AAON CB-060 User Manual

CB SERIES
Condensing Units
Installation, Operation
FOR YOUR SAFETY
Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance.
WARNING
If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or loss of life.
WARNING
QUALIFIED INSTALLER
Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Startup and service must be performed by a Factory Trained Service Technician. A copy of this IOM should be kept with the unit.
WARNING
& Maintenance
3
Table of Contents
Safety .............................................................................................................................................. 5
CB Base Model and Features Description ...................................................................................... 8
General Description ........................................................................................................................ 9
Codes and Ordinances................................................................................................................. 9
Receiving Unit ............................................................................................................................ 9
Storage ........................................................................................................................................ 9
Direct Expansion (DX) Condensing Units ............................................................................... 10
Wiring Diagrams ....................................................................................................................... 10
Installation..................................................................................................................................... 11
Locating Unit ............................................................................................................................ 11
Lifting the Unit ......................................................................................................................... 12
Electrical ................................................................................................................................... 12
Thermostat ................................................................................................................................ 14
Refrigerant Piping ..................................................................................................................... 14
General .................................................................................................................................. 14
Determining Refrigerant Line Size ....................................................................................... 15
Liquid Line Sizing ................................................................................................................ 15
Suction Line Sizing ............................................................................................................... 16
Hot Gas Bypass Line ............................................................................................................ 17
Hot Gas Reheat ..................................................................................................................... 18
Predetermined Line Sizes ..................................................................................................... 18
Startup ........................................................................................................................................... 21
Compressors .............................................................................................................................. 21
Charging Refrigerant & Adjusting Refrigerant Charge ............................................................ 21
Before Charging .................................................................................................................... 21
Checking Liquid Sub-cooling ............................................................................................... 22
Checking Evaporator Superheat ........................................................................................... 22
Adjusting Sub-cooling and Superheat Temperatures ........................................................... 22
Air Flow .................................................................................................................................... 23
Operation....................................................................................................................................... 25
Thermostat Operation ............................................................................................................... 25
Compressor ............................................................................................................................... 25
Variable Capacity Compressor Controller .................................................................................... 25
Low Ambient Options................................................................................................................... 28
Maintenance .................................................................................................................................. 28
Coils .......................................................................................................................................... 28
E-Coated Coil Cleaning ............................................................................................................ 28
DX Cooling ............................................................................................................................... 30
Condenser Fan Motor ............................................................................................................... 30
Replacement Parts ..................................................................................................................... 30
Warranty, Service, and Parts Department ................................................................................. 30
Refrigerant Piping Diagrams ........................................................................................................ 31
CB Series Startup Form ................................................................................................................ 43
Literature Change History............................................................................................................. 45
4
Index of Tables and Figures
Tables:
Table 1 - Recommended Elevation Minimums ............................................................................ 12
Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A .......... 20
Table 3 - Sub-cooling and Superheat ............................................................................................ 22
Table 4 - Performance Testing Air Flow Setpoints ...................................................................... 23
Table 5 - R-410A Refrigerant Temperature-Pressure Chart ......................................................... 24
Table 6 - Demand Signal vs. Compressor Capacity Modulation .................................................. 26
Table 7 - Thermistor Temperature vs. Resistance Values ............................................................ 27
Figures:
Figure 1 – Condensing Unit Clearances ....................................................................................... 11
Figure 2 - Riser height versus total equivalent line length ........................................................... 20
Figure 3 - Variable Capacity Compressor Controller ................................................................... 26
Figure 4 - Compressor Controller Flash Code Details.................................................................. 27
Figure 5– A/C only piping, AHU above CU ................................................................................ 31
Figure 6 – A/C only piping, AHU below CU ............................................................................... 32
Figure 7 – Modulating hot gas reheat piping, AHU above CU .................................................... 33
Figure 8 – Modulating hot gas reheat piping, AHU below CU .................................................... 34
Figure 9 – Hot gas bypass piping, AHU above CU ...................................................................... 35
Figure 10 – Hot gas bypass piping, AHU below CU .................................................................... 36
Figure 11 – Modulating hot gas reheat with hot gas bypass piping, AHU above CU .................. 37
Figure 12 – Modulating hot gas reheat with hot gas bypass piping, AHU below CU .................. 38
Figure 13 – Heat pump piping, AHU above CU .......................................................................... 39
Figure 14 – Heat pump piping, AHU below CU .......................................................................... 40
Figure 15 – Heat pump with modulating hot gas reheat piping, AHU above CU ........................ 41
Figure 16 – Heat pump with modulating hot gas reheat, AHU below CU ................................... 42
R57611 · Rev. - · 130603
(ACP J00187)
5

Safety

Attention should be paid to the following statements:
NOTE - Notes are intended to clarify the unit installation, operation and maintenance.
CAUTION - Caution statements are given to prevent actions that may result in
equipment damage, property damage, or personal injury.
WARNING - Warning statements are given to prevent actions that could result in
equipment damage, property damage, personal injury or death.
DANGER - Danger statements are given to prevent actions that will result in equipment
damage, property damage, severe personal injury or death.
ELECTRIC SHOCK, FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings exactly could result in dangerous operation, serious injury, death or property damage.
Improper servicing could result in dangerous operation, serious injury, death or property damage.
Before servicing, disconnect all
electrical power to the unit. More than one disconnect may be provided.
When servicing controls, label all
wires prior to disconnecting. Reconnect wires correctly.
Verify proper operation after
servicing. Secure all doors with key-lock or nut and bolt.
WARNING
Electric shock hazard. Before servicing, disconnect all electrical power to the unit, including remote disconnects, to avoid shock hazard or injury from rotating parts. Follow proper Lockout-Tagout procedures.
WARNING
FIRE, EXPLOSION OR CARBON MONOXIDE POISONING HAZARD
Failure to replace proper controls could result in fire, explosion or carbon monoxide poisoning. Failure to follow safety warnings exactly could result in serious injury, death or property damage. Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this appliance.
WARNING
6
GROUNDING REQUIRED
All field installed wiring must be completed by qualified personnel. Field installed wiring must comply with NEC/CEC, local and state electrical code requirements. Failure to follow code requirements could result in serious injury or death. Provide proper unit ground in accordance with these code requirements.
WARNING
During installation, testing, servicing and troubleshooting of the equipment it may be necessary to work with live electrical components. Only a qualified licensed electrician or individual properly trained in handling live electrical components shall perform these tasks.
Standard NFPA-70E, an OSHA regulation requiring an Arc Flash Boundary to be field established and marked for identification of where appropriate Personal Protective Equipment (PPE) be worn, should be followed.
WARNING
UNIT HANDLING
To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor. Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage, injury or death.
WARNING
ROTATING COMPONENTS
Unit contains fans with moving parts that can cause serious injury. Do not open door containing fans until the power to the unit has been disconnected and fan has stopped rotating.
WARNING
Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access. Always re-install screws on the panel after installation or service is completed.
CAUTION
Rotation must be checked on all MOTORS AND COMPRESSORS of 3 phase units at startup by a qualified service technician. Scroll compressors are directional and can be damaged if rotated in the wrong direction. Compressor rotation must be checked using suction and discharge gauges. Fan motor rotation should be checked for proper operation. Alterations should only be made at the unit power connection
CAUTION
7
Do not clean DX refrigerant coils with hot water or steam. The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil.
Some chemical coil cleaning compounds are caustic or toxic. Use these substances only in accordance with the manufacturers usage instructions. Failure to follow instructions may result in equipment damage, injury or death.
WARNING
To prevent damage to the unit, do not use acidic chemical coil cleaners. Do not use alkaline chemical coil cleaners with a pH value greater than
8.5, after mixing, without first using an aluminum corrosion inhibitor in the cleaning solution.
CAUTION
CAUTION
Do not use oxygen, acetylene or air in place of refrigerant and dry nitrogen for leak testing. A violent explosion may result causing injury or death.
WARNING
Do not work in a closed area where refrigerant or nitrogen gases may be leaking. A sufficient quantity of vapors may be present and cause injury or death.
WARNING
COMPRESSOR CYCLING
5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes. 5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes. The cycle rate must not exceed 6 starts per hour.
WARNING
1. Startup and service must be performed
by a Factory Trained Service Technician.
2. The unit is for outdoor use only. See
General Information section for more unit information.
3. Every unit has a unique equipment
nameplate with electrical, operational and unit clearance specifications. Always refer to the unit nameplate for specific ratings unique to the model you have purchased.
4. READ THE ENTIRE INSTALLATION,
OPERATION AND MAINTENANCE MANUAL. OTHER IMPORTANT SAFETY PRECAUTIONS ARE PROVIDED THROUGHOUT THIS MANUAL.
5. Keep this manual and all literature
safeguarded near or on the unit.
8

CB Base Model and Features Description

CB - B - 060 - 3 - B - 1 : A D 0 0 0 A 0
Series and Generation
Design
Sequence
Unit Size
Voltage
Compressor
Type
Number
of
Circuits
1 2 3 4 5 6
7
BASE MODEL
SERIES AND GENERATION
CB
REVISION
B = Design Sequence
UNIT SIZE
024 = 24 MBH - 2 Ton - Vertical Discharge 036 = 36 MBH - 3 Ton - Vertical Discharge 048 = 48 MBH - 4 Ton - Vertical Discharge 060 = 60 MBH - 5 Ton - Vertical Discharge
VOLTAGE
1 = 230V/1Φ/60Hz 2 = 230V/3Φ/60Hz 3 = 460V/3Φ/60Hz 4 = 575V/3Φ/60Hz 8 = 208V/3Φ/60Hz 9 = 208V/1Φ/60Hz
COMPRESSOR TYPE
B = R-410A Two Step Scroll Compressor D = R-410A Variable Capacity Scroll Compressor F = R-410A Two Step Scroll Compressor with Sound Blanket H = R-410A Variable Capacity Scroll Compressor with Sound Blanket
NUMBER OF CIRCUITS
1 = One Circuit
FEATURE 1: AMBIENT CONTROL
0 = Standard (55°F Ambient) B = Adjustable Fan Cycling (35°F Ambient) D = Modulating Fan Pressure Control (35°F Ambient) F = Flooded Condenser Ambient Controls + Option B G = Flooded Condenser Ambient Controls + Option D
FEATURE 2: REFRIGERATION OPTIONS
0 = Standard - Split System Air Conditioner A = External Hot Gas Bypass B = Split System Heat Pump D = Modulating Hot Gas Reheat F = Options A + D G = Options B + D
FEATURE 3: CONTROLS
0 = Standard - Terminal Block A = Suction Pressure Transducer (F1- Wattmaster Reheat) H = Control Circuit Transformer J = Variable Capacity Compressor Integrated Controls S = Suction Pressure Transducer (Not F1 ­Wattmaster Controls) T = Control Circuit Transformer w/ Suction Pressure Transducer W = Wattmaster CB/F1 Controller
FEATURE 4: COIL PROTECTION
0 = Standard A = Polymer E-Coated Coil
FEATURE 5: CABINET OPTIONS
0 = Standard – Louvered Panels A = Wire Grille D = Corrosion Protection Paint G = Options A + D
FEATURE 6: WARRANTY
0 = Standard A = Second to Fifth Year Extended Compressor Warranty
FEATURE 7: TYPE
0 = Standard X = Special Pricing Authorization
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General Description

Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Startup and service must be performed by a Factory Trained Service Technician.
WARNING
Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment.
WARNING
The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1, 1992. Approved methods of recovery, recycling, or reclaiming must be followed.
CAUTION
Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty.
WARNING
AAON® CB Series condensing units have been designed for outdoor installation only. Startup and service must be performed by a Factory Trained Service Technician.

Codes and Ordinances

System should be sized in accordance with the American Society of Heating, Refrigeration and Air Conditioning Engineers Handbook.
Installation of CB Series units must conform to the ICC standards of the International Mechanical Code, the International Building Code, and local building, plumbing and waste water codes. All appliances must be electrically grounded in accordance with local codes, or in the absence of local codes, the current National Electric Code, ANSI/NFPA 70 or the current Canadian Electrical Code CSA C22.1.

Receiving Unit

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.
Nameplate should be checked to ensure the correct model sizes and voltages have been received to match the job requirements.
The warranty card must be completed in full and returned to AAON not more than 3 months after unit is delivered.

Storage

If installation will not occur immediately following delivery, store equipment in a dry protected area away from construction traffic and in the proper orientation as marked on the packaging with all internal packaging in place. Secure all loose-shipped items.
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Direct Expansion (DX) Condensing Units

CRANKCASE HEATER
OPERATION
Units are equipped with compressor crankcase heaters, which should be energized at least 24 hours prior to cooling operation, to clear any liquid refrigerant from the compressors.
CAUTION
CB Series condensing units are factory assembled and wired, including a full charge of R-410A refrigerant for up to 25 feet of line set. Systems with the modulating hot gas reheat option will require refrigerant to be field added because of the additional refrigerant components and piping associated with the system.
Refrigeration system includes factory provided liquid line filter drier and fully hermetic scroll compressor with a positive pressure forced lubrication system.
Never cut off the main power supply to the unit, except for servicing, emergency, or complete shutdown of the unit. When power is cut off from the unit, compressors using crankcase heaters cannot prevent refrigerant migration. This means the compressor may cool down and liquid refrigerant may accumulate in the compressor. Since the compressor is designed to pump refrigerant gas, damage may occur when power is restored.
If power to the unit must be off for more than an hour, turn the thermostat system
switch to “Off”, or turn the unit off at the
control panel, and then cut off the main power supply. Leave the unit off until the main power supply has been turned on again
for at least 24 hours. 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 servicing, emergency, or complete shutdown of the unit.
Note: Low Ambient Operation Units without a low ambient option, such as condenser fan cycling or the 0°F low ambient option, will not operate in the cooling mode of operation properly when the outdoor temperature is below 55°F. Low ambient and/or air handling unit economizer options are recommended if cooling operation below 55°F is expected.
Note: Multiple Systems with Multiple Thermostats When several heating and cooling split systems are used to condition a space all thermostat switches must be set in either heating mode, cooling mode or off. Do not leave part of the systems switched to the opposite mode. Cooling only systems should be switched off at the thermostat during the heating season.

Wiring Diagrams

Unit specific wiring diagram is laminated in plastic and located inside the controls compartment door.
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Installation

AAON equipment has been designed for quick and easy installation.

Locating Unit

CB Series condensing units are designed for outdoor application and placement at ground level or on a rooftop. Units must be placed on a level and solid foundation that can support the unit’s weight.
When rooftop mounted, a steel frame must be provided that will support the unit above the roof itself for load distribution.
When installed at ground level, a one-piece concrete slab or composite condenser pad should be used with footings that extend below the frost line (a substantial base that will not settle). Slab should be surrounded by a graveled area for proper drainage and should not adjoin the building as sound and vibration may be transmitted to the structure. Care must also be taken to protect the coils and fins from damage due to vandalism or other hazards.
Airflow to and from the condensing unit must not be restricted. Coils and fans must be free of any obstructions and debris in order to start and operate properly with a correct amount of airflow. Obstruction to air flow will result in decreased performance and efficiency.
The installation position must provide at least one foot of clearance from the wall for proper air flow to the coils. When multiple units are mounted adjacent to each other, the clearance required between them is three feet.
Service compartment must be accessible for periodic servicing of controls, safety devices, and refrigerant service/shutoff
valves. At least two feet of clearance on this corner of the unit is recommended for service.
Figure 1 – Condensing Unit Clearances
Condensing units should not be installed in an enclosure or pit that is deeper than the height of the unit. When recessed installation is necessary, the clearance to maintain proper airflow is at least three feet.
CB Series condensing units are single circuited with vertical air discharge. There must be no obstruction above the equipment. Do not place the unit under an overhang.
Placement relative to the building air intakes and other structures must be carefully selected. Consider the effects of outdoor fan noise on conditioned space and any adjacent occupied space. It is recommended that the unit be placed so that discharge does not
12
blow toward windows less than 25 feet
Design
Temperature
Suggest Minimum
Elevation
+15 F and above
3”
-5 F to +17 F
8”
Below -5 F
12”
Incorrect lifting can cause damage to the unit.
CAUTION
Electric shock hazard. Before attempting to perform any installation, service, or maintenance, shut off all electrical power to the unit at the disconnect switches. Unit may have multiple power supplies. Failure to disconnect power could result in dangerous operation, serious injury, death or property damage.
WARNING
away.
Heat pumps require special location consideration in areas where snow accumulation can become an obstruction and in areas with prolonged continuous subfreezing temperatures. Heat pump unit bases are cutout under the outdoor coil to permit drainage of frost accumulation. The unit must be situated to permit free unobstructed drainage of the defrost water and ice. A minimum 3 inches clearance under the outdoor coil is required in the milder climates. In more severe weather locations, it is recommended that the unit be elevated to allow unobstructed drainage and airflow.
Table 1 - Recommended Elevation
Minimums

Lifting the Unit

CB Series condensing units have channels underneath the base which provide lifting access to the underside of the equipment and allow moving and placement without physical damage.
Dollies and/or carts are recommended to lift and place the unit to prevent damage to the equipment and injury to the installer.
Care should be taken if using spreader bars, blocking, or other lifting devices to prevent
any damage to the cabinet, coil or condensing fans.
Before lifting unit, be sure that all shipping material has been removed from unit.
Hoist unit to a point directly above the condenser pad, and lower unit into the proper place. Unit may also be positioned with a dolly. When the unit is in place, remove the dolly or lifting device. Make sure the unit is properly seated and level.

Electrical

Verify the unit nameplate agrees with the power supply. Connect power and control field wiring as shown on the unit wiring diagram provided with the unit.
Route power and control wiring through the utility entries on the unit. It is recommended not to run power and control signal wires in the same conduit. If the control wires are to run inside the same conduit, 600 volt wires should be used, or as required by applicable codes.
Size supply conductors based on the unit MCA rating. Supply conductors must be rated a minimum of 75°C.
Protect the branch circuit in accordance with code requirements. The unit must be
13
electrically grounded in accordance with
Scroll compressors are directional and will be damaged by operation in the wrong direction. Low pressure switches on compressors have been disconnected after factory testing. Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection.
Three phase voltage imbalance will cause motor overheating and premature failure.
CAUTION
Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units. Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection.
CAUTION
CAUTION
local codes, or in the absence of local codes, the current National Electric Code, ANSI/NFPA 70 or the current Canadian Electrical Code CSA C22.1.
Note: Units are factory wired for 208V, 230V, 460V or 575V. In some units, the 208V and 230V options may also be provided in single or three phase configurations. The transformer configuration must be checked by a qualified technician prior to startup.
Wire power leads to the unit terminal block or compressor contactor. All wiring beyond this point has been done by the manufacturer and cannot be modified without effecting the unit's agency/safety certification.
All units require field supplied electrical overcurrent and short circuit protection. Device must not be sized larger than the Maximum Overcurrent Protection (MOP) shown on the unit nameplate.
Codes may require a disconnect switch be within sight of the unit.
It is recommended that the field installed overcurrent protection or disconnect switch not be installed on the unit.
Supply voltage must be within the min/max range shown on the unit nameplate. Available short circuit current should not exceed the short circuit current rating (SCCR) shown on the unit nameplate.
Three phase voltage imbalance will cause motor overheating and premature failure. The maximum allowable imbalance is 2.0%.
Voltage imbalance is defined as 100 times the maximum deviation from the average voltage divided by the average voltage.
Example: (221V+230V+227V)/3 = 226V, then 100*(226V-221V)/226V = 2.2%, which exceeds the allowable imbalance.
Check voltage imbalance at the unit disconnect switch and at the compressor terminal. Contact your local power company for line voltage corrections.
Installing contractor must check for proper motor rotation and check blower motor amperage listed on the motor nameplate is not exceeded.
14
Wire control signals to the unit’s low
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 condenser or condensing unit and the air handling unit. AAON is not responsible for interconnecting refrigerant piping. Consult ASHRAE Handbook – Refrigeration and ASME Standards.
CAUTION
voltage terminal block located in the controls compartment.
If any factory installed wiring must be replaced, use a minimum 105°C type AWM insulated conductors.

Thermostat

If a thermostat is used for unit control, thermostat should be located on an inside wall 4-5 feet above the floor where it will not be subjected to drafts, sun exposure, or heat from electrical fixtures or appliances.
Follow thermostat manufacturer’s
instructions for general installation procedure.
Thermostat control wiring size must be large enough to prevent excess voltage drop and ensure proper operation.
All external devices must be powered via a separate external power supply.
Units with the modulating hot gas reheat dehumidification feature must use a humidistat or a thermostat with a normally closed (NC) dehumidification option. The following thermostats have been approved for usage with the dehumidification feature,
Robertshaw® 9825i2 Thermostat
Honeywell VisionPRO® IAQ Thermostat
AAON Mini Controller

Refrigerant Piping

(See back of the manual for refrigerant piping diagrams.)

General

Piping from the condensing unit to the air handler is the responsibility of the installing contractor.
Use only clean type “ACR” copper tubing
that has been joined with high temperature brazing alloy.
The pipe or line sizes must be selected to meet the actual installation conditions and not simply based on the connection sizes at the condensing unit or air handler.
All CB Series condensing units are provided with in-line shutoff valves on both the liquid and suction lines. These should remain closed until the system is ready for start-up after piping and vacuuming.
Piping should conform to generally accepted practices and codes.
Upon completion of piping connection, the interconnecting piping and air handler MUST BE evacuated to 500 microns or less; leak checked and charged with refrigerant.
15

Determining Refrigerant Line Size

Line sizes must be selected to meet actual installation conditions, not simply based on the connection sizes at the condensing unit or air handling unit.
CAUTION
The piping between the condenser and low side must ensure:
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 Thermal Expansion Valve (TXV) 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.
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. Pressure losses through the liquid line due to frictional contact, installed accessories, and vertical risers are inevitable. Maintaining adequate sub­cooling at the condenser to overcome these losses is the only method to ensure that liquid refrigerant reaches the TXV.
Liquid refrigerant traveling upwards in a riser loses head pressure. If the evaporator 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 field 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.
16
Liquid Line Routing
Circuits with variable capacity scroll compressors require suction riser traps every 10 feet.
CAUTION
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 sub­cooling through heat gain.
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 1-2°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 shut off valves and filter driers are factory provided. Filter driers must be field 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 foot per 120 feet 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.
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.
17
A double suction riser can be applied to the situation of part load operation with a suction riser. A double suction riser is designed to return oil at minimum load while not incurring excessive frictional losses at full load. A 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 so that flow through both pipes provides acceptable pressure drop at full load.
Suction Line Insulation
The entire suction line should be insulated with a minimum 1 inch thick Armaflex insulation. 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 4,000 fpm maximum are recommended. The minimum velocity required to return oil is dependent on the pipe diameter, however, a general guideline of 1,000 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 runs and vertical drop sections. This will however require additional refrigerant charge.
Circuits with variable capacity scroll compressors require suction riser traps every 10 feet.
Suction Line Accessories
If the job requirements specify suction accumulators, they must be separately purchased and field installed.
Hot Gas Bypass Line Hot Gas Bypass (HGB) 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.
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.
18
When installing hot gas bypass risers, an oil drip line must be provided at the lowest point in the system. The oil drip line 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 oil drip line for observation. Run an oil return line, using 1/8 inch capillary tube, 10 feet in length, from the oil drip line to the suction line. Connect the oil return line below the sight glass and 1 inch above the bottom of the oil drip line.
HGB valves are adjustable. Factory HGB valve settings will be sufficient for most applications, but may require slight adjustments for some applications, including some make up air applications.
Insulate the entire length of the HGB line with a minimum 1 inch thick Armaflex insulation.
Hot Gas Bypass Piping Considerations for Evaporator Below Condensing Unit
The line must slope downward from the HGB valve toward the evaporator.
Hot Gas Bypass Line Guidelines
Choose a small size line to ensure oil return, and minimize refrigerant charge.
Maintain velocities below a maximum of 4,000 fpm. A general minimum velocity guideline to use is approximately 1,000 fpm.

Hot Gas Reheat

The AAON modulating hot gas reheat system diverts hot discharge gas from the condenser to the air handling unit through the hot gas line. Field piping between the
condensing unit and the air handler is required.
The line delivers the hot discharge gas to the reheat coil and/or the hot gas bypass valve, so it is sized 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.
When installing hot gas reheat risers, an oil drip line must be provided at the lowest point in the system. The oil drip line must be vertical, its diameter should be the same as the diameter of the riser, and it should be 1 foot long. Run a drip line, using 1/8 inch capillary tube, 10 feet in length, from the oil drip line to the suction line. Connect the oil return line below the sight glass and 1 inch above the bottom of the oil drip line.
Insulate the entire length of the hot gas line with a minimum 1 inch thick Armaflex insulation.
Hot Gas Reheat Guidelines
Maintain velocities below a maximum of 3,500 fpm. A general minimum velocity guideline is 2,000 fpm.

Predetermined Line Sizes

To aid in line sizing and selection, AAON has predetermined line sizes for the liquid, suction, and hot gas lines in 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.
19
The liquid lines have been chosen to
Before using this table read the
When to Use Predetermined Line Sizes section. Do not assume that
these line sizes are appropriate for every case. Consult ASHRAE Handbook Refrigeration for generally accepted system piping practices. The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing.
CAUTION
maintain velocities between 100 and 350 fpm. The suction line diameters are selected to limit velocities to a 4,000 fpm maximum, while a minimum velocity restriction is imposed by the ability to entrain oil up vertical suction risers (ASHRAE Handbook
- Refrigeration).
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 sub­cooling 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 sub-cooling 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 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. 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 for generally accepted system piping practices.
How to Use Predetermined Line Sizing First, read the previous section, When to Use Predetermined Line Sizing, to decide if this
method is applicable. Next, consult Table 2 below for pipe diameters.
Examine Figure 2 below to determine the acceptable line dimensions associated with the pipe diameters determined in Table 2 below. The figure is shown as total available riser height versus total equivalent line length for the liquid line. The 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 sub­cooling, and additional pressure losses in the suction and hot gas 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.
The figure below is presented in terms of the liquid line, but it assumes that the suction line length is similar, as these lines are commonly routed together to minimize the space and cost required for split system installation.
20
Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A
Model
Connection Sizes
Predetermined Line Size
Liquid
Suction
Hot Gas
Liquid
Suction
HGBP*
HGRH**
CB-024
3/8”
3/4”
3/8”
3/8”
3/4”
3/8”
3/8”
CB-036
3/8”
3/4”
3/8”
3/8”
3/4”
3/8”
1/2”
CB-048
3/8”
7/8”
1/2”
1/2
7/8”
1/2”
1/2”
CB-060
3/8”
7/8”
1/2”
1/2”
7/8”
1/2”
1/2”
Total Equivalent Line Length in this figure is limited to 160 equivalent feet.
CAUTION
* Hot Gas Bypass line ** Hot Gas Reheat line
Figure 2 - Riser height versus total equivalent line length
Note: Figure 2 is for R-410A split system applications with two step compressor CB-024 through CB-060 units. The region of acceptable riser height is the lighter area. Select the corresponding predetermined line size from Table 2 above.
21

Startup

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units. Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection.
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 trained, qualified installer.
WARNING
Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.
WARNING
CAUTION
Scroll compressors are directional and will be damaged by operation in the wrong direction. Low pressure switches on compressors have been disconnected after factory testing. Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection.
CAUTION
The Clean Air Act of 1990 bans the intentional venting of refrigerant
(CFC’s and HCFC’s) as of July 1,
1992. Approved methods of recovery, recycling or reclaiming must be followed. Fines and/or incarceration may be levied for non-compliance.
CAUTION
(See back of the manual for startup form.)

Compressors

All compressors are equipped with crankcase heaters, which should be energized at least 24 hours prior to cooling operation of the compressor.

Charging Refrigerant & Adjusting Refrigerant Charge

The unit comes with full charge based on a 25 foot line set. Charging a system in the field must be based on determination of liquid sub-cooling and evaporator superheat. On a system with a TXV, liquid sub-cooling is more representative of the charge than evaporator superheat but both measurements must be taken.

Before Charging

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.
22
Units equipped with hot gas reheat must be
Air-Cooled Condenser
Sub-Cooling*
12-18°F
Sub-Cooling with
Hot Gas Reheat*
15-22°F
Superheat**
8-15°F
Air-Source Heat Pump
Sub-Cooling*
2-4°F
Sub-Cooling with
Hot Gas Reheat*
15-22°F
Superheat**
16-22°F
charged with the hot gas valves closed while the unit is in cooling mode. After charging, unit should be operated in reheat (dehumidification) mode to check for correct operation.
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 3 below 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.

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as it leaves the condenser coil.
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.
Convert the pressure obtained to a saturated temperature using the appropriate refrigerant temperature-pressure chart or Table 5 below.
Subtract the measured liquid line temperature from the saturated temperature to determine the liquid sub-cooling.
Compare calculated sub-cooling to Table 3 below for the appropriate unit type and options.

Checking Evaporator Superheat

Measure the temperature of the suction line close to the compressor.
Read gauge pressure at the suction line close to the compressor.
Convert the pressure obtained to a saturated temperature using the appropriate refrigerant temperature-pressure chart or Table 5 below.
Subtract the saturated temperature from the measured suction line temperature to determine the evaporator superheat.
Compare calculated superheat to Table 3 below for the appropriate unit type and options.
Table 3 - Sub-cooling and Superheat
* Sub-cooling must be increased by 2°F per 20 feet of vertical liquid line rise for R-410A ** Superheat will increase with long suction line runs.

Adjusting Sub-cooling and Superheat Temperatures

The system is overcharged if the sub-cooling temperature is too high and the evaporator is fully loaded (low loads on the evaporator result in increased sub-cooling) and the evaporator superheat is within the temperature range as shown in Table 3 above (high superheat results in increased sub-cooling)
23
Correct an overcharged system by reducing
Model
Cooling Stage 2
(cfm)
Cooling Stage 1
(cfm)
Heating Stage 2
(cfm)
Heating Stage 1
(cfm)
CB-B-024-*-*-1
885
663.75
885
796.5
CB-B-036-*-*-1
1250
937.5
1250
1125
CB-B-048-*-*-1
1500
1125
1500
1350
CB-B-060-*-*-1
1545
1158.75
1545
1390.5
DO NOT OVERCHARGE!
Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure.
CAUTION
Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly.
CAUTION
the amount of refrigerant in the system to lower the sub-cooling.
The system is undercharged if the superheat is too high and the sub-cooling is too low

Air Flow

Table 4 - Performance Testing Air Flow Setpoints
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.
24
Table 5 - R-410A Refrigerant Temperature-Pressure Chart
°F
PSIG
°F
PSIG
°F
PSIG
°F
PSIG
°F
PSIG
20
78.3
47
134.7
74
213.7
101
321.0
128
463.2
21
80.0
48
137.2
75
217.1
102
325.6
129
469.3
22
81.8
49
139.7
76
220.6
103
330.2
130
475.4
23
83.6
50
142.2
77
224.1
104
334.9
131
481.6
24
85.4
51
144.8
78
227.7
105
339.6
132
487.8
25
87.2
52
147.4
79
231.3
106
344.4
133
494.1
26
89.1
53
150.1
80
234.9
107
349.3
134
500.5
27
91.0
54
152.8
81
238.6
108
354.2
135
506.9
28
92.9
55
155.5
82
242.3
109
359.1
136
513.4
29
94.9
56
158.2
83
246.0
110
364.1
137
520.0
30
96.8
57
161.0
84
249.8
111
369.1
138
526.6
31
98.8
58
163.8
85
253.7
112
374.2
139
533.3
32
100.9
59
166.7
86
257.5
113
379.4
140
540.1
33
102.9
60
169.6
87
261.4
114
384.6
141
547.0
34
105.0
61
172.5
88
265.4
115
389.9
142
553.9
35
107.1
62
175.4
89
269.4
116
395.2
143
560.9
36
109.2
63
178.4
90
273.5
117
400.5
144
567.9
37
111.4
64
181.5
91
277.6
118
405.9
145
575.1
38
113.6
65
184.5
92
281.7
119
411.4
146
582.3
39
115.8
66
187.6
93
285.9
120
416.9
147
589.6
40
118.1
67
190.7
94
290.1
121
422.5
148
596.9
41
120.3
68
193.9
95
294.4
122
428.2
149
604.4
42
122.7
69
197.1
96
298.7
123
433.9
150
611.9
43
125.0
70
200.4
97
303.0
124
439.6
44
127.4
71
203.6
98
307.5
125
445.4
45
129.8
72
207.0
99
311.9
126
451.3
46
132.2
73
210.3
100
316.4
127
457.3
25

Operation

COMPRESSOR CYCLING
5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes.
5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes.
The cycle rate must not exceed 6 starts per hour.
WARNING
Unit operations should be controlled with thermostat, or unit controller, never at the main power supply, except for emergency, servicing, or complete shutdown of the unit.

Thermostat Operation

Heating Thermostat system switch - "Heat" Thermostat fan switch - "Auto" or "On" Thermostat temperature set to desired point.
Cooling Thermostat system switch - "Cool" Thermostat fan switch - "Auto" or "On" Thermostat temperature set to desired point.
Air Circulation Thermostat system switch - "Off" Thermostat fan switch - "Auto" or "On" No change of the thermostat temperature. With these settings, the air handler’s supply fan will run continuously but the supply air will not be heated, cooled, or dehumidified.
System Off Thermostat system switch - "Off" Thermostat fan switch - "Auto" No change of the thermostat temperature. With these settings, the system is shut down, with the exception of the control system power (24 VAC), and the crankcase heaters (about 60 watts/compressor).
Night and Weekend Unoccupied Operation To reduce the operating time of the unit when the space is unoccupied, such as nights and weekends, it is recommended that the temperature setting be raised about 5°F while unoccupied during the cooling season and lowered about 10°F during the heating season.

Compressor

The compressors must be off for a minimum of 5 minutes and on for a minimum of 5 minutes. Short cycling of the compressors can causes undue stress and wear.

Variable Capacity Compressor Controller

Units with variable capacity scroll compressors may include variable capacity compressor controller. The following is an explanation of the terminals and troubleshooting of the alert flash codes on the controller. For more information on the compressor controller, see Emerson Climate Bulletin AE8-1328.
26
Figure 3 - Variable Capacity Compressor
Demand
Signal (VDC)
Loaded %
Unloaded %
Time Loaded
Time
Unloaded
% Compressor
Capacity
1.00
Off
Off
Off
Off
0%
1.44
10%
90%
1.5 sec
13.5 sec
10%
3.00
50%
50%
7.5 sec
7.5 sec
50%
4.20
80%
20%
12 sec
3 sec
80%
5.00
100%
0%
15 sec
0 sec
100%
To avoid damaging the compressor controller, DO NOT connect wires to terminals C3, C4, T3, T4, T5, or T6.
WARNING
Controller
Low Voltage Terminals
24COM Module Common 24VAC Module Power C1 & C2 Demand Input P1 Pressure Common P2 Pressure Input P3 Pressure Power 5VDC P4 Pressure Shield P5 & P6 Pressure Output T1 & T2 Discharge Temperature Sensor
Table 6 - Demand Signal vs. Compressor Capacity Modulation
High Voltage Terminals
A1 & A2 Alarm Relay Out M1 & M2 Contactor L1 Control Voltage N L2 Control Voltage L U1 & U2 Digital Unloader Solenoid V1 & V2 Vapor Injection Solenoid
The compressor controller modulates the compressor unloader solenoid in an on/off pattern according the capacity demand signal of the system. The following table shows the linear relationship between the demand signal and compressor capacity modulation. The compressor controller also protects the compressor against high discharge temperature. Refer to Table 7 for the relationship between thermistor temperature readings and resistance values.
27
Figure 4 - Compressor Controller Flash Code Details
°C
°F
°C
°F
-40
-40
2889.60
75
167
12.73
-35
-31
2087.22
80
176
10.79
-30
-22
1522.20
85
185
9.20
-25
-13
1121.44
90
194
7.87
-20
-4
834.72
95
203
6.77
-15
5
627.28
100
212
5.85
-10
14
475.74
105
221
5.09
-5
23
363.99
110
230
4.45 0 32
280.82
115
239
3.87 5 41
218.41
120
248
3.35
10
50
171.17
125
257
2.92
15
59
135.14
130
266
2.58
20
68
107.44
135
275
2.28
25
77
86.00
140
284
2.02
30
86
69.28
145
293
1.80
35
95
56.16
150
302
1.59
40
104
45.81
155
311
1.39
45
113
37.58
160
320
1.25
50
122
30.99
165
329
1.12
55
131
25.68
170
338
1.01
60
140
21.40
175
347
0.92
65
149
17.91
180
356
0.83
70
158
15.07
Table 7 - Thermistor Temperature vs. Resistance Values
28

Low Ambient Options

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 trained, qualified installer.
WARNING
Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.
WARNING
The condenser fan cycling option is used to operate a refrigerant system down to 35°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 0°F low ambient system maintains normal head pressure during periods of low ambient by effectively reducing the heat transfer surface area, reducing capacity and increasing condensing pressure, allowing the system to operate properly. During periods with higher ambient temperatures the entire condenser is required to condense refrigerant.

Maintenance

(See back of the manual for maintenance log.)
At least once each year, a qualified service technician should check out the unit. This includes reading and recording suction pressures and checking for normal sub­cooling and superheat.
Only trained and qualified service technicians experienced in both condensing units and air conditioning are permitted to service the CB Series units to keep warranties in effect.

Coils

The condenser coils should be inspected yearly to ensure unrestricted airflow. If the coils contain a large amount of airborne dust or other material, they should be cleaned. Care must be taken to prevent bending of the aluminum fins on the coils.
Before attempting to clean the coils; set thermostat to the "OFF" position; turn the electrical power to the unit to the "OFF" position at the disconnect switch. The condenser coil can be cleaned by washing from the inside out with water and a coil cleaner. If coil is extremely dirty with clogged fins, a service professional specializing in coil cleaning should be called.

E-Coated Coil Cleaning

Documented routine cleaning of e-coated coils is required to maintain coating warranty coverage.
Surface loaded fibers or dirt should be removed prior to water rinse to prevent restriction of airflow. If unable to back wash the side of the coil opposite of the coils entering air side, then surface loaded fibers or dirt should be removed with a vacuum cleaner. If a vacuum cleaner is not available, a soft non-metallic bristle brush may be
29
used. In either case, the tool should be
High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin and/or coil damages. The force of the water or air jet may bend the fin edges and increase airside pressure drop. Reduced unit performance or nuisance unit shutdowns may occur.
CAUTION
Harsh chemicals, household bleach, or acid cleaners should not be used to clean outdoor or indoor e-coated coils. These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating. If there is dirt below the surface of the coil, use the recommended coil cleaners.
CAUTION
applied in the direction of the fins. Coil surfaces can be easily damaged (fin edges bent over) if the tool is applied across the fins.
Use of a water stream, such as a garden hose, against a surface loaded coil will drive the fibers and dirt into the coil. This will make cleaning efforts more difficult. Surface loaded fibers must be completely removed prior to using low velocity clean water rinse.
A monthly clean water rinse is recommended for coils that are applied in coastal or industrial environments to help to remove chlorides, dirt, and debris. It is very important when rinsing, that water temperature is less than 130°F and pressure is than 900 psig to avoid damaging the fin edges. An elevated water temperature (not to exceed 130°F) will reduce surface tension, increasing the ability to remove chlorides and dirt.
Quarterly cleaning is essential to extend the life of an e-coated coil and is required to maintain coating warranty coverage.
Coil cleaning shall be part of the unit’s
regularly scheduled maintenance procedures. Failure to clean an e-coated coil will void the warranty and may result in reduced efficiency and durability.
For routine quarterly cleaning, first clean the coil with the below approved coil cleaner. After cleaning the coils with the approved cleaning agent, use the approved chloride remover to remove soluble salts and revitalize the unit.
Recommended Coil Cleaner The following cleaning agent, assuming it is
used in accordance with the manufacturer’s
directions on the container for proper mixing and cleaning, has been approved for use on e-coated coils to remove mold, mildew, dust, soot, greasy residue, lint, and other particulate:
Enviro-Coil Concentrate, Part Number H­EC01.
Recommended Chloride Remover CHLOR*RID DTS™ should be used to remove soluble salts from the e-coated coil, but the directions must be followed closely. This product is not intended for use as a degreaser. Any grease or oil film should first be removed with the approved cleaning agent.
Remove Barrier - Soluble salts adhere themselves to the substrate. For the effective use of this product, the product must be able to come in contact with the salts. These salts
30
may be beneath any soils, grease or dirt; therefore, these barriers must be removed prior to application of this product. As in all surface preparation, the best work yields the best results.
Apply CHLOR*RID DTS - Apply directly onto the substrate. Sufficient product must be applied uniformly across the substrate to thoroughly wet out surface, with no areas missed. This may be accomplished by use of a pump-up sprayer or conventional spray gun. The method does not matter, as long as the entire area to be cleaned is wetted. After the substrate has been thoroughly wetted, the salts will be soluble and is now only necessary to rinse them off.
Rinse - It is highly recommended that a hose be used, as a pressure washer will damage the fins. The water to be used for the rinse is recommended to be of potable quality, though a lesser quality of water may be used if a small amount of CHLOR*RID DTS is added. Check with CHLOR*RID International, Inc. for recommendations on lesser quality rinse water.

DX Cooling

Set unit controls to cooling mode of operation with supply fans on. Check compressor operation, rotation, amperage and voltage to the unit nameplate (check the amperage on the load side of the compressor contactor).
The scroll compressors are fully hermetic and require no maintenance except for keeping the shell clean.
Refrigerant circuit includes factory provided and field installed line filter drier. The unit does not include a liquid line solenoid valve. This must be field furnished and installed if required by job conditions.

Condenser Fan Motor

All original motors and bearings are furnished with factory lubrication. They require no lubrication.
The electrically commutated condenser fan motor (ECM) is factory preprogrammed and requires no maintenance.

Replacement Parts

Parts for AAON equipment may be obtained from AAON at www.aaonparts.com. When ordering parts, reference the unit serial number and part number.
AAON – Longview Warranty, Service, and Parts Department
203 Gum Springs Rd. Longview, TX 75602 Ph: 903-236-4403 Fax: 903-247-9219 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.
31

Refrigerant Piping Diagrams

Figure 5– A/C only piping, AHU above CU
32
Figure 6 – A/C only piping, AHU below CU
33
Figure 7 – Modulating hot gas reheat piping, AHU above CU
34
Figure 8 – Modulating hot gas reheat piping, AHU below CU
35
Figure 9 – Hot gas bypass piping, AHU above CU
36
Figure 10 – Hot gas bypass piping, AHU below CU
37
Figure 11 – Modulating hot gas reheat with hot gas bypass piping, AHU above CU
38
Figure 12 – Modulating hot gas reheat with hot gas bypass piping, AHU below CU
39
Figure 13 – Heat pump piping, AHU above CU
40
Figure 14 – Heat pump piping, AHU below CU
41
Figure 15 – Heat pump with modulating hot gas reheat piping, AHU above CU
42
Figure 16 – Heat pump with modulating hot gas reheat, AHU below CU
Date:______________
Job Name:_____________________________________________________________________
Address:______________________________________________________________________
Model Number:_________________________________________________________________
______________________________________________________________________________
Serial Number:_____________________________________________
Tag:_______________
Startup Contractor:______________________________________________________________
Address:__________________________________________________ _________________________________________________________
Phone:_____________
Pre Startup Checklist
Installing contractor should verify the following items.
1. Is there any visible shipping damage?
Yes
No
2. Is the unit level?
Yes
No
3. Are the unit clearances adequate for service and operation?
Yes
No
4. Do all access doors open freely and are the handles operational?
Yes
No
5. Have all shipping braces been removed?
Yes
No
6. Have all electrical connections been tested for tightness?
Yes
No
7. Does the electrical service correspond to the unit nameplate?
Yes
No
8. On 208/230V units, has transformer tap been checked?
Yes
No
9. Has overcurrent protection been installed to match the unit nameplate requirement?
Yes
No
10. Have all set screws on the fans been tightened?
Yes
No
11. Do all fans and pumps rotate freely?
Yes
No
12. Is all copper tubing isolated so that it does not rub?
Yes
No
Ambient Temperature
Ambient Dry Bulb Temperature ________°F
Ambient Wet Bulb Temperature ________°F
Refrigeration System 1 - Cooling Mode
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
Suction
Liquid

CB Series Startup Form

Refrigeration System 1 - Heating Mode (Heat Pump Only)
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
Suction
Liquid
Air-Cooled Condenser Fan
Alignment_____
Check Rotation_____
Nameplate Amps________
Number
hp
L1
L2
L3
1
Entry Date
Action Taken
Name/Tel.
Maintenance Log
This log must be kept with the unit. It is the responsibility of the owner and/or maintenance/service contractor to document any service, repair or adjustments. AAON Service and Warranty Departments are available to advise and provide phone help for proper operation and replacement parts. The responsibility for proper start-up, maintenance and servicing of the equipment falls to the owner and qualified licensed technician.
Literature Change History June 2013
New installation and operation manual
AAON
2425 South Yukon Ave.
Tulsa, OK 74107-2728
Phone: 918-583-2266
Fax: 918-583-6094
www.aaon.com
CB Series
Installation, Operation &
Maintenance
R57611 · Rev. - · 130603
(ACP J00187)
It is the intent of AAON to provide accurate and current product information. However, in the interest of product improvement, AAON reserves the right to change pricing, specifications, and/or design of its product without notice, obligation, or liability.
Copyright © AAON, all rights reserved throughout the world.
AAON® and AAONAIRE® are registered trademarks of AAON, Inc., Tulsa, OK.
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