021 0.952 1.005 0.900 0.956 12 6.7 0.978 1.025 0.956 1.008 0.904 0.958 14 6.8 0.982 1.027 0.959 1.011 0.909 0.960 16 8.9 0.986 1.028 0.961 1.015 0.911 0.961

6 3.3 0.953 1.025 0.930 1.009 0.884 0.961

8 4.4 0.955 1.028 0.934 1.011 0.887 0.962 10 5.6 0.959 1.031 0.939 1.013 0.890 0.964 12 6.7 0.963 1.034 0.942 1.017 0.895 0.966 14 6.8 0.968 1.036 0.946 1.020 0.899 0.968 16 8.9 0.972 1.037 0.949 1.024 0.902 0.969

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

Fouling Factor

AGZ-AM with Upper Panels Remove d

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Figure 7, Pressure Drop Curve

AGZ 035AM - 040AM

CDE 1004-1

GZ 045AM - 050AM

CDE 1204-3

CDE

AGZ-AM Unit Size

1004-1 035AM 9.2 82 5.17 23.1 137 8.62 3.9 51 3.23

1204-3 045AM 11.2 106 6.69 28.2 177 11.15 4.8 66 4.18

Minimum and maximum flows are established to ensure the Delta-T for each unit size falls within the 6 - 16°F range for proper unit control.

Unit Size

x 040AM 11.5 93 5.87 28.8 155 9.78 4.9 58 3.67

x 050AM 13.4 117 7.38 33.6 195 12.30 5.7 73 4.61

Pressure Drop Flow Pressure Drop Flow Pressure Drop Flow

(ft) of Water (gpm) (lps) (ft) of Water (gpm) (lps) (ft) of Water (gpm) (lps)

NOMINAL MAXIMUM MINIMUM

Evaporator Flow and Pressure Drop

Evaporator flow rate must fall between the minimum and maximum values shown in the evaporator

pressure drop table on Figure 7.

Measure the chilled water pressure drop through the evaporator at factory installed pressure taps. It is

important not to include the effect of valves or strainers in these readings.

Va rying chilled water flow through the evaporator while the compressor(s) are operating is not

recommended.

12 IOMM ACZ/AGZ-2

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Refrigerant Piping

Introduction

Proper refrigerant piping can represent the difference between a reliable, trouble free system and months or years of inefficient, problematic performance.

System concerns related to piping are:

Refrigerant pressure drop

Solid liquid feed to the expansion valve(s)

Continuous oil return

The most important and least understood is number 3. “Continuous oil return”. The failure of oil to return at or close to the rate of displacement from the compressor can result in oil trapping and ultimate compressor failure.

On the other hand, the instantaneous return of a large volume of compressor oil (slug) can be equally damaging to a compressor.

All compressors displace some oil during operation. Reciprocating compressors displace more than centrifugals, scroll and McQuay screw compressors. Oil is carried into compressor cylinders with suction gas; and that same gas entrains oil present on cylinder walls as it is being compressed. The sum of the two is then pumped into the discharge piping.

More oil is displaced at compressor start-up than during the normal running periods. If a compressor experiences excessive starts because of recycling pumpdown control, the oil may be pumped out and trapped in the condenser with the refrigerant charge. This oil may not return regardless of the adequacy of the piping system.

A similar problem to a lesser extent occurs when the equipment is oversized for the available cooling load.

In short, extreme care should be exercised to assure that both piping and controls are suitable for the application such that displaced oil is returned to the compressor moderately. Note that oil loss to the system can be due to a hang up in the evaporator, as well as in the piping.

Suction Lines

McQuay recommends the use of ASHRAE for guidelines in sizing and routing piping with one exception. See the 1998 ASHRAE Handbook Refrigeration Edition, Chapter 2 for tables and guidelines. The single exception is to the piping of direct expansion cooling coils located above the compressors. In all cases, regardless of whether the equipment has pumpdown control or not, a trap in the suction line equal to the height of the coil section is recommended. In its absence, upon a power failure, all of the liquid in the coil will fall by gravity to the compressor below.

Suction line gas velocities may range between 900 and 4000 feet per minute. Consideration should be given to the possibility of objectionable noise in or adjacent to occupied space. Where this is a concern, gas velocities on the low side are recommended.

Routing must also take into account the requirement established in the latest ANSI/ASHRAE 15. To size the suction line, determine:

The maximum t ons for the circuit

The actual length in feet

The equivalent length contributed by elbows, fittings, valves or other refrigerant specialties.

ASHRAE Tables 2-10, 11 & 12

If a vertical riser exists including the trap at the coil, determine the minimum tons for the

circuit.

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Add b and c above to obtain the total equivalent feet. Use ASHRAE Table 3 (for R22) or Table 4 (for

R134a). Suction line selections are based upon the pressure equivalent of a 2ºF loss per 100

equivalent feet.

Select a line size that displays an equal or slightly larger tons then that determined in 1a) above.

To determine the actual line loss:

Modify the table tons by the value in Note 4 of Table 3 or 4 for the design condensing

temperature.

Use the formula in Note 3 to calculate the line loss in terms of the saturation temperature.

Convert the saturation temperature loss calculated to a pressure drop equivalent using the (Delta)

listed in the table for the comparable delta temperature.

Caution: Excessive pressure drop is undesirable because:

• It reduces available compressor capacity.

•

It increases power consumed for the net tons realized.

•

It may affect the performance of both the evaporator and the expansion valve previously selected

for the application.

The line loss calculated, expressed in temperature, or PSID pressure drop will be used to establish the

temperature required at the evaporator to produce the required cooling, as well as, the suction

pressure that the compressor must operate at to deliver the required capacity.

Having selected the suction line siz e, based upo n total equivale nt length and maximum tons, verify

the line size selected will maintain entrainment of the lubricating oil up any vertical risers at the

minimum tons for the circuit. See d above, and ASHRAE Table 2-13.

If the line size selected will not maintain satisfactory oil return in a suction riser, the following options

are available:

The vertical length can be sized smaller to accommodate the lower circuit tons at reduced load.

Minimum compressor capacity can be increased by eliminating the lowest step of compressor

capacity.

Hot gas bypass can be introduced at the distributor to the evaporator, increasing the volume of gas

available in the suction line to entrain the oil.

An oil separator may be installed in the discharge line.

With reciprocating compressor units only, and only as a last resort, double suction risers can be

utilized. Since a double suction riser works by providing an oil trap to assure the return of some oil,

with refrigerant, up the smaller diameter line, a) the trap must be as small as possible, b) there must

not be multiple traps, and c) whenever double risers are used in a suction line, a suction accumulator

with a controlled oil return must be installed in the line ahead of the compressor.

Note: In horizontal refrigerant gas lines, oil return to compressors is assured by sizing lines at a

velocity above the minimum recommended and pitching the lines in the direction of refrigerant flow.

Sizing A Double Riser

At maximum circuit tons, the line size should be selected from the table based upon the recommended

maximum line loss .

With the minimum tons known, a smaller line size should be selected from ASHRAE Chapter 2, Table

13 or 14 capable of entraining oil at the reduced tons. The smaller sized line should be the one

installed to be always active.

The net internal area of this smaller sized line (see Table 13 or 14) should be deducted from the area

of the size selected in paragraph 1) immediately above. The remainder represents the area of the

14 IOMM ACZ/AGZ-2

Page 15

other riser. From Table 13 or 14, select a line size with an area equal, or close, to the calculated net

area. The combination of these two risers will provide the required performance at full circuit tons. The line selected for the minimum load should always be active; and both lines should enter the overhead horizontal line in a manner to prevent spillage of oil back down the other riser.

Underground Refrigerant Lines

McQuay does not recommend the installation of suction lines underground. If job conditions require that they be located below ground, a suitable sized suction accumulator must be installed ahead of the compressor to interrupt liquid refrigerant slugs at start-up.

Long Vertical Riser Installation

Where job conditions require refrigerant gas lifts of more than 25 feet, McQuay recommends the installation of a short trap half-way up the riser or at not more than 20 feet intervals. These traps are required to capture and hold small quantities of oil during off cycles.

Figure 8, DX Coil Piping

Condensing Unit Above Coil Condensing Unit Below Coil

LIQUID TO

COIL

LIQUID TO

COIL

SUCTION TRAP SHORT AS FITTINGS PERMIT

DUAL RISER SUCTION TRAP SHORT AS FITTINGS PERMIT

EXPANSION VALV CONTROL BULB STRAP TO LINE

ND INSULATE

LIQUID TO

COIL

SUCTION TRAP SHORT AS FITTINGS PERMIT

EXPANSION VALVE CONTROL BULBS STRAP TO LINE AND INSULATE

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Liquid Lines

Liquid lines are generally sized for 1 to 2 degree F line losses or their equivalent in pressure drop.

Actual selection can vary based upon the pressure drop expected from refrigerant specialties such as

solenoids, refrigerant driers, valves, etc. piping lifts or risers and the amount of condenser sub-cooling

expected.

The principal concern in sizing and routing liquid lines is assurance that liquid is present in the line at

start-up of the compressor, and that liquid and not vapor is available at the inlet to the expansion valve

during system operation.

Liquid may not be available in a liquid line at start-up if:

The solenoid valve is located adjacent to the condenser or condensing unit; remote from the

expansion valve.

An excessive length of liquid line is located in a heated ambient and the application permits

migration of the refrigerant to a cold air-cooled condenser.

Liquid refrigerant is permitted to gravitate from the liquid line to the condenser because of the

relative location of components.

Liquid line solenoid valves should be located adjacent to the expansion valve with possibly only

a sight glass interposing the two.

In the event 2) or 3) above are possible, the application should include a check valve at the condenser

end of the liquid line. The check valve should be a low pressure drop valve. The line between the

check valve and the solenoid valve can be comparable to a pressure vessel and as the line becomes

heated refrigerant trapped in the confined space will increase in pressure. The check valve should

include a pressure relief devise, relieving from the line side to the condenser side of the circuit. The

relief can be sized for a pressure differential from 80 to 180 psi, but not more than 180 psi, and should

be auto-resetting as the pressure is relieved.

CAUTION: The liquid line should not include a check valve unless the line also

includes an automatic resetting pressure relief device.

CAUTION: If the relief device being used is relieving from the line to the condenser side of the check valve, the maximum desirable pressure differential with R-22 refrigerant is 180 psi. With 134a, 100 psi.

If liquid lines are short, they may be of smaller diameter than the size indicated in the ASHRAE Refrigerant Handbook, 1998 Edition, Chapter 2, Tables 3 or 4. As indicated above, the designer must size the liquid line to assure that pure liquid will reach the inlet of the expansion valve. If the condenser is sized to produce 10ºF of subcooling, and each degree represents 3.05 psi with R-22 (or

2.2. psi with R-134a), the liquid line and its refrigerant specialties may have pressure losses totaling 10 x 3.05 psi (or 10 x 2.2) and still satisfy the objective of believing pure liquid to the expansion valve.

In calculating the pressure losses, or gains, note that each foot of rise in a liquid line results in an approximate 0.5 psi loss. Thus a 10 foot rise represent 5 pounds per square inch loss in refrigerant pressure, or the equivalent of 1.6ºF subcooling with R-22. Total line losses will include values for line friction, equivalents for valves and elbows and pressure losses from manufacturers’ catalogs for driers, solenoids, sight glasses, etc.

In estimating condenser subcooling, note that saturated condensing pressure should be read, or estimated, at the same point in the system where the liquid refrigerant temperature is obtained. That

16 IOMM ACZ/AGZ-2

Page 17

condensing pressure is not the discharge pressure read at the compressor outlet. Because it is less, the net value of subcooling will be lower than might otherwise be assumed.

Where rises in liquid lines result in a 0.5 psi loss per foot of lift, a drop in the liquid line results in a rise in the refrigerant pressure. A substantial drop in the liquid line can assure the existence of pure liquid at the valve. If it is a substantial increase because of a large drop, the expansion valve selection must be re-checked to confirm that the valve to be used is not radically oversized.

Liquid Lines from Condensers to Receivers

Receivers in a refrigerant system have both liquid and gas contained within the same vessel. In aircooled condenser applications, the condensing temperature can change rapidly resulting in the requirement for more liquid at a lower temperature and pressure to be introduced into the receiver.

In order for this flow of lower temperature and pressure refrigerant to enter the receiver:

The receiver must be located below the condenser outlet with no restrictions in the line.

The liquid line connecting the condenser and the receiver must be sized for a maximum velocity

of 100 fpm. Piping sizes for this are shown in the ASHRAE tables.

Note: If the interconnecting piping described above contains a SeasonTrol type head pressure control valve representing a restriction in the liquid line, a separate vent from the top of the receiver to the discharge line entering the condenser is required.

Liquid Line Components

To assist in laying out and specifying split systems, the following recommended (or equal) components can be used.

Table 7, Liquid Line Components

Unit

Model

ACZ030A Circuit #1 15.9 (191) C-487 E19S270 SA-17S OVE-20 7/8-1-3/8

ACZ035A Circuit #1 15.9 (191) C-487 E19S270 SA-17S OVE-20 7/8-1-3/8

ACZ040A Circuit #1 19.2 (230) C-487 E19S270 SA-17S OVE-20 7/8-1-3/8

ACZ045A Circuit #1 21.8 (262) C-487 E19S270 SA-17S OVE-20 7/8-1-3/8

ACZ050A Circuit #1 22.1 (265) C-487 E19S270 SA-17S OVE-20 7/8-1-3/8

ACZ055A Circuit #1 26.8 (322) C-967 E19S270 SA-17S OVE-30 7/8-1-3/8

Circuit

Circuit #2 19.1 (229) C-487 E19S270 SA-17S OVE-20 7/8-1-3/8

Circuit #2 26.8 (322) C-967 E19S270 SA-17S OVE-30 7/8-1-3/8

Nom.R-22

Tons

(mbh)

Sporlan Part Number Shown - (Equivalents Are Acceptable)

Filter Drier

Solenoid

Valve

Sight

Glass

Expansion

Valve

Unit Conn.

In/Out

IOMM ACZ/AGZ-2 17

Page 18

Physical Data

AGZ-AM

Table 8, AGZ 035AM - 050AM

CAPACITY @ ARI Conditions (1), Tons (kW) 34.3 (120.5) 38.9 (136.7) 44.3 (156.0) 48.9 OUTDOOR UNIT BASIC DATA Ckt.1 Ckt.2 Ckt.1 Ckt.2 Ckt.1 Ckt.2 Ckt.1 Ckt.2

Add'l Weight If Copper Finned Coils, Lb (kg) 445 (200) 445 (200) 445 (200) 445 (200)

COMPRESSORS

CAPACITY REDUCTION STEPS - PERCENT OF COMPRESSOR DISPLACEMENT

CONDENSERS - HIGH EFFICIENCY FIN AND TUBE TYPE WITH INTEGRAL SUBCOOLING

Maximum Relief Valve Pressure Setting, psig

CONDENSER FANS - DIRECT DRIVE PROPELLER TYPE

REMOTE DIRECT EXPANSI ON EVAPORATOR - BAFFLED SHELL AND THRU-TUBE

Maximum Refrigerant Working Pressure, psig

Water Inlet / Outlet Victaulic Connections, In.

NOTES:

1. Nominal capacity based on 95°F ambient air and 54°F/44°F water range, no refrigerant line loss.

2. Includes evaporator. Does not include suction and liquid line charge. Outdoor unit and evaporator are shipped with R-22

3. Units with 1.0 Hp Fan Motors, Uses 1.5 Hp Fan Motors when unit is 380V / 60 Hz and 575V / 60Hz.

PHYSICAL DATA AGZ-AM MODEL NUMBER

STANDARD EFFICIENCY 035AM 040AM 045AM 050AM

Number Of Refrigerant Circuits 2 2 2 2 Unit Operating Charge, R-22, Lbs.(2) 36 36 40 40 42 42 44 44 Unit Operating Charge, R-22, (kg) (2) (16.3) (16.3) (18.1) (18.1) (19.0) (19.0) (19.9) (19.9)

Cabinet Dimensions, LxWxH, In. 94.0 x 88.2

Cabinet Dimensions, LxWxH, (mm) 2388 x 2241

Unit Operating Weight, Lb (kg) 2925 (1330) 2980 (1355) 3025 (1375) 3075 (1395)

Unit Shipping Weight, Lb (kg) 2865 (1300) 2920 (1325) 2950 (1340) 3000 (1360)

Type Tandem Scrolls Tandem Scrolls Tandem Scrolls Tandem Scrolls

Nominal tonnage of each Compressor 9.0 9.0 10.0 10.0 10.0 13.0 13.0 13.0

Number Of Compressors per Circuit 2 2 2 2 2 2 2 2

Oil Charge Per Compressor, Oz. 140 140 140 140 140 140 140 140 Oil Charge Per Compressor, (g) (496) (496) (496) (496) (496) (496) (496) (496)

Standard Staging - Circuit #1 in Lead

Standard 4 Stages

Standard Staging - Circuit #2 in Lead

Standard 4 Stages

Coil Face Area,Sq. Ft. 46.4 46.4 46.4 46.4 46.4 46.4 46.4 46.4

Coil Face Area, (M2) (4.3) (4.3) (4.3) (4.3) (4.3) (4.3) (4.3) (4.3)

Finned Height x Finned Length, In. 80

Finned Height x Finned Length, (mm) 2032

Fins Per Inch x Rows Deep 16 x 2 16 x 2 16 x 2 16 x 2 16 x 2 16 x 2 16 x 2 16 x 2

(kPa)

Number Of Fans - Fan Diameter, In. (mm) 4 - 28 (712) 4 - 28 (712) 4 - 28 (712) 4 - 28 (712)

Number Of Motors - HP (kW) (3) 4 - 1.0 (0.7) 4 - 1.0 (0.7) 4 - 1.5 (1.1) 4 - 1.5 (1.1)

Fan And Motor RPM, 60Hz 1140 1140 1140 1140

60 Hz Fan Tip Speed, FPM (M/Sec) 8357 (35.4) 8357 (35.4) 8357 (35.4) 8357 (35.4)

60 Hz Total Unit Airflow, CFM (M3/sec) 34400 (16.2) 34400 (16.2) 388000 (17.9) 388000 (17.9)

Model Number 1004-1 1004-1 1204-3 1204-3

Diameter, in. - Length, Ft. 10 - 04 10 - 04 12 - 04 12 - 04 Diameter, (mm) - Length, (mm) (254) - (1220) (254) - (1220) (305) - (1220) (305) - (1220) Unit Operating Weight, Lb (kg) 555 (250) 555 (250) 777 (350) 777 (350)

Unit Shipping Weight, Lb (kg) 540 (245) 540 (245) 745 (340) 745 (340)

Water Volume, Gallons, (L) 9.1 (34.5) 9.1 (34.5) 12.8 (48.5) 12.8 (48.5)

Maximum Water Pressure, psig (kPa) 175 (1207) 175 (1207) 175 (1207) 175 (1207)

(kPa)

(mm)

Drain - NPT int, In. (mm) .375 (9.5) .375 (9.5) .375 (9.5) .375 (9.5)

Vent - NPT int, In. (mm) .375 (9.5) .375 (9.5) .375 (9.5) .375 (9.5)

holding charge.

x 86.2

x 2190

0-25-50-75-100 0-25-50-75-100 0-22-50-72-100 0-25-50-75-100

0-25-50-75-100 0-25-50-75-100 0-28-50-78-100 0-25-50-75-100

x 83.580x 83.580x 83.580x 83.580x 83.580x 83.580x 83.580x 83.5

x 2121

(3103)

2032

x 2121

450

(3103)

225 (1552) 225 (1552) 225 (1552) 225 (1552)

4 (101.6) 4 (101.6) 4 (101.6) 4 (101.6)

94.0 x 88.2 x 86.2

2388 x 2241

x 2190

2032

x 2121

450

(3103)

2032

450

94.0 x 88.2 x 86.2

2388 x 2241

x 2190

2032

x 2121

450

(3103)

2032

x 2121

450

(3103)

94.0 x 88.2 x 86.2

2388 x 2241

x 2190

2032

x 2121

450

(3103)

2032

x 2121

450

(3103)

18 IOMM ACZ/AGZ-2

Page 19

ACZ Condensing Units

Table 9, ACZ 030A - 040A

PHYSICAL DATA ACZ MODEL NUMBER

UNIT CAPACITY @ ARI Conditions (1), Tons (kW) 31.8 (111.7) 35.0 (123.0) 38.4 (134.9) BASIC DATA Ckt.1 Ckt.2 Ckt.1 Ckt.2 Ckt.1 Ckt.2

Add'l Weight If Copper Finned Coils, Lbs. (kg) 445 (200) 445 (200) 445 (200)

COMPRESSORS

CAPACITY REDUCTION STEPS - PERCENT OF COMPRESSOR DISPLACEMENT

CONDENSERS - HIGH EFFICIENCY FIN AND TUBE TYPE WITH INTEGRAL SUBCOOLING

Maximum Relief Valve Pressure Setting, psig (kPa) 450 (3103) 450 (3103) 450 (3103) 450 (3103) 450 (3103) 450 (3103)

CONDENSER FANS - DIRECT DRIVE PROPELLER TYPE

NOTES:

1. Nominal capacity based on 95°F ambient air and 45°F saturated suction temperature, no refrigerant line loss.

2. Does not include evaporator, suction or liquid line charge. Unit shipped with R-22 holding charge.

3. Units with 1.0 Hp Fan Motors, Uses 1.5 Hp Fan Motors when unit is 380V / 60 Hz and 575V / 60Hz.

STANDARD EFFICIENCY 030A 035A 040A

Number Of Refrigerant Circuits 2 2 2 Unit Operating Charge, R-22, Lbs. (2) 30 30 30 30 30 30 Unit Operating Charge, R-22, (kg) (2) (13.6) (13.6) (13.6) (13.6) (13.6) (13.6)

Cabinet Dimensions, LxWxH, In. 94.0 x 88.2 x 86.2 94.0 x 88.2 x 86.2 94.0 x 88.2 x 86.2

Cabinet Dimensions, LxWxH, (mm) 2388 x 2241 x 2190 2388 x 2241 x 2190 2388 x 2241 x 2190

Unit Operating Weight, Lbs. (kg) 2945 (1336) 2945 (1336) 3000 (1361)

Unit Shipping Weight, Lbs. (kg) 2885 (1309) 2885 (1309) 2940 (1334)

Nominal Horsepower of each Compressor 7.5 7.5 7.5 9.0 9.0 9.0

Number Of Compressors per Circuit 222222

Oil Charge Per Compressor, Oz. 140 140 140 140 140 140

Oil Charge Per Compressor, (g) (496) (496) (496) (496) (496) (496)

Standard Staging - Circuit #1 in Lead

Standard Staging - Circuit #2 in Lead

Finned Height x Finned Length, In. 80 x 83.5 80 x 83.5 80 x 83.5 80 x 83.5 80 x 83.5 80 x 83.5

Finned Height x Finned Length, (mm) 2032 x

Fins Per Inch x Rows Deep 16 x 2 16 x 2 16 x 2 16 x 2 16 x 2 16 x 2

Pumpdown Capacity @ 90% Full (Ibs) 51 51 51 51 51 51

Pumpdown Capacity @ 90% Full (kgs) (23.1) (23.1) (23.1) (23.1) (23.1) (23.1)

Number Of Fans - Fan Diameter, In. (mm) 4 - 28 (712) 4 - 28 (712) 4 - 28 (712)

Number Of Motors - HP (kW) (3) 4 - 1.0 (0.7) 4 - 1.0 (0.7) 4 - 1.0 (0.7)

Fan And Motor RPM, 60Hz 1140 1140 1140

60 Hz Fan Tip Speed, FPM (m/Sec) 8357 (35.4) 8357 (35.4) 8357 (35.4)

60 Hz Total Unit Airflow, CFM (m3/sec) 34400 (16.2) 34400 (16.2) 34400 (16.2)

Type Tandem Scrolls Tandem Scrolls Tandem Scrolls

Standard 4 Stages 0-25-50-75-100 0-23-50-73-100 0-25-50-75-100

Standard 4 Stages 0-25-50-75-100 0-27-50-77-100 0-25-50-75-100

Coil Face Area,Sq. Ft. 46.4 46.4 46.4 46.4 46.4 46.4

Coil Face Area, (M2) (4.3) (4.3) (4.3) (4.3) (4.3) (4.3)

2121

2032 x

2121

2032 x

2121

2032 x

2121

2032 x

2121

2032 x

2121

IOMM ACZ/AGZ-2 19

Page 20

Table 10, ACZ 045A - 055A

PHYSICAL DATA ACZ MODEL NUMBER

BASIC DATA Ckt.1 Ckt.2 Ckt.1 Ckt.2 Ckt.1 Ckt.2 Unit Capacity @ ARI Conditions (1), Tons (kW) 43.6 (153.2) 48.8 (171.4) 53.5 (188.0)

Add'l Weight If Copper Finned Coils, Lbs. (kg) 445 (200) 445 (200) 445 (200)

COMPRESSORS

CAPACITY REDUCTION STEPS - PERCENT OF COMPRESSOR DISPLACEMENT

CONDENSERS - HIGH EFFICIENCY FIN AND TUBE TYPE WITH INTEGRAL SUBCOOLING

Maximum Relief Valve Pressure Setting, psig (kPa) 450 (3103) 450 (3103) 450 (3103) 450 (3103) 450 (3103) 450 (3103)

CONDENSER FANS - DIRECT DRIVE PROPELLER TYPE

NOTES:

1. Nominal capacity based on 95°F ambient air and 45°F saturated suction temperature, no refrigerant line loss.

2. Does not include evaporator, suction or liquid line charge. Unit shipped with R-22 holding charge.

3. Units with 1.0 Hp Fan Motors, Uses 1.5 Hp Fan Motors when unit is 380V / 60 Hz and 575V / 60Hz.

STANDARD EFFICIENCY 045AS 050AS 055AS

Number Of Refrigerant Circuits 2 2 2 Unit Operating Charge, R-22, Lbs. (2) 30 30 35 35 35 35 Unit Operating Charge, R-22, (kg) (2) (13.6) (13.6) (15.9) (15.9) (15.9) (15.9)

Cabinet Dimensions, LxWxH, In. 94.0 x 88.2 x 86.2 94.0 x 88.2 x 86.2 94.0 x 88.2 x 86.2

Cabinet Dimensions, LxWxH, (mm) 2388 x 2241 x 2190 2388 x 2241 x 2190 2388 x 2241 x 2190

Unit Operating Weight, Lbs. (kg) 3055 (1386) 3095 (1404) 3145 (1427)

Unit Shipping Weight, Lbs. (kg) 2995 (1359) 3025 (1372) 3075 (1395)

Nominal Horsepower of each Compressor 10.0 10.0 10.0 13.0 13.0 13.0

Number Of Compressors per Circuit 222222

Oil Charge Per Compressor, Oz. 140 140 140 140 140 140

Oil Charge Per Compressor, (g) (496) (496) (496) (496) (496) (496)

Standard Staging - Circuit #1 in Lead

Standard Staging - Circuit #2 in Lead

Finned Height x Finned Length, In. 80 x 83.5 80 x 83.5 80 x 83.5 80 x 83.5 80 x 83.5 80 x 83.5

Finned Height x Finned Length, (mm) 2032 x

Fins Per Inch x Rows Deep 16 x 2 16 x 2 16 x 2 16 x 2 16 x 2 16 x 2

Pumpdown Capacity @ 90% Full (Ibs) 51 51 63 63 63 63

Pumpdown Capacity @ 90% Full (kgs) (23.1) (23.1) (28.6) (28.6) (28.6) (28.6)

Number Of Fans - Fan Diameter, In. (mm) 4 - 28 (712) 4 - 28 (712) 4 - 28 (712)

Number Of Motors - HP (kW) (3) 4 - 1.0 (0.7) 4 - 1.5 (1.1) 4 - 1.5 (1.1)

Fan And Motor RPM, 60Hz 1140 1140 1140

60 Hz Fan Tip Speed, FPM (M/Sec) 8357 (35.4) 8357 (35.4) 8357 (35.4)

60 Hz Total Unit Airflow, CFM (M3/sec) 34400 (16.2) 36800 (17.4) 36800 (17.4)

Type Tandem Scrolls Tandem Scrolls Tandem Scrolls

Standard 4 Stages 0-25-50-75-100 0-22-50-72-100 0-25-50-75-100

Standard 4 Stages 0-25-50-75-100 0-28-50-78-100 0-25-50-75-100

Coil Face Area,Sq. Ft. 46.4 46.4 46.4 46.4 46.4 46.4

Coil Face Area, (M2) (4.3) (4.3) (4.3) (4.3) (4.3) (4.3)

2121

2032 x

2121

2032 x

2121

2032 x

2121

2032 x

2121

2032 x

2121

20 IOMM ACZ/AGZ-2

Page 21

Electrical Data

Field Wiring

Power Wiring

Internal power wiring to the compressors for single and multiple point option are differ ent. Field wiring must be installed according to unit wiring diagram.

Wiring must comply with all applicable codes and ordinances. Warranty is void if wiring is not in accordance with specifications. Copper wire is required for all power lead terminations at the unit. Aluminum or copper can be used for all other wiring.

AGZ-AM and ACZ units have internal power wiring for single point power connection. A single large power terminal block is provided and wiring within the unit is sized in accordance with the National Electrical Code. A single field supplied fused disconnect is required. An optional factory mounted transformer may be installed.

AGZ-AM remote water chillers and CDE chillers are equipped with a 420W electric heater to provide freeze protection if mounted in locations subject to below freezing temperatures. The heater comes with a receptacle plug which can be used as is, or removed to hard wire to a power supply.

CAUTION

Control Wiring

AGZ-AM chillers are equipped with either a Johnson Controls UNT control or a McQuay MicroTech microprocessor control mounted in the outdoor unit. The control sensor for capacity control must be mounted in the leaving chilled water line in a thermowell provided in the water chiller nozzle. A sensor well is also located in the entering nozzle for use with some control options. The sensor is wired to the control with 30 ft. of cable. If a longer length is required, it is necessary to field splice the cable.

ACZ condensing units are not equipped with a capacity control device and one must be field furnished and installed. Refer to Figure 20. Up to four steps of control are available.

AGZ-AM and ACZ units connected to water chillers must have a flow switch mounted in the chilled water line and wired to the control panel per the field wiring diagram. It is recommended that ACZ units connected to DX air coils have an interlock to prevent compressor operation when there is no air flow.

IOMM ACZ/AGZ-2 21

Page 22

Electrical Data AGZ-AM Electrical Data ACZ

Table 11, AGZ-030AM - 050AM, ACZ 030A - 055A, 60 Hz, Single Point Power Electrical Data

ACZ

Unit Size

All Electrical Data notes are on page 23

AGZ-AM

Unit Size

035AM

045A 040AM

050A 045AM

055A 050AM

Volts

Minimum

Circuit

Ampacity

(MCA)

208 146 3 1/0 1 1.50 (38) 175 230 146 3 1/0 1 1.50 (38) 175 380 93 3 3 1 1.25 (32) 110 460 76 3 4 1 1.00 (25) 90 575 58 3 6 1 1.00 (25) 70

208 166 3 2/0 1 1.50 (38) 200 230 166 3 2/0 1 1.50 (38) 200 380 111 3 2 1 1.25 (32) 125 460 78 3 4 1 1.00 (25) 90 575 67 3 4 1 1.00 (25) 80

208 187 3 3/0 1 2.00 (51) 225 230 187 3 3/0 1 2.00 (51) 225 380 122 3 1 1 1.25 (32) 150 460 94 3 3 1 1.25 (32) 110 575 76 3 4 1 1.00 (25) 90

208 200 3 3/0 1 2.00 (51) 225 230 200 3 3/0 1 2.00 (51) 225 380 133 3 1 1 1.25 (32) 150 460 104 3 2 1 1.25 (32) 125 575 83 3 4 1 1.00 (25) 100

Field Wire Hub

Quantity

POWER SUPPLY

Wire

Gauge

Quantity

Nominal

Size

Max. Fuse

HACR

Breaker

Size

Table 12, AGZ-AM, ACZ A, 60 Hz, Compressor & Condenser Fan Motor Amp Draw

Rated Load Amps Locked Rotor Amps

ACZ Unit Size

045A 040AM

050A 045AM

055A 050AM

All Electrical Data notes are on page 23

AGZ-AM

Unit Size

035AM

Volts

208 30.5 30.5 4.0 4 17.0 232 232 230 30.5 30.5 4.0 4 17.0 232 232 380 18.6 18.6 3.4 4 14.4 144 144 460 15.8 15.8 2.0 4 8.5 125 125 575 11.6 11.6 2.2 4 10.3 100 100

208 35.2 35.2 4.0 4 17.0 255 278 230 35.2 35.2 4.0 4 17.0 255 278 380 22.8 22.8 3.4 4 14.4 151 151 460 16.5 16.5 2.0 4 8.5 127 127 575 13.7 13.7 2.2 4 10.3 100 100

208 35.2 41.5 5.8 4 23.7 255 350 230 35.2 41.5 5.8 4 23.7 255 350 380 22.8 28.0 3.4 4 14.4 151 195 460 16.5 21.8 2.8 4 10.7 127 158 575 13.7 17.3 2.3 4 11.5 100 125

208 41.5 41.5 5.8 4 23.7 318 350 230 41.5 41.5 5.8 4 23.7 318 350 380 28.0 28.0 3.4 4 14.4 195 195 460 21.8 21.8 2.8 4 10.7 158 158 575 17.3 17.3 2.3 4 11.5 125 125

Compressors Compressors

No.

1 & 3

(Each)

No.

2 & 4

(Each)

Fan

Motors

(Each)

No. Of

Fan

Motors

Fan

Motors

(Each)

Across-The-Line

No.1 & 3

(Each)

No.2 & 4

(Each)

22 IOMM ACZ/AGZ-2

Page 23

Table 13, AGZ-AM, ACZ A, 60 Hz Single Point Power, Field Wiring Data

ACZ AGZ-AM Power Block Non-Fused Disconnect Switch

Unit Size Unit Volts Terminal Connector Wire Range Terminal Connector Wire Range

Size Amps (Copper Wire Only) Amps (Copper Wire Only)

208 335 # 4 - 400 MCM 225 # 3 - 300 MCM 230 335 # 4 - 400 MCM 225 # 3 - 300 MCM

035AM 380 175 #12 - 2/0 100 #14 - 1/0

460 175 #12 - 2/0 100 #14 - 1/0 575 175 #12 - 2/0 100 #14 - 1/0

208 335 # 4 - 400 MCM 225 # 3 - 300 MCM 230 335 # 4 - 400 MCM 225 # 3 - 300 MCM

045A 040AM 380 175 #12 - 2/0 150 #4 - 4/0

460 175 #12 - 2/0 100 #14 - 1/0 575 175 #12 - 2/0 100 #14 - 1/0

208 335 # 4 - 400 MCM 225 # 3 - 300 MCM 230 335 # 4 - 400 MCM 225 # 3 - 300 MCM

050A 045AM 380 175 #12 - 2/0 150 #4 - 4/0

460 175 #12 - 2/0 100 #14 - 1/0 575 175 #12 - 2/0 100 #14 - 1/0

208 335 # 4 - 400 MCM 225 # 3 - 300 MCM 230 335 # 4 - 400 MCM 225 # 3 - 300 MCM

055A 050AM 380 335 # 4 - 400 MCM 150 #4 - 4/0

460 175 #12 - 2/0 150 #4 - 4/0 575 175 #12 - 2/0 150 #4 - 4/0

All Electrical Data notes are on page 23

Wiring to Standard Wiring to Optional

Electrical Notes

Notes for “Electrical Data Single Point” Power:

1. Unit wire size ampacity (MCA) is equal to 125% of the largest compressor-motor RLA plus

100% of RLA of all other loads in the circuit including the control transformer.

If the control transformer option is furnished, no separate 115V power is required.

If a separate 115V power supply is used for the control circuit, then the wire sizing amps is 10

amps for all unit sizes.

Recommended power lead wire sizes for 3 conductors per conduit are based on 100% conductor

ampacity in accordance with NEC. Voltage drop has not been included. Therefore, it is recommended that power leads be kept short. All terminal block connections must be made with copper (type THW) wire.

“Recommended Fuse Sizes” are selected at approximately 150% to 175% of the largest

compressor RLA, plus 100% of all other loads in the circuit.

“Maximum Fuse or HACR breaker size” is selected at approximately 225% of the largest

compressor RLA, plus 100% of all other loads in the circuit.

The recommended power lead wire sizes are based on an ambient temperature of 86°F (30°C).

Ampacity correction factors must be applied for other ambient temperatures. Refer to the National Electrical Code Handbook.

Must be electrically grounded according to national and local electrical codes.

MCA may vary slightly due to fan motor options such as SpeedTrol, TEFC.

Voltage Limitations:

Within ± 10 percent of nameplate rating.

IOMM ACZ/AGZ-2 23

Page 24

Notes for “Compressor and Condenser Fan Amp Draw”:

1. Compressor RLA values are for wiring sizing purposes only but do not reflect normal operating

current draw at rated capacity. If unit is equipped with SpeedTrol condenser fan motors, the first motor on each refrigerant circuit is a single phase, 1hp motor, with a FLA of 2.8 amps at 460 volts, 5.6 amps at 208, 230, and 575 volts.

Compressor LRA for reduced inrush start are for the first winding only. If the unit is equipped

with SpeedTrol motors, the first motor is a single phase, 1 hp motor, with a LRA of 7.3 amps at 460 volts, 14.5 amps at 208, 230, and 575 volts.

Notes for “Field Wiring Data”

1. Requires a single disconnect to supply electrical power to the unit. This power supply must

either be fused or use an HACR type circuit breaker.

All field wiring to unit power block or optional non-fused disconnect switch must be copper.

All field wire size values given in table apply to 75°C rated wire per NEC.

Electrical Legend

Figure 9, Electrical Legend

24 IOMM ACZ/AGZ-2

Page 25

Wiring Diagrams

Figure 10, AGZ-AM, Typical Field Wiring with Global UNT Controller

(

)

(

)

(

)

(

A S

)

(

)

(

E R *

)

IOMM ACZ/AGZ-2 25

Page 26

Figure 11, AGZ-AM, Typical Field Wiring Diagram with MicroTech Controller

(BY

)

(

)

(BY

)

(BY

(

)

(

A S

)

(

2 1

)

(

)

L .

(

P )

(

(BY

)

4 4

5 4

26 IOMM ACZ/AGZ-2

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Figure 12, AGZ-AM, Single-point Connection with FanTrol

IOMM ACZ/AGZ-2 27

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Figure 13, AGZ-AM, Single-point Connection with SpeedTrol

28 IOMM ACZ/AGZ-2

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Figure 14, AGZ-AM, Unit Control Schematic (UNT)

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Figure 15, AGZ-AM, Staging Schematic (UNT)

30 IOMM ACZ/AGZ-2

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Figure 16, AGZ-AM, MicroTech Controller Schematic

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Figure 17, AGZ-AM, Unit Control Schematic (MicroTech)

32 IOMM ACZ/AGZ-2

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Figure 18, AGZ-AM, Staging Schematic (MicroTech)

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Figure 19, ACZ Field Connection Diagram (No Capacity Control)

34 IOMM ACZ/AGZ-2

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Figure 20, ACZ Field Wiring Diagram (Capacity Control Staging)

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Dimensional Data

AGZ-AM ACZ

Figure 21, Dimensions AGZ 035AM - 050AM and ACZ 045A - 055A

ACZ

MODEL

NUMBE

045A 040AM 86.2 (2190) 81.7 (2075) 42.8 (1087) 36.0 (914) 39.9 (1013) 3055 (1386) 2995 (1359) 445 (200) 050A 045AM 86.2 (2190) 81.7 (2075) 42.8 (1087) 35.2 (894) 40.3 (1024) 3095 (1404) 3025 (1372) 445 (200) 055A 050AM 86.2 (2190) 81.7 (2075) 42.8 (1087) 35.3 (897) 40.3 (1024) 3145 (1427) 3075 (1395) 445 (200)

AGZ

MODEL

NUMBE

035AM 86.2 (2190) 81.7 (2075) 42.8 (1087) 35.9 (911) 40.0 (1016) 3000 (1361) 2940 (1334) 445 (200)

DIMENSIONS

inches (mm)

ABXYZ

CENTER OF GRAVITY

inches (mm)

UNIT WEIGHTS

OPERATIN

lbs (kgs)

SHIPPING

ADD’L. WEIGHT

FOR COPPER

FINS lbs (kgs)

36 IOMM ACZ/AGZ-2

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CDE

Figure 22, CDE 1004-1 - 1204-3

CDE

MODEL

NUMBER

CDE-1004-1 39.3 (998) 8.5 (216) 4.0 (102) 5.4 (137) 1 5/8 (41) 1 3/8 (35) CDE-1204-3 39.3 (998) 9.5 (241) 4.0 (102) 5.4 (137) 1 5/8 (41) 1 3/8 (35) CDE-1204-2 39.3 (998) 9.5 (241) 4.0 (102) 5.4 (137) 2 1/8 (54) 1 3/8 (35)

CDE

MODEL

NUMBER

CDE-1004-1 52.5 (1334) 15.5 (394) 6.6 (168) 16.3 (414) 11.1 (282) 2.0 (51) 2.0 (51) 2.0 (51) CDE-1204-3 53.5 (1359) 17.5 (445) 7.1 (180) 17.5 (445) 12.1 (307) 2.3 (58) 2.0 (51) 2.0 ((51) CDE-1204-2 53.5 (1359) 17.5 (445) 7.1 (180) 17.5 (445) 12.1 (307) 2.3 (58) 2.0 (51) 2.5 (64)

CDE

MODEL

NUMBER

CDE-1004-1 3.0 (76) 50.0 (1270) 52.0 (1321) 1.8 (45) 2.8 (71) 14.0 (356) 12.0 (305) ---CDE-1204-3 3.0 (76) 50.0 (1270) 52.0 (1321) 1.8 (45) 2.8 (71) 16.0 (406) ---- 14.0 (356) CDE-1204-2 3.0 (76) 50.0 (1270) 52.0 (1321) 1.8 (45) 2.8 (71) 16.0 (406) ---- 14.0 (356)

CDE

MODEL

NUMBER

CDE-1004-1 9.1 (34.4) 0.83 (.0235) 1.9 (.86) 1.9 (.86) 555 (252) 540 (245) CDE-1204-3 12.8 (48.4) 1.25 (.0353) 2.8 (1.27) 2.8 (1.27) 777 (352) 745 (338) CDE-1204-2 12.8 (48.4) 1.25 (.0353) 2.8 (1.27) 2.8 (1.27) 777 (352) 745 (338)

CLPTMN

ABDEFGHJ

KRSUVWAABB

WATER

VOLUME

GAL (litre) CU. FT. (cu.m) SYSTEM #1 SYSTEM #2 OPERATING SHIPPING

WATER CONNECTION

INCHES (mm)

REFRIGERANT

VOLUME

DIMENSIONAL DATA

INCHES (mm)

DIMENSIONAL DATA

INCHES (mm)

OPERATING CHARGE R-22

LBS (kgs)

REFRIGERANT CONNECTION

INCHES (mm)

UNIT WEIGHTS

LBS (kgs)

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Startup

Pre Start-up

The system components must be inspected to ensure that nothing has became loose or damaged during shipping or installation.

Start-Up

For AGZ-AM units refer to the Global UNT Controller or MicroTech Controller sections to become familiar with the operation before starting chiller.

For ACZ units, the field furnished and installed capacity control system should be thoroughly understood prior to starting the unit.

There should be adequate stable building load (50% of unit capacity minimum) to properly check the operation of the system’s refrigerant circuits.

Record all operating parameters required by the “Compressorized Equipment Warranty Form”. Return this information within 10 working days to McQuay International as instructed on the form to obtain full warranty benefits.

Verify chilled water pressure drop across the evaporator or air flow for DX coil.

Verify remote start / stop or time clock has requested the chiller to start.

For UNT control, set the chilled water or leaving air control setpoint to required temperature.

(The system water temperature must be greater than the total of the leaving water temperature setpoint plus 1/2 the control band before the Global UNT controller will stage on cooling.)

Set the control band to 4°F as a starting point.

Put both circuit switches to the AUTO position.

Put switch S1 to AUTO position.

There will be a delay of 2 minutes after closing S1. The time delay is due to the compressor

inherent motor protection. This may allow more than one compressor to start after this time period. This should only occur on initial start-up or when power to the chiller has been turned off and back on. The panel Alarm Light will turn off.

After the system has been operating for a period of time and has become stable, check the

following:

 Compressor oil level. (Some Scroll compressors do not have oil sight glasses)  Refrigerant sight glass for flashing.  Rotation of c ondenser fans.

Complete the “Compressorized Equipment Warranty Form”.

Shutdown

Temporary

1. Put both circuit switches to Pumpdown and Stop.

After compressors have stopped, put System Switch (S1) to Emergency Stop.

Turn off chilled water pump on water chilling applications. Chilled water pump to operate while

compressors are pumping down.

To start the chiller after a temporary shutdown follow the start up instructions.

38 IOMM ACZ/AGZ-2

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Extended

1. Front seat both condenser liquid line service valves.

Put both circuit switches in Pumpdown and Stop position.

After the compressors have stopped, put System Switch (S1) in Emergency Stop position.

Front seat both refrigerant circuit discharge valves.

If chilled water system is not drained, maintain power to the evaporator heater to prevent

freezing. Maintain heat tracing on the chilled water lines.

Drain evaporator and water piping to prevent freezing.

If electrical power is on to unit, the compressor crankcase heaters will keep the liquid refrigerant

out of the compressor oil. This will minimize start up time when putting the unit back into service. The evaporator heater will be able to function.

If electrical power is off, make provisions to power the evaporator heater (if chilled water system

is not drained). Tag all opened electrical disconnect switches to warm against startup before the refrigerant valves are in the correct operating position. When starting the unit, electrical power must be on for 24 hours before starting the chiller.

To start the chiller after an extended shutdown, follow the pre startup and startup instructions.

Water Piping Checkout

1. Check the pump operation and vent all air from the system.

Circulate evaporator water checking for proper system pressure and pressure drop across the

chiller barrel. Compare the pressure drop to the Evaporator water pressure drop curve.

Clean all water strainers before placing the chiller into service.

Refrigerant Piping Checkout

1. Check all exposed brazed joints for evidence of leaks. Unit joints may have been damaged

during shipping or when the unit was installed.

Check that all refrigerant valves are either opened or closed as required for proper operation of

the chiller.

Check all valve stem packing for leaks. Replace all refrigerant valve caps and tighten.

Check all refrigerant lines to insure that they will not vibrate against each other or against other

chiller components.

Check all flare connections and all refrigerant threaded connectors.

Look for any signs of refrigerant leaks around the condenser coils and for damage during

shipping or installation.

Leak detector is applied externally to refrigerant joints at the factory. Do not confuse this residue

with an oil leak.

Connect refrigerant service gauges to each refrigerant circuit before starting unit.

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Refrigerant Charging

Liquid line subcooling at the liquid shut-off valve should be between 15 and 20 degrees F at full load. If the unit is at steady full load operation and bubbles are visible in the sightglass, then check liquid subcooling. The charge for lines, outdoor units, and CDE evaporators are shown below. The charge for DX evaporators is usually small but should be added in.

Table 14, Refrigerant Charge in Lines

Tubing

Size

(inches)

7/8 N/A 24.0 (10.9) 1 1/8 N/A 40.8 (18.5) 1 3/8 N/A 62.2 (28.2) 1 5/8 1.7 (0.77) 88.0 (39.8) 2 1/8 2.9 (1.3) 153.1 (69.3) 2 5/8 4.5 (2.0) N/A 3 1/8 6.4 (2.9) N/A

Table 15, Refrige rant Charge in Outdoor Unit

AGZ-AM

Model

030AM 035A 15.9 (7.2) 19.1 (8.6) 035AM 040A 19.2 (8.7) 19.2 (8.7) 040AM 045A 21.8 (9.9) 21.8 (9.9) 045AM 050A 22.1 (10.0) 26.8 (12.1) 050AM 055A 26.8 (12.1) 26.8 (12.1)

Refrigerant Charge lb of R-22

Suction Line

Per 100 ft. lb (kg)

ACZ,

Model

030A 15.9 (7.2) 15.9 (7.2)

Circuit #1

R-22 Charge

lb (kg)

Liquid Line

Per 100 Ft. @ 100°°°°F

Circuit #2

R-22 Charge

lb (kg)

Table 16, Refrigerant Charge in CDE

CDE Model R-22 Charge lb (kg)

1004-1 1.9 (0.86) 1204-3 2.8 (1.27)

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Electrical Check Out

CAUTION

Electrical power must be applied to the compressor crankcase heaters 24 hours before starting unit.

1. Open all electrical disconnects and check all power wiring connections. Start at the power block

and check all connections through all components to and including the compressor terminals. These should be checked again after 3 months of operations and at least yearly thereafter.

Check all control wiring by pulling on the wire at the spade connections and tighten all screw

connections. Check plug-in relays for proper seating and to insure retaining clips are installed.

Put System Switch (S1) to the Emergency Stop position.

Put both circuit #1 & #2 switches to the Pumpdown and Stop position.

Apply power to the unit. The panel Alarm Light will stay on until S1 is closed. Ignore the Alarm

Light for the check out period. If you have the optional Alarm Bell, you may wish to disconnect it.

Check at the power block or disconnect for the proper voltage and proper voltage between

phases.

Check for 120Vac at the optional control transformer and at TB-2 terminal #1 and the neutral

block (NB).

Check between TB-2 terminal #7 and NB for 120Vac supply for transformer #2.

Check between TB-2 terminal #2 and NB for 120Vac control voltage. This supplies the

compressor crank case heaters.

10.

Check between TB-3 terminal #17 and #27 for 24Vac control voltage.

11.

Check on the Global UNT controller between terminals marked 24Vac and common for 24Vac

control vo ltage. Green light on Global UNT controller should be fl ashing.

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Operation

Sequence of Operation

Starting

With control power on, 115Vac power is applied through F1 to the compressor crankcase hea ters and control transformer T2. T2 supplies 24Vac to the Global UNT controller. The green light on the Global UNT controller will begin to flash. The panel Alarm Light will illuminate. Put the System Switch S1 into the AUTO position. This applies power to the control circuit and a digital input to the Global UNT controller. Control power is applied through the MHP’s to the compressor inherent motor protectors. After approximately a two (2) minute time delay, the MP’s are energized and the panel Alarm Light will turn off. If this is a first start, depress the Freezestat Reset Button for 1 seconds. There is a default time delay of 5 minutes on the Freezestat reset.

Start the chiller water pump and put the chiller into the run mode by closing the remote start / stop input or time clock input. After the flow switch has made, the Global UNT controller will begin to ramp up if the chilled water temperature is above the leaving water setpoint dial plus 1/2 the control band dial. Internal timing functions will vary the stage up time.

The refrigerant circuit starting is switched between circuits every ten (10) starts. This maintains equal starts on the first compressor of each refrigerant circuit. Refrigerant circuit #1 is assumed as the starting circuit for the following.

When the first stage of cooling is required, relay BO1 will be energized and if the evaporator pressure is above the LPSS (low pressure starting setpoint), relay BO7 will be energized starting Compressor #1 and energizing the liquid line solenoid valve (SV1) through c ontrol relay CCR1.

As additional cooling is required, relay BO2 will be energized and if the evaporator pressure is above the LPSS (low pressure starting setpoint), relay BO8 will be energized starting Compressor #2 and energizing the liquid line solenoid valve (SV2) through control relay CCR2.

As additional cooling is required, relays BO3 and BO4 will start compressor #3 and #4 respectively. The reverse will occur as the cooling requirements are reduced. Relays BO4 and BO3 will open

stopping compressors #4 and #3. Relay BO2 will open closing the #2 refrigerant liquid line solenoid valve. Compressor #2 will continue to operate until the LPLL (low pressure low limit) is reached or the PDTD (pumpdown delay time period) timer times out. Relay BO8 will open stopping compressor #2. Relay BO1 will open closing the #1 refrigerant liquid line solenoid valve. Compressor #1 will continue to operate until the LPLL is reached or the PDTD timer times out. Relay BO7 will open stopping compressor #1. The compressors will not cycle on if the evaporator pressure exceeds the LPSS setpoint. The Global Scroll Chiller has a one time pumpdown.

Standard Controller Setpoints (optional Zone Terminal required to change values)

TEMPLATE

NAME

OA/AI3 Lim SP 80°F 0 to 100°F

OA/AI3 Reset SP -40°F -100 to 100°F

LvgWtr Rband SP 0°F 0 to 15°F

Unoccpd Lvg SP 70°F 40 to 90°F

OA Lockout SP -10°F -20 to 65°F

Lvg Low Lim SP 20°F 20 to 40°F

SoftSta Capcty 50% 0 to 100%

SoftStart Time 2 min 0 to 20 minutes

FACTORY SETPOINT RANGE

VALUES

42 IOMM ACZ/AGZ-2

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Software Description (Global UNT Interface Kit required to read or change variables)

Variable

Name

LPSS Low Pressure Starting Setpoint 10 psi 5 to 15 psi

SLPT Starting Low Pressure Time 260 sec 90 to 300 seconds MLPS Minimum Low Pressure Setpoint 5 psi Calculated (LPSS-LPSD) 5 psi LPSD Low Pressure Starting Differential 5 psi 3 to 10 psi

LPFS Low Pressure Freezestat setpoint 54 psi 30 to 55 psi

LPHL Low Pressure High Limit 57 psi 40 to 60 psi

LPLL Low Pressure Low Limit 55 psi 40 to 55 psi

FSTP Freezestat Time Period 60 sec 60 seconds fixed PDTD Pumpdown Delay Time Period 60 sec 60 seconds fixed

Description

Default

Value

Range

Hot Gas Bypass (Optional)

This option allows the system to operate at low loads without the ON-OFF cycling of the compressor. When the hot gas bypass option is used it is required to be on both refrigerant circuits because of the lead / lag feature of the Global UNT controller.

This option allows passage of discharge gas into the evaporator inlet (between the TX valve and the evaporator) which generates a false load to supplement the actual chilled water load.

The valve that is supplied is sized for operation in chilled water systems or DX systems above 40°F saturated suction temperatures.

A solenoid valve in the hot gas bypass lines is wired in parallel with both circuit’s liquid line solenoid valves SV1 and SV2. The hot gas bypass is available whenever a refrigerant circuit is operating. The hot gas valve is regulating by the evaporator pressure and the remote adjustable bulb. The pressure regulating valve is factory set to begin opening at 5 8 psig (32°F fo r R-22). This se tting can be changed by adjusting the remote adjustable bulb. Remove the cap on the remote bulb and raise the pressure by turning the adjustment screw clockwise. Lower the pressure by turning the adjusting screw counterclockwise. This changes the pressure that the hot gas bypass valve will start to open. Do not force the adjusting screw as this can damage the adjusting assembly.

WARNING

The hot gas line may become hot enough to cause injury. Be careful during valve checkout.

Note: The remote adjusting bulb must be installed on the outside of the suction line insulation. The bulb has to have a stable ambient air temperature for proper operation. Placing the bulb in contact with the evaporator refrigerant line will limit the operation of the hot gas bypass valve.

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Filter Driers

Each refrigerant circuit is furnished with a full flow filter drier or an optional replaceable core type filter-drier. The core assembly of the replaceable core drier consists of a filter core held tightly in the shell in a manner that allows full flow without bypass.

Pressure drop across the filter drier at full load conditions must not exceed 10 psig. If pressure drop is more than 10 psig, then replace the filter drier. See Table 58 for maximum pressure drop at other load points.

CAUTION

Pump out refrigerant before removing end flange for replacement of core(s).

A condenser liquid line service valve is provided for isolating the charge in the condenser, but also serves as the point from which the liquid line can be pumped out. With the line free of liquid, the filter-drier core(s) can be easily replaced.

System A djustment

To maintain peak performance at full load operation, the system superheat and liquid subcooling may require adjustment. Read the following subsections closely to determine if adjustment is required.

Liquid Sightglass and Moisture Indicator

The color of the moisture indicator is an indication of the dryness of the system and is extremely important when the system has been serviced. Immediately after the system has been opened for service, the element may indicate a wet condition. It is recommended that the equipment operate for about 12 hours to allow the system to reach equilibrium before deciding if the system requires a change of drier cores.

Bubbles in the sightglass to expansion valve at constant full load conditions indicates a shortage of refrigerant, a plugged filter-drier, or a restriction in the liquid line. However, it is not unusual to see bubbles in the sightglass during changing load conditions.

Thermostatic Expansion Valve

The expansion valve performs one specific function. It keeps the evaporator supplied with the proper amount of refrigerant to satisfy the load conditions.

The sensing bulb of the expansion valve is installed in the closest straight run of suction line from the evaporator. The bulb is held on by clamps around the suction line and is insulated to reduce the effect of surrounding ambient temperatures. In case the bulb must be removed, simply slit the insulation on each side of the bulb, remove the clamps and then remove the capillary tubing that runs along the suction line from the valve.

The power element is removable from the valve body without removing the valve from the line.

Note: The superheat is factory set and adjustment is not needed unless operation is outside the 8°F to 12°F range.

44 IOMM ACZ/AGZ-2

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CAUTION

Before adjusting superheat, chec k unit char ge is corr ect and liquid line sightglas s is full with no bubbles.

The suction superheat for the suction leaving the evaporator is set at the factory for 8° to 12°F at full load. To have full rated unit performance the superheat must be about 8°F at 95°F outdoor ambient.

Crankcase Heaters

The scroll compressors are equipped with externally mounted band heaters located at the oil sump level. The function of the heater is to keep the temperature in the crankcase high enough to prevent refrigerant from migrating to the crankcase and condensing in the oil during off-cycle.

Power must be supplied to the heaters 24 hours before starting the compressors.

Water Cooler

The water cooler is of the direct expansion type with removable internally finned tubes. The copper tubes are individually rolled into heavy duty steel tube sheets and sealed by a steel refrigerant head.

The water connection nozzles which enter and leave the shell are on the same side of the unit. No special attention is required for the cooler except that clean, filtered water should be supplied.

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Global UNT Controller, AGZ-AM

This section provides installation, setup and troubleshooting information for the Global UNT controller.

All operational descriptions are based on the Global UNT software SUZE4-2A. Operational characteristics may vary with other versions of software.

General Description

The Global UNT is a microprocessor based leaving water controller designed for multiple stage operation.

The Global UNT’s operation is based on an adjustable setpoint and control band. Controller software is available for different reset options, refrigerants and metric units. Optional equipment includes a Zone Terminal that can be installed in the unit or remotely. The Zone Terminal provides a user interface to all reset options and adjusts specific setpoints. Downloading of software or changing selected operating parameters requires the Global UNT Interface Kit.

Optional Sensors

• Return water temperature sensor

•

Zone temperature sensor

Sensors and Transducers Sensors and transducers are mounted and connected to the Global UNT controller with sensor cable.

The evaporator pressure transducers depress the Schrader fittings and can be replaced without pumping the unit down. The pressure transducers are connected to the Global UNT controller analog inputs with IDC connectors (Insulation Displacement Connectors). The low pressure transducers have a blue dot. The leaving water sensor is in a thermal well for easy replacement without draining the water system. As standard, an outside air sensor is provided on the back of the control box. When other reset options are selected, the outside air sensor is not provided as only one (1) type of reset is available.

Control Wiring Low voltage control wiring is installed, labeled and tested by the factory before shipment.

External Voltage Inputs The signal for remote reset option (2 to 10Vdc) or demand limit (0 to 10Vdc) is provided by the

installing contractor. Connect to TB -7 terminals #134 (+) and #135 (-) as indicated by the unit wiring diagram. A 4 to 20mA signal conditioned by a 500 ohm resistor can provide the 2 to 10Vdc input for the remote reset option. Polarity of the external DC signal must match the controller polarity.

Interlock Wiring All interlock wiring to field devices (such as a flow switch or time clock) is provided by the installing

contractor. All interlocking wiring must be connected to the Global UNT 24Vac power supply. External power supplies connected to the Global UNT controller can damage the controller. See unit wiring diagram.

46 IOMM ACZ/AGZ-2

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Unit Set Points and Calibration The control software is installed and tested by the factory before shipping. No periodic calibration of

the controller is necessary. All control and safety set points must be checked by the installing contractor and adjusted as necessary before starting the unit.

The “setpoint” control knob adjusts the leaving water setpoint. The “Control Band” knob adjusts the

controller temperature control band. To set, divide the chilled water temperature range by the number of unloading steps and add 0.5°F.

Optional Sensors Optional sensor kits, available from the factory, can be installed in the field. The optional sensor kits

have the same characteristics as the leaving water sensor.

Field Wiring Interconnecting wiring for the control panel may consist of the following:

•

115Vac power wiring

•

Analog input signals

•

Digital input signals

•

Digital output signals

•

Communications to a personal computer

Power Wiring The installing contractor provides the unit voltage power source, disconnect, fuses and necessary

wiring for these circuits. All wiring must conform to the National Electrical Code and applicable local building codes. If the evaporator heater power source (120Vac) is supplied from a separate external supply, remove wires 540 and 545 as indicated on the unit wiring diagram.

Power Supplies There are several internal power supplies used by the controller and related circuitry. The regulated

5Vdc power is supplied by RSP1 and provides power to pressure transducers. Do not use this power supply to operate external devices. A 24Vac power supply is available for the alarm bell option. Wire according to the unit wiring diagram.

Analog input signals All sensors and transducers required for normal chiller operation are installed and wired at the factory.

All optional analog input signal wiring is provided by the installing contractor must be twisted, shielded pair (Belden #8760 or equal). The optional demand limit and remote reset signals are 0 to 10Vdc signals. The controlling range of the remote reset signal is from 2Vdc to 10Vdc.

Digital input signals Remote contacts for all digital inputs into the Global UNT controller must be dry contacts suitable for

the 24Vac control signals from the control panel. Do not connect 120Vac power to the digital inputs or 24Vac from an external power source.

Remote Stop/Start If remote stop/start control is selected, remove the jumper between terminals #140 and #141 on TB-7

and install the input between these terminals. When the remote stop/start switch is open, the controller will be in the unoccupied mode.

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Chilled Water Flow Sw itch The chilled water flow switch is connected to field wiring terminals #142 and #143 on TB-7. When

the chilled water pump is enabled, the Glob al UNT controller checks for proof-of-flow through the flow switch digital input.

Digital Outputs The digital outputs are controlled by the Global UNT controller. The outputs are double pole double

throw plug-in type relays, with a 24Vac holding coil and 120Vac - 7.0 amp rated contacts. These relays are field replaceable. Only one contact is used per relay. The contact that is used can be normally open or normal closed and is dependent on the relay function.

External Alarm A nnunciator Circuitry An audible alarm can be connected to the Alarm Output terminals #19 and #28 of TB-3 of the control

panel and is highly recommended to make certain the operator is alerted to any alarm condition. This output can also be used to alert a building automation system by paralleling a 24Vac control relay with the alarm light. This circuit is a 24Vac 1.8 amp maximum load output. The alarm output will be activated when an alarm condition occurs. Refer to the unit schematic.

Note: The alarm signal is not active during a power failure and will not provide a “Loss of Power” alarm.

PC Connection The Global UNT controller can be connected to an IBM or IBM compatible computer for setpoint

changes and downloading of different software’s. A Global UNT Interface Kit is available from your local McQuay Sales Representative.

Software Identification Control software is factory installed and tested in each panel prior to shipment. The software is

identified by a program code which is printed on the a small label attached to the controller.

Controller Inputs /Outputs

Analog Inputs Analog inputs are used to read the various temperatures and pressures on the chiller as well as any

customer supplied reset signals. The regulated 5Vdc power supply provides correct operating voltage for the pressure transducers. This 5Vdc supply cannot be used for other inputs.

Table 17, Analog Inputs

Input Description Location Range

AI-1 Leaving Chilled Water Temp Leaving Chw nozzle 0 to 120°F(0 - 49°C) AI-2 Circuit #1 Evap Pressure Circuit #1 Suction Line 0 to 150 psi (0 - 1034kPa) AI-3 Optional Reset input TB-7 #134 and #135 0/2 to 10VDC / temp sensor AI-4 Leaving Water Temp Setpoint Dial Control Panel 10 to 60°F ( -12 to 15° C) AI-5 Circuit #2 Evap Pressure Circuit #2 Suction Line 0 to 150 psi (0 - 1034kPa) AI-6 Control Band Setpoint Dial Control Panel 0 to 10°F (-17 to -12°C)

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Digital Inputs Note: All Digital Inputs are 24Vac supplied by transformer T2 in the control panel. Do not

use inputs from another power supply external to the unit. This can cause failure of the Global UNT controller.

Table 1 8, Digital Inputs

Input Description Location Closed Open

BI-1 Time Clock BI-2 BI-3

Auto / Pumpdown and Stop Switch Circuit

BI-4 Chilled Water Flow Switch

Field Installed to TB-7 #140 &

#141

Control Panel Run Control Panel Run

Field Installed to TB-7 #142 &

#143

Run Stop

Pumpdown

Stop

Pumpdown

Stop

Run Stop

Relay Outputs All of the relay outputs are controlled by the Global UNT controller. The relays are double pole

double throw relays with contacts rated for 120Vac - 7.0 amp and a 24Vac holding coil. Refer to the unit staging schematic.

Table 19, Relay Board Outputs

Relay Output

Number

Output

Description 1 Circuit #1 Liquid Line Solenoid Valve 2 Circuit #2 Liquid Line Solenoid Valve 3 Compressor #3 Contactor M3 4 Compressor #4 Contactor M4 5 Spare 6 Spare 7 Low Pressure Relay Circuit #1 8 Low Pressure Relay Circuit #2

Reset Options The Global UNT controller is capable of one reset option. The reset option should be selected at the

time of purchase. Outside Air is the standard option and a Zone Terminal is necessary to activate this option or any other reset option. Other reset options, such as chilled water, are available and requires a software download. Field modifications can be accomplished with the Global UNT Interface Kit Part Number 0074642001; consisting of cable supply, cable pro, and connector board.

Outside A ir Reset When selected, a Outdoor Air Temperature (OAT) sensor is connected to TB-7 terminals #134 and

#135. Four variables are used to setup the reset ramp that calculates the Actual Leaving Water Setpoint. These are: Leaving Water Setpoint (AI-4), Reset Band selected with a Zone Terminal, Outdoor Air High Limit (OAHL), and Outdoor Air Reset Band (OARB).

Figure 23, Outside Air Reset

LWRB

LWSP

OALL OAHL

(OALL=OAHL - OARB)

OARB

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As the OAT increases above the Outdoor Air Low Limit (OALL), the Actual Leaving Water Setpoint is decreased from its Leaving High Limit (Leaving Water Setpoint plus Leaving Reset Band) to the Leaving Water Setpoint. When OAT reaches the OAHL, the Actual Leaving Water Setpoint equals the Leaving Water Setpoint (AI4). If the OAT sensor is missing or unreliable, no reset occurs and the Actual Leaving Water Setpoint equals the Leaving Water Setpoint. If the Leaving Water Sensor (AI1) becomes unreliable, the compressor command is forced to 0%.

Return Water Reset (optional Return Water Sensor is required) When selected, a Return Water Temperature (RWT) sensor is connected to TB-7 terminals #134 and

#135. Four variables are used to setup the reset ramp that calculates the Actual Leaving Water Setpoint. These are: Leaving Water Setpoint (AI-4), Reset Band selected with a Zone Terminal, Return Water High Limit (RWHL), and Return Water Reset Band (RWRB).

Figure 24, Return Water Reset

LWRB

LWSP

RWLL RWHL

(RWLL=RWHL - RWRB)

RWRB

As the RWT increases above the Return Water Low Limit (RWLL), the controller decreases the Actual Leaving Water Setpoint from its Leaving High Limit (Leaving Water Setpoint plus Leaving Reset Band) to the Leaving Water Setpoint. When RWT reaches the RWHL, the Actual Leaving Water Setpoint equals the Leaving Water Setpoint (AI-4). If the RWT sensor is missing or unreliable, no reset occurs and the Actual Leaving Water Setpoint equals the Leaving Water Setpoint. If the Leaving Water Sensor (AI-1) becomes unreliable, the compressor command is forced to 0%.

When Return Water Reset is chosen, a Fail Smart Logic option is also available. This option works as

follows. If the Leaving Water Sensor (AI-1) becomes unreliable, the controller switches from Leaving Water control to Return Water control. Actual Return Water Setpoint equals Leaving Water Setpoint (AI-4) plus an adjustable Leaving Water Setpoint Offset. This value takes into account the temperature differential between Leaving and Return water temperatures, which is typically about

F. If both the Leaving and Return water sensors are unreliable, the compressor is forced to 0%.

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Zone Temperature (optional Zone Temperature Sensor) When selected, a Zone Temperature Sensor is connected to TB-7 terminals #134 and #135. Four

variables are used to setup the reset ramp that calculates the Actual Leaving Water Setpoint. These are: Leaving Water Dial Setpoint (AI-4), Reset Band SP selected with the Zone Terminal, Zone Temperature High Limit (ZTHL), and Zone Temperature Reset Band (ZTRB).

Figure 25, Zone Temperature Reset

LWRB

LWSP

ZTLL ZTHL

(ZTLL=ZTHL - ZTRB)

ZTRB

As the Zone Temperature increases above the Zone Temperature Low Limit (ZTLL), the controller decreases the Actual Leaving Water Setpoint from its Leaving High Limit (Leaving Water Setpoint plus Leaving Reset Band) to the Leaving Water Setpoint. When the Zone Temperature reaches the ZTHL, the Actual Leaving Water Setpoint equals the Leaving Water Setpoint (AI-4). If the Zone Temperature sensor is missing or unreliable, no reset occurs and the Actual Leaving Water Setpoint equals the Leaving Water Setpoint. If the Leaving Water Sensor (AI-1) becomes unreliable, the compressor command is forced to 0%.

The Zone Terminal is required to activate and change the reset values. Remote Reset (2 to 10Vdc input)

When selected, a 2 to 10Vdc signal is connected to TB-7 terminals #134 and #135. This input can be

achieved by using a 4-20mA signal and conditioning it with a 500 ohm resistor. This input resets the leaving water temperature to a higher value based on the reset input signal magnitude. At a 2Vdc (4mA) chiller signal input, the controller uses the Setpoint Dial setting. At a 10Vdc (20mA) signal input, the controller adds the reset value to the Dial Setpoint for the controlling temperature. Between 2Vdc and 10Vdc, a proportional value is added to the Dial Setpoint for the controlling temperature. The leaving water temperature can be reset upwards an additional 15

F. The Zone

Terminal is required to change the reset values. Requires different dip switch settings.

Demand Limit (0 to 10Vdc input) When selected, a 0 to 10Vdc signal is connected to TB-7 terminals #134 and #135. This input limits

the cooling capacity (0 to 100%). At 0Vdc signal input, the controller does not limit compressor staging. At 10Vdc signal input, the chiller would be off. Between 0Vdc and 10Vdc, a proportional percentage capacity is available. Requires different dip switch settings.

Additional UNT Features

Remote Stop/Start In the occupied mode, when the remote stop/start switch is open, the controller will be in the

unoccupied mode. The unit will be enabled when the remote start / stop switch is closed and will control at the leaving water temperature setpoint.

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Unoccupied Mode When the remote start / stop input is opened, the unoccupied mode is initiated. The chiller will

maintain a higher leaving water temperature setpoint (default 70°F) if the chilled water circulation is maintained. The unoccupied leaving water setpoint can be changed from the Zone Terminal.

Soft Start Soft loading limits the number of available stages when the unit is started to prevent excessive power

consumption and possible overshoot of the leaving water temperature set point. Soft loading is in effect whenever the unit is started from an “off” cycle. When stage up starts, the controller starts a countdown timer to indicate how long the unit has been in the cool stage mode. The number of stages allowed during soft loading is determined by the Soft Start Capacity. T he duration of the soft load sequence is determined by the Soft Start Timer. If the Soft Start Timer is set to zero, no soft loading will take place. The Zone Terminal is required to change the Soft Start values.

Compressor Staging The AGZ Scroll chiller has two refrigerant circuits and each circuit has two scroll compressors.

When the first stage of cooling is required, the #1 refrigerant circuit will start. This circuit will be the first to start for the next ten Starts. The Global UNT controller will then select the #2 refrigerant circuit to start first for the next ten starts. This cycle will continue and balance the number of starts between the refrigerant circuits. This is an automatic lead / lag control.

The compressors are always started in a fixed order. Refrigerant circuit #1 has compressor #1 and

compressor #3. Compressor #1 will always start first on refrigerant circuit #1. Refrigerant circuit #2 has compressor #2 and compressor #4. Compressor #2 will always start first on refrigerant circuit #2.

There are four stages of cooling capacity on the Global Scroll chiller unit. The first stage of cooling

will be the first compressor of the lead refrigerant circuit. The second stage of cooling will be the first compressor of the lag refrigerant circuit. Cooling stage three will always be compressor #3 and cooling stage four will always be compressor #4.

Stage down is the reverse of the above paragraph.

Pumpdown Control The AGZ units have a one time pump down. The pump down is activated when a circuit’s liquid line

solenoid valve is de-energized. After the circuit’s liquid line solenoid valve is de-energized, the operating compressor(s) on that refrigerant circuit will operate until the Low Pressure Low Limit (LPLL) setting is reached or the Pump Down Time Delay (PDTD) expires and stops that compressor(s). The compressor will not cycle on if the evaporator pressure exceeds the low pressure cut-in value. The compressor will start if the Global UNT controller calls for cooling.

The Pumpdown and Stop switch will open its respective circuit’s digital input to the Global UNT

controller. This will open the associate circuit’s output and open the circuit’s solenoid valve. If a compressor is operating on that circuit, the compressor will operate until the low pressure switch stops the compre ssor. If a compressor is not running, the switch does not activate a pumpdown for that circuit but will not allow the circuit to stage on and operate.

Certain alarm conditions will not permit chiller pumpdown. These alarm conditions are:

•

High Condenser Pressure

•

Bad Evap Pressure Sensor

•

Compressor Motor Protect

•

Freezestat Alarm

•

Flow Failure

52 IOMM ACZ/AGZ-2

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Freezestat Control On startup the Global UNT controller will check the evaporator pressure after the SLPT (starting low

pressure time) timer times out. If the evaporator pressure is greater than the low pressure high limit (LPHL) value, the Global UNT controller will continue to stage up as additional cooling is required. If the evaporator pressure is less than the LPHL, the Global UNT controller will de-energize BO7 or BO8 (depends on circuit starting) which will stop the compressor. This is a Freezestat alarm (alarm will indicate on the optional Zone Terminal) and will require the resetting by depressing the FREEZESTAT RESET on the control panel. The circuit will not go through a pumpdown.

If the chiller has been operating and the evaporator pressure in either circuit is less than the low

pressure Freezestat setpoint (LPFS) the Global UNT controller starts the Freezestat time period (FSTP). If the evaporator pressure is below the LPHL after the FSTP times out, BO7 or BO8 (depends on evaporator circuit with the low pressure) will be de-energized stopping the operating compressor(s) and closing that refrigerant circuit’s liquid line solenoid valve. This is a Freezestat alarm (alarm will indicate on the optional Zone Terminal) and will require the resetting by depressing the FREEZESTAT RESET on the control panel. There is a five minute time delay after the freezestat reset switch has been depressed. The circuit will not go through a pumpdown upon alarm.

Starting Timers The Global UNT controller has a starting timer which delays checking the evaporator pressure for

260 seconds. After the timer times out, the evaporator pressure is checked. If the pressure is above the low pressure high limit (LPHL), the controller stages up on leaving water temperature requirements. If the evaporator pressure is below the LPHL, then the controller will stop that circuit and indicate a freezestat alarm on the (optional) Zone Terminal.

Head Pressure Control There are two condenser fans per refrigerant circuit. These fans are cycled on and off according to

the circuit’s condenser pressure. Fan #1 of a refrigerant circuit will start when number one compressor of that refrigerant circuit has started. This fan will not cycle off until the circuit is stopped. The second fan on a refrigerant circuit will cycle on and off according to its head pressure controller (PC12 or PC22).

Optional Head Pressure Control (SpeedTrol) The first condenser fan on each circuit can have the SpeedTrol option. The fan rpm’s is varied to

maintain a minimum condenser head pressure for stable operation at low ambient temperatures. Wind baffles may be required in addition to the SpeedTrol option for low ambient operation.

Alarms

Circuit Alarm Conditions The “Circuit Alarm Conditions” are those alarms which only affect one circuit and can stop the

compressors of that circuit. These alarms are:

•

Compressor Motor Protection

•

High Condenser Pressure

•

Freezestat Protection

The Alarm Light on the control panel will illuminate if either circuit has a high head pressure

occurrence or a compressor motor protection occurrence. Freeze protection would be indicated on the optional Zone Terminal. If a circuit is off and the panel alarm light is not on, try depressing the Freezestat reset on the control panel. There is a five minute time delay after depressing the reset button.

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The chiller must have the manual reset system alarm conditions cleared before normal operation can

resume. If the alarm which occurred is an auto-clearing alarm, once the condition has corrected, the chiller will resume normal operation provided the anti-cycle timers have cleared and sufficient load exists.

System A larm Conditions The “System Alarm Conditions” are those alarms which are common to both refrigeration circuits and

require all compressors to be temporarily shut off or locked out, whichever applies.

System alarm conditions are:

•

Loss of Water Flow

•

Phase Voltage Monitor PVM (Optional)

•

Ground Fault Protection GFP (Optional)

The Alarm Light on the control panel will illuminate if either the PVM or GFP has a fault occurrence.

Loss of water flow is indicated on the optional Zone Terminal.

The chiller must have the manual reset system alarm conditions cleared before normal operation can

ZONE TERMINAL (optional)

The Zone Terminal (ZT) is a hand-held or unit mounted device that monitors and adjusts your

McQuay Global Scroll Chiller information.

A standard telephone-style jack directly connects the ZT to the McQuay Global UNT controller.

Features

• Portability

•

Simultaneous monitoring of three different settings or values

•

Easy operation with only seven buttons

•

Flashing numbers to show which items are ZT adjustable

•

Flashing symbols to notify you of alarm conditions

Capabilities With the ZT, you can:

•

Quickly identify a chiller alarm and its location

•

Monitor and adjust up to 18 different settings

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Figure 26, Zone Terminal

Display Item List

Display Indicator Dot

Warning Signal

On/Off Stat u s

Display Button 1

Mode Selector Button

Mode Selector Panel

Door

McQuay AGZ/AGR Global Chiller

Lvg Water Temp

Evap Pres #1 Evap Pres #2

OA/AI3 Input OA/AI3 HiLimSP OA/AI3 ResetSP

Lvg Water SP

LvgWtr RBnd SP

ENTER

Contrl Band SP

Actual Lvg SP

Unoccpd Lvg SP

OA Lockout SP

% Unit Load

Lvg Low Lim SP SoftSta Capcty SoftStart Time

Cir #1 Starts Cir #2 Starts

Operating Mode Indicator

MONITOR ADJUST TIME SCHEDULE PASSWORD

INSERT 10

Display Area 11

Display Area 21

Display Area 31

Up/Down Arrow Keys

ON OFF

OPERATING MODES Two operating modes are included: Monitor and Adjust.

Occupied Flow Failure OA Lockout Cir#2Lead=On Pmp/Stp #1=0 Pmp/Stp #2=0

Solenoid #1

Solenoid #2 Frzstat#1Alm

Frzstat#2Alm MinLowPres#1 MinLowPres#2

Compressor 1 Compressor 2 Stage 3 Stage 4 Stage 5 Opt. Stage 6 Opt.

ALARM

Alarm Light

AGZ-AGR

Monitor Mode

As soon as the ZT is connected, it completes a self-check, and starts up in the Monitor Mode. Monitor Mode lets you view up to three of chiller settings/sensed values at a time.

To allow you to monitor your system, a clear plastic Insert (factory made and installed) relates the

ZT’s output to your McQuay Global UNT controller.

You can simultaneously monitor the chiller in three ways:

•

Monitor up to three settings/sensed values. A maximum of six items are accessible in each of the

three displays.

•

Read the symbols to the right of the display numbers to learn the on/off status of various inputs,

outputs, or mod es (| = On status; m = Off status). This provides conti nuous monitoring of 18 different status (on/off).

•

Monitor al arm status–a flashing red alarm light and any flashing symbol ( |, m, s) visually notifies

you when your chiller has an alarm condition.

Adjust Mode

In Adjust Mode, the ZT displays information in each of the three numerical displays. Typically, the displays are set up so that the relationship between the values can be viewed simultaneously. For example:

Display 1 = Lvg Water Temp Display 2 = Lvg Water SP Display 3 = % Unit Load This operating mode allows you to adjust any flashing setpoints. Setpoints adjusted by the ZT remain

in effect until you change them.

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DISPLAYS, SYMBOLS, KEYS, AND BUTTONS

The Zone Terminal simultaneously displays three set points or sensed values. In addition, flashing symbols indicate when items are in a state of alarm. The keys, buttons, displays, and symbols are explained below.

Table 20, Displays, Symbols, Keys, Buttons

DISPLAYS, SYMBOLS,

KEYS, BUTTONS

Display Button

1, 2, 3

Enter Key

Flashing Numbers

Flashing s, m, ( | )

Mode Selector Button

On/Off Status Symbols( | )

for On/a circle (m) for Off

Red Alarm Light

Up (↑↑↑↑) or Down (↓↓↓↓) Arrow

Keys

Select the value you want to monitor or

Use to commit your changes. Adjustments

are not processed unless you press Enter.

Appear in Display 1, 2, or 3 to indicate

numbers you can adjust. Numbers that do

not flash are monitor only numbers.

Press this button to select Operating

Modes: Monitor, Adjust, Password, Time

Scheduling. A green Mode Indicator light

Observe On/Off conditions of a point in the

HVAC controller with these symbols. A

bar (| ) for On, a circle (m) for Off. These

are always monitor only items. If the

Flashes anytime a problem exists

regardless of which Operating Mode you

Use these keys to adjust a flashing number.

Appears in the displays, and corresponds

to the item you are monitoring or adjusting.

DESCRIPTION

adjust.

Shows an item is in alarm.

moves through the modes.

symbol flashes, item is in alarm.

have entered.

INSTALLING THE PLASTIC LABELS

Note: The insert is normally factory-installed. These steps are required only if the insert is

not already installed.

To use the ZT, you'll need the plastic label which is included with your ZT.

Insert

The clear plastic Insert is a custom-made label unique to your chiller. Use this Insert when monitoring or adjusting specific items of your system:

With the ZT on a flat surface, press the white tab with your index finger (Figure 27).

Pull the front cover of the ZT away from the back and slide the Insert into position.

Press the ZT together. With the Insert in place and the ZT connected, the l in the top position of

each display lines up with the first word.

Figure 27, Installing the Insert

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CONNECTING THE ZONE TERMINAL

You can unit mount the ZT, or use it as a portable tool for convenient access to any chiller information.

McQuay Global Scroll Controller Connection

A standard telephone-style jack connects the ZT to a McQuay Chiller Controller directly.

Figure 28, Connecting ZT to a Global UNT Controller Using 6 to 8 Pin Cable

1 2 3 4 5 6 7 8

OFF

AS-UNT330-1

6 Pin Connection

+15VDC

COMMO N

BINARY INANALOG INPUTS

BINARY COM

BINARY INANALOG INPUTS

Connection

1 2 3 4 5 6 1 2 3 4

ANALOG INPUTS

8 Pin

BINARY OUTPUT

COM

1 2 3 4 5 6 7 8

TO ZONE STAT

PWR

24V

24VAC TO LOADS

BINA RY OUTPUTS

Connect ZT

here.

ALARM STATUS

The ZT indicates an alarm as follows:

•

The warning signal (s) flashes to the right of the Display Indicator dot ( l ) if the system operating

values are in alarm.

•

The On/Off Status bar ( | ) or circle (m) flashes when an On/Off status is in alarm.

•

The red alarm light to the right of the Mode Selector Panel flashes when any of the above items

are in alarm.

Alarms cannot be cleared with the ZT. The problem must be corrected by maintenance or repair of the affected item.

MAKING ZONE TERMINAL ADJUSTMENTS

Adjusting Control Settings

1. You can adjust only a flashing number with the ZT. If the number does not flash, that item is a

monitor only item. Adjust Control Settings in Display 1, 2, or 3 as follows:

Press the Mode Selector Button until the green Mode Indicator Light moves next to the word

Adjust.

Press either Display Button 1, 2, or 3 to locate adjustable items, which are indicated by flashing

numbers. If you continue pressing the display butto ns, the dot (

corresponding number appears.

Press the Up () or Down () Arrow key until you reach the number you want to enter. If you

hold down the Up (

) or Down () Arrow keys, you can speed through the numbers more

quickly. Press Enter. After you press Enter, the numbers stop flashing for a few seconds. This pause tells you the ZT has processed your adjustment.

Press any of the Display Buttons to make other adjustments, and repeat Steps 2 and 3.

| ) in each display changes positions and the

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Adjustable Points

The following McQuay Global Scroll Chiller points are adjustable by the Zone Terminal.

Table 21, Adjustable Points

TEMPLATE

NAME

OA/AI3 HiLim SP 80°F 0 to 100°F OA/AI3 Reset SP -40°F -100 to 100°F

LvgWtr Rband SP 0°F 0 to 15°F

Unoccpd Lvg SP 76°F 40 to 90°F

OA Lockout SP -10°F -20 to 65°F

Lvg Low Lim SP 20°F 20 to 40°F

SoftSta Capcty 50% 0 to 100%

SoftStart Time 2 min 0 to 20 minutes

FACTORY SETPOINT RANGE

VALUES

Zone Terminal Glossary

Lvg W ater Temp - Shows the temperature of the water leaving the evaporator. Evap Pres #1 - Shows the evaporator pressure for refrigerant circuit #1. Evap Pres #2 - Shows the evaporator pressure for refrigerant circuit #2. OA/AI3 Input - Reset input signal (Outdoor Air Temp. is standard), non-adjustable OA/AI3 HiLimSP - Used in algorithm for Outside Air Reset. Adjusts Outdoor Air High Limit

(OAHL)(default is 80°F).

OA/AI3 Reset SP - Used in algorithm for Outside Air Reset. Adjusts Outdoor Air Reset Band

(OARB)(default is -40°F; therefore outdoor air reset is 40-80 DegF).

Lvg W ater SP - Shows the dial adjustment setpoint. Non-adjustable from ZT. LvgWtr Rbnd SP - Can be adjusted through the ZT, 0° - 15°F (default is 0°F) . Used in algorithm for

Outside Air Reset. (For an example of 10°F reset; 45 DegF Leaving Water Setpoint reset up to 55°F).

Contrl Band SP - Indicates what the Control Band Knob is set at. Non-adjustable from ZT. Actual Lvg SP - Shows the actual setpoint, including any reset that is occurring. Unoccpd Lvg SP - Adjustable from 40°F - 90°F (default is 70°F). The setpoint is activated by a

timeclock in unoccupied mode.

OA Lockout SP - Adjustable from -20°F to 65°F (default is -10°F). Shuts the unit off when the

Outside Air reaches the setpoint. (Differential = 5°F).

% Unit Load - Indicates the % of the unit load. Lvg Low Lim SP - Adjustable from 20°F - 40°F (default is 20°F). This safety that will shut the

chiller off based on the leaving water temperature going below this setpoint.

NOTE: Some models may have substitute Freezstat SP.at 54 psig

SoftSta Capcty - Adjusts the ramping of steps from 0% - 100% (default is 50%). SoftStart Time - Adjustable ramping time from 0 - 20 minutes (default is 2 minutes). Cir #1 Starts - Counts the number of starts for circuit #1.

•

58 IOMM ACZ/AGZ-2

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Cir #2 Starts - Counts the number of starts for circuit #2. Note: If power is lost to the controller, this data is lost and will start counting over. When power is applied and kept on, the controller will allow 10 starts for circuit #1 as the lead circuit, then will switch to circuit #2 for the next 10 starts, etc (Automatic Lead/Lag).

Occupied - |= On, 0 = Off Flow Failure - |= Alarm, 0 = Normal OA Lockout - Indicates whether your in OA lockout (see OA Lockout SP). No alarm. Cir#2Lead=On - Indicates which circuit is in the lead e.g., ½= On, 0 = Off indicates that circuit #2 is

in the lead.

Pmp/Stp #1=0 - |= Auto, circuit #1 allowed to run if cooling capacity is needed, 0 = Pump down

circuit #1 and stop.

Pmp/Stp #2=0 - |= Auto, circuit #2 allowed to run if cooling capacity is needed, 0 = Pump down

circuit #2 and stop.

Solenoid #1 - On a call for cooling on circuit 1, the solenoid is energized and opened. Solenoid #2 - On a call for cooling on circuit 2, the solenoid is energized and opened. Frzstat#1Alm - If circuit #1 fails on freeze, the alarm light on the ZT will light. To clear the alarm,

the Freez-Stat Reset button (located on the Control Panel) must be pushed once to clear.

Frzstat#2Alm - If circuit #2 fails on freeze, the alarm light on the ZT will light. To clear the alarm,

the Freez-Stat Reset button (located on the Control Panel) must be pushed once to clear.

MinLowPres#1 - If circuit #1 falls below the Minimum Low Pressure Setpoint (default is 10 psig) -

Differential (default is 5 psig) the ZT alarm will light. Once it increases above the Minimum Low Pressure Setpoint, the alarm will clear.

MinLowPres#2 - If circuit #2 falls below the Minimum Low Pressure Setpoint (default is 10 psig) -

Differential (default is 5 psig) the ZT alarm will light. Once it increases above the Minimum Low Pressure Setpoint, the alarm will clear.

Compressor #1 - Compressor 1 is On or Off Compressor #2 - Compressor 2 is On or Off Stage 3 to 6 - Indicates how many additional compressor (or unloading) stages are on at the time.

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Global UNT Controller Troubleshooting Chart

PROBLEM POSSIBLE CAUSES CORRECTIVE ACTIONS

Compressor will not

run

High Discharge

Pressure

Low Discharge

Pressure

High Suction

Pressure

Low Suction

Pressure

Compressor Oil

Loss

Compressor

Overloads or Circuit

Breakers Open

Compressor

Internal Motor

Switch Open

Freeze Protection

Trips

Erratic Loading and

Unloading

1. Main switch, circuit breakers open.

2. Fuse blown.

3. Thermal overloads tripped or fuses blown.

4. Defective contactor or coil.

5. System shut down by safety devices.

6. No cooling required.

7. Liquid line solenoid will not open.

8. Motor electrical trouble.

9. Loose wiring.

1. Dirty condenser coils.

2. Fan not operating.

3. High Ambient conditions.

4. High return water temperature.

5. Overcharge of refrigerant.

6. Non condensable.

7. Discharge valve partially closed.

1. Fan contactor failed in closed position.

2. Fan pressure switch defective.

3. Low ambient temps.

4. Low on refrigerant charge.

5. Reduced chilled water flow.

6. No load and on hot gas bypass.

1. Excessive load (high return water temp).

2. Controller not staging up.

3. Compressor capacity reduced.

4. Can be associated with high condenser pressure.

1. Low refrigerant charge.

2. Defective expansion valve.

3. Dirty filter drier.

4. Reduced water flow.

5. Hot gas bypass valve not set properly.

6. Liquid line solenoid valve not opening.

7. UNT controller defective.

8. Gasket failure in evap head ring.

1. Excessive refrigerant flood back.

2. Defective crankcase heater.

3. Low refrigerant charge.

4. Hot gas bypass not set properly.

1. Low line voltage.

2. High compressor amps.

3. Loose power wiring.

4. High condenser pressures.

5. Single phasing.

1. Compressor amps high.

2. Motor winding damaged.

1. Pressure transducers defective.

2. Low water flow.

3. Low loads / erratic water flow.

4. Controller stage timing.

5. Defective TXV.

6. Hot gas bypass not set properly.

7. Low ambient operation.

1. Chilled water flow erratic.

2. System load erratic.

3. Bad water sensor.

4. Reset function calibration.

5. Defective UNT controller.

1. Close switch.

2. Check electrical circuits and motor winding for shorts or grounds. Possible overloading. Replace fuse or reset breakers after fault is corrected.

3. Overloads are auto reset. Check unit closely when operating again.

4. Repair or replace.

5. Determine type and cause of shutdown and correct it before resetting safety.

6. None. Wait for load.

7. Repair or replace.

8. Check motor for opens, shorts circuit or burnout.

9. Check all wire junctions. Tighten all terminals.

1. Clean.

2. Check fan motor, contactor, contactor coil, fan pressure switch. Repair or replace defective part.

3. Check against design conditions.

4. Disable a compressor on each.

5. Remove excessive amount of charge.

6. Remove non condensable.

7. Back seat valve

1. Repair or replace.

2. Replace pressure switch.

3. Install SpeedTrol Kit.

4. Add refrigerant.

5. Check flow and correct.

6. Adjust hot gas bypass to maintain a higher evaporator pressure.

1. Check water flow, reduce load.

2. Check UNT controller. Replace if defective.

3. Replace compressor.

4. Check reasons for high condenser pressure.

1. Add refrigerant.

2. Check operation. Repair or replace.

3. Replace cores.

4. Increase water to design GPM.

5. Set valve for a higher pressure.

6. Repair or replace.

7. Check water sensor, set point dial, control band dial. Calibrate, repair or replace.

8. Replace gasket.

1. Check TXV. Repair or replace.

2. Replace heater.

3. Add refrigerant.

4. Increase hot gas flow.

1. Check incoming voltage. Report to electrical supplier.

2. Determine cause and correct.

3. Tighten all connections.

4. Refer to High Condenser Pressure.

5. Replace fuses or breaker.

1. Refer to the above concerning high compressor amps.

2. Check motor winding resistance. Replace if defective.

1. Compare output to actual refrigerant pressures.

2. Check water GPM and correct.

3. Check pump operation, water strainer, air handler control valves.

4. Check timing and reset as necessary.

5. Check and repair or replace.

6. Set hot gas bypass.

7. Install SpeedTrol, wind baffles.

1. Check for reasons and correct.

2. Check water flow control valve operation.

3. Replace.

4. Re-calibrate

5. Replace

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MicroTech Controller, AGZ-AM

All operational descriptions are based on the MicroTech controller software versions AGZ2E01A. Operating characteristics and menu selections may vary with other versions of software. Contact McQuay Technical Support for software update information.

General Description

The MicroTech control panel contains a model 250-06 microprocessor based controller which provides all control functions. The operator can review and change operating parameters from the interface keypad which consists of twelve input keys and a two line by sixteen character display. In addition to providing all normal operating controls, the controller monitors all safety devices on the unit and will shut the system down and alarm through a set of dedicated alarm contacts. Important operating conditions at the time of the alarm are retained in the controller’s memory to aid in troubleshooting and unit diagnostics. McQuay MicroTech Monitor software is available for remote adjustment and monitoring of the chiller.

The system is protected by a simple password scheme which allows access by authorized personnel. A valid password must be entered into the panel by the operator before any setpoints can be changed.

Optional Sensor Packages

• Refrigerant Sensor Package

 Suction line temperature, circuit #1  Suction line temperature, circuit #2  Liquid line temperature, circuit #1  Liquid line temperature, circuit #2

•

Unit amp package

 Unit amperage - Percent total unit amperage including compressors and condenser fans.

Does not include externally powered equipment such as water pumps.

Installation

The MicroTech controller is shipped factory tested with default values for the type of refrigerant. All

control values must be entered for the specific application of the chiller.

Sensors and transducers Sensors and transducers are mounted and connected to the analog / digital input (ADI) board with

shielded cable. The evaporator and condenser pressure transducers depress the Schrader fittings and can be replaced without pumping the unit down. The pressure transducers are connected to the MicroTech analog inputs with IDC connectors (Insulation Displacement Connectors). High pressure transducers have a red dot and low pressure transducers have a blue dot. Water sensors are in thermal wells for easy replacement without draining the water system. Optional refrigerant line temperature sensors are in a copper sleeve brazed to the appropriated refrigerant line.

Control wiring Low voltage control wiring is installed, labeled and tested by the factory before shipment.

Remote 4-20 milliamp signals Signals for leaving water reset or demand limit are provided by the installing contractor and

connected to the terminal block as indicated by the unit wiring diagram. See Field Wiring diagram for details.

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Interlock wiring All interlock wiring to field devices (such as flow switches and pump starters) is provided by the

installing contractor. See unit wiring diagrams and field wiring diagram.

Unit set points and calibration The control software is installed and tested by the factory before shipping. Calibration of the

controller is not necessary. All control and safety set points must be checked by the installing contractor and adjusted as necessary before starting the unit. Controllers for McQuay chillers have default set points. Refer to the menu items listed below.

•

Control mode

•

Leaving water temperature

•

Head pressure settings

•

Compressor staging

•

Soft loading

•

Holiday dates

•

Internal scheduling

•

Alarm functions

The default settings are suitable for most installations. The control mode is factory set for “Manual

Unit Off”. Check and set the control and safety settings for the application before starting the unit. For more information on menu items, see the menu description section.

Modem kit An optional modem kit allowing remote monitoring of the chiller from an off-site PC running

McQuay Monitor software is available from your local McQuay International sales representative. The modem kit comes complete with modem, mounting bracket, wiring harness, and installation instructions. The modem kit can be field installed or as an option at the factory. Modem wiring is shown on the field wiring diagram.

Lead-Lag A feature on all McQuay AGZ air-cooled chillers is a system for alternating the sequence in which the

compressors start to balance the number of starts and run hours. Lead-Lag of the refrigerant circuits is accomplished automatically through the MicroTech Controller. When in the auto mode the circuit with the fewest number of starts will be started first. If all circuits are operating and a stage down in the number of operating compressors is required, the circuit with the most operating hours will cycle off first. The operator may override the MicroTech controller, and manually select the lead circuit as circuit #1, #2, #3 or circuit #4.

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Field Wiring Interconnecting wiring for the control panel may consist of the following:

•

115Vac power wiring

•

Chilled water pump relay

•

Analog input signals

•

Digital input signals

•

Digital output signals

•

Network communicatio ns

•

Communications to a personal computer

•

Telephone line for remote modem access

Power Wiring

The installing contractor provides the unit voltage power source, disconnect, fuses and necessary wiring for these circuits. All wiring must conform to the National Electrical Code and applicable local building codes. If the control power source (120Vac) or the evaporator heater power source (120Vac) or both are supplied from a separate external supply, remove wires 540 and 545 as indicated on the field wiring diagram.

Power Supplies

There are several internal power supplies used by the controller and related circuitry. The regulated 5Vdc power is supplied by the controller and provides power to all analog inputs into the ADI board. Do not use this power supply to operate external devices. A 24Vac power supply is available for the alarm bell option. Wire according to the field wiring diagram.

Analog Input Signals

All sensors and transducers required for normal chiller operation are installed and wired at the factory, All optional analog signal wiring provided by the installing contractor must be twisted, shielded pair (Belden #8760 or equal). The optional demand limit and leaving water reset signals are 4 to 20 milliamp DC signals. The resistive load that conditions the milliamp signal is a 249 ohm resistor mounted on the ADI board at the factory.

Digital Input Signals

Remote contacts for all digital inputs into the MicroTech controller must be dry contacts suitable for the 24Vac control signals from the control panel. Do not connect 120Vac power to the digital inputs.

Remote Stop/Start

If remote stop/start control is selected, remove the jumper between terminals #140 and #141 on TB-7. When the remote stop/start switch is open, the controller will be in the “Off: Remote Sw” mode. The unit will be enabled when the switch is closed.

Chilled Water Flow Switch

The chilled water flow switch is connected to field wiring terminals #142 and #143 on TB-7. When the chilled water pump is enabled, the MicroTech controller checks for proof-o f-flow through the flow switch digital input.

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Digital Outputs

The digital output board has normally open solid-state relays with an on-board replaceable 5 amp fuse. The status of all outputs are shown by the individual output red LEDs.

Chilled Water Pump Relay

The optional chilled water pump relay is connected to terminal #10 and #9 on TB-2. When the unit is enabled, the chilled water pump relay is energized. Be sure the relay coil is rated for a maximum load of 1.8 amps at 120Vac. There is a 5 amp fuse on the digital output board for this control circuit.

External Alarm A nnunciator Circuitry

An audible alarm can be connected to the Alarm Output terminals #19 and #28 of TB-3 of the control panel and is highly recommended to make certain the operator is alerted to any alarm condition. This output can also be used to alert a building automation system or other controls as required. This circuit is a 24Vac 1.8 amp maximum load output but can be used as a dry contact or another voltage by rewiring the circuit. Refer to the unit schematic.

The alarm output can be programmed to activate when an alarm or pre-alarm condition is detected. The alarm signal is de-energized during normal operations. During a fault alarm condition the alarm circuit will energize and the alarm status light will be on. During a pre-alarm condition the alarm output and status light will pulse “on” for one-half second and “off” for four seconds.

Note: The alarm signal is not active during a power failure and will not provide a “Loss of Power” alarm.

PC Connection

The MicroTech controller can be connected to an IBM or IBM compatible computer for local or remote system monitoring. Communication network wiring uses low voltage shielded twisted pair cable (Belden 8760 or equal). The network uses the RS232 communications standard with a maximum cable length of 50 Feet. An RS232/485 adapter may be used to allow for cable runs to 5000 feet.

Telephone line

If remote access and monitoring of the unit is chosen, then a voice quality direct dial telephone line is required. The line must be a dedicated line and used only for modem access. The phone line must be terminated with a standard RJ-11 modular phone plug.

Software Identification

Control software is factory installed and tested in each panel before shipment. The software is identified by a program code printed on a small label attached to the controller. T he software version may also be displayed on the keypad display by viewing the menu items in the Misc. Setup menu.

Example of typical software identification: AGZ 2

Unit Model

2=R-22, 3=R-134a

E 01 A

Revision

Version

Inch-Pound=E, SI=S

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Controller Inputs /Outputs

Analog Inputs

Analog inputs are used to read the various temperatures and pressures on the chiller as well as any customer supplied 4-20mA reset signals. The controller’s internal regulated 5Vdc and 12Vdc supplies provide correct operating voltage for the sensors. See Table 22 for details.

Table 22, Analog Inputs

Input LED Description Location Range Resolution

0 0 Leaving Chilled Water Temp Leaving Chw nozzle -40 to 263°F 0.1°F 1 1 Circuit #1 Evap Pressure Circuit #1 Suction Line 0 to 145 psi 0.1 psi 2 2 Circuit #2 Evap Pressure Circuit #2 Suction Line 0 to 145 psi 0.1 psi 3 3 Circuit #1 Cond Pressure Compressor Discharge Line- 20 to 450 psi 0.5 psi 4 4 Circuit #2 Cond Pressure Compressor Discharge Line- 20 to 450 psi 0.5 psi 5 5 Voltage Ratio Signal EnGinn Power Supply 4.1 to 5.1 VDC -6 6 Chw Water Reset Supplied by others 4 to 20 mA DC -7 7 Demand Limit Signal Supplied by others 4 to 20 mA DC -8 8 Entering Evap Water Temp Entering Chw Nozzle -40 to 263°F 0.1°F

9 9 Entering Cond Water Temp Enter Cond Water Nozzle -40 to 263°F 0.1°F 10 10 Leaving Cond Water Temp Leaving Cond Water Nozzle -40 to 263°F 0.1°F 11 11 % Total Unit Amps Control Cabinet 0 to 4 VDC -12 12 Circuit #1 Suction Temp Circuit #1 Suction Line -40 to 263°F 0.1°F 13 13 Circuit #2 Suction Temp Circuit #2 Suction Line -40 to 263°F 0.1°F 14 14 Circuit #1 Liquid Line Temp Circuit #1 Liquid Line -40 to 263°F 0.1°F 15 15 Circuit #2 Liquid Line Temp Circuit #2 Liquid Line -40 to 263°F 0.1°F

Digital Inputs

All Digital Inputs are 24Vac. At 7.5Vac to 24Vac the digital input contacts are considered closed. Below 7.5Vac, the contracts are considered open. See Table 23 for details and operating characteristics.

Table 23, Digital Inputs

Input LED Description Circuit Closed Open

0 0 Mechanical High Pressure Switch Circuit #1 Normal Alarm

2 2 Motor Protect Switch Compressor Compressor #1 Normal Alarm

4 4 Motor Protect Switch Compressor Compressor #3 Normal Alarm

5 5 System Switch Unit Run Stop

6 6 Phase/Voltage Monitor Unit Normal Alarm

7 7 Pumpdown Switch Unit Pmp Dn Normal

8 8 Mechanical High Pressure Switch Circuit #2 Normal Alarm

99 10 10 Motor Protection Switch Compressor #2 Normal Alarm 11 11 12 12 Motor Protection Switch Compressor #4 Normal Alarm 13 13 Chiller Remote Stop Switch Unit Run Stop 14 14 Evap Water Flow Switch Unit Run Stop 15 15 Pumpdown Switch Circuit #2 Pmp Dn Normal

Relay Board Outputs

All of the MicroTech panel outputs are controlled by solid-state relays which are driven by the model 250 controller. The controller activates a solid-state relay by sending a “trigger” signal to the output board via the attached ribbon cable. The relay responds to the trigger by lowering it’s resistance which allows current to flow through it’s “contacts”. When the controller removes the trigger signal, the relay’s resistance becomes very high, causing the current flow to stop. The outputs are individually protected by a 5 amp fuse mounted on the output board adjacent to each relay. Table 24 provides additional information about each output. Refer to the MicroTech Staging schematic for digital output wiring.

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Table 24, Relay Board Outputs

Digital Output

Number

0 Alarm Circuit 1 Chilled Water Pump Relay 2 Liquid Line Solenoid Circuit #1 3 Liquid Line Solenoid Circuit #2 4 Compressor #1 Circuit #1 5 Compressor #2 Circuit #2 6 Hot Gas Bypass Circuit #1 7 Hot Gas Bypass Circuit #2 8 Compressor #3 Circuit #1

9 Compressor #4 Circuit #2 10 Condenser Fan (M11) 11 Condenser Fan (M12) 12 Spare 13 Condenser Fan (M21) 14 Condenser Fan (M22) 15 Spare

Output

Description

Reset Options

User reset options are located in the “Leaving Water Setpoint” menu. The options are:

None

“None” is the default value and the leaving evaporator water temperature controls the unit.

Return

When selecting “Return” as the reset mode, the controller resets the leaving water temperature set point as required to maintain the selected return water temperature.

4 - 20 mA (remote reset signal)

When selecting “4-20mA” as the reset mode, the controller will reset the leaving water temperature to a higher value based on a percentage of the “Maximum Chilled Water Reset”. At 4mA or less, the leaving water temperature is not reset. At 20mA the leaving water temperature is reset to the maximum. Between 4 and 20mA, the leaving water temperature is reset proportionally to the reset input signal.

Outside A ir

When selecting “Outside Air” as the reset mode, the controller will reset the leaving water temperature to a higher value based on the temperature of the outside air (ambient). As the outside air temperature decreases, the leaving water temperature is reset up until the maximum reset is obtained. When the outside air temperature is above the outside air temperature reset setpoint the leaving water temperature is not reset and is controlled to the leaving water temperature setpoint.

Ice (for lower ice setpoint requirements, consult McQuay Marketing Support)

When in “Ice” reset mode, and adequate amount of glycol must be added to the system to protect the evaporator from freezing. McQuay recommends a minimum of 30% solution of ethylene glycol to protect to 7°F with the minimum leaving water temperature at unit shut down of 21°F. At 21°F shut down, the saturated refrigerant temperature can approach 10°F.

The leaving water setpoint must be calculated according to the following formula; LvgEvapSpt = Desired Ice Temperature + 1/2 Control B and + Shut down Delta T

Lvg EvapSpt = 21°F + 1/2 (4)°F + 1.5°F Lvg Evap Spt = 21°F + 2°F + 1.5°F Lvg Evap Spt = 24.5°F

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The remote 4-20mA input must be 4mA or less and the leaving water temperature will be controlled to the calculated setpoint. When the remote reset input is above 4mA, the value “MaxChwRst” is added to the leaving water setpoint. This will be the day operating setpoint. This value cannot be reset when in the day mode by any other reset options.

The alarm setpoints must be adjusted to allow operation of the chiller at the lower temperatures. The following values should be adjusted and the example assumes 30% ethylene glycol solution with a 21°F shut down temperature:

“FrzStat” Set to the saturated suction pressure that corresponds to a temperature several degrees

higher than the freeze point of the water / glycol solution. (10°F = 33psig.)

“Frz H2O” Set at least 4°F below the shut down temperature, but not lower than the freezing

point of the water / glycol solution. (21°F - 4°F = 17°F)

“LP cutout” Set 8 to 10 psi below the “Frz State” pressure but never below 20 psig. (33psi - 10

psi = 23 psi)

“LP Cutin” Set to a saturated suction pressure equal to the shut down temperature plus 1/2 the

control band. (21°F + 2°F = 23°F; 23°F = 46psig)

Network

A network refers to a McQuay MicroTech control panel (CSC or RMS) that can provide controlling functions to several McQuay chillers. One function is to control the chiller leaving water temperature according to some control logic in the network control panel. The network control panel will control the leaving water setpoint when the “Network” option in the chiller is selected. The network control panel will send a signal that reflects 0 to 100% reset of the leaving water set point according to the value entered into the “MaxChwRst” of the unit controller.

Soft Loading

Soft loading limits the number of available stages when the unit is started to prevent excessive power consumption and possible overshoot of the leaving water temperature set point. Soft loading is in effect whenever the unit is started from an “off” cycle. On initial start-up, the chiller will turn on the chilled water pump and sample the loop water temperature for a time equal to the Load Delay set point (“LoadDelay”). If cooling is required at the end of the time-delay, a start procedure is initiated. On entering the “Stage mode” the controller starts a countdown timer to indicate how long the unit has been in the cool stage mode. The number of stages allowed during soft loading is determined by the Soft Load Maximum Stages (“SoftLdMaxStg”). The duration of the soft load sequence is determined by the Soft Load Timer. If the Soft Load Timer is set to zero, no soft loading will take place. When the soft load option is enabled, any time remaining in the Soft Load Timer will be displayed in the menu Soft Load Set points under item “Time Left”. The following set points may be adjusted in SoftLoadSpts menu:

•

Soft Load: This is the amount of time soft loading will be in effect after the controller begins

staging. If set to zero, soft loading is canceled.

•

SoftLdMaxStg: Determines the maximum number of cooling stages which may be energized

while soft loading is in effect.

•

LoadDelay: The amount of time allowed for the controller to sample the loop water temperature

before initiating cooling.

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Manual Operation Manual operating modes are available to simplify setup and troubleshooting of the unit. Any of the

following manual modes may be sele cted from the Control Mode Menu.

Note: These manual settings are intended to aid in troubleshooting and should not be considered to be normal operating modes. The equipment should not be left unattended during manual operation as the automatic staging controls are disabled. The chiller will remain in the manual mode until Automatic operation is selected or a problem alarm occurs which will change back to the “Automatic mode”.

• ManualOff: Manual unit off.

•

Auto1Off2: Automatic Circ#1, Circ#2 off.

•

Auto2Off1: Automatic Circ#2, Circ#1 off.

•

ManualStaging: Ma nual Staging, Circ#1 & 2.

Compressor Staging The AGZ Scroll chiller has two (2) refrigerant circuits and each circuit has two (2) scroll

compressors. When in the Automatic mode and stage 1 of cooling is required, the compressor with the lowest number of starts will be the first compressor to start. Stage 2 of cooling will start the compressor with the lowest number of starts in the other refrigerant circuit. Stage 3 of cooling will start the next compressor with the lowest number of starts regardless of refrigerant circuit. Stage 4 will start the last compressor.

If a compressor is not available for starting due to a safety, the number of cooling stages will be

decreased and always equal to the number of available compressors for operation. At all times the second stage of cooling will have a compressor from each refrigerant circuit operating. The exception to this is when “LOW AMBIENT” is selected and the outside air temperature is below the low ambient setting. The staging logic will be modified to start the compressor with the lowest starts and stage 2 will start the other compressor on that refrigerant circuit. Both compressors on one refrigerant circuit will operate at low ambient to improve head pressure control. If additional cooling is required, the next refrigerant circuit will be started.

On a stage down (4 compressors operating), the compressor with the most run hours will be stopped.

The next stage down will be the compressor on the other refrigerant circuit with the most run hours. The next stage down will be the compressor with the most run hours.

Head Pressure Control There are two condenser fans per refrigerant circuit. These fans are cycled on and off according to

the circuit’s condenser pressure. Fan #1 of circuit will start when a compressor in the circuit has started and the condenser pressure exceeds fan on setpoint (230psig R-22). This fan will not cycle off until the circuit is stopped. The second fan will cycle on and off to maintain minimum lift pressure. If the condenser pressure increases rapidly, the second fan will be turned on at 290psig (R-22 setpoint) and remain on until minimum lift pressure regains control.

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Pumpdown Control The AGZ units have a one time pump down. If two compressors are operating on a refrigerant circuit

and the chiller is commanded to stop, the lag compressor on that circuit will stop and the lead compressor will pump the circuit down. Pump down pressure depends on the chiller’s refrigerant type.

Certain alarm conditions will not permit chiller pumpdown. These alarm conditions are:

•

High Condenser Pressure

•

Bad Evap Pressure Sensor

•

Bad Phase Voltage

•

Volts Ratio Protect

•

Mechanical High Pressure

•

Compressor Motor Protect

Safety Systems MicroTech continuously performs self-diagnostic checks, monitoring all system temperatures,

pressures and safeties, and will automatically shut down a refrigerant circuit or the entire unit should a fault occur. The cause of the shutdown, time and date of occurrence and conditions at the same time of alarm will be retained in memory and can be displayed for the operator to review.

The MicroTech controller has several safety systems to safeguard against potential damage of the

chiller equipment. There are alarm and pre-alarm conditions. Alarm conditions cause the compressors to shut off and/or lockout. Pre-alarm conditions cause the unit to stage down in capacity in an attempt to avoid an alarm condition. For alarm conditions, the red “Alarm Status” light on the control panel will be solid. For all pre-alarm conditions, the light will pulse at the rate of 0.5 seconds on, 4 seconds off. When an alarm of pre-alarm condition exists, the MicroTech display automatically switches to the alarm menu to alert the user of the condition.

The MicroTech controller alarms can either be of the manual reset type or the auto reset type. Critical

alarm conditions such as High Condenser Pressure, Refrigerant Freeze Protection, and Low Evaporator Pressure which protect against equipment damage are manual reset, which means they lockout compressor operation and must be cleared at the MicroTech keypad before operation can resume. Auto-clearing alarm conditions cause the compressors to shut off on the affected circuit until the condition is corrected. When the condition is corrected, the chiller will resume normal operation on that circuit, provided the anti-cycle timers have cleared and sufficient load exists. All pre-alarm conditions are auto-clearing. After the controller stages down the unit on an alarm condition and the potential alarm condition has been avoided, the alarm will clear y itself and the unit will resume normal operation. If the alarm condition is not avoided, the alarm will be logged on the MicroTech display, causing lockout of compressors. Thus, the alarm must be manually cleared.

When a McQuay Chiller with a MicroTech controller is used with the McQuay RMS (Remote

Monitoring and Sequencing) Panel, the user must note that alarm nomenclature varies. The RMS has three possible categories of alarms: faults, problems, and warnings. The chiller alarm condition corresponds with the RMS “fault” condition. Thus, there are system and circuit faults. Chiller prealarm conditions correspond to the RMS “problem” designation. Reciprocating chillers do not have warning alarms.

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Circuit Alarm Conditions The “Circuit Alarm Conditions” are those alarms which only affect one circuit and can stop the

compressors of that circuit. These alarms are:

•

Compressor Motor Protection

•

High Condenser Pressure

•

Mechanical High Pressure Switch

•

Low Evaporator Pressure

•

Refrigerant Freeze Protection

•

Bad Pressure Transducer

The chiller must have the manual reset system alarm conditions cleared before normal operation can

System A larm Conditions The “System Alarm Conditions” are those alarms which are common to both refrigeration circuits and

require all compressors to be temporarily shut off or locked out, whichever applies. The following alarm conditions are checked continuously during all modes of operation by the controller. If one of the following alarm conditions is detected, the mode of the controller will switch to “ Off:Alarm “. The controller disables all compressor operation by turning off all Compressor Enable Outputs. Alarm Output #0 will be turned on to notify the operator of the alarm condition. The red “Alarm Status” light on the front of the control panel will be solid on the alarm condition and the MicroTech display will show the current alarm condition. System alarm conditions are:

•

Loss of Water Flow

•

Bad Phase /Voltage

•

Chilled Water Freeze Protection

•

Volts Ratio Protectio n

•

Bad Leaving Water Sensor

The chiller must have the manual reset system alarm conditions cleared before normal operation can resume. If the alarm which occurred is an auto-clearing alarm, once the condition has corrected, the chiller will resume normal operation provided the anti-cycle timers have cleared and sufficient load exists.

Sequence of Operation

Off Conditions

With power supplied to the unit, 115Vac power is applied through the control fuse F1 to the compressor crankcase heaters (HTR1-4), the compressors motor protectors (MP1-4), the evaporator heater and the primary of the 24V control circuit transformer. The 24V transformer provides power to the MicroTech controller and related components. With 24V power applied, the controller will check the position of the front panel System Switch. If the switch is in the “stop” position the chiller will remain off and the display will indicate the operating mode to be OFF:System Sw. The controller will then check the PumpDown Switches. If either switch is n the “stop” position, that circuit’s operating mode will be displayed as OFF:PumpDownSw. If the remote Start/Stop Switch is open, the chiller will be OFF:Remote Sw. The chiller may also be commanded off via the communications network if a separate System Master Panel is installed. The display will show OFF:Remote Comm if this operating mode is in effect.

If an alarm condition exists which prevents normal operation of both refrigerant circuits, the chiller will be disabled and the display will indicate OFF:Alarm.

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Assuming none of the above “OFF” conditions are true, the controller will examine the internal time clock schedule to determine if the chiller should start. The operating mode will be OFF:TimeClock if the time schedule indicates an “OFF” time period.

Start - Up

If none of the “OFF” conditions are true, the controller will initiate a start sequence. The chilled water pump relay output is energized any time the chiller is enabled and the chiller will remain in the “Waiting For Flow” mode until the field installed flow switch indicates the presence of chilled water flow. If flow is not proven within 30 seconds, the alarm “Loss of Water Flow” will be activated and the chiller will continue to wait for proof of chilled water flow. Once flow is established, the alarm will automatically be cleared and the unit will go into the “Wait For Load” mode.

Once flow is established, the controller will sample the leaving water temperature and compare it against the leaving water temperature set point, the control band, the start up delta T and the start timers. If all values indicate a start (stage 1 cooling), the controller will start the lead circuit by energizing that circuits liquid line solenoid valve (SV). When the circuit pressure exceeds the LPCutIn pressure, the compressor on that circuit with the lowest starts will be started. If additional cooling is required (stage 2 cooling), the controller will energize the lag circuit liquid line solenoid valve (SV). When that circuit’s pressure exceeds the LPCutIn pressure, the compressor with the lowest starts will be started. If additional cooling is required (stage 3 cooling), the next compressor with the lowest starts will be started. Stage 4 cooling will start the last compressor.

When the evaporator water temperature is satisfied, the reverse will occur with the compressor with the most run hours being stopped in each stage down. If the chiller is operating at minimum capacity (stage 1) and the chilled water temperature falls below the Leaving Evap Water Set Point, control band and shut down delta T, the controller will stop the last operating compressor. The controller enters the “Waiting For Load” mode and monitor the leaving water temperature.

Low Ambient Start

If the “LOW AMBIENT” option was selected and the out side air temperature is below 50°F, the low ambient start logic will replace the normal starting logic. The compressor with the lowest starts on the lead circuit will start when the liquid line solenoid valve is energized. The LPCutIn will be ignored and the refrigerant freeze protect set point will be ignored for 180 seconds to allow time for the refrigerant pressure to build. After the 180 second time and the evaporator pressure is below the freeze stat set point, the circuit will shut down and the alarm “LoEvapPressure” will be indicated.

The chilled water freeze alarm set point is enforced during low ambient starts and will shut down the chiller if a water freeze conditions is detected. During the low ambient start period, the evaporator pressure is monitored and if the evap pressure drops to 2 psi for more than 20 seconds, the chiller will shut off and a “LoEvap Pressure” alarm will be generated. This protects the compressor from operating i n a vacuum during start-up.

Pumpdown

As the system chilled water requirements diminish, the controller will stage down the compressors. As the system load continues to drop, the liquid line solenoid valve will be de-energize and the refrigerant circuit will go through a one time pump down sequence. As the evaporator pressure falls below the LPCutOut set point, the compressor and condenser fan will stop. The evaporator pump output relay will remain energized and the unit status will indicate “Waiting For Load”.

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Start-Up and Shutdown

Pre-Start Checkout

Configuration default set points are entered at the factory and all values must be checked and reset for each installation. Make sure the field wiring for all flow switches, interlocks or jumpers matches the connections detailed on the field wiring drawing.

Setting of the HEX Address Switches

The controller HEX address switches for each unit determine its logical address in a MicroTech network or in an Open Protocol network. If the chiller is not connected to a RS485 communications loop, set the address switches as follows: Hi=0; Lo=1.

Network addresses are pre-assigned and will be located in the installation instructions for the particular network panel.

Control Switches

Before applying power to the unit, verify that the Unit System Switch is in the stop position and that each Circuit Switch is in the Pumpdown and Stop position. It an optional Remote Start / Stop input is installed, it should be in the start position.

Ribbon Cables

Check the ribbon cables that connect the keypad, ADI board and output board to the controller. They should be fully seated with the locking tabs engaged.

Powering the MicroTech Controller

There are three status LEDs located on the model 250 controller which will indicate the controller’s operating condition. When power is first applied to the control panel through the circuit b reaker (CB), the red RESET LED will illuminate for approximately 3 seconds. During this time, the controller is checking the control software and performing internal hardware tests. When these tests are completed, the RESET LED will turn off and the green RUNNING LED will illuminate indicating the controller’s circuitry and software are operating correctly. If the RESET LED stays on or the RUNNING LED fails to illuminate, consult the trouble shooting section of the manual.

Any alarms showing should be cleared by pressing the alarm key then the clear key. Watch the LEDs on the output board and ADI board to determine the operating status of the controller’s inputs and outputs while performing the following system checks. Initially all LEDs on the output board will be off.

Table 25, Initial condition ADI board LEDs

DH1 DH2 0ON8ON 1 OFF 9 OFF 2ON10ON 3OFF11OFF 4ON12ON 5OFF13ON 6 ON 14 ** OFF 7ON15ON

** Flow switch may be on if not controlled by the unit controller

Move the system switch to the Auto position. LED #5 on the ADI board will turn on. If the time schedule is in occupied, the chilled water pump relay output board #2 will turn on.

Move both pumpdown switches to the auto position. DH1-7 and DH2-15 will turn off. The controller will then activate one of the refrigerant circuit solenoids depending upon which is the lead circuit. (output relay #4 circuit #1or output relay #5 circuit #2) When the evaporator pressure rises

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above the LPCutIn value, a compressor on the lead circuit will start. Refer to the unit staging schematic to determine which LED is associate to a compressor. The controller will stage up and down to maintain the desired leaving water temperature.

Temporary Shutdown

Close both pumpdown switches. After pumpdown is completed, turn off the system switch. Open the remote start / stop input and the evaporator pump will stop. Perform the reverse to start up after a temporary shutdown.

Extended Shutdown

CAUTION

The operator must provide protection against water circ uit freezing on all chiller units. All water must be drained form the evaporator and associated piping and power for the cooler heating cable should be applied via separate disconnect if freezing ambient conditions ar e expected.

1. Close the manual liquid line shut off valves. Move the circuit #1 and #2 switches to the

“Pumpdown and Stop” position. Each operating circuit will pumpdown and the compressors will stop.

After both circuits have been pumped down, open the “Remote Start / Stop’ input and the

controller will open output relay #1 to stop the evaporator pump.

Move the system switch to the stop position. Turn off main power to the chiller unit and to the

chilled water pump.

Tag all open electrical switches and related water valves. This will prevent premature operation

of the equipment.

If the chiller will be exposed to freezing ambient temperatures, drain all water from the unit

evaporator and chilled water piping and leave power applied to the evaporator heating cable via separate disconnect. If external water piping is heat traced, leave power on to heat tracing to protect from freezing.

Keypad / Display

Figure 29, Keypad / Display

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Menu Structure (general description)

The information stored in the MicroTech controller can be accessed through the keypad using a treelike structure. This tree structure is divided into Categories, Menus and Menu Items. There are three Categories which make up the tree structure: STATUS, CONTROL, and ALARM. Each category is divided into Menus and each Menu into Menu Items. The three categories are described below:

•

Status category - Menus and menu items in this category provide information on the MicroTech

and unit operating conditions. The entries under each menu item in this category provide information only and are not change able through the MicroTech keypad. Menus 1 through 12 are Status Menus.

•

Control category - Menus and menu items in this category provide for the input of all the unit

control parameters. These include cooling and heating control, compressor control and condenser fan control parameters as well as time schedules and alarm limits. The entries under these menu items are changeable through the MicroTech keypad. Menu Items 13 through 23 are Control Menus.

•

Alarm category - Menu and menu items in this category provide information regarding current

and previous alarm conditions. Menus 23 through 27 are Alarm Menus.

Display Format

The information stored in the MicroTech controller tree structure can be viewed (one menu and menu item at a time) thro ugh a two line by sixteen character LCD display. The curre nt MENU is shown on the top line and the current MENU item is shown on the bottom line of the display.

Either U.S. or S.I. units may be displayed by installing the appropriate software. U.S. Units

Temperature:°F Pressure: psi, psig, psid

S.I. Units

Temperature:°C Pressure: kPa, kPag, kPad

MicroTech Menu Structure

1. Status category - Where ore than one menu item entry is listed under a menu item, the list

includes all the entries which can appear in the display for the particular item. The entry that shows in the display depends on the operating status of the unit.

Control category - Where more than one menu item entry is listed under a menu item, the list

includes all the choices from which the user can select. The selected entry appears in the display.

Alarm category - The entries listed include all the possible alarm messages. The display will

show the current and previous alarm conditions for each circuit.

Password Information

When changing any menu item entry, the user is prompted to enter the access password. The change will not be allowed until the correct password is entered. The password for AGZ units is always the successive pressing of the following “ACTIO N” group keys:

“E

NTER” “ENTER” “ENTER” “ENTER”

Once this has been done, the user can make changes to the menu item entries. After entering the correct password, the controller will allow a 5 minute time period during which the operator may make any necessary setpoint adjustments. Any keypad activity will reset the timer for the full 5 minutes so the password only needs to be entered once per session. After 5 minutes of inactivity, the password access time will expire providing protection against unauthorized users.

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Keypad Key Functions

The MicroTech keypad consists of twelve pressure sensitive membrane switches (refer to Figure 29). These keys are used to step through, access, and manipulate the information in the MicroTech controller tree structure. The keypad keys are divided into four groups with two or four keys in each. These groups of keys and their functions are described below.

Category Group

The keys in this group provide quick access to strategic menus throughout the menu tree-structure. This reduces the need to step through all the menus, one by one, in ord e r to reach the desired menu. Status-Pressing the “STATUS” key at any time shifts the display to Menu #1 (Unit Status) which is the first menu of the Status category.

Control - Pressing the “CONTROL” key at any time shifts the display to Menu #13 (Control Mode) which is the first menu of the Control category. Alarms-Pressing the “ALARMS” key at any time shifts the display to Menu #24, (Circ 1 Current Alarm) which is the first menu of the Alarms category. Switch - Pressing the “SWITCH” key at any time toggles the display between the current menu (status/control) item and the related menu (control/status) item somewhere else in the tree-structure. For example, if this key is pressed while the current menu item is Menu Item 4A (Leaving Evaporator=), the display shifts to Menu 146 (Leaving Evaporator Set Point=). This provides for easy review of actual versus set point values. Tables 7, 8 and 9 include a listing of all the currently supported switching functions.

Menu Group

The keys in this group are for stepping from menu to menu in the menu tree-structure. Prev. - Pressing “PREV.” shifts the display to the previous menu. Note: When Menu #I is currently in the display (the first menu in the menu tree-structure), pressing “PREV.” causes an “end of menus” message to appear in the display. Pressing “PREV.” again causes the display to wrap around to Menu #27 (the last menu in the tree-structure). Next- Pressing “NEXT” shifts the display to the next menu.

Note: When Menu #27 is currently in the display (the last menu in the menu tree-structure), pressing

“NEXT” causes and “end of menus” message to appear in the display. Pressing “NEXT” again causes the display to wrap around to Menu #1 (the first menu in the menu tree structure).

Item Group

The keys in this group are for stepping from item to item within a menu. Prev. - Pressing “PREV.” shifts the display to the previous item in a menu. Note: When the first item in a menu is currently in the display, pressing “PREV.” causing an “end of items” message to appear in the display pressing “PREV.” Again causes the display to wrap around to the last item in the menu.

NextPressing “NEXT” shifts the display to the next item in a menu. Note: When the last item in a menu is currently in the display, pressing “NEXT” causes an “end of items” message to appear in the display. Pressing “NEXT” again causes the display to wrap around to the first item in the menu.

Action Group

The keys in this group are for making changes to unit control parameters or for clearing alarm conditions.

Note: Before a change to a parameter can be made or before an alarm can be cleared, the display prompts the user with an “Enter Password” message. At this point, the password must be entered before the user can continue with the action.

“EN T E R” “EN T E R” “EN T E R” “EN T E R” IncrWhen changing the value of a menu item entry, pressing “INCR. +” shifts the menu item

display line to the next higher or next available selection.

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Decr.When changing the value of a menu item entry, pressing “DECR. -” shifts the menu item display line to the next lower value or previous available selection.

EnterOnce a change has been made to a desired value, pressing “ENTER” locks in the new value. ClearPressing “ALARMS” followed by “CLEAR” clears the current alarm. Also, when a change is

made to a menu item pressing “CLEAR” returns the display to the original value as long as “ENTER” has not been pressed.

Note: The cause of an alarm should always be determined and corrected before resetting the alarm

through the keypad.

Example of Keypad Operation -As an example of using the keypad key functions, consider reprogramming the Leaving Evaporator Set Point from 44°F to 42°F. This consists of changing the Menu Item 148 (Leaving Evaporator Set Point) entry from “44°F to 42°F”. Assume Menu #I (Unit Status) is currently in the display. The following key sequence is followed.

Press the ”CATEGORY” group ”CONTROL” key one time. This switches the display to Menu

#I13 (the first menu in the “CONTROL” category).

Press the “MENU” group “NEXT” key once. This shifts the display to Menu Item 14A (Active

Set Point).

Press the “ITEM” group “NEXT’ key once. This shifts the display to Menu Item 14B. (Leaving

Evaporator setpoint).

Press the “ACTION” group ‘DEC -” key one time. This prompts the user to enter the password.

“ENTER” “EN T E R” “EN T E R ” “EN T E R”

After the “Password Verified” message, press the “ACTION” group “DEC -” key four times. This

changes the menu item entry to 42°F.

Press the “ACTION” group “ENTER” key one time. This stores the new entry into the

MicroTech controller memory.

Pressing the “CATEGORY” group “STATUS” key then shifts the display back to Menu #I.

Menu Descriptions

Status Menus

Menus 1 through 12 provide chiller operating information and display of sensor readings. The items listed under these status menus are affected by the settings under the associated control menus and are not directly adjusted via the keypad.

Menu #l: Unit StatusThe unit operating status is displayed as item 1 within this menu. The second

item is the number of seconds remaining in the unit interstage timer. The third item displays the user chosen unit operation of chiller or Templifier (heat pump). Option chosen on Menu 23.

Menu #2: Circuit #l StatusThe current operating condition of refrigerant circuit #l is displayed

whenever this menu is selected. There is only one item displayed in this menu.

Menu #3: Circuit #2 StatusThe current operating condition of refrigerant circuit #2 is displayed

whenever this menu is selected. There is only one item displayed in this menu.

Menu #4: Water TemperaturesThe evaporator leaving water temperature is displayed under item #l

under this menu. Additional items under this menu display the evaporator entering water temperature as well as the entering and leaving condenser temperatures if these optional sensors have been installed on the unit.

Menu #5: Circuit #l PressuresThe circuit #l evaporator and condenser refrigerant pressure readings

are displayed under this menu. The calculated minimum and maximum condenser pressure values are also shown.

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Menu #6: Circuit 62 PressuresThe circuit #2 evaporator and condenser refrigerant pressure

readings are displayed under this menu. The calculated minimum and maximum condenser pressure values are also shown.

Menu #7: Circuit #l TemperaturesThe circuit #I refrigerant temperatures are calculated from their

corresponding pressure sensors and displayed here. If the optional Sensors are not present, the line item will flash “Open”.

Menu #8: Circuit #2 TemperaturesThe circuit #2 refrigerant temperatures are calculated from their

corresponding pressure sensors and displayed here. If the optional sensors are not present, the line item will flash “Open”,

Menu#9: Chiller AmpsDisplays the present amp draw of the chiller expressed as a percentage of

the unit rated load amps under full load conditions (optional feature).

Menu #10: Compressor Run Hours The total run hours for each compressor is available under this

menu.

Menu #11: Compressor StartsThe total number of starts for each compressor is available under this

menu.

Menu#12: Air Temperatu reDisplays the current outdoor air temperature if the optional OAT sensor

is installed on the air cooled chiller and “Lcl” is selected from Menu 23. Also displayed here is the air temperature received from a network if the “Rmt” OAT select option from Menu 23 is selected.

Control Menus

Menus 13 through 23 are the set point menus. All adjustable control parameters and set points, time schedules, control options, and alar m thresholds are accessed through these menus.

CAUTION

Any changes to these parameters must be determined and implemented by qualified personnel with a thorough understanding of how these parameters affect the operation of the unit. Negligent or improper adjustm ent of these c ontrols may result in dam age to the unit or personal injury.

Menu #13: Control ModeOne of several automatic and manual operating modes may be selected

from within this menu. Typically, the selected control mode will be Automatic which will allow the MicroTech controller to handle all compressor and condenser fan staging. Refrigerant circuit #2 may be locked off while still allowing circuit #1 to stage automatically by selecting AutoCir#1 -Off#2 as the operating mode. OffCirc#1 -Auto#2 allows the normal staging of refrigerant circuit #2 but circuit #1 is locked off. Select Manual Staging if manual control is desired. In this operating mode, the condenser fans are controlled by the MicroTech but the number of stages is determined manually via the keypad. If manual staging is selected, the second item under this menu indicates the number of active cooling stages. Use the INCR or DECR keys to increase or decrease the number of active stages.

Menu#14: Leaving Water Set PointsThe leaving wafer set points, control band, maximum pull

down rate and water reset options are adjusted from this menu. The first menu item is The Active Set Point ("Active Spt"). The current control temperature is displayed here. The Leaving Chilled Water Set Point ("Lvg Evap") appear towards the top of this menu. These are the set points that will be maintained for chillers if no reset options are in effect. The Active Control Set Point ("Active Spt") will display the calculated chilled or heated water temperature to be maintained when one of the reset options is enabled.

If the 4-20 milliamp reset option is enabled, the controller will reset the leaving chilled water temperature to a higher value based on a percentage of the Maximum Chilled Water Reset set point ("MaxChWRst"). At 4mA or less, no reset will occur. At 20mA, the chilled water set point will be

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reset to a value equaling the Leaving Evaporator Water Set Point ("Lvg Evap") plus the value stored in the "MaxChWRst". Any milliamp value between 4 and 20mA will cause a proportional value of the Maximum Chilled Water Reset to be added to the Leaving Chilled Water Set Point. The external 4-20 milliamp control signal and current reset set point will be displayed under "Reset Sig" and "Active Spt", respectively, on Menu 14.

By selecting Return as the reset mode, the leaving chilled water temperature will be reset by the controller as required to maintain a constant return water temperature. The user must select the "Return" option under "ResetOpt" and select the return set point to be maintained under "ResetSpt". The current leaving chilled water reset set point will be displayed under "Active Spt".

If the chiller is to be used for ice storage, select the "Ice" option in Menu 14 "LvgWater Spt", "ResetOpt=". To calculate the leaving chilled water set point, the control band (Menu 14 "CntrlBand=") and shut down delta-T (Menu 1 4 ShutDn D-T=") must first be selected. The equation to determine leaving chilled water temperature is:

Lvg Evap = Desired Ice Temp + ½ "CntrlBand =" + " ShutDn D - T ="

Lvg Evap = 21°F + ½ (4) + 105°F

Lvg Evap = 21 + 2 + 1.5

Lvg Evap = 24.5

For day operation the maximum chilled water reset (Menu 14 "MaxChWRst=") is added to the "Lvg Evap" as calculated above to reach the desired day operating leaving chilled water temperature.

When the Ice option is selected, the resetting of the leaving chilled water set point (during day operation) via the 4-20mA input is not a functional option. To retain the option, the set points in Menu 14 must be changed by a Building Automation System through our MicroTech Open Protocol Monitor Software.

The "Network" reset option allows a signal to be sent reflecting 0-100% reset of the "Lvg Evap" set point (chillers) or "Lvg Cond" set point (THRs) based on the Maximum Chilled Water Reset set point. This function acts much like the 4-20 milliamp reset option as described above.

The Maximum Pull Down Rate set point ("MaxPullDn") will prevent overshooting the active water set point during initial start-up and normal operation. The controller will limit the rate at which the chilled water loop temperature is reduced based on an adjustable set point (default of 0.5°F/min). Every minute, the controller checks the leaving water temperature and compares it to the last reading. If the pull rate has been exceeded, the controller will delay additional unit stages.

The Control Band ("CntrlBand") set point defines the temperature range on either side of the active water set point that must be exceeded in order for a stage up or stage down to occur. The Start Up Delta-T ("StartUpD-T") and Shut Down Delta-T ("ShutDn D-T") define when the unit will start and shut down. The unit will cycle on from a shut down mode once the leaving chilled water temperature has reached the Leaving Chilled Water Set Point plus half of the Control Band plus the Start Up Delta-T. After the chiller starts, it will stage up and down according to the leaving chilled water temperature (plus or minus) half the Control Band. Once the load is met and the chiller has staged down to stage 1, the unit will shut completely off once the leaving chilled water temperature has reached the Leaving Chilled Water Set Point minus half of the Control Band minus the Shut Down Delta-T.

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Figure 30, Delta-T Setpoints for Chillers

Menu #15: Softload Set Points—The controller can limit the number of available stages when the

unit is initially started to prevent excessive power consumption and help control overshoot of the water temperature set point. The maximum number of stages will equal the Soft Load Maximum Stages for the time period defined in the softload timer set point. If the softload timer is set to zero, no soft loading will take place. Any time remaining in the softload timer will be displayed when the soft load option is enabled. During morning start-up, the controller will run the chilled water pump and sample the loop water temperature for a time equal to the Load Delay set point. If cooling or heating is required at the end of this time delay, the first compressor will be started.

Menu #16: Compressor Set Points—This menu is used to set the lead-lag order of the refrigerant

circuits. The lead compressor may be manually set to circuit #1 or circuit #2 or the Automatic mode may be enabled. In Automatic mode, the MicroTech controller will select the refrigerant circuit with the lowest number starts as the lead. The interstage timer set point sets the delay time between the current cooling stage and the next stage up request. The stage down request time delay is a fixed ratio of the stage up delay.

The minimum Start/Start and Stop/Start timers provide protection against compressor short cycling. During normal operation the Compressor Interstage Timers provide a time delay between cooling or heating stages.

Menu #17: Head Pressure Set Points—The set points for head pressure control are adjusted from

within this menu. The Minimum Lift Pressure is the minimum differential pressure to be maintained across the expansion valve. The dead band defines the pressure differential range within which no fan staging will occur. If the head pressure moves outside of the deadband, the controller will integrate the pressure error over time. When the Pound/Second exceeds the Stage Up Error or Stage Down Error set point, the controller will adjust the fan staging up or down to bring the head pressure back within the deadband. Refer to the section on head pressure control in this manual for details.

Menu #18: Demand Limit—The Demand Limit set point defines the maximum number of cooling

stages allowed by an external demand limit signal. The actual remote demand limit signal level in milliamps is also displayed here.

In place of demand limit input, a 0 or 5 volts signal from a unit switch open or cool (5 volts - switch closed) modes.

Menu #19: Time/Date—The MicroTech controller uses an internal calendar and clock to provide

automatic operation for each day of the year. Provision is made for Manual Override to accommodate unscheduled building occupancy. Press the Control key to enter the control area of the menu structure then press the Next Menu key until the display shows Menu Item #24, Set Date/Time. If the date is incorrect, press the Incr or Decr key and the controller will prompt you for your password. When you have entered the correct password, the controller will return to the Set Date/ Time display. Press the Incr or Decr keys to scroll the month up or down. Press the Enter key when the display shows the correct month. The cursor will advance to the Date position on the display which can be set in the same manner. After pressing the Enter key to set the Date, the cursor will advance to the Year position on the display. Use the Incr, Decr, and Enter keys to set the correct Year.

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Press the Next Item key. The display will show the current Day, Hour, Minute and Second. If this information needs to be changed, follow the same procedure used to set the Date in the previous section.

Menu #20: Daily Schedule—This section will help you to set the Daily Start/Stop time for automatic

operation of the chiller. Pressing the Next Menu key and the Next item key will advance the display to the Daily Time Schedule. This is where the Start and Stop times for each day of the week will be set using the 24 hour format. Beginning with Sunday, use the Incr and Decr keys to set the de sired start and stop time and press the Enter key to store the information in the controller. If the chiller is to be programmed to run continuously 24 hours a day, set the stop tie for 1 minute before start time (Stop=23: 59; Start=00 :00). Press the Next Item key to advance through the remaining week days and Holiday Start/ Stop times.

Menu #21: Holiday Date—Up to 14 holiday dates may be entered. When the MicroTech controller's

current date matches a date set in the holiday schedule, the normal daily start/stop times are replaced by the holiday start/stop ties which were set in the previous section. At the date prompt, use the Incr and Decr keys to set the first holiday month and press Enter to advance to the Day position of the display. Use the lncr, Decr and Enter keys to set the first day of the holiday. Press Next Item to advance to Holiday 1 Duration. If the scheduled holiday spans more than one day, use the lncr and Decr keys to set the holiday duration and press Enter to store the information in the controller. Use the Next Item key to set additional holiday dates and duration’s for the entire year.

Menu#22: Alarm Set Points—On a call for cooling or heating, the controller will open the liquid line

solenoid valve. When the evaporator pressure rises above the Low Pressure Cutin set point, the first compressor will be started. The Low Pressure cut out set point determines the point at which the compressors will shut off during a pumpdown sequence. The Refrigerant Freeze and Water Freeze alarm set points may be adjusted as required. Water and refrigerant freeze alarm time delays may also be adjusted for this menu. If the condenser High Pressure set point is exceeded, the controller will shut off the unit.

Menu #23: Miscellaneous Setup—Several general operating characteristic are defined here. These

are set at the factory prior to unit delivery and should not require adjustment. The control software version number is displayed form this menu. Outdoor air temperature is displayed on Menu 12.

Alarm Menus

Menus 24 through 27 are used to display any alarm conditions which may be present in the unit. All alarm messages are accompanied by the date and time when the alarm occurred. Important operating conditions at the time of the alarm are stored in the controller's memory and may be viewed within the following alarm menus.

Menu #24: Circuit #1 Current Alarm—If refrigerant circuit # 1 is in an alarm condition, the

appropriate alarm message will be displayed here. The temperature and pressure readings at the time of the alarm will be stored in the controllers memory and may be displayed for analysis from this menu.

Menu #25: Circuit #2 Current Alarm—If refrigerant circuit #2 is in an alarm condition, the

Menu #26: Circuit #1 Previous Alarm—The alarm type for the last recorded circuit #1 alarm may be

displayed from this menu. The time and date at which the previous alarm occurred are also displayed here. This information will be replaced when a current alarm condition is cleared.

Menu #27: Circuit #2 Previous Alarm—The alarm type for the last recorded circuit #2 alarm may be

displayed from this menu. The time and date at which the previous alarm occurred are also displayed here. This information will be replaced when a current alarm condition is cleared.

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Menus for the AGZ MicroTech Controller

Table 26, MENU 1 Chiller Status

Screen Display

2 Capacity % 3 InterStg=xxx sec

OFF: Manual Mode

OFF: System Sw

OFF: Remote Comm

OFF: Remote Sw

OFF: Time Clock

OFF: Alarm

OFF: PumpDnSw's

Starting WaitForFlow WaitForLoad

StageUp StageDn

Stage

Manual

Table 27, MENU 2 Circ #1 Status

Screen Display

OFF: SystemSw

OFF: ManualMde

OFF: Alarm OFF: PumpDwnSw OFF: CycleTime xx

OFF: Ready

PumpingDown

OpenSolenoid

% Capacity

Starting

LowAmbStart

Table 28, MENU 3 Circ #2 Status

Screen Display

OFF: SystemSw

OFF: ManualMde

OFF: Alarm OFF: PumpDwnSw OFF: CycleTime xx

OFF: Ready

PumpingDown

OpenSolenoid

% Capacity

Starting

Table 29, MENU 4 Water Temp's

Screen Display

Lvg Evap= xxx.x °F (°C)

Short °F (°C)1

Open °F (°C)

Ent Evap= xxx.x °F (°C)

Short °F (°C)2

Open °F (°C)

D-T Evap

Short °F (°C)3

Open °F (°C)

Table 30, MENU 5 Circ #1 Pres's

Screen Display

3 MinCondPr = 0# 4 MaxCondPr = 0# 5 LiftD-P= psi 6 Cond Fan Stage = x

Evap= xxx.x psi(kPa) xx°F (°C)

Evap 145 +psi(kPa) **°F (°C)

Open N/A ** °F (°C)

Short N/A **°F Cond xxx.x psi (kPa) xxx° Cond 450+ psi (kPa) xxx°

Open N/A ** °F (°C)

Short N/A **°F

Table 31, MENU 6 Circ #2 Pres's

Screen Display

3 MinCondPr = 0# 4 MaxCondPr = 0# 5 LiftD-P= psi 6 Cond Fan Stage = x

Evap= xxx.x psi(kPa) xx°F (°C)

Evap 145 +psi(kPa) **°F (°C)

Open N/A ** °F (°C)

Short N/A **°F Cond xxx.x psi (kPa) xxx° Cond 450+ psi (kPa) xxx°

Open N/A ** °F (°C)

Short N/A **°F

LowAmbStart

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Table 32, MENU 7 Circ #1 Temp's

Screen Display

4 5 CondD-T °F (°C) 6

Satur Evap=xxx°F (°C)

N/A **°F (°C)

SuctLine = xxx.x°F (°C)

Open °F (°C)2

Short °F (°C)

Super Ht =xxx.x°F (°C)

N/A ** °F (°C)

Satur Cond = xxx°F (°C)

N/A **°F (°C)

Liquid Ln = xxx.x°F (°C)

N/A ** °F (°C)

SubCoolg= xxx.x°F (°C)

N/A ** °F (°C)

Table 33, MENU 8 Circ #2 Temp's

Screen Display

4 5 CondD-T °F (°C) 6

Satur Evap=xxx°F (°C)

N/A **°F (°C)

SuctLine = xxx.x°F (°C)

Open °F (°C)2

Short

Super Ht =xxx.x°F (°C)

N/A ** °F (°C)

Satur Cond = xxx°F (°C)

N/A **°F (°C)

Liquid Ln = xxx.x°F (°C)

N/A ** °F (°C)

SubCoolg= xxx.x°F (°C)

N/A ** °F (°C)

Table 35, MENU 10 Comp RunHours

Screen Display

1 Comp #1 =xxxxxx 2 Comp #2=xxxxxx 3 Comp #3=xxxxxx 4 Comp #4=xxxxxx 5 6 7 8 9

Table 36, MENU 11 Compr Starts

Screen Display

1 Comp #1 =xxxxxx 2 Comp #2=xxxxxx 3 Comp #3=xxxxxx 4 Comp #4=xxxxxx

Table 37, MENU 12 Air Temp

Screen Display

1 OutDoor = xxx.x °F( °C)

Table 34, MENU 9 Chiller Amps

Screen Display

1 PercentRLA=xxx%

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Table 38, MENU 13 Control Mode

Screen Display Factory Setpoint Range

2 Manual Stage=xx 0 1 - 8

Manual Unit Off

Automatic

Manual Staging

Manual Unit Off

Table 39, MENU 14 Lvg Evap Spts

Values for R-22 refrigerant, ( ) indicates Centigrade values

Screen Display Factory Setpoint Range

1 Lvg Evap=xxx.x °F (°C) 44 (6.7) 10 - 80 (-12.2 - 26.7) 2 Actv Spt=xxx.x °F (°C) Not Changeable 3 CntrlBand x.x °F (°C) 3.0 (1.6) 1.0 - 5.0 (0.5 - 2.7) 4 StartUpD-T= x.x °F (°C) 3.0 (1.6) 1.0 - 5.0 (0.5 - 2.7) 5 ShutDn D-T= x.x °F (°C) 1.5 (0.8) 0.0 - 3.0 (0.0 - 1.6) 6 MaxPullDn= x.x °F (°C) 0.5 (0.2) 0.1 - 1.0 (0.0 - 0.5)

ResetOpt=None

8 ResetSig= xx.xma Not Changeable 9 MaxChWRst=xx.x °F (°C) 10.0 (5.5) 0.0 - 45.0 (0.0 - 25.0)

10 ReturnSpt= xx.x °F (°C) 54.0 (12.3) 15.0 - 80.0 (-9.4 - 26.7)

[ ] the minus sign is not displayed with three digit numbers

Return

4-20 Ma

Network

Ice

None

Table 40, MENU 14 Lvg Evap Spts

Values for 134a refrigerant, ( ) indicates Centigrade values

Screen Display Factory Setpoint Range

1 Lvg Evap=xxx.x °F (°C) 44 (6.7) 10 - 80 (-6.6 - 26.7) 2 Actv Spt=xxx.x °F (°C) Not Changeable 3 CntrlBand x.x °F (°C) 3.0 (1.6) 1.0 - 5.0 (0.5 - 2.7) 4 StartUpD-T= x.x °F (°C) 3.0 (1.6) 1.0 - 5.0 (0.5 - 2.7) 5 ShutDn D-T= x.x °F (°C) 1.5 (0.8) 0.0 - 3.0 (0.0 - 1.6) 6 MaxPullDn= x.x °F (°C) 0.5 (0.2) 0.1 - 1.0 (0.0 - 0.5)

8 ResetSig= xx.xma Not Changeable 9 MaxChWRst=xx.x °F (°C) 10.0 (5.5) 0.0 - 45.0 (0.0 - 25.0)

10 ReturnSpt= xx.x °F (°C) 54.0 (12.3) 15.0 - 80.0 (-9.4 - 26.7)

[ ] the minus sign is not displayed with three digit numbers

ResetOpt=None

Return

4-40 Ma

Network

Ice

None

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Table 41, MENU 15 SoftLoad Spts

Screen Display Factory Setpoint Range

1 Time Left= xxmin 2 SoftLoad= xx min 20 0 - 254 3 SoftLdMaxStg= x 4 1 - 4 4 LoadDelay= xxsec 15 0 - 254

Table 42, MENU 16 CompressorSpt

Screen Display Factory Setpoint Range

1 Sequence=Auto Auto

2 StageUp= xxx sec 3 StageDn= xxx sec 4 MinST-ST=xx min 15 5 - 40

MinSP-ST xx min 3 - 30

Comp #1 Disable / Enable Comp #2 Disable / Enable Comp #3 Disable / Enable Comp #4

1234 1432 2143 2341 3214 3412 4123 4321

Disable / Enable

Table 43, MENU 17 Head Pres Spt

Values for R-22 refrigerant, ( ) indicates Centigrade values

Screen Display Factory Setpoint Range

1 MinLift 50%=xxx 90 (621) 70 - 100 (483 - 690) 2 MinLift100%=xxx 120 (828) 100 - 140 (690 - 966) 3 DeadBand 50%= x.x 50 0 - 255 4 DeadBand100% = x.x 90 0 - 255 5 Cond Pres 1 = xxx 200 180 - 220 6 Cond Pres 2 = xxx 300 280 - 320 7 StageUpErr= xxx 400 (2760) 300 - 990 (2070 - 6830) 8 StageDnErr = xxx 100 (690) 50 - 400 (340 - 2760)

Table 44, MENU 17 Head Pres Spt

Values for 134a refrigerant, ( ) indicates Centigrade values

Screen Display Factory Setpoint Range

1 MinLift 50%=xxx 50 (345) 50 - 80 (345 - 552) 2 MinLift100%=xxx 70 (483) 80 - 122 (552 - 841) 3 DeadBand 50%= x.x 23 0 - 255 4 DeadBand 100% = x.x 50 0 - 255 5 CND PRS 1 = xxx 128 180 - 220 6 CND PRS 2 = xxx 201 280 - 320 7 StageUpErr= xxx 275 (1897) 300 - 990 (2070 - 6830) 8 StageDnErr = xxx 57 (393) 50 - 400 (340 - 2760)

Table 45, MENU 18 Demand Limits

Screen Display Factory Setpoint Range

1 Demand Lim= xstg 3 Not Changeable at this screen 2 DemandSg= xx.x ma Actual Value

Indicates the Magnitude of the

Demand Limit Signal

Table 46, MENU 19 Time / Date

Screen Display Factory Setpoint Range

1 Time= xx:xx:xx Actual Time 2 Mon xx/xx/xx Actual Day and Date

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Table 47, MENU 20 Schedule

Screen Display Factory Setpoint Range

1 Override= xx.xx hr 0.00 Hr 00:00 - 63.50 2 NMPSchedule= N/A N/A 3 Sun 00:00-23:59 00:00 - 23:59 00:00 - 23:59 4 Mon 00:00-23:59 00:00 - 23:59 00:00 - 23:59 5 Tue 00:00-23:59 00:00 - 23:59 00:00 - 23:59 6 Wed 00:00-23:59 00:00 - 23:59 00:00 - 23:59 7 Thu 00:00-23:59 00:00 - 23:59 00:00 - 23:59 8 Fri 00:00-23:59 00:00 - 23:59 00:00 - 23:59 9 Sat 00:00-23:59 00:00 - 23:59 00:00 - 23:59

10 Hol 00:00-23:59 00:00 - 23:59 00:00 - 23:59

Table 48, MENU 21 Holiday Date

Screen Display Factory Setpoint Range

1 #1 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 2 #1 Dur = 0 Day(s) 0 0 - 31 3 #2 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 4 #2 Dur = 0 Day(s) 0 0 - 31 5 #3 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 6 #3 Dur = 0 Day(s) 0 0 - 31 7 #4 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 8 #4 Dur = 0 Day(s) 0 0 - 31

9 #5 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 10 #5 Dur = 0 Day(s) 0 0 - 31 11 #6 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 12 #6 Dur = 0 Day(s) 0 0 - 31 13 #7 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 14 #7 Dur = 0 Day(s) 0 0 - 31 15 #8 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 16 #8 Dur = 0 Day(s) 0 0 - 31 17 #9 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 18 #9 Dur = 0 Day(s) 0 0 - 31 19 #10 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 20 #10 Dur = 0 Day(s) 0 0 - 31 21 #11 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 22 #11 Dur = 0 Day(s) 0 0 - 31 23 #12 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 24 #12 Dur = 0 Day(s) 0 0 - 31 25 #13 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 26 #13 Dur = 0 Day(s) 0 0 - 31 27 #14 Date = N/A 0 N/A 0 Jan - Dec 1 - 31 28 #14 Dur = 0 Day(s) 0 0 - 31

Table 49, MENU 22 Alarm Spts

Values for R-22 refrigerant, ( ) indicates Centigrade values

Screen Display Factory Setpoint Range

1 FreezStat= xxpsi (kPa) 54 (372) 20 - 60 (138 - 414)

2 FreezH2O= xx.x °F (°C) 36.0 (2.3) 0.0 - 40.0 (-17.5 - 4.5)

3 FreezeTim= xxx sec

4 Hi Press = xxxpsi (kPa) 380 (2622) 280 - 426 (1932 - 2939)

Table 50, MENU 22 Alarm Spts

Values for 134a refrigerant, ( ) indicates Centigrade values

Screen Display Factory Setpoint Range

1 FreezStat= xxpsi (kPa) 26 (179) 4 - 26 (27 - 179)

2 FreezH2O= xx.x °F (°C) 36.0 (2.3) 0.0 - 40.0 (-17.5 - 4.5)

3 FreezeTim= xxx sec

4 Hi Press = xxxpsi (kPa) 380 (2622) 280 - 426 (1932 - 2939)

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Table 51, MENU 23 Misc Setup

Screen Display Factory Setpoint Range

1 Unit Type= Air Cooled - 2 Model AGZ 4 Stages - 3 # Compressors = 4 - 4 # Stages = 4 - 5Fan Stg/Cir = 2 6 Begin PD = xx PSI 54 42 – 70 psi 7 End PD – xx PSI 34 20 - 40 8 Full Pump DN - NO NO NO - YES

9 EndFullPD = xx PSI 20 psi 10 – 30 psi 10 Low Ambi Opr = NO NO No - YES 11 12 13 14 #1 EvapAdj = 0.0 psi -13.8 – +13.8 15 #2 EvapAdj = 0.0 psi -13.8 – +13.8 16 #1 CondAdj= 0.0 psi (-13.8 - 13.8) 17 #2 CondAdj= 0.0 psi (-13.8 - 13.8) 18 OAT Select = Lc1 Lc1 NONE-LcL-Rmt 19 OAL Lockout = No NO NO – YES 20 21 Alarm = Closed CLOSED CLOSED – OPEN-BLINK(N/O) 22 IDENT = GZ2E01A

Low Ambi Temp = xx°°°°F

LvgEvapAdj = 0.0°°°°F

EntEvapAdj = 0.0°°°°F

Lockout T = x°°°°F0°°°°F 0°

60 10 - 100

-0.8 – +0.8

0°F - 80°°°°F

0°0°

Table 52, MENU 24 #1 Curr Alarm

Screen Display

1 Current Alarm

2 @ 0:00 0/00/00

3 Evap = x.x psi (kPa)

4 Cond = x.x psi (kPa)

5 SuctLine=xxx.x °F(°C)

6 LiquisLn=xxx.x °F(°C) 7 Evap Lvg=xxx.x °F(°C) 8 OAT=xx.xx°F(°C)

9 Capacity= xxx%

10 Fan Stage = x

Table 53, MENU 25 #2 Curr Alarm

Screen Display

1 Current Alarm

2 @ 0:00 0/00/00

3 Evap = x.x psi (kPa)

4 Cond = x.x psi (kPa)

5 SuctLine=xxx.x °F(°C)

6 LiquisLn=xxx.x °F(°C) 7 Evap Lvg=xxx.x °F(°C) 8 OAT=xx.xx°F(°C)

9 Capacity= xxx%

10 Fan Stage = x

Table 54, MENU 26 #1 PrevAlarm

Screen Display

1 1 Current Alarm 2 1 x:xx x/xx/xx 3 2 Current Alarm 4 2 x:xx x/xx/xx

5 3 Current Alarm 6 3 x:xx x/xx/xx 7 4 Current Alarm 8 4 x:xx x/xx/xx

9 5 Current Alarm

10 5 x:xx x/xx/xx

Table 55, MENU 27 #2 PrevAlarm

Screen Display

1 1 Current Alarm

2 1 x:xx x/xx/xx

3 2 Current Alarm

4 2 x:xx x/xx/xx

5 3 Current Alarm 6 3 x:xx x/xx/xx 7 4 Current Alarm 8 4 x:xx x/xx/xx

9 5 Current Alarm

10 5 x:xx x/xx/xx

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Trouble Analysis for the AGZ MicroTech Controller

Microprocessor Control Board

The Microprocessor Control Board (MCB) is shown in Figure 31. It contains a microprocessor that is preprogrammed with the software required to monitor and control the chiller. The various MCB connections and components are described below.

Figure 31, Microprocessor Control Board (MCB)

Hex switches

DIGITAL OUTPUTS

EXPANSION BUS

FUSE 1

PORT A PORT B

COMMUNICATIONS

[FUSE: BUSSMAN MCR-1/4]

3 4

ANALOG INPUTS DIGITAL INPUTS

RUNNING

RESET

ACTIVE OUTPUT 0

POWER FUSES

[BUSSMAN GDC-T2A]

POWER IN

[18-24 VCT]

AC AC GND GND

AUX/OUT

ADDRESS

LCD DISPLAY

KEYPAD

CPU STATUS

Microprocessor status LED's

Digital Inputs Connection

The MCB receives digital inputs from the Analog Digital Input (ADI) board through the Digital Inputs connector via a plug-in ribbon cable. The ADI board conditions these inputs.

Analog Inputs Connection

The MCB receives conditioned analog inputs from the ADI board through the Analog Inputs connector via a plug-in ribbon cable. The ADI board conditions these inputs. After having been conditioned, all analog inputs enter the MCB through the Analog Inputs port as 0–5Vdc signals.

Digital Outputs Connection

After processing all input conditions, the MCB sends the appropriate output signals to output devices through the Digital Outputs port via a plug-in ribbon cable.

Power In Connector

The MCB receives 18Vac, center-tapped power from transformer T4 through the Power In connector. This power drives all logic and communications circuitry.

Power Fuses

Two identical 2-amp fuses are located to the right of the Power In connector. These fuses are in the MCB power supply circuit.

Microprocessor Status LEDs

The green, red, and amber LEDs on the MCB provide information about the operating status of the microprocessor. The amber LED also indicates the existence of alarm conditions.

Following is the normal start-up sequence that the three status LED’s should follow when power is applied to the MCB:

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1. The red (“Reset”) LED turns on and remains on for approximately 5 seconds. During this period

the MCB performs a self-test.

The red LED turns off and the green (“Running”) LED turns on. This indic ates that the

microprocessor has passed the self-test and is functioning properly.

The amber (“Active”) LED remains off continually if no alarm conditions exist in the network. If

alarm conditions exist, the amber LED will flash as shown in Table 5.

If the above sequence does not occur after power is applied to the controller, there is a problem with the MCB or its power supply.

Table 56 and Table 57 summarize the green, red, and amber status LED indications.

Table 56, Gree n and Red Status LED Indication

Green

LED State

Off Off No power to MCB Off On* On Off MCB operating normally

* For longer than 5 seconds.

Table 57, Amber Status LED Indication

Amber LED State Indication

On 1/2 second;

Off 1/2 second

Red

LED State

Self-test failure or power supply

Off Normal operation

Indication

problem

Alarm condition

Keypad/LCD Display Connection

The MCB receives input commands and operating parameters from the keypad and sends requested information to the display through the Keypad/LCD Display port via a plug-in r ibbon cable.

Hex Switches

The MCB includes two hex (hexadecimal) switches that are used to set the network address. The HI and LO hex switches are shown in Figure 32. A “hex switch setting” is defined as the HI

switch digit followed by the LO switch digit. For example, a hex switch setting of 2°F would have the HI switch set to “2” and the LO switch set to “F.”

Note: You can change the setting of a hex switch with a 3/32-inch tip slotted-blade screwdriver. If a hex switch setting is changed, power to the MCB must be cycled in order to enter the new setting into memory. This can be done by turning the panel’s power switch off and then back on.

Figure 32, Hex Switches

HI (left) hex switch LO (right) hex switch

* Hex switch setting 01 shown

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Communication Ports

The MCB has two communication ports: port A and port B. Each port has six terminals and is set up for both the RS-232C and RS-485 data transmission interface standards. The male and female connectors for these ports are manufactured by AMP. Therefore, they are referred to as “AMP plugs” or “AMP connectors” throughout this manual. Socket fuses located next to the ports protect the communications drivers from voltage in excess of ±12Vdc. Following are brief descriptions of each port’s function.

Port A: Port A is for communications with an IBM compatible PC using the RS-232C interface standard. The PC can be directly connected, over a limited distance, with a twisted, shielded pair cable, or it can be remotely connected via phone lines with a modem. Port A can also be used to connect a licensed building automation system to the MicroTech network via Open Protocol. The default communications rate is 9600 baud.

Port B: Port B is for MicroTech network communications using the RS-485 interface standard. A twisted, shielded pair cable should be connected to port B via terminals B+, B–, and GND on terminal block T11. The communications rate is 9600 baud.

Output Board

The Output Board (OB) accepts up to 16 digital outputs from the MCB. Each output has fused sockets and can be used to switch AC or DC power by selecting a particular relay output module. Screw terminals allow for field wiring connections to the output device. Each output has an onboard LED that illuminates when an output socket that contains a relay is activated by the MCB. Following are the Output Board’s power ratings:

•

120V ~ 50/60 Hz

•

250V ~ 50/60 Hz

Power

Above each edge card connector are field wiring terminals for 5Vdc (regulated) and 24Vac (ground referenced). These terminals can be used to power peripheral devices. The 5Vdc is also used to power the LEDs in the Output Board.

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Test Procedures

Status LED Diagnostics

The MCB status LED indications can aid in controller diagnostics. If the status LEDs do not operate normally there is a problem with the MCB. Following are troubleshooting procedures for the various symptoms.

Red LED Remains On

If the red LED remains on after the 5-second self-test period, it is likely that the MCB is defective. However, this can also occur in some instances if there is a power supply problem. Refer to “Troubleshooting Power Problems” below.

Red and Green LEDs Off

If the red and green LEDs do not turn on after power is applied to the controller, there is likely a defective component or a problem in the controller’s power distribution circuits. Refer to “Troubleshooting Power Problems” below.

Troubleshooting Power Problems

The MCB receives 18Vac, center-tapped power from transformer T4. It then distributes both 5Vdc and 13Vdc power to various MicroTech components. A problem that exists in any of these components can affect the MCB and thus the entire control system. Power problems can be caused by an external short, which can blow a fuse, or a defective component, which can either blow a fuse or create an excessive load on the power supply. An excessive load can lower the power supply voltages to unacceptable levels. Use the following procedure to isolate the problem. Note that this procedure may require two or three spare MCB fuses . Refer to the panel wiring diagram.

Verify that circuit breaker CB1 is closed.

Remove the MCB Power In connector and check for 9Vac between the terminals on the plug

corresponding to terminals 2 and 3 on the board. Then check for 9Vac between the terminals on the plug corresponding to terminals 1 and 3 on the board. (Readings of 9–12Vac are acceptable.) If 9Vac is present between both sets of terminals, go to step 3. If 9Vac is not present between both sets of terminals, check transformers T2 and T3 and all wiring between the 115Vac source and the Power In plug.

Remove power from the controller by opening circuit breaker CB1. Check the MCB power

supply input fuses (F1 and F2) with an ohmmeter. A good fuse will have negligible resistance through it (less tha n 2 ohms). If either or both fuses are blown, replace them. Go to step 4. If the fuses are intact, the MCB is defective.

Reconnect the Power In connector and disconnect all other connectors on the MCB. Cycle power

to the controller (close and then open CB1) and check the power fuses. If both fuses are intact, go to step 5. If either fuse blows, the MCB is defective.

Reconnect the keypad/display ribbon cable. Cycle power to the controller and check the power

fuses. If both fuses are intact, go to step 6. If either fuse blows check the keypad/display and the connecting ribbon cable for shorts. Either one may be defective.

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6. Reconnect the analog input ribbon cable. Cycle power to the controller and check the power

fuses. If both fuses are intact, go to step 7. If either fuse blows check the ADI board, the connecting ribbon cable, and the field wiring for shorts. Any of these may be defective. Try repeating this step after removing or swapping the ADI board.

Reconnect the digital input ribbon cable. Cycle power to the controller and check the power

fuses. If both fuses are intact, go to step 8. If either fuse blows check the ADI board, the connecting ribbon cable, and the field wiring for shorts. Any of these may be defective. Try repeating this step after removing or swapping the ADI board.

Reconnect the digital output ribbon cable to the MCB. Cycle power to the controller and check

the power fuses. If both fuses are intact, go to step 9. If either fuse blows, check Output Board and the connecting ribbon cable. Either of these may be defective.

If there are any AOX-4 boards, reconnect the expansion bus ribbon cable to the MCB; otherwise,

go to step 10. Cycle power to the controller and check the power fuses. If both fuses are intact, go to step 10. If either fuse blows, check the analog output expansion modules (if any), the connecting ribbon cables, and the field wiring for shorts. Any of these may be defective.

10.

With circuit breaker CB1 open, measure the resistance between field terminals “DC-GRD” and

“5Vdc.” It should be greater than 20 ohms. If the resistance is greater than 20 ohms, go to step 11 if the controller is equipped with at least one AOX-4 board or a modem. Otherwise, the problem is indeterminate. Obtain factory service. If the resistance is less than 20 ohms, it is likely that the keypad/display, the Output Board o r an external (field supplied) load is excessively loading the MCB’s 5Vdc power supply. Isolate the problem by taking resistance measurements on each of these devices with the wiring disconnected. The resistance across the power input terminals on the keypad/display (G and 5V) should be close to infinite. The resistance across the power input terminals on the Output Board (+ and –) should not be less than 3000 ohms. If the component's resistance is proper, check the resistance of the field supplied loads (if any) and check the wiring and connections througho ut the 5Vdc power supply circuit.

11.

Disconnect the connector plugs from the modem and the power plug from all AOX-4 boards (as

applicable). With circuit breaker CB1 open, measure the resistance between field terminals “DCGRD” and “13Vdc.” It should be infinite. If the resistance is infinite, go to step 12. If the resistance is not infinite, a short exists somewhere in the 13Vdc power supply wiring.

12.

Reconnect the Aux/Out connector plug to the MCB. If there’s a modem, reconnect its AMP plug

to port A. With circuit breaker CB1 open, measure the resistance between field terminals “DCGRD” and “13Vdc.” It should steadily rise to a value greater than 5000 ohms (within approximately 30 seconds). If the resistance rises above 5000 ohms, go to step 13. If the resistance does not rise above 5000 ohms, the MCB is defective.

13.

One at a time, reconnect the modem and each AOX-4 board (as applicable). Each time a

component is reconnected, measure the resistance between field terminals “DC-GRD” and “13Vdc.” It should steadily rise to a value greater than 5000 ohms. If the resistance rises above 5000 ohms, repeat this step until the modem and all AOX-4 boards (as applicable) have been checked out. If the problem persists, it is indeterminate. Obtain factory service. If the resistance does not rise above 5000 ohms, the modem or the AOX-4 board just connected is defective. (With the power plug disconnected, the resistance across an AOX-4 board’s “DC” and “G” terminals should not be less than 3 million ohms.)

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Figure 33, MCB Power Supply Terminals

POWER FUSES

[BUSSMAN GDC-T2A]

POWER IN

3 2

[18-24 VCT]

AC AC GND GND

9 8 7 6 5 4 3 2 1

AUX/OUT

Fuse F1 Fuse F2

Troubleshooting the Keypad/Display Interface

The Keypad/Display Interface is connected to the MCB via a ribbon cable and discrete wiring for the backlight. The MCB provides operating voltages, control signal outputs for the display, and input conditioning for the keypad inputs.

Display is Hard to Read

The clarity of the LCD display can be affected by ambient temperature. Typically, less contrast will result with cooler temperatures. If the display is difficult to read, adjust the contrast trim pot, which is located on the back of the keypad/display assembly.

Back Light Not Lit

The Keypad/Display Interfaces supplied with the controller is equipped with a backlight. If the light does not come on, check for 5Vdc at terminal 9 on the IDC connector on the KDI and for 5Vdc on the CSC field wiring terminal strip.

Check for 5Vdc on the IDC connector on the To check for the 5Vdc on the IDC connector, pull back the plug about one-eighth of an inch and place the test leads against the exposed pins. If there is no voltage, check the wiring and the connections between the controller’s 5Vdc field wiring terminal strip and the KDI. If the wiring is intact the MCB is probably defective.

Display is Blank or Garbled

If the MCB appears to be functioning properly and the display is completely blank or garbled, perform the following procedure:

Try cycling power to the controller by opening and then closing circuit breaker CB1 (see note

below).

Try adjusting the contrast trim pot, which is located on the back of the keypad/display assembly.

If the contrast trim pot has no effect, it is likely that either the keypad/display or its ribbon cable is defective.

After removing power from the controller, check the ribbon cable and connections between the

keypad/display and the MCB. Look for bent pins. Restore power after reconnecting the ribbon cable.

Try swapping a known good ribbon cable and keypad/display. Swap these components separately

to isolate the problem. Remove power from the controller before disconnecting the suspect component, and restore power after connecting the replacement component. If the problem persists, it is likely that the MCB is defective.

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T roubleshooting An alog Inputs

An analog input, such as a temperature sensor, is connected to the ADI board. The ADI board then conditions the analog input. The conditioned input is transferred to the MCB via a ribbon cable.

Analog Input not Read by the MCB

If the MCB appears to be functioning properly and the analog input is not being read by the MCB, perform the following procedure:

Try cycling power to the controller by opening and then closing circuit breaker CB1.

Check the ribbon cable, power wiring connector, and the field wiring connections from the

analog input device. Look for bent pins, cable on backwards, or incorrect-wiring. Restore power after reconnecting all cables and wires.

If the problem persists, try swapping a known good ribbon cable or analog input device. Swap

these components separately to isolate the problem. Remove power from the controller before disconnecting the suspect component, and restore power after connecting the replacement component. If the problem persists, it is likely that the MCB is defective.

Troubleshooting Digital Inputs

A digital input device is connected to the ADI board. 24Vac, supplied by transformer T2, is sent to the digital input device via a supply wire. When a contact in the digital device makes, a return signal is sent back to the ADI board. The ADI board then conditions the signal. The conditioned digital input is then sent to the MCB via a ribbon cable.

Digital Input not Read by the MCB

If the MCB appears to be functioning properly and the digital input is not being read by the MCB, perform the following procedure:

Try cycling power to the controller by opening and then closing circuit breaker CB1.

Check the ribbon cable, power wiring connector, and the field wiring connections from the digital

input device. Look for bent pins, cable on backwards, or incorrect-wiring. Restore power after reconnecting all cables and wires.

If the problem persists, try swapping a known good ribbon cable or a digital input device. Swap

Troubleshooting Output Boards

Each output on the Output Board consists of a solid-state relay, an LED, 5-amp fuse, and an MOV (metal oxide varistor).

Normally, when the MCB commands an output to energize, the solid-state relay contacts will close and the LED will glow. The contacts of each solid-state relay are in series with a 5-amp fuse. These fuses resemble small resistors and are located on the board adjacent to the relays they serve (see Figure 34). The fuses are pressed into place. They can be removed with needle nose pliers. The MOV, which is located on the underside of the output board, protects the solid-state relay from high transient voltages. MOVs are part of the output board and cannot be replaced.

Following are troubleshooting procedures for various symptoms of output board problems:

Note: It should be possible to determine whether a solid-state relay is defective by using these procedures.

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Figure 34, Output Board Relay Socket

*250V ~ 50/60 Hz *120V ~ 50/60 Hz

LED

Fuse

Test Resistor 330-680 Ohm

WARNING

Electric shock hazard. Can caus e severe injury or death. Even when power to the panel is off, solid-state relay socket terminals 1 and 2 on the output board could be connected to high voltage. Avoid them.

One LED Out

If one of the Output Board LEDs fails to illuminate when the MCB is commanding the associated output to energize, perform the following procedure:

Remove power from the controller by opening CB1. Swap the suspect relay with a known good

relay. Try to choose a relay that will not affect unit operation. Restore power by closing CB1. If the LED does not light, go to step 2. If the LED lights, the suspect relay is defective.

Remove power from the controller. Check the ribbon cable and connections between the OB and

the MCB. Look for bent pins. If the cable and connections are intact, go to step 3.

Remove the relay from the suspect socket. Install a 330-680 ohm resistor between terminals 3

and 5 as shown in Figure 34. Restore power by placing CB1 to the ON position. The LED should light regardless of the controller’s command. If the output LED illuminates, it is likely that the MCB is defective. If the output LED does not illuminate, the output board is defective.

All LEDs Out

If the MCB is commanding at least two outputs to energize and none of the Output Board LEDs are lit, perform the following procedure:

Verify that 5Vdc is present at the Output Board’s power terminals.

If 5Vdc is not present, go to step 2. If 5Vdc is present, check the ribbon cable and connections between the output board and MCB. Look for bent pins. If the cable and connections are intact, the Output Board or the MCB is defective.

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2. Remove power from the controller by placing CB1 to the OFF position. Disconnect at least one

wire from the power input terminals of the Output Board. The resistance should not be less than

3000 ohms.

If the resistance is greater than the acceptable value, go to step 3.

If the resistance is less than the acceptable value, the Output Board is defective.

Check the discrete wiring and connections between the Output board and the Controller.

Aux/Out terminal strip and the field wiring terminal strip.

Note: The MCB Aux/Out connector plug terminals displace wire insulation to make contact with the conductor. If a faulty Aux/Out connection is suspected, try pressing down on the wire in the terminals with a small screwdriver.

LED Lit, Output not Energized

If the LED of a suspect output is lit but the load connected to it is not energized, and everything is intact between the MCB and the coil side of the relay, perform the following procedure to isolate the problem:

Verify that 24 or 120Vac power is present at the suspect output’s screw terminal on the Output

Board.

Remove power from the controller by opening CB1. Pull the 5-amp fuse on the contact side of

the relay and check it for continuity with an ohmmeter.

If the fuse is not bad, reinstall it and go to step 3.

If the fuse is bad, replace it and inspect the load and associated wiring before restoring power.

Note that a fuse from an unused output can be substituted for the bad fuse.

Remove power from the controller by opening CB1. Swap the suspect relay with a known good

relay. Try to choose a relay that will not affect unit operation. Restore power by closing CB1.

If the output load energizes, the suspect relay is bad. Replace the relay.

If the output load does not energize (when LED is lit again), check the load circuit wiring and

components.

Output Energized, LED not Lit

If the LED of a suspect output is not lit, but the load connected to it is energized, either the SolidState relay or the MOV is bad. The Solid-State relay contacts and the MOV, which are in parallel, can both fail closed. Perform the following procedure to isolate the problem:

Remove power from the controller by opening CB1. Pull the Solid-State relay from the suspect

output’s socket.

Restore power by closing CB1.

If the output load remains energized when there is no relay in the socket, the output’s MOV has

failed and the Output Board must be replaced.

If the output load de-energizes, the relay that was pulled is defective.

Contact Chatter

Contact chatter is very rapid opening and clos ing of contacts. It is usually caused by low voltage at the electromechanical relay or contactor coil. If contact chatter is occurring on a relay or contactor connected to one of the Output Board Solid-State relays, it is also possible that a faulty connection exists on the power supply terminals of the Aux/Out plug connector on the MCB. In very rare instances, contact chatter can be caused by a faulty Solid-State relay. Perform the following procedure to isolate the problem.

Verify that the voltage at the load’s power supply and at the Solid-State relay contacts is

adequate.

Remove power from the controller by opening CB1. Swap the suspect relay with a known good

relay. Try to choose a relay that will not affect unit operation. Restore power by closing CB1.

If the chatter does not stop, go to step 3.

If the chatter stops, the suspect relay is defective. Replace the relay.

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3. Remove power from the controller by opening CB1. Try to improve the connections in the

Aux/Out plug insulation displacement terminals by pressing down on the wires with a small screwdriver.

Check all other wiring and connectors for bent pins or mis-wires.

If the chatter does not stop, the electromechanical relay or contactor is probably defective.

Troubleshooting Solid-State Relays

As shown on the unit wiring diagrams, the Solid-State relays on the Output Boards all have normally open “contacts.” Actually, these contacts do not exist as they do in an electromechanical relay. Instead of using contacts to switch the load, the Solid-State relay changes its resistance from low (closed), when it is energized, to high (open), when it is de-energized. (This high resistance is approximately 100K ohms.) Because the output circuit through the Solid-State rela y remains continuous regardless of whether the relay is energized, troubleshooting a Solid-State relay with a voltmeter can be tricky.

In a typical circuit, a power source is connected across a single relay output and a load. In this circuit, a Solid-State relay will behave like an electromechanical relay. If the relay is energized, the relay output will be hot. If the relay is de-energized, voltage cannot be measured at the relay output.

The circuit shown in Figure 35 is similar to a typical circuit; the difference is that there is an open set of contacts, or a disconnection between the relay output and the load. In this circuit, a Solid-State relay will not behave like an electromechanical relay. if the Solid-State relay is energized, the relay output will be hot (as expected). However, if the Solid-State relay is de-energized, the relay output will still appear to be hot. This is because the relay output and the voltmeter form a continuous circuit in which the relay’s resistance, though high, is insigni ficant compared to the voltmeter’s resistance.

This means that nearly all the voltage is dropped across the voltmeter. Therefore, the voltmeter indicates that voltage is present. If a low wattage light bulb of the appropriate voltage is used instead of a voltmeter, the bulb’s low resistance will load the circuit enough to e liminate the false voltage indication. In this situation, an incandescent test lamp is a better tool than a voltmeter.

Figure 35, Testing a Typical Relay Circuit Figure 36, Testing a Relay Circuit with a Disconnection

115 VAC

Output Board

DO 13

28 27

M10

Neutral

115V

115 VAC

Output Board

DO 13

28 27

M10

Neutral

96 IOMM ACZ/AGZ-2

Page 97

Unit Maintenance

General

On initial start-up and periodically during operation, it will be necessary to perform certain routine service checks. Among these are checking the liquid line sightglasses, taking condensing and suction pressure readings, and checking to see that the unit has normal superheat and subcooling readings. A recommended maintenance schedule is located at the end of this section.

Compressor Maintenance

The scroll compressors are fully hermetic and require no maintenance.

Lubrication

No routine lubrication is required on AGZ and ACZ units. The fan motor bearings are permanently lubricated and no further lubrication is required. Excessive fan motor bearing noise is an indication of a potential bearing failure.

Compressor oil should be standard refrigeration mineral oil such as Suniso 3GS.

Electrical Terminals

WARNING

Electric shock hazard. Turn off all power before continuing with following service.

Check terminals for tightness on a sched uled basis.

Condensers

The condensers are air-cooled and constructed of 3/8" (9.5mm) O.D. internally finned copper tubes bonded in a staggered pattern into louvered aluminum fins. No maintenance is ordinarily required except the routine removal of dirt and debris from the outside surface of the fins. McQuay recommends the use of foaming coil cleaners available at most air conditioning supply outlets. Use caution when applying such cleaners as they may contain potentially harmful chemicals. Care should be taken not t o damage the fins during cleaning.

If the service technician has reason to believe that the refrigerant circuit contains noncondensables, purging may be required strictly following Clean Air Act regulations gove rning refrigerant discharge to the atmosphere. The purge Schrader valve is located on the vertical coil header on both sides of the unit at the control box end of the coil. Access panels are located at the end of the condenser coil directly behind the control panel. Purge with the unit off, after shutdown of 15 minutes or longer, to allow air to collect at the top of the coil. Restart and run the unit for a brief period. If necessary, shut unit off and repeat the procedure. Follow accepted environmentally sound practices when removing refrigerant from the unit.

Refrigerant Sightglass

The refrigerant sightglasses should be observed periodically. (A weekly observation should be adequate.) A clear glass of liquid indicates that there is adequate refrigerant charge in the system to insure prop er feed through the expansion valve. Bubbling refrigerant in the sightglass, during stable run conditions, indicates that the system may be short of refrigerant charge. Refrigerant gas flashing in the sightglass could also indicate an excessive pressure drop in the liquid line, possibly due to a clogged filter-drier or a restriction elsewhere in the liquid line. See Table 58 for maximum allowable pressure drops). If subcooling is low add charge to clear the sightglass. If subcooling is normal (10°- 15°F) and flashing is visible in the sightglass check the pressure drop across the filter-drier.

IOMM ACZ/AGZ-2 97

Page 98

Subcooling should be checked at full load with 70°F (21.1°C) outdoor air temperature and all fans running.

An element inside the sightglass indicates the moisture condition corresponding to a given element color. If the sightglass does not indicate a dry condition after about 12 hours of operation, the circuit should be pumped down and the filter-drier changed.

Preventative Maintenance Schedule

PREVENTATIVE MAINTENANCE SCHEDULE

OPERATION WEEKLY

General Complete unit log and review (Note 3) X Visually inspect unit for loose or damaged components X Inspect thermal insulation for integrity X Clean and paint as required X

Electrical Check terminals for tightness, tighten as necessary X Clean control panel interior X Visually inspect components for signs of overheating X Verify compressor heater operation X Test and calibrate all safety an operating controls X

Megger compressor motor every five years *

MONTHLY

(Note 1)

ANNUAL

(Note 2)

Refrigeration Leak test X Check sight glasses for clear flow X Check filter-drier pressure drop (see manual for spec) X

Condenser (air-cooled) Clean condenser coils (Note 4) X Check fan blades for tightness on shaft (Note 5) X Check fans for loose rivets and cracks X Check coil fins for damage X

Notes:

1. Monthly operations include all weekly operations.

2. Annual (or spring start-up) operatio ns includes all weekly and monthly operations.

3. Log readings may be taken daily for a higher level of unit observation.

4. Coil cleaning may be required more frequently in areas with a high level of airborne particles.

Be sure fan motors are electrically locked out.

* Never Megger motors while they are in a vacuum.

98 IOMM ACZ/AGZ-2

Page 99

Service

CAUTION

1. Service on this equipment is to be performed by qualified refrigeration personnel familiar

with equipment operation, maintenance, correct servicing procedures, and the safety

hazards inherent in this work. Causes for repeated tripping of safety controls must be

investigated and corrected.

2. Disconnect all power before doing any service inside the unit.

3. Anyone servicing this equipment shall comply with the requirements set forth by the EPA

in regards to refrigerant reclamation and venting.

Filter-Driers

A replacement of the filter-drier is recommended any time excessive pressure drop is read across the filter-drier and/or when bubbles occur in the sightglass with normal subcooling. The maximum recommended pressure drops across the filter-drier are as follows:

Table 58, Filter-Drier Pressure Drop

PERCENT CIRCUIT

LOADING (%)

100% 10 (69)

75% 8 (55.2) 50% 5 (34.5) 25% 4 (27.6)

MAXIMUM RECOMMENDED PRESSURE

DROP ACROSS FILTER DRIER PSIG (KPA)

The filter-drier should also be changed if the moisture indicating liquid line sightglass indicates excess moisture in the system.

During the first few months of operation the filter-drier replacement may be necessary if the pressure drop across the filter-drier exceeds the values listed in the paragraph above. Any residual particles from the condenser tubing, compressor and miscellaneous components are swept by the refrigerant into the liquid line and are caught by the filter-drier.

Liquid Line Solenoid Valve

The liquid line solenoid valves that shut off refrigerant flow in the event of a power failure does not normally require any maintenance. The solenoids may, however, require replacement of the solenoid coil or of the entire valve assembly.

The solenoid coil can be checked to see that the stem is magnetized when energized by touching a screwdriver to the top of the stem. If there is no magnetization either the coil is bad or there is no power to the coil.

The solenoid coil may be removed from the valve body without opening the refrigerant piping after pumpdown. For personal safety shut off and lock out the unit power.

The coil can then be removed from the valve body by simply removing a nut or snap-ring located at the top of the coil. The coil can then be slipped off its mounting stud for replacement.

To replace the entire solenoid valve follow the steps involved when changing a filter-drier.

IOMM ACZ/AGZ-2 99

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Evaporator

The remote evaporator on AGZ-AM units and CDE evaporators are the direct expansion, shell-andtube type with refrigerant flowing through the tubes and water flowing through the shell over the tubes. The tubes are internally finned to provide extended surface as well as turbulent flow of refrigeration through the tubes. Normally no service wor k is required on the evaporator.

Refrigerant Charging

AGZ-AM and ACZ units are shipped with a factory holding charge of refrigerant and it is necessary to charge them at the job site after leak testing and evacuating the field installed refrigerant lines. Follow these recommendations when field charging. Refer to the unit operating charge found in the “Charging Section”.

Final unit charging can be done at any steady load condition (preferably at 75 to 100% load) and at any outdoor temperature (preferably higher than 70°F (21.1°C). Unit must be allowed to run 5 minutes or longer so that the condenser fan staging is stabilized at normal operating discharge pressure. For best results charge with two or more condenser fans operating on each refrigerant circuit.

The AGZ and ACZ units have a condenser coil design with approximately 15% of the coil tubes located in a subcooler section of the coil to achieve liquid cooling to within 5°F (3°C) of the outdoor air temperature when all condenser fans are operating. This is equal to about 15 degrees F-20 degrees F (8.3 degrees C-11.1 degrees C) subcooling below the saturated condensing temperature when the pressure is read at the liquid valve between the condenser coil and the liquid line filter drier. Once the subcooler is filled, extra charge will not lower the liquid temperature and does not help system capacity or efficiency. However, a little extra (10-15 lbs.) will make the system less sensitive.

Note: As the unit changes load or fans cycle on and off, the subcooling will vary but should recover

within several minutes and should never be below 6°F (3.3°C) subcooling at any steady state condition. Subcooling will vary somewhat with evaporator leaving water temperature and suction superheat. As the evaporator superheat decreases the subcooling will drop slightly.

One of the following three scenarios w ill be experienced with an undercharged unit:

1. If the unit is slightly undercharged the unit will show bubbles in the sightglass. Recharge the unit as described in the charging procedure below.

2. If the unit is moderately undercharged it will normally trip on freeze protection. Recharge the unit as described in the charging procedure below. However, freezestat trips can also be an indication of low flow or poor heat transfer due to tube fouling. Anti-freeze solutions may also cause freezestat trips.

3. If the unit is severely undercharged the unit will trip due to lack of liquid flow to the expansion valve. In this case either remove the remaining charge by means of a proper reclamation system and recharge the unit with the proper amount of refrigerant as stamped on the unit nameplate, or add refrige rant through the suction valve on the compressor slowly. Feed liquid into the suction valve when the compressor is running. If the unit is severely undercharged the unit may nuisance trip during this charging procedure. If this happens close off the refrigerant from the tank and restart the unit. Once the unit has enough charge so that it does not trip out, continue with step 2 of the charging procedure below.

Procedure to charge a moderately undercharged AGZ unit:

1. If a unit is low on refrigerant you must first determine the cause before attempting to recharge the unit. Locate and repair any refrigerant leak. Evidence of oil is a good indicator of leakage, however oil may not be visible at all leaks. Liquid leak detector fluids work well to show bubbles at medium size leaks but electronic leak detectors may be needed to locate small leaks.

100 IOMM ACZ/AGZ-2

McQuay ACZ 045A Installation Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Nomenclature

Inspection

Installation

Handling

Location

Unit Placement

Clearances

Sound Isolation

Service A ccess

Vibration Isolators

Water Piping

Flow Switch

Glycol Solutions

Evaporator Flow and Pressure Drop

Refrigerant Piping

Introduction

Suction Lines

Sizing A Double Riser

Underground Refrigerant Lines

Long Vertical Riser Installation

Liquid Lines

Liquid Lines from Condensers to Receivers

Liquid Line Components

Physical Data

AGZ-AM

ACZ Condensing Units

Electrical Data

Field Wiring

Power Wiring

Control Wiring

Electrical Notes

Notes for “Electrical Data Single Point” Power:

Voltage Limitations:

Notes for “Compressor and Condenser Fan Amp Draw”:

Notes for “Field Wiring Data”

Electrical Legend

Wiring Diagrams

Dimensional Data

Startup

Pre Start-up

Start-Up

Shutdown

Temporary

Extended

Water Piping Checkout

Refrigerant Piping Checkout

Refrigerant Charging

Electrical Check Out

Operation

Sequence of Operation

Starting

Standard Controller Setpoints (optional Zone Terminal required to change values)

Hot Gas Bypass (Optional)

Filter Driers

System A djustment

Liquid Sightglass and Moisture Indicator

Thermostatic Expansion Valve

Crankcase Heaters

Water Cooler

Global UNT Controller, AGZ-AM

General Description

Optional Sensors

Sensors and Transducers Sensors and transducers are mounted and connected to the Global UNT controller with sensor cable.

Control Wiring Low voltage control wiring is installed, labeled and tested by the factory before shipment.

External Voltage Inputs The signal for remote reset option (2 to 10Vdc) or demand limit (0 to 10Vdc) is provided by the

Interlock Wiring All interlock wiring to field devices (such as a flow switch or time clock) is provided by the installing

Unit Set Points and Calibration The control software is installed and tested by the factory before shipping. No periodic calibration of

Optional Sensors Optional sensor kits, available from the factory, can be installed in the field. The optional sensor kits

Field Wiring Interconnecting wiring for the control panel may consist of the following:

Analog input signals

Digital input signals

Power Wiring The installing contractor provides the unit voltage power source, disconnect, fuses and necessary

Power Supplies There are several internal power supplies used by the controller and related circuitry. The regulated

Remote Stop/Start If remote stop/start control is selected, remove the jumper between terminals #140 and #141 on TB-7

Chilled Water Flow Sw itch The chilled water flow switch is connected to field wiring terminals #142 and #143 on TB-7. When