CN Series Condensing Units Installation, Operation, & Maintenance WARNING WARNING QUALIFIED INSTALLER FOR YOUR SAFETY 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. Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance.
Table of Contents Safety .............................................................................................................................................. 5 CN Series Feature String Nomenclature ......................................................................................... 9 General Information ...................................................................................................................... 12 Codes and Ordinances .................................................
Index of Tables and Figures Tables: Table 1 - Service Clearances......................................................................................................... 15 Table 2 - Condenser Flooding....................................................................................................... 24 Table 3 - Condenser Fan Pin Location ......................................................................................... 28 Table 4 - Condenser Fan Pin Location .....................................
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.
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 Electric shock hazard.
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. CAUTION Door compartments containing hazardous voltage or rotating parts are equipped with door latches that allow locks. Door latches are shipped with a nut and bolt requiring tooled access.
WARNING Some chemical coil cleaning compounds are caustic or toxic. Use these substances only in accordance with the manufacturer’s usage instructions. Failure to follow instructions may result in equipment damage, injury or death. CAUTION 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.
CN Series Feature String Nomenclature : CN A - 055 - A - 0 - 3 - C A 0 0 E : 0 - 0 0 - E 0 - D 0 - 0 0 0 - 0 - DA 0 15 14 13 12 11 10 9 8C 8D 8B 8A 7 6C 6B 6A 5 4 3B 3A 2B 2A Unit Feature Options 1 A5 A4 A3 A2 A1 VLT MNREV SERIES SIZE MJREV 0 - 0 0 0 0E0 0 CN Series Feature String Nomenclature MODEL OPTIONS Series and Generation CN Major Revision A Unit Size 055 = 55 ton Capacity 065 = 65 ton Capacity 075 = 75 ton Capacity 090 = 90 ton Capacity 105 = 105 ton Capacity 12
CN Series Feature String Nomenclature : CN A - 055 - A - 0 - 3 - C A 0 0 E : 0 - 0 0 - E 0 - D 0 - 0 0 0 - 0 - DA 0 0 - 0 0 0 15 14 13 12 11 10 9 8C 8D 8B 8A 7 6C 6B 6A 5 4 3B 3A 2B 2A Unit Feature Options 1 A5 A4 A3 A2 A1 VLT MNREV SERIES SIZE MJREV 0E0 0 4: Refrigeration Accessories 0 = None A = Sight Glass B = Compressor Isolation Valves C = Options A + B D = Flooded Condenser 0°F Low Ambient Controls One Circuit E = Options A + D F = Options B + D G = Options A + B +
CN Series Feature String Nomenclature : 15 14 13 12 11 10 9 8C 8D 8B 8A 7 6C 6B 6A 5 4 3B 3A 2B 2A Unit Feature Options 1 A5 A4 A3 A2 A1 VLT MNREV SERIES SIZE MJREV GEN Model Options CN A - 055 - A - 0 - 3 - C A 0 0 E : 0 - 0 0 - E 0 - D 0 - 0 0 0 - 0 - D A 0 0 - 0 0 11: Maintenance Accessories 0 = None A = 115VAC Convenience Outlet - Factory Wired B = 115VAC Convenience Outlet - Field Wired C = Service Access Lights E = Remote Unit Start/Stop Terminals F = Options A + C
General Information AAON CN Series condensing units are complete air-cooled condensing units ranging from 55 to 140 tons of cooling capacity. They are assembled, wired, and tested. WARNING 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 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. Failure to observe the following instructions will result in premature failure of your system, and possible voiding of the warranty.
Compressor life will be seriously shortened by reduced lubrication, and the pumping of excessive amounts of liquid oil and liquid 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.
Installation Unit Placement The AAON CN Series 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. 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 condensing unit for operational and service clearances.
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. Hoist unit to a point directly above the curb or mounting rail. Be sure that the gasket material has been applied to the curb or mounting rail. Figure 1 - Curb Mounting with Dimensions Carefully lower and align unit with utility and duct openings. Lower the unit until the unit skirt fits around the curb.
the flashings must be installed on each end of the unit to complete the finished seal at the base. The flashings are unit specific and designed to cover the slot at each end of the unit to prevent water run-off into the curb. Failure to attach and seal the end of unit with the flashings may result in water leakage into the curb. Figure 5 - CN Series A Cabinet Top Lifting Detail Figure 6 - CN Series B and C Cabinet Bottom Lifting Detial Lifting slot locations are unit specific.
CAUTION PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals. Polyolester (POE) oils used with R-410A and other refrigerants, even in trace amounts, in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure. Mounting Isolation For roof mounted applications or anytime vibration transmission is a factor, full perimeter vibration isolators may be used.
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.
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 expansion valve, 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.
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.
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.
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 (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. Figure 7 - Piping Schematic of Example System Using the LAC Valve.
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. Verify the unit nameplate voltage agrees with the power supply. Connect power and control field wiring as shown on the unit specific wiring diagram provided with the unit.
CAUTION Figure 8 - Terminal Block Startup technician must check for proper motor rotation and check fan motor amperage listed on the motor nameplate is not exceeded. Motor overload protection may be a function of the variable frequency drive and must not be bypassed. Note: All units are factory wired for 208/230V, 460V, or 575V. Wire control signals to the unit’s low voltage terminal block located in the controls compartment.
Startup (See back of the manual for startup form) WARNING Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts. WARNING 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 Before the startup of the condensing unit be sure that the following items have been checked. 1.
2. Determine the direction of rotation Right, R, is clockwise when facing the discharge side of the fan and Left, L, is counterclockwise when facing the discharge side of the fan. 3. Determine the bushing mount location The bushing mount 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. Location A is with the bushing mount on air inlet side of the fan.
6. Determine the current blade pitch and the pin location for the new blades Type 5Z Bushing Mount A B Type Rot. 5Z R L 20° - 20° - Table 3 - Condenser Fan Pin Location Blade Pitch Angle 25° 28° 30° 33° 35° 38° RET RET RET RET HUB HUB HUB HUB HUB RET 40° HUB RET 45° HUB RET 50° HUB RET Table 4 - Condenser Fan Pin Location Blade Pitch Angle 25° 28° 30° 33° 35° 38° 4 3 2 1 4 1 2 3 4 1 40° 3 2 45° 2 3 50° 1 4 7. Replace fan blades in the new pin location and reassemble the fan 3.
Fan Assembly Bushings The fan assembly bushings should be tightened to the specifications listed in the following table. Table 5 - Fan Assembly Bushing Torque Specifications Tightening Torque Bushing (in-lbs.) H X 1.125" 95 H X 1.375" 95 SH X 1.125" 108 SH X 1.375" 108 SD X 1.125" 108 SD X 1.375" 108 SD X 1.625" 108 SD X 1.875" 108 SK X 2.
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 sub-cooling and superheat. Air-cooled condenser units require maintenance schedules/procedures. Unit specific instructions are included in this manual. Compressors The scroll compressors are fully hermetic and require no maintenance except keeping the shell clean.
For units equipped with low ambient (0°F) option see the special charging instructions at the end of this section. Checking Liquid Sub-cooling Measure the temperature of the liquid line as it leaves the condenser coil. Read the gauge pressure at 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.
CAUTION DO NOT OVERCHARGE! Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure. The system is undercharged if the superheat is too high and the sub-cooling is too low. 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.
Table 8 - R-410A Refrigerant Temperature-Pressure Chart °F 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 PSIG 78.3 80.0 81.8 83.6 85.4 87.2 89.1 91.0 92.9 94.9 96.8 98.8 100.9 102.9 105.0 107.1 109.2 111.4 113.6 115.8 118.1 120.3 122.7 125.0 127.4 129.8 132.2 °F 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 PSIG 134.7 137.2 139.7 142.2 144.8 147.4 150.1 152.8 155.5 158.2 161.0 163.8 166.7 169.6 172.5 175.4 178.4 181.5 184.5 187.6 190.
Lubrication All original motors and bearings are furnished with an original factory charge of lubrication. 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.
that does not contain chlorides, sulfates, copper, iron, nickel, or titanium is required. 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. Field installed coil coatings are not recommended with microchannel coils.
Refrigerant Piping Diagrams Figure 14 - A/C Only Piping, AHU Above CU 36
Figure 15 - A/C Only Piping, AHU Below CU 37
Figure 16 - Modulating Hot Gas Reheat Piping, AHU Above CU 38
Figure 17 - Modulating Hot Gas Reheat Piping, AHU Below CU 39
Figure 18 - Hot Gas Bypass Piping, AHU Above CU 40
Figure 19 - Hot Gas Bypass Piping, AHU Below CU 41
Figure 20 - Modulating Hot Gas Reheat with Hot Gas Bypass Piping, AHU Above CU 42
Figure 21 - Modulating Hot Gas Reheat with Hot Gas Bypass Piping, AHU Below CU 43
CN Series Startup Form Job Name:_______________________________________________ Date:______________ Address:______________________________________________________________________ ______________________________________________________________________________ Model Number:_________________________________________________________________ Serial Number:_____________________________________________ Tag:_______________ Startup Contractor:______________________________________________________________ Address:___
Compressors/DX Cooling Check Rotation Number Model # L1 L2 L3 Head Pressure PSIG Suction Pressure PSIG Crankcase Heater Amps 1 2 3 4 Refrigeration System 1 - Cooling Mode Saturated Pressure Temperature Discharge Suction Liquid Refrigeration System 2 - Cooling Mode Saturated Pressure Temperature Discharge Suction Liquid Refrigeration System 3 - Cooling Mode Saturated Pressure Temperature Discharge Suction Liquid Refrigeration System 4 - Cooling Mode Saturated Pressure Temperature Discharge Suction L
Condenser Fans Alignment Number 1 2 3 4 5 6 7 8 46 hp Check Rotation L1 Nameplate Amps________ L2 L3
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. Entry Date Action Taken Name/Tel.
Literature Change History March 2014 Initial version.
AAON 2425 South Yukon Ave. Tulsa, OK 74107-2728 Phone: 918-583-2266 Fax: 918-583-6094 www.aaon.com CN Series Installation, Operation, & Maintenance V28960 · Rev. A · 140331 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.
