Aaon CL-060 Installation Manual

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Page 1

CL SERIES

Condensing Units

Installation, Operation

& Maintenance

Page 2

Table of Contents

SECTION

Page

GENERAL DESCRIPTION…………………………………………………………………………………………………

Unpacking…………………………………………………………………………………………………………..

05 05

OWNER’S INFORMATION………………………………………………………………………......................................

Wiring Diagrams……………………………………………………………………................................................

General Maintenance………………………………………………………………………………………………..

05 05 06

INSTALLATION…………………………………………………………………………….……………………………....

Lifting and Handling……………………………………….………………………………………………………. Condenser Placement………………………………………………………………………………………………. Compressor Compartment Exhaust Fan……………………………………………………………………………. Mounting Isolation………………………………………………………………………………………………….

Access Doors………………………………………………………………………………………………………. Low Ambient Operation……………………………………………………………………………………………. LAC Valve………………………………………………………………………………………………………….. OROA Valve………………………………………………………………………………………………………... ORI/ORD Valves…………………………………………………………………………………………………… Condenser Flooding………………………………………………………………………………………………… Electrical……………………………………………………………………………………………………………. Refrigerant Piping Connection………………………………………………………………………………………

Evaporative-Cooled Condenser Field Piping Connections………………………………………………………….

06 06 06 06 06 06 07 07 08 08 09 10 10 10

STARTUP……………………………………………………………………………………………………………………

Pre Startup………………………………………………………………………………………………………….. Startup……………………………………………………………………………………………………………… Axial Flow Fans…………………………………………………………………………………………………….

12 12 12 12

SERVICING & MAINTENANCE……………………………………………………………………………………….......

General ……………………………………………………………………………………………………………... Compressors………………………………………………………………………………………………………... Refrigerant Filter Driers…………………………………………………………………………………………….. Evaporator/Heat Exchanger…………………………………………………………………………….…………... Charging Refrigerant ……………………………………………………………………………………………….. Checking Liquid Sub-Cooling……………………………………………………………………………………… Checking Evaporator Superheat……………………………………………………………………………………. Adjusting Sub-cooling and Superheat Temperatures………………………………………………………………. Special Charging Instructions………………………………………………………………………………………. Lubrication……………………………………………………………….……………………………………...….. Service Information…………………………………………………….……………………………………………

14 14 14 14 15 15 15 15 16 16 16 17

EVAPORATIVE-COOLED CONDENSER SECTION……………………………………………………………………... General Information………………………………………………………………………………………………… Pre Start-Up………………………………………………………………………………………………………… Maintenance Recommendations……………………………………………………………………………………. Water Quality……………………………………………………………………………………………………….. AIR-COOLED CONDENSER SECTION…………………………………………………………………………………...

REFRIGERANT PIPING FOR CL SERIES…………………………..………………………………….………..…….......

Equivalent Line Length…………………………………………………………………………………….………. Liquid Line Sizing…………………………………………………………………...……………………………... Suction Line Sizing……………………………………………………………………………………..…………... Hot Gas Bypass Line Sizing..………………………………………………………………….………….………... Predetermined Line Sizes…………………………………………………………………………………………...

TABLE RP-1 Predetermined Line sizes for Dual Circuit CL units with R-410A……………………….…………. TABLE RP-2 Predetermined Line sizes for Dual Circuit CL units with R-22………………………….…………..

TABLE RP-3 Predetermined Line sizes for Single Circuit CL units with R-410A………………….……….. TABLE RP-4 Predetermined Line sizes for Single Circuit CL units with R-22 ……………………….…………..

FIGURE RP-1 Riser height versus total equivalent line length Dual Circuit CL Units with R-410A .….………… FIGURE RP-2 Riser height versus total equivalent line length Dual Circuit CL Units with R-22….. ….………… FIGURE RP-3 Riser height versus total equivalent line length Single Circuit CL Units with R-410A ……………

17 17 19 21 22 23 23 23 23 24 25 26 28 29 30 30 31 31 32

Page 3

FIGURE RP-4 Riser height versus total equivalent line length Single Circuit CL Units with R-22… …………… Hot Gas Bypass Line Routing Diagrams……………………………………………………………………………

32 33

CL SERIES STARTUP FORM………………………………………………………………………………………………

Literature Change History……………………………………………………………………………………………………..

It is the intent of AAON, Inc. to provide accurate and current specification information. However, in the interest of product improvement, AAON, Inc. reserves the right to change pricing, specifications, and/or

design of its products without notice, obligation or liability

AAON & AAONAIRE are registered trademarks of AAON, Inc., Tulsa, OK.

R10110 · Rev. B · 150727

Page 4

AAON® CL Series Features and Options Introduction

Energy Efficiency

 Air-Cooled or Energy Saving Evaporative-

Cooled Condenser

 Direct Expansion Systems  Tandem Scroll Compressors  VFD Controlled Condenser Fans

Humidity Control

 Modulating Hot Gas Reheat

Safety

 Phase and Brownout Protection  Automatic Low Pressure and Manual Reset

High Pressure Safety Cut-outs

 Schrader Valves  Internal Overload Protection on Tandem

Scroll Compressors

 Aluminum Tread Plate Floor Covering  Compressor Isolation Valves

Installation and Maintenance

 Access Doors with Hinges, Lockable Handles

and Rain Gutters

 Walk-In Weatherproof Compressor

Compartment

 Run Test Report and Installation Manuals

Included in Controls Compartment

 Color Coded Wiring and Wiring Diagrams  Double Pane Viewing Windows  Compressors are Deck Mounted with Rubber

Isolation

 Three-Chemical Water Treatment System for

Evaporative-Cooled Condenser

 Aluminum Tread Plate Floor  Foam Insulated Double Wall Construction

 Replaceable Core Filter Driers

System Integration

 Single Point Power Connection  Air-Cooled or Evaporative Condensers

Environmentally Friendly

 R-410A Refrigerant

Extended Life

 2,500 Hour Salt Spray Tested Exterior

Corrosion Paint

 Optional 5 Year Non-Prorated Compressor

Warranty

 Sloped Condenser Coils with Outer Protection

Page 5

GENERAL DESCRIPTION

All AAON 'CL Series' condensers are factory assembled, wired, and charged with 15 lbs. of refrigerant per system. Models are available for air-cooled and evaporative-cooled applications.

Unpacking:

When received, the unit should be checked for damage that might have occurred in transit. If damage is found it should be noted on the

carrier’s Freight Bill. A request for inspection by carrier’s agent should be made in writing at once.

Also, check the unit nameplate to ensure the correct model size and voltage have been received to match the job requirements.

the compressor. Since the compressor is designed to pump refrigerant gas, damage may occur when power is restored.

• Before unit operation, the main power switch

must be turned on for at least twenty four hours for units with compressor crankcase heaters. This will give the crankcase heater time to clear any liquid accumulation out of the compressor before it is required to run.

• Always control the system from the thermostat,

or control panel, never at the main power supply (except for emergency or for complete shutdown of the system).

• Improper installation, adjustment, alteration,

service, or maintenance can cause property damage, personal injury or loss of life. Installation and service must be performed by a qualified installer, service agency or if gas fired units, the gas supplier. Refer to installation instructions provided with the unit and this manual.

• The compressors must be on a minimum of 4 minutes and off for a minimum of 5 minutes. The cycle rate must be no more than 8 starts per hour.

OWNER'S INFORMATION

Warning:

• Failure to observe the following instructions will result in premature failure of your system, and possible voiding of the warranty.

• Never cut off the main power supply to the unit, except for complete shutdown. When power is cut off from the unit, any compressors using crankcase heaters cannot prevent refrigerant migration. This means the compressor will cool down, and liquid refrigerant may accumulate in

The compressor life will be seriously shortened by reduced lubrication, and the pumping of excessive amounts of liquid oil and refrigerant.

Wiring Diagrams:

• A complete set of unit specific wiring diagrams

in both ladder and point-to-point form are laminated in plastic and located inside the control compartment door.

Page 6

Location

Unit Size

045-135

134-230

Front - Vestibule Door Side

100"

142"

Back - Opposite of Front

100"

142"

Left Side - Condenser End

100"

Right Side - Opposite of Left

100"

Top

UNOBSTRUCTED

OWNER'S INFORMATION cont.

General Maintenance:

When the initial startup is made and on a periodic schedule during operation, it is necessary to perform routine service checks on the performance of the condenser. This includes reading and recording suction pressures and checking for normal sub-cooling and superheat. See the evaporative-cooled condenser and aircooled condenser sections in this manual for specific details.

INSTALLATION

Lifting and Handling:

• If cables or chains are used to hoist the unit

they must be the same length and care should be taken to prevent damage to the cabinet.

• Before lifting unit, be sure that all shipping

material has been removed from unit. Secure hooks and cables at all lifting points/lugs provided on the unit.

• Do not push, pull or lift the unit from anything other than its base.

UNIT MUST BE RIGGED AT ALL

MARKED LIFTING POINTS (Typical)

Condenser Placement:

• The AAON condenser is designed for outdoor applications and mounting at ground level or on a rooftop. It must be placed on a level and solid foundation that has been prepared to support its weight. When installed at ground level, a onepiece concrete slab should be used with footings that extend below the frost line.

• With ground level installation, care must be taken to protect the coil fins from damage due to vandalism or other causes.

• The placement relative to the building air

intakes and other structures must be carefully selected. Be sure to observe the dimensions that are on the rating plate of the condenser for operational and service clearances, which will appear as follows:

Service Clearances

• Condenser coils and fans must be free of any

obstructions in order to start and operate properly with a correct amount of airflow.

• For proper unit operation, the immediate area

around condenser must remain free of debris that may be drawn in and obstruct airflow in the condensing section.

• Consideration must be given to obstruction

caused by snow accumulation when placing the unit.

Compressor Compartment Exhaust Fan:

Prior to unit operation the compressor compartment exhaust fan shipping support MUST BE removed from the exterior of the unit. The exhaust fan also requires the installation of the exterior rain hood provided with the unit.

Mounting Isolation:

• For roof mounted applications or anytime

vibration transmission is a factor, vibration isolators may be used.

Access Doors:

• A lockable access door is provided to the

compressor and electrical compartment.

• A light switch is on the wall of the compressor

control compartment.

Page 7

INSTALLATION cont.

Low Ambient Operation:

• The AAON low ambient (condenser floodback) system is used to operate a refrigerant system below 25°F outside air temperature. As the ambient temperature drops, the condenser becomes more effective therefore lowering the head pressure. When the head pressure gets too low, there will be insufficient pressure to operate the expansion valve properly. During low ambient temperatures, it is difficult to start a system because the refrigerant will migrate to the cold part of the system (condenser) and make it difficult for refrigerant to flow.

• The AAON low ambient system maintains normal head pressure during periods of low ambient by restricting liquid flow from the condenser to the receiver, and at the same time bypassing hot gas around the condenser to the inlet of the receiver. This backs liquid refrigerant up into the condenser reducing its

capacity that in turn increases the condensing pressure. At the same time the bypassed hot gas raises liquid pressure in the receiver, allowing the system to operate properly.

• There are different types of low ambient control used. The following describe the different systems. Inspect the unit to determine the system used.

LAC Valve:

The LAC valve is a non-adjustable three way valve that modulates to maintain receiver pressure. As the receiver pressure drops below the valve setting (180 psig for R-22 and 295 psig for R-410A), the valve modulates to bypass discharge gas around the condenser. The discharge gas warms the liquid in the receiver and raises the pressure to the valve setting. The following schematic shows an example system using the LAC valve.

Piping Schematic of Example system using the LAC valve.

Page 8

INSTALLATION cont.

OROA Valve:

This system uses a nonadjustable head pressure control valve that performs the function of limiting the flow of liquid refrigerant from the

condenser and at the same time regulates the flow of the hot gas around the condenser to the receiver. The valve setpoint is 180 psig. This valve is called an OROA valve (Open on Rise of Outlet pressure). The following schematic shows an example system using the OROA valve.

Piping Schematic of Example system using the OROA valve.

ORI/ORD Valves:

This system uses a two-valve arrangement. The head pressure control valve is an inlet pressure regulating valve and responds to changes in condensing pressure. This valve is located in the discharge of the condenser and is called an ORI valve (Open on Rise of Inlet pressure). As the ambient temperature drops, the condenser capacity increases and the condensing pressure falls, causing the ORI to modulate toward the closed position. The condenser bypass valve is a pressure differential valve that responds to changes in the pressure differential across the valve. This valve is called an ORD valve (Open

on Rise of Differential pressure). As the ORI starts to restrict liquid flow from the condenser, a pressure differential is created across the ORD. When the differential reaches the setpoint, the ORD starts to open and bypass hot gas to the liquid line. The ORI valve is adjustable from 65 to 225 psig (factory setting of 180 psig). The ORD is not adjustable. On refrigeration systems that are too large for a single ORI and ORD valve, there will be two ORI and two ORD valves in parallel. The schematic on the following page shows an example system using the ORI/ORD valves.

Page 9

PERCENTAGE OF CONDENSER TO BE FLOODED

Ambient

Temperature

(°F)

Evaporating Temperature (°F)

0°

10°

20°

30°

35°

40°

45°

50°

70°

24 0 0 0 0 0 0

60°

50°

40°

30°

20°

0°

-20°

INSTALLATION cont.

Piping Schematic of Example system using the ORI/ORD valve.

The pressure setting of the ORI valve determines how well the system will operate. The proper setting is a function of the specific system in which is installed. Generally, the setting should be equivalent to a condensing temperature of 90°F to 100°F or a receiver pressure equivalent to a temperature of 80°F to 90°F. This means that as the ambient temperature falls below 70°F, the head pressure control valve will begin to throttle. To adjust the ORI valve, remove the cap and turn the adjustment screw with the proper size hex wrench (1/4” for ORI-6 and 5/16” for ORI-10). A clockwise rotation increases the valve setting while a counter-clockwise rotation decreases the setting. To obtain the desired setting, a pressure gauge should be used at the compressor discharge service valve so the effects of any adjustment can be observed. Small adjustments are recommended in order to allow the system adequate time to stabilize after each adjustment.

Condenser Flooding:

In order to maintain head pressure in the refrigeration system, liquid refrigerant is backed up in the condenser to reduce condenser surface. The following chart shows the percentage that a condenser must be flooded in order to function properly at the given ambient temperature.

Page 10

INSTALLATION cont.

During higher ambient temperatures the entire condenser is required to condense refrigerant. During these higher ambient temperatures, a receiver tank is used to contain the refrigerant that was required to flood the condenser during low ambient operation. The receiver must be sized to contain all of the flooded volume otherwise there will be high head pressures during higher ambient conditions.

Electrical:

• The single point electrical power connections are made in the electrical control compartment.

• Check the unit data plate voltage to make sure

it agrees with the power supply. Connect power to the unit according to the wiring diagram provided with the unit.

• The power and control wiring may be brought

up through the utility entry. Protect the branch circuit in accordance with code requirements. Control wires and power should not be run inside the same conduit. The unit must be electrically grounded in accordance with the current National Electric Code.

• Power wiring is to the unit terminal block or main disconnect. All wiring beyond this point has been done by the manufacturer and cannot be modified without effecting the unit's agency/safety certification.

Note: Startup technician must check motor amperage to ensure that the amperage listed on the motor nameplate is not exceeded.

Refrigerant Piping Connections

• CL condensing unit refrigerant piping

connections are located in the upper corner of the

service vestibule side of the unit (opposite the condenser section) as shown in the figure.

• The piping connections are protected with a

shipping cover that must be removed prior to copper connection and installation.

Evaporative-cooled Condenser Field Piping Connections:

• There are two field water connections that must be made for the evaporative-cooled condenser.

There is a ¾” PVC socket city make-up water

connection and a 2” PVC socket drain

connection (as shown on the next page). This drain should connect to a sanitary sewer or other code permitted drain. These connections can go through the base or the wall of the unit.

• There is a cutout in the base with a cap that is

1” tall and the cap is sealed to the unit base to

prevent any leaks in the unit from penetrating into the building. Any piping through the base should go through a field cutout in this cap. The pipes must be sealed to the cap once the piping is complete to prevent any leaks in the unit from penetrating into the building.

• A field cutout must be made in the wall if the evaporative-cooled condenser piping is to go through the unit wall. This cutout must be sealed once the piping is installed to prevent water from leaking into the unit.

Page 11

Diagram of Evaporative-cooled condenser Section including field water connections and base cutout

tap

Page 12

STARTUP

Pre-Startup:

After the installation and immediately before the startup of the condenser be sure that these items have been checked.

1. Verify that electrical power is available to the unit.

2. Verify that any remote stop/start device is requesting the condenser to start.

While performing the Startup, use the Condensing Startup Form at the back of this booklet to record motor amps and any other comments.

Startup:

• Use the General Check List at the top of the Startup Form to make a last check that all the components are in place and the power supply is energized.

Note: Condensing fan operation should start with the first compressor.

• Cycle through all the compressors to confirm

that all are operating within tolerance.

• When unit is running, observe the system for a complete operation cycle to verify that all systems are functioning properly.

• While performing the check, use the Condenser Startup Form to record observations of amps and refrigerant pressures.

• When all is running properly, place the controller in the Run mode and observe the system until it reaches a steady state of operation.

Axial Flow Fans:

Multi-Wing Z Series Aluminum Fan Blade Pitch Angle Setting Instructions:

Before You Begin, to maintain balance of fan:

• Mark the hub castings across a joint, so the fan

hub can be reassembled in the same orientation.

• Mark the location of any balancing weight.

Balancing weight will be on the outer bolt circle, in the form of washers, and/or longer bolts, or an additional balancing nut.

• Number the blades and blade sockets, so that

they are replaced into their original position.

• If possible, note the location of the pitch setting

pin in the blade socket, and whether pin is located in the Hub or Retainer half of the fan.

Step 1. Determine Boss Location Code: “A” or

“B” The boss is the center section of the hub

through which the fan is mounted to the shaft, and typically contains either setscrews or a center-tapered hole where the bushing inserts. Select boss location A or B: A is the boss on air inlet, including AS configurations. B is the boss on air discharge, including BS. For flange mounted fans, use boss location A for R rotation fans, and boss location B for L rotation fans.

Page 13

STARTUP cont.

Step 2. Find Blade Pitch Angle:

( 20, 25, 27.5, 30, 32.5, 35, 37.5, 40, 45 or 50 )

• Carefully disassemble fan on flat surface and

note in which groove the pin is located. Refer to groove number code diagram.

• Using diagrams in step 5, determine if the pin

was in the hub (HUB) or retainer side (RET) of fan.

• Using table in step 4, find the possible blade

pitch.

• Using table in step 3, select your blade angle

based on whether your pin was in the HUB or RET.

Step 3. Determine Hub/Retainer Code: “HUB” or “RET”

Step 4. - Determine Groove Number: 1 or 2 or 3 or 4

Step 5. Final Assembly Definition of HUB and RET for purposes of instructions. For 2-piece hubset:

Using the HUB or RET code found in Step 3:

• If code is HUB, place the hub down on work surface first (one or two pieces, depending on above).

• If code is RET, place one retainer ring only down on the work surface first. (A weighted coffee can could be used to elevate the fan from the work surface).

• Using the groove number, place the locking pin in the groove number that was found in Step 4.

Insert Blades:

• Place the blade over the pin in the hub/retainer

blade socket, so that the pin also fits into the appropriate pitch angle groove in the blade.

• Repeat for all blades.

• Assemble hub set together, aligning the match

marks that were made.

• Replace any balancing weight to its original

position.

Page 14

STARTUP cont.

• To finish, tighten the bolts in a cross pattern to

5 to 6 ft-lbs of torque.

Multi-Wing W Series Black Glass Reinforced Polypropylene Fan Blade Pitch Angle Setting Instructions:

Step 1. Note original position of retaining plates,

center boss and all hardware including additional hardware used for balancing.

Step 2. Remove all the bolts and nuts.

Step 3. Determine blade rotation – on the

concave side of the blade is a blade marking showing 6WR, 6WL, 7WL, 7WR, or 9WR. The “L” and “R” denote the rotation of the blade.

Step 4. Replace the pitch insert in the blade root with an insert of the desired pitch.

Step 8. Tighten nuts and bolts to 14 ft-lbs of torque.

SERVICING AND MAINTENANCE

General:

• Qualified technicians must perform routine service checks and maintenance. This includes reading and recording the condensing and suction pressures and checking for normal subcooling and superheat (see charging information beginning on page 14).

• Air-cooled and evaporative-cooled condenser units require different maintenance schedules/procedures. Unit specific instructions for both types are included in this manual.

Compressors:

The scroll compressors are fully hermetic and require no maintenance except keeping the shell clean.

Refrigerant Filter Driers:

Each refrigerant circuit contains a replaceable core filter drier. Replacement is recommended when there is excessive pressure drop across the assembly or moisture is indicated in a liquid line sight glass.

Step 5. Replace blades to their original location.

Step 6. Replace all nuts, bolts, and washers on

the fan hub.

Step 7. Replace retaining plates and center boss to original location.

The filter driers are provided with pressure taps and shutoff valves for isolation when changing the core. For safety purposes a service manifold must be attached prior to filter maintenance.

Page 15

SERVICING AND MAINTENANCE cont.

Evaporator/Heat Exchangers:

Normally no maintenance or service work will be required for a matching direct expansion evaporator with a thermal expansion valve to regulate refrigerant.

Charging Refrigerant:

• Charging a system in the field must be based on determination of liquid sub-cooling and evaporator superheat. On a system with a thermostatic expansion valve liquid sub-cooling is more representative of the charge than evaporator superheat but both measurements must be taken.

Before Charging:

• Refer to the Unit Nameplate to determine the proper refrigerant to charge the system with.

• The unit being charged must be at or near full

load conditions before adjusting the charge.

• Units equipped with hot gas bypass must have

the hot gas bypass valve closed to get the proper charge.

• Units equipped with hot gas reheat must be

charged with the hot gas valve closed while the unit is in cooling mode.

• After adding or removing charge the system

must be allowed to stabilize, typically 10-15 minutes, before making any other adjustments.

• The type of unit and options determine the

ranges for liquid sub-cooling and evaporator superheat. Refer to Table 1 when determining the proper sub-cooling.

• The vertical rise of the liquid line must be

known in order to adjust the sub-cooling range for proper charge.

• Units equipped with low ambient (0°F) option

see special charging instructions at the end of the charging instructions.

Checking Liquid Sub-cooling:

1. Measure the temperature of the liquid line as

it leaves the condenser coil.

2. Read the gauge pressure reading of the liquid line close to the point where the temperature was

taken. You must use liquid line pressure as it will vary from discharge pressure due to condenser coil pressure drop.

3. Convert the pressure obtained in Step 2 to a saturated temperature using the appropriate refrigerant temperature-pressure chart.

4. Subtract the measured liquid line temperature in Step 1 from the saturated temperature in Step 3 to determine the liquid sub-cooling.

5. Compare calculated sub-cooling to TABLE 1. for the appropriate unit type and options.

Checking Evaporator Superheat:

1. Measure the temperature of the suction line

close to the compressor.

2. Read gauge pressure at the suction line close to the compressor.

3. Convert the pressure obtained in Step 2 to a saturated temperature using the appropriate refrigerant temperature-pressure chart.

4. Subtract the saturated temperature in Step 3 from the measured suction line temperature in Step 1 to determine the evaporator superheat.

5. Compare calculated superheat to TABLE 1 for the appropriate unit type and options.

Page 16

SERVICING AND MAINTENANCE

TABLE 1

Sub-

cooling

(°F)

Superheat

(°F)

Sub-cooling

W/Hot Gas

Reheat (°F)

Air Cooled Condenser

12-18*

8-15**

15-22*

Evaporative

Cooled

Condenser

6-10*

8-15**

8-12*

Water

Cooled

Condenser

6-10*

8-15**

8-12*

cont.

* Sub-cooling must be increased by 3°F per 20 feet of vertical liquid line rise for R-22 and 2°F for R-410A ** Superheat will increase with long suction line runs.

Adjusting Sub-cooling and Superheat Temperatures: The system is overcharged if:

1. the sub-cooling temperature is too high and

2. the evaporator is fully loaded (low loads on

the evaporator result in increased sub-cooling)

and

3. the evaporator superheat is within the

temperature range as shown in TABLE 1 (high superheat results in increased sub-cooling)

Correct an overcharged system by reducing the amount of refrigerant in the system to lower the sub-cooling.

The system is undercharged if:

1. the superheat is too high and

2. the sub-cooling is too low

• Correct an undercharged system by adding refrigerant to the system to reduce superheat and raise sub-cooling.

• If the sub-cooling is correct and the superheat is too high, the TXV may need adjustment to correct the superheat.

Special Charging Instructions:

• For units equipped with low ambient refrigerant flood back option being charged in the summer when the ambient temperature is warm: Once enough charge has been added to get the evaporator superheat and sub-cooling values to the correct setting more charge must be added. Add approximately 80% of the receiver tank volume to the charge to help fill the receiver tank. The additional charge is required for the system when running in cold ambient conditions.

• For units equipped with low ambient refrigerant flood back option being charged in the winter when the ambient temperature is cold:

1. Once enough charge has been added to get the evaporator superheat and sub-cooling values to the correct setting more charge may need to be added. If the ambient temperature is 0°F no more charge is required. If the ambient temperature is around 40°F add approximately 40% of the receiver tank volume.

2. The unit will have to be checked for proper operation once the ambient temperature is above 80°F.

Lubrication:

• All original motors and bearings are furnished

with an original factory charge of lubrication. Certain applications require bearings be relubricated periodically. The schedule will vary depending on operating duty, temperature changes, or severe atmospheric conditions.

• Bearings should be re-lubricated at normal operating temperatures, but not when running.

Page 17

SERVICING AND MAINTENANCE cont.

Rotate the fan shaft by hand and add only enough grease to purge the seals. DO NOT

OVERLUBRICATE.

Service Information:

If the unit will not operate correctly and a service company is required, only a company with service technicians qualified and experienced in both condensing units and air conditioning are permitted to service the systems to keep warranties in effect. If assistance is required, the service technician must contact AAON.

Replacement Parts

Parts for AAON equipment may be obtained from your local AAON representative. When ordering parts reference the unit serial number and part number.

AAON Warranty, Service and Parts Department

2424 S. Yukon Ave. Tulsa, OK 74107 Ph: 918-583-2266 Fax: 918-382-6364 www.aaon.com

Note: Before calling, technician should have model and serial number of the unit available for the service department to help answer questions regarding the unit

EVAPORATIVE-COOLED CONDENSER

• Evaporative cooling equipment rejects heat by

evaporating a portion of the recirculated water spray and discharging it from the unit with the hot, saturated air. As the spray water evaporates, it leaves behind the mineral content and impurities of the supply water. If these residuals are not purged from the water distribution system, they will become concentrated and lead

to scaling, corrosion, sludge build-up and biological fouling.

• A water treatment monitoring and control

system has been furnished with this unit. Be sure to read the complete manual that has been furnished. All water treatment is a combination of bleed water and chemical treatment for proper control of the residuals and to prevent any biological contamination.

GENERAL INFORMATION

Severe Service:

The following recommended maintenance procedures are basic requirements for normal operating environments. For severe operating conditions, the frequency of inspection and service should be increased. Air containing industrial and chemical fumes, salt, dust, or other airborne contaminates and particulates will be absorbed by the recirculating water system and may form solutions and deposits harmful to the products and personnel.

Safety:

The recirculating water system contains chemical additives for water quality control and biological contaminants removed from the air by the washing action of the water. Personnel exposed to the saturated effluent, drift, or direct contact should use proper precaution. Proper location of the evaporative-cooled condenser requires good judgment to prevent the air discharge from entering fresh air intakes or to avoid allowing contaminated building exhaust from entering the condenser.

Page 18

EVAPORATIVE-COOLED CONDENSER cont.

Follow local and national codes in locating the evaporative-cooled condenser but as minimum the evaporative-cooled condenser sump must be 15 feet from the nearest intake.

Performance:

Improper location of the evaporative-cooled condenser may seriously degrade the capacity of the equipment. Make sure the equipment is located such that discharge air from the condenser does not enter the condenser air inlet.

Warranties: Please refer to the limitation of warranties in

effect at the time of purchase.

Condenser Tube Inspection:

The coil is leak tested at 450 P.S.I.G. before shipment. AAON will not be responsible for loss of refrigerant. It is the responsibility of the installer to verify that the system is sealed before charging with refrigerant. If the unit is operated during low ambient temperature conditions, freeze protection for the recirculating water system must be provided.

Freeze Protection:

In order to prevent water temperatures from dropping below 50°F, this unit is equipped with a variable frequency drive (VFD) on the fan motors when the refrigeration system is operating.

Recirculating Water System:

Electric sump heaters are available to keep the sump water from freezing when the refrigeration system is not operating. An electric resistance heater is supplied in the vestibule when sump heaters are selected.

Note: The condenser should not be operated with the fan on and the pump cycled on and off to maintain head pressure control under any conditions. The unit is equipped with a water temperature controller which varies fan speed to maintain sump water temperature. This unit is not equipped with a compressor discharge pressure controller for fan speed modulation and therefore can not be operated without water flow.

Page 19

EVAPORATIVE-COOLED CONDENSER cont.

PRE START-UP

Do not start the evaporative-cooled condenser or compressors without installation of proper water treatment chemicals. Contact your local water treatment expert for correct selection of water treatment chemical, adjustment of chemical feed and bleed rates.

Cleanliness:

Dirt and debris may accumulate in the sump during shipping and storage. The sump should be cleaned prior to start-up to prevent clogging the water distribution system. Any surfaces that show contamination should be cleaned ONLY with a commercial stainless steel cleaner to restore the initial appearance. The inlet screens should be inspected for foreign material.

Pump Operation:

Before initial start of the pump, check as follows:

1. Be sure that pump operates in the direction indicated by the arrow on the pump casing. Check rotation each time motor leads have been disconnected.

2. Check all connections of motor and starting device with wiring diagram. Check voltage, phase and frequency of line circuit with motor name plate.

3. Check suction and discharge piping and pressure gauges for proper operation.

4. Turn rotating element by hand to assure that it rotates freely.

Running:

Periodically inspect pump while running, but especially after initial start-up and after repairs.

1. Check pump and piping for leaks. Repair immediately.

2. Record pressure gauge readings for future reference.

3. Record voltage, amperage per phase, and kW.

Condenser Fan Motors:

• The direct-drive condenser motors on AAON evaporative-cooled condensers are 1200-rpm

premium efficiency motors controlled by a VFD. These motors are totally enclosed air over motors with weep holes in the bottom end bell so that any condensation can drain out of the motor.

• The motors have a small electric resistance heater installed inside the casing to keep the motors warm when they are deactivated. The heaters are designed to keep the interior of the motor 10°F warmer than the surrounding ambient temperature. This prevents condensation from forming inside the motor.

• Ensure that fan is tightly mounted to the motor shaft and the motor mounting bolts are aligned and secure.

Water Make-up Valve:

• The sump water level is controlled by a set of conductivity probes at different levels in the sump. This water level controller is located in the vestibule behind the condenser pump. There are four conductivity probes in this controller. There is a reference probe (shown as “ref” on the wiring diagram). This probe is one of the two longest probes. The other long probe is the low

water level probe (shown as “lo” on the wiring

diagram). The medium length probe is for the

medium water level (shown as “med” on the

wiring diagram). The short probe is for the high

water level (shown as “hi” on the wiring

diagram). There is a solenoid valve in the makeup water line that is activated by the water level controller. The water level controller determines the level of water in the sump based on conductivity between two probes. If the controller sees conductivity between two probes, it knows that water is at least at the level of that probe.

• If the water in the sump is below the low probe,

it will not allow the condenser pump or the sump heater to operate. It will activate the make-up water solenoid to try to fill the sump assuming water is flowing to the unit. Once water is above the low probe, it will allow the condenser pump and sump heater (if ordered and the ambient temperature is below 40°F) to operate. The make-up water solenoid will remain activated until water gets to the high water level.

Page 20

EVAPORATIVE-COOLED CONDENSER cont.

The make-up water solenoid will deactivate until water gets to the medium water level. In normal operation, the water level should swing between the medium and high water levels. The

maximum high water level should be 1” below

the overflow drain which occurs after the makeup water valve shuts off when the water level reaches the high level probe.

• Make-up water supply pressure should be maintained between 15 and 60 psig for proper operation of the valve. The make-up water valve assembly should be inspected monthly and adjusted as required. Replace the valve seat if leakage occurs when the valve is in the closed position.

Water Treatment System:

• All AAON evaporative-cooled condensers come equipped with a water treatment system that should be maintained by a local water treatment professional trained in the water treatment of evaporative condensers. This system consists of a controller, three chemical pumps and storage tanks, a conductivity sensor, a motorized ball valve for water bleed, and a water meter.

• One chemical pump and tank is typically used

for a descaling chemical to prevent scale from forming in the condenser. The other two pumps and tanks are typically used for two different biocides (to kill any microorganisms that could grow in the condenser). Two biocides are used to prevent organisms from becoming resistant to one chemical.

• The mineral content of the water must be

controlled. All make-up water has minerals in it. As water is evaporated from the condenser, these minerals remain. As the mineral content of the water increases, the conductivity of the water increases. The water treatment controller monitors this conductivity. As the water conductivity rises above set point, the controller will open a motorized ball valve on the discharge side of the condenser pump and dumps water into the condenser drain until conductivity is lowered. While the motorized ball valve is opened, the controller will not disperse chemicals.

• The chemicals are dispersed by the water

treatment controller based on the scheduled input by the water treatment professional. (See the separate manual for the water treatment controls for specific programming information.)

• The water meter measures the quantity of

make-up water used by the condenser.

• Any water treatment program must be

compatible with stainless steel, copper, aluminum, ABS plastic and PVC. Batch feed processes should never be used as concentrated chemicals can cause corrosion. Never use hydrochloric acid (muriatic acid) as it will corrode stainless steel.

Sequence of Operation:

• On a call for cooling, the condenser pump is activated. A pressure switch in the pump discharge is bypassed for six seconds by a time delay relay in order for the pump to establish recirculating water flow. If flow is not proven within the six seconds, the pressure switch opens, breaking the safety circuit, thereby shutting down the entire system. This pressure switch is set to close at 3 psi and open at 1 psi.

Page 21

EVAPORATIVE-COOLED CONDENSER cont.

• A Johnson Controls S350C measures the water

temperature in the pump discharge line. If the sump water temperature exceeds 105°F, the cooling system will be shut down thereby preventing damage to the evaporative condenser.

• If a fault occurs in the evaporative condenser

fan motor VFD, normally closed fault terminals on the VFD will interrupt the safety circuit, thereby shutting down the system.

• If the VFD does fault and cannot be reset, there

is a VFD bypass switch mounted near the VFD. This switch has four positions—line, off, drive,

and test. The “line” position will bypass the

VFD, sending power to the motor. In this position, the condenser fans will run at full

speed. The “off” position will not allow power

to pass through the switch. This functions as a

disconnect switch. The “drive” position runs

power through the VFD. This is the normal

operation for the switch. The “test” position

routes power to the VFD but not to the motor. This is useful for running tests on the VFD without sending power to the motor.

• A Johnson Controls A350P controls the VFD

speed. This device sends a 0-10 VDC signal to the VFD. This controller is set to maintain a sump temperature of 70°F. On a rise in sump temperature, the controller increases the voltage to the VFD, increasing the speed of the condenser fans. Conversely, on a drop in sump temperature, the controller will decrease the voltage to the VFD, decreasing the speed of the condenser fans.

• An outside air thermostat does not allow the

condenser to operate when the ambient temperature is below 35°F.

MAINTENANCE RECOMMENDATIONS

Pump Maintenance:

• Cleaning - Remove oil, dust, water, and chemicals from exterior of motor and pump. Keep motor air inlet and outlet open. Blow out interior of open motors with clean compressed air at low pressure.

• Labeled Motors - It is imperative for repair of a

motor with Underwriters’ Laboratories label that

original clearances be held; that all plugs, screws, other hardware be fastened securely, and that parts replacements be exact duplicates or approved equals. Violation of any of the above invalidates Underwriters’ Label.

Fan Motor Maintenance:

Same as pump maintenance

Access Doors:

If scale deposits or water is found around the access doors, adjust door for tightness. Adjust as necessary until leaking stops when door is closed.

Bearings - Lubrication:

Every 6 months or after a prolonged shut down. Use waterproof, lithium based grease. Below 32°F - Esso Exxon or Beacon 325. Above 32°F – Mobil Mobilox EP2, Shell Alvania EP2 or Texaco RB2.

Recommended Monthly Inspection:

1. Clean sump section interior. Dirt and other

impurities which have accumulated in the sump should be removed from the sump area. Shut off make-up water ball valve and open the drain connection for flushing of the sump.

2. Clean dirt out of sump using a water hose (not a pressure washer).

3. Clean sump suction strainer.

4. Check water operating level. Adjust float as

required.

5. Inspect fan motor(s) and water circulation pump(s) and lubricate per the lubrication nameplate or manufacture’s recommendations.

6. Inspect axial fans and eliminators removing any debris which may have accumulated during operation.

7. Inspect the water distribution system to insure that nozzles and spray orifices are functioning correctly. The inspection should be made with the circulation pump on and fans off.

Page 22

EVAPORATIVE-COOLED CONDENSER cont.

Mist Eliminators:

The mist eliminators must be correctly positioned when they are replaced during cleaning or service.

Air Inlet:

Inspect the air inlet louvers and mist eliminators into the condenser section on a monthly basis to remove any paper, leaves or other debris that may block the airflow.

Stainless Steel Base Pan:

The base pan under the tube bundles is stainless steel and may sometimes become tarnished due to contamination. These surfaces should be inspected yearly to ensure they remain clean of any contamination that may result in damage. Any surfaces that show contamination should be cleaned ONLY with a commercial stainless steel cleaner to restore the initial appearance.

Propeller Fans and Motors:

The fans are directly mounted on the motor shafts and the assemblies require minimal maintenance except to assurance they are clear of dirt or debris that would impede the airflow.

Recommended Annual Inspection:

In addition to the above maintenance activities, a general inspection of the unit surface should be completed at least once a year. Remove spray header and flush out.

Cleaning:

Mechanical cleaning, including pressure washing, should never be performed as surfaces and seals could be damaged. Chemical cleaning that is safe for stainless steel, copper, aluminum, ABS plastic and PVC is the only acceptable means of cleaning the evaporative condenser. A proper water treatment program should reduce cleaning needs.

WATER QUALITY

Recirculating Water Quality Guidelines:

• Cycles of concentration (the ratio of dissolved

solids in recirculated water to dissolved solids in make-up), should be determined and monitored frequently by a competent water treatment expert.

• To limit cycles of concentration to maintain the

above guideline, it is necessary to “bleed” a

certain portion of the recirculated water. This is achieved automatically with a solenoid valve actuated by a conductivity meter set at the desired conductivity corresponding to the desired cycles of concentration. It should be noted that these are guidelines and even though these individual values are met, under certain conditions the water quality can be aggressive. For example, water with very low alkalinity and levels of chlorides and sulfates approaching maximum recommended levels can be corrosive.

Mechanical Cleaning:

Do not attempt to mechanically clean the copper tubing in the evaporative-cooled condenser. Do not use wire brushes or any other mechanical device on the copper tubing. Severe damage may result. Contact your water treatment expert for recommendations on chemical cleaning procedures.

Parts:

Contact your local AAON Representative for factory authorized parts. Orders must include the Serial Number from the product nameplate OR visit www.aaonparts.com for more information.

Page 23

AIR-COOLED CONDENSER

• The air-cooled condenser section rejects heat by passing outdoor air over the fin tube coils for cooling of the hot refrigerant gas from the compressors. The heated air will discharge from the top of the section through the axial flow fans.

• The condenser coils should be inspected yearly

to ensure unrestricted airflow. If the installation has a large amount of airborne dust or other material, the condenser coils should be cleaned with a water spray in a direction opposite to airflow. Care must be taken to prevent bending of the aluminum fins on the copper tube.

REFRIGERANT PIPING FOR THE CL SERIES

Note: This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condensing unit and air handling equipment. AAON Inc. is not responsible for interconnecting refrigerant piping. Consult ASHRAE Handbook 2006 – Refrigeration and ASME Standards.

General:

• Use only clean type L copper tubing (type K for underground) that has been joined with high temperature brazing alloy.

• All AAON CL condensing units have factory furnished liquid and suction line shutoff valves.

Determining Refrigerant Line size:

The piping between the condenser and low side must assure:

1. Minimum pressure drop, and

2. Continuous oil return, and

3. Prevention of liquid refrigerant slugging, or

carryover

• Minimizing the refrigerant line size is favorable from an economic perspective, reducing installation costs, and reducing the potential for

leakage. However, as pipe diameters narrow, pressure-reducing frictional forces increase.

• Excessive suction line pressure drop causes loss of compressor capacity and increased power usage resulting in reduced system efficiency. Excessive pressure drops in the liquid line can cause the liquid refrigerant to flash, resulting in faulty expansion valve operation and improper system performance. In order to operate efficiently and cost effectively, while avoiding malfunction, refrigeration systems must be designed to minimize both cost and pressure loss.

The pipe sizes must be selected to meet the actual installation conditions, and not simply based on the connection sizes at the evaporator and/or condensing unit. Refer to TABLES RP-1 through RP-4 for connection size information.

Equivalent Line Length:

All line lengths discussed in this manual, unless specifically stated otherwise, are Equivalent Line Lengths. The frictional pressure drop through valves, fittings, and accessories is determined by establishing the equivalent length of straight pipe of the same diameter. Always use equivalent line lengths when calculating pressure drop. Special piping provisions must be taken when lines are run underground, up vertical risers, or in excessively long line runs.

Liquid line sizing:

• When sizing the liquid line, it is important to minimize the refrigerant charge to reduce installation costs and improve system reliability. This can be achieved by minimizing the liquid line diameter. However, reducing the pipe diameter will increase the velocity of the liquid refrigerant which increases the frictional pressure drop in the liquid line, and causes other undesirable effects such as noise. Maintaining the pressure in the liquid line is critical to ensuring sufficient saturation temperature, avoiding flashing upstream of the TXV, and maintaining system efficiency.

Page 24

REFRIGERANT PIPING cont.

Pressure losses through the liquid line due to frictional contact, installed accessories, and vertical risers are inevitable. Maintaining adequate sub-cooling at the condenser to overcome these losses is the only method to ensure that liquid refrigerant reaches the TXV.

• Liquid risers decrease head pressure. If the evaporator section is below the condenser, and the liquid line does not include risers, the gravitational force will increase the pressure of the liquid refrigerant. This will allow the refrigerant to withstand greater frictional losses without the occurrence of flashing prior to the TXV.

• A moisture indicating sight glass may be factory installed in the liquid line to indicate the occurrence of premature flashing or moisture in the line. The sight glass should not be used to determine if the system is properly charged. Use

temperature and pressure measurements to determine liquid sub-cooling, not the sight glass.

Liquid Line Routing:

Care should be taken with vertical risers. When the system is shut down, gravity will pull liquid down the vertical column, and back to the condenser when it is below the evaporator. This could potentially result in compressor flooding. A check valve can be installed in the liquid line where the liquid column rises above the condenser to prevent this. The liquid line is typically pitched along with the suction line, or hot gas line, to minimize the complexity of the configuration.

Liquid Line Insulation:

When the liquid line is routed through regions where temperature losses are expected, no insulation is required, as this may provide additional sub-cooling to the refrigerant. When routing the liquid line through high temperature areas, insulation of the line is appropriate to avoid loss of sub-cooling.

Liquid Line Guidelines:

• In order to ensure liquid at the TXV, frictional losses must not exceed available sub-cooling. A commonly used guideline to consider is a system design with pressure losses due to friction through the line not to exceed a corresponding 12°F change in saturation temperature.

• If the velocity of refrigerant in the liquid line is too great, it could cause excessive noise or piping erosion. The recommended maximum velocities for liquid lines are 100 fpm from the condenser to a receiver tank to discourage fluid backup, and 300 fpm from receiver tank to the evaporator to minimize valve induced liquid hammer.

Liquid Line Accessories:

Liquid line accessories including sight glasses and filter driers are available and factory installed. The total length equivalent of pressure losses through valves, elbows and fittings must be considered when adding additional components in the field. It is a good practice to utilize the fewest elbows that will allow the mating units to be successfully joined.

Suction Line Sizing:

The suction line is more critical than the liquid line from a design and construction standpoint. More care must be taken to ensure that adequate velocity is achieved to return oil to the compressor at minimum loading conditions. However, reducing the piping diameter to increase the velocity at minimal load can result in excessive pressure losses, capacity reduction, and noise at full load.

Suction Line Routing:

• Pitch the suction line in the direction of flow (about 1 ft. per 100 ft of length) to maintain oil flow towards the compressor, and keep it from flooding back into the evaporator. Crankcase heaters are provided to keep any condensed refrigerant that collects in the compressor from causing damage or wear. Make sure to provide support to maintain suction line positioning, and insulate completely between the evaporator and condensing unit.

Page 25

REFRIGERANT PIPING cont.

• It is important to consider part load operation

when sizing suction lines. At minimum capacity, refrigerant velocity may not be adequate to return oil up the vertical riser. Decreasing the diameter of the vertical riser will increase the velocity, but also the frictional loss. A double suction riser can be applied in this situation. The double suction riser is designed to return oil at minimum load while not incurring excessive frictional losses at full load. The double suction riser consists of a small diameter riser in parallel with a larger diameter riser, and a trap at the base of the large riser. At minimum capacity, refrigerant velocity is not sufficient to carry oil up both risers, and it collects in the trap, effectively closing off the larger diameter riser, and diverting refrigerant up the small riser where velocity of the refrigerant is sufficient to maintain oil flow. At full load, the mass flow clears the trap of oil, and refrigerant is carried through both risers. The smaller diameter pipe should be sized to return oil at minimum load, while the larger diameter pipe should be sized for acceptable pressure drop at full load.

Suction Line Insulation:

The entire suction line should be insulated. This prevents condensation from forming on the line, and reduces any potential loss in capacity associated with heat gain placing additional load on the system.

Suction Line Guidelines:

• For proper performance, suction line velocities less than a 4000 fpm maximum are recommended. The minimum velocity required to return oil is dependent on the pipe diameter, however a general guideline of 1000 fpm minimum may be applied.

• In a fashion similar to the liquid line, a common

guideline to consider is a system design with pressure losses due to friction through the line not to exceed a corresponding 1-2°F change in saturation temperature.

• At points where small pipe size can be used to provide sufficient velocity to return oil in vertical

risers at part loads, greater pressure losses are incurred at full loads. This can be compensated for by over sizing the horizontal and vertical drop sections. This will however require additional refrigerant charge.

Suction Line Accessories:

If the job requirements specify suction accumulators, they must be separately purchased and installed.

Hot Gas Bypass Line:

• Hot Gas Bypass is available for use with DX systems that may experience low suction pressure during the operating cycle. This may be due to varying load conditions associated with VAV applications or units supplying a large percentage of outside air. The system is designed to divert refrigerant from the compressor discharge to the low pressure side of the system in order to keep the evaporator from freezing and to maintain adequate refrigerant velocity for oil return at minimum load.

• Hot discharge gas is redirected to the evaporator inlet via an auxiliary side connector (ASC) to false load the evaporator when reduced suction pressure is sensed. Field piping between

the condensing unit and the evaporator is required.

See figures RP-5 through RP-10 for hot gas bypass piping configurations.

Hot Gas Bypass Piping Considerations for Evaporator Above Condensing Unit:

• Pitch the hot gas bypass line downward in the direction of refrigerant flow, toward the evaporator.

• When installing hot gas bypass risers, a drain leg must be provided at the lowest point in the system. The drain leg must be vertical, its diameter should be the same as the diameter of the riser, and it should be 1 foot long. Install a sight glass in the drain leg for observation. Run an oil return line, using 1/8 inch capillary tube, 5 feet in length, from the drain leg to the suction line. Connect the oil return line below the sight glass, 1 inch above the bottom of the drain leg.

Page 26

REFRIGERANT PIPING cont.

• HGBP valves are adjustable. Factory HGBP valve settings will be sufficient for most applications, but may require slight adjustments for some make up air or other process cooling applications.

• Insulate the entire length of the HGBP line with a minimum 1 inch thick Armaflex insulation.

• Refer to figure RP-5 for piping diagram

Hot Gas Bypass Piping Considerations for Evaporator Below Condensing Unit:

• The line must slope downward from the hot gas bypass valve toward the evaporator.

• Refer to figure RP-6 for piping diagram

Hot Gas Bypass Line Guidelines:

• Choose a small size line to ensure oil return, and minimize refrigerant charge.

• Maintain velocities below a maximum of 4000 fpm. A general minimum velocity guideline to use is approximately 1000 fpm.

Hot Gas Reheat:

• The AAON modulating hot gas reheat system diverts hot discharge gas from the condenser to the air handling unit to supply the reheat coil and/or the hot gas bypass valve. Size this line as a discharge line.

• Discharge lines should be sized to ensure adequate velocity of refrigerant to ensure oil return, avoid excessive noise associated with velocities that are too high, and to minimize efficiency losses associated with friction.

• Pitch the hot gas line in the direction of flow for oil return.

• Insulate the entire length of the hot gas line with a minimum 1 inch thick Armaflex insulation.

• Refer to figures RP-7 through RP-10 for piping diagrams.

Hot Gas Reheat Guidelines:

• Maintain velocities below a maximum of 3500 fpm. A general minimum velocity guideline is 2000 fpm.

Predetermined Line Sizes:

• To aid in line sizing and selection, AAON has predetermined line sizes for comfort cooling applications.

• In order to generate this information, the following cycle assumptions are made: Saturated suction temperature = 50°F, Saturated condensing temperature = 125°F, Sub-cooling = 10°F, Superheat = 15°F.

• The liquid lines have been chosen to maintain velocities between 100 and 350 fpm. The suction line diameters are selected to limit velocities to a 4000 fpm maximum, while a minimum velocity restriction is imposed by the ability to entrain oil up vertical suction risers (ASHRAE Handbook 2006 - Refrigeration p.

2.19). Hot gas bypass pipe diameters are selected to maintain velocity below a maximum 4000 fpm, while a minimum criteria guarantees oil return up vertical rise sections, as with the suction line (ASHRAE Handbook 2006 – Refrigeration p. 2.20).

• Acceptable pressure loss criteria are applied to each of the lines: The total equivalent length of the liquid line available is determined such that 3°F of liquid sub-cooling remain at the TXV. This includes the pressure losses in horizontal and vertical sections, accessories, elbows, etc. Recall that the available sub-cooling for the cycle is assumed as 10°F. To maintain at least 3°F subcooling as a factor of safety to avoid flashing at the TXV, we consider a maximum pressure loss equivalent to a 7°F change in saturation temperature. Pressure losses in the suction line are not to exceed 2°F. When sizing the hot gas bypass line we consider a maximum acceptable pressure loss in the hot gas bypass line with R-22 to be 20 psi, 30 psi with R-410A refrigerant.

When to use predetermined line sizing:

The line sizes presented are not the only acceptable pipe diameters, they are however appropriate for general comfort cooling applications, and satisfy common job requirements.

Page 27

REFRIGERANT PIPING cont.

Examine the conditions, assumptions, and constraints used in the generation of the predetermined pipe diameters to ensure that this method is applicable to a particular case. Do not assume that these line sizes are appropriate for every case. Consult ASHRAE Handbook – Refrigeration 2006 for generally accepted system practices.

How to use predetermined line sizing:

First, read the previous section entitled (When to use predetermined line sizing) to decide if this

method is applicable. Second, determine the refrigerant being used, AAON offers CL products with R-410A and R22 refrigerants, and the line sizes are not identical for both. Next, determine whether the product is operating with single, or dual circuited compressors. Locate the appropriate table of line sizes: TABLE RP-1: Dual Circuited R-410A condensers TABLE RP-2: Dual Circuited R-22 condensers TABLE RP-3: Single Circuited R-410A condensers TABLE RP-4: Single Circuited R-22 condensers Locate the Model number in the table. For each model, the circuits are listed, along with the pipe diameters of the connection sizes, and the diameters of the predetermined line size.

A figure accompanies each table. FIGURE RP-1: Dual circuited R-410A condensers FIGURE RP-2: Dual circuited R-22 condensers FIGURE RP-3: Single circuited R-410A condensers FIGURE RP-4 Single circuited R-22 condensers Examine the appropriate figure to determine the acceptable line dimensions. The figure is shown as total available riser height versus total equivalent line length for the liquid line. This curve identifies a region of acceptable piping configuration when the predetermined line sizes are selected for any model in the table. A piping configuration above the curve falls outside the assumptions used to determine the line size and will result in a loss of sub-cooling, and additional pressure losses in the suction and hot gas bypass lines. The total equivalent line length definition includes the height of vertical rise, pressure drop through elbows and accessories, and horizontal line length, so elbows, accessories and vertical rise must be considered when determining horizontal length available from the total equivalent line length. This figure is presented in terms of the liquid line, but it assumes that the line lengths for the suction and hot gas bypass are similar, as these lines will commonly be routed together to minimize the space and cost required for split system installation.

Page 28

REFRIGERANT PIPING cont.

Tons

System

R-410A

Connection Size

Predetermined Line Size

Suction Line

Liquid Line

Hot Gas Bypass

Reheat

Suction Line

Liquid Line

Hot Gas Bypass

Reheat

45 1 1-3/8 in.

7/8 in.

1-5/8 in.

7/8 in.

3/4 in.

1-1/8 in.

60 1 1-5/8 in.

7/8 in.

1-1/8 in.

2-1/8 in.

1-1/8 in.

3/4 in.

1-1/8 in.

70 1 1-5/8 in.

7/8 in.

1-1/8 in.

2-1/8 in.

1-1/8 in.

3/4 in.

1-1/8 in.

1-3/8 in.

7/8 in.

1-3/8 in.

75 1 1-5/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

1-5/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

1-3/8 in.

100 1 1-5/8 in.

7/8 in.

1-1/8 in.

2-1/8 in.

1-1/8 in.

3/4 in.

1-1/8 in.

1-3/8 in.

7/8 in.

1-3/8 in.

110 1 1-5/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

125

1-5/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2 3 2-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

134

1-5/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2 3 2-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

135

1-5/8 in.

7/8 in.

1-1/8 in.

2-1/8 in.

1-1/8 in.

3/4 in.

1-1/8 in.

2-1/8 in.

1-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

1-3/8 in.

155

1-5/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

170 1 2-1/8 in.

1-1/8 in.

7/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

1-3/8 in.

190

1-5/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

210

1-5/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

230 1 2-1/8 in.

1-1/8 in.

7/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

1-3/8 in.

TABLE RP-1 Predetermined Line sizes for Dual Circuit CL units with R-410A

Page 29

REFRIGERANT PIPING cont.

Tons

System

R-22

Connection Size

Predetermined Line Size

Suction Line

Liquid Line

Hot Gas Bypass

Reheat

Suction Line

Liquid Line

Hot Gas Bypass

Reheat

45 1 1-3/8 in.

5/8 in.

7/8 in.

2-1/8 in.

7/8 in.

1-1/8 in.

60 1 2-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

70 1 2-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

75 1 2-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

2-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-5/8 in.

1-3/8 in.

100 1 2-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

110 1 2-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

125

2-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

2 3 2-5/8 in.

1-3/8 in.

1-5/8 in.

1-3/8 in.

134

2-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

2 3 2-5/8 in.

1-3/8 in.

1-5/8 in.

1-3/8 in.

135

2-1/8 in.

7/8 in.

1-3/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-3/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

1-5/8 in.

155

2-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-5/8 in.

1-3/8 in.

170 1 2-5/8 in.

1-3/8 in.

7/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

1-5/8 in.

190

2-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-5/8 in.

1-3/8 in.

210

2-1/8 in.

7/8 in.

1-3/8 in.

2-5/8 in.

1-1/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-5/8 in.

1-3/8 in.

230 1 2-5/8 in.

1-3/8 in.

7/8 in.

1-5/8 in.

2-5/8 in.

1-3/8 in.

1-1/8 in.

1-5/8 in.

TABLE RP-2 Predetermined Line sizes for Dual Circuit CL units with R-22

Page 30

REFRIGERANT PIPING cont.

Tons

System

R-410A

Connection Size

Predetermined Line Size

Suction Line

Liquid Line

Hot Gas Bypass

Reheat

Suction Line

Liquid Line

Hot Gas Bypass

Reheat

1-1/8 in.

5/8 in.

7/8 in.

1-3/8 in.

5/8 in.

3/4 in.

2 3 4

1-3/8 in.

5/8 in.

7/8 in.

1-3/8 in.

3/4 in.

7/8 in.

2 3 4

1-3/8 in.

5/8 in.

7/8 in.

1-3/8 in.

3/4 in.

7/8 in.

1-5/8 in.

7/8 in.

1-1/8 in.

1-3/8 in.

3/4 in.

7/8 in.

1-5/8 in.

7/8 in.

1-1/8 in.

1-5/8 in.

5/8 in.

7/8 in.

1-5/8 in.

7/8 in.

3/4 in.

1-1/8 in.

2 3 4

1-5/8 in.

5/8 in.

7/8 in.

1-5/8 in.

7/8 in.

3/4 in.

1-1/8 in.

7/8 in.

1-1/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

5/8 in.

7/8 in.

1-5/8 in.

7/8 in.

3/4 in.

7/8 in.

1-1/8 in.

2-1/8 in.

1-1/8 in.

7/8 in.

Tons

System

R-22

Connection Size

Predetermined Line Size

Suction Line

Liquid Line

Hot Gas Bypass

Reheat

Suction Line

Liquid Line

Hot Gas Bypass

Reheat

1-3/8 in.

5/8 in.

7/8 in.

1-5/8 in.

5/8 in.

3/4 in.

7/8 in.

1-3/8 in.

5/8 in.

7/8 in.

1-5/8 in.

3/4 in.

7/8 in.

1-1/8 in.

2 3 4

1-3/8 in.

5/8 in.

7/8 in.

1-5/8 in.

3/4 in.

7/8 in.

1-1/8 in.

2-1/8 in.

1-5/8 in.

2-1/8 in.

1-3/8 in.

5/8 in.

7/8 in.

2-1/8 in.

3/4 in.

7/8 in.

1-1/8 in.

1-3/8 in.

5/8 in.

7/8 in.

2-1/8 in.

3/4 in.

7/8 in.

1-1/8 in.

2-1/8 in.

7/8 in.

1-3/8 in.

1-1/8 in.

1-3/8 in.

5/8 in.

7/8 in.

3/4 in.

7/8 in.

1-1/8 in.

2-1/8 in.

7/8 in.

1-3/8 in.

1-1/8 in.

1-3/8 in.

TABLE RP-3 Predetermined Line sizes for Single Circuit CL units with R-410A

TABLE RP-4 Predetermined Line sizes for Single Circuit CL units with R-22

Page 31

REFRIGERANT PIPING cont.

Acceptable Region

FIGURE RP-1. Riser height versus total equivalent line length for R-410A split system applications with dual circuited CL-045 through CL-230 units. The region of acceptable riser height is the lighter area. Select the corresponding predetermined line size from TABLE RP-1 on page 26.

FIGURE RP-2. Riser height versus total equivalent line length for R22 split system applications with dual circuited CL-045 through CL-230 units. The region of acceptable riser height is the light area. Select the corresponding predetermined line size from TABLE RP-2 on page 27.

Page 32

REFRIGERANT PIPING cont.

Acceptable Region

FIGURE RP-3. Riser height versus total equivalent line length for R-410A split system applications with single circuited CL-045 through CL-230 units. The region of acceptable riser height is the lighter area. Select the corresponding predetermined line size from TABLE RP-3 on page 28.

FIGURE RP-4. Riser height versus total equivalent line length for R22 split system applications with single circuited CL-045 through CL-230 units. The region of acceptable riser height is the light area. Select the corresponding predetermined line size from TABLE RP-4 on page 28.

Page 33