AAON CF Series Installation Operation & Maintenance
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Condenser and Condensing Units
Installation, Operation,
& Maintenance
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.
Installation and service must be
performed by a Factory Trained
Service Technician. A copy of this
IOM should be kept with the unit.
WARNING
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
Table of Contents
AAON CF Series Features and Options Introduction..................................................................... 5
Safety .............................................................................................................................................. 6
CF Series Feature String Nomenclature ....................................................................................... 11
General Information ...................................................................................................................... 14
Codes and Ordinances ............................................................................................................... 14
Receiving Unit ........................................................................................................................... 14
Storage ....................................................................................................................................... 15
Wiring Diagrams ....................................................................................................................... 16
General Maintenance ................................................................................................................. 16
Installation..................................................................................................................................... 17
Forklifting the Unit .................................................................................................................... 17
Lifting the Unit .......................................................................................................................... 18
Locating the Unit ....................................................................................................................... 18
Mounting Isolation .................................................................................................................... 19
Access Doors ............................................................................................................................. 19
Low Ambient Operation ............................................................................................................ 19
Fan Cycling Low Ambient ........................................................................................................ 20
Variable Speed Low Ambient ................................................................................................... 20
Flooded Condenser Low Ambient ............................................................................................ 20
LAC Valve ................................................................................................................................ 20
Condenser Flooding .................................................................................................................. 21
Refrigerant Piping ..................................................................................................................... 22
Determining Refrigerant Line Size ........................................................................................ 22
Liquid Line ............................................................................................................................ 23
Suction Line ........................................................................................................................... 24
Discharge Line ....................................................................................................................... 26
Hot Gas Bypass Line ............................................................................................................. 28
Hot Gas Reheat ...................................................................................................................... 29
Electrical .................................................................................................................................... 30
Startup ........................................................................................................................................... 32
Compressor Operation ............................................................................................................... 32
Variable Capacity Compressor Controller ................................................................................ 33
Low Voltage Terminals ............................................................................................................. 33
High Voltage Terminals ............................................................................................................ 33
Compressor Lockouts ................................................................................................................ 35
Maintenance .................................................................................................................................. 36
General ...................................................................................................................................... 36
Compressors .............................................................................................................................. 36
Refrigerant Filter Driers ............................................................................................................ 36
Adjusting Refrigerant Charge ................................................................................................... 36
Lubrication ................................................................................................................................ 40
Condenser Tube Inspection ....................................................................................................... 40
Maintenance Recommendations ............................................................................................... 40
E-Coated Coil Cleaning ............................................................................................................ 41
Service ....................................................................................................................................... 43
Warranties ................................................................................................................................. 43
Replacement Parts ..................................................................................................................... 43
AAON - Longview Warranty, Service, and Parts Department ................................................. 43
Split System Refrigerant Piping Diagrams ................................................................................... 44
Index of Tables and Figures
Tables:
Table 1 –Clearances for Proper Operation.................................................................................... 18
Table 2 – Clearances for Coil Pull ................................................................................................ 18
Table 3 - Condenser Flooding....................................................................................................... 21
Table 4 - Demand Signal vs. Compressor Capacity Modulation.................................................. 34
Table 5 - Thermistor Temperature vs. Resistance Values ............................................................ 35
Table 6 - Max Filter Drier Pressure Drops ................................................................................... 36
Table 7 - Acceptable Refrigeration Circuit Values ....................................................................... 37
Table 8 - R-410A Refrigerant Temperature-Pressure Chart ......................................................... 40
Figures:
Figure 1 - Forklifting a CF Series A Cabinet ................................................................................ 17
Figure 2 - Forklifting a CF Series B and C Cabinet ..................................................................... 17
Figure 3 – Lifting Details and Orientation of a CF Series 9-70 ton Condensing Unit ................. 18
Figure 4 - Orientation of Series 2-7 ton Condensing Unit ............................................................ 18
Figure 5 - Adjustable Fan Cycling Switch .................................................................................... 20
Figure 6 - Piping Schematic of Example System using the LAC Valve ...................................... 21
Figure 7 - Double Suction Riser Construction .............................................................................. 25
Figure 8 – Heat Pump Piping Schematic of Suction Vapor Flow Down in Double Riser ........... 27
Figure 9 – Heat Pump Piping Schematic of Discharge Vapor Flow Up in Double Riser ............ 27
Figure 10 – Oil Return Line .......................................................................................................... 29
Figure 11 - Variable Capacity Compressor Controller ................................................................. 33
Figure 12 - Compressor Controller Flash Code Details................................................................ 34
Figure 13 - Adjustable compressor lockout .................................................................................. 35
Figure 14 - Ambient sensor cover ................................................................................................. 35
Figure 15 - A/C Split System Piping, Suction Down ................................................................... 44
Figure 16 - A/C Split System Piping, Suction Up ........................................................................ 45
Figure 17 - A/C with LAC Split System Piping, Suction Down .................................................. 46
Figure 18 - A/C with LAC Split System Piping, Suction Up ....................................................... 47
Figure 19 - A/C with Modulating Hot Gas Reheat Split System Piping, Suction Down ............. 48
Figure 20 - A/C with Modulating Hot Gas Reheat Split System Piping, Suction Up .................. 49
Figure 21 - A/C with Modulating Hot Gas Reheat Split + LAC System Piping, Suction Down . 50
Figure 22 - A/C with Modulating Hot Gas Reheat Split + LAC System Piping, Suction Up ...... 51
Figure 23 - A/C with Hot Gas Bypass Split System Piping, Suction Down ................................ 52
Figure 24 - A/C with Hot Gas Bypass Split System Piping, Suction Up ..................................... 53
Figure 25 - A/C with Hot Gas Bypass + LAC Split System Piping, Suction Down .................... 54
Figure 26 - A/C with Hot Gas Bypass + LAC Split System Piping, Suction Up ......................... 55
Figure 27 - A/C with Modulating Hot Gas Reheat and Hot Gas Bypass Split System Piping,
Suction Down................................................................................................................................ 56
Figure 28 - A/C with Modulating Hot Gas Reheat and Hot Gas Bypass Split System Piping,
Suction Up .................................................................................................................................... 57
Figure 29 - A/C with Modulating Hot Gas Reheat and Hot Gas Bypass + LAC Split System
Piping, Suction Down ................................................................................................................... 58
Figure 30 - A/C with Modulating Hot Gas Reheat and Hot Gas Bypass + LAC Split System
Piping, Suction Up ........................................................................................................................ 59
Figure 31 - Heat Pump Split System Piping, Suction Down ........................................................ 60
Figure 32 - Heat Pump Split System Piping, Suction Up ............................................................. 61
Figure 33 - Heat Pump with Modulating Hot Gas Reheat Split System Piping, Suction Down .. 62
Figure 34 - Heat Pump with Modulating Hot Gas Reheat Split System Piping, Suction Up ....... 63
Figure 35 - Heat Pump with Hot Gas Bypass Split System Piping, Suction Down ..................... 64
Figure 36 - Heat Pump with Hot Gas Bypass Split System Piping, Suction Up .......................... 65
Figure 37 – Heat Pump with Modulating Hot Gas Reheat and Hot Gas Bypass Split System
Piping, Suction Down ................................................................................................................... 66
Figure 38 – Heat Pump with Modulating Hot Gas Reheat and Hot Gas Bypass Split System
Piping, Suction Up ........................................................................................................................ 67
V45040 · Rev. A · 180319
(ACP J00424)
AAON CF Series Features and Options Introduction
Energy Efficiency
•
Staged, Two-Step, 10-100% Variable
Capacity, or Tandem R-410A Scroll
Compressors
•
Air-Source Heat Pump
•
VFD Controlled or ECM Driven
Condenser Fans
Humidity Control
•
Modulating Hot Gas Reheat
Safety
•
Phase and Brownout Protection
•
Adjustable Compressor Lockout
Installation and Maintenance
•
Isolated Controls and Compressor
Compartment
•
Access Doors with Full Length Stainless
Steel Piano Hinges
•
Molded Lockable Handles
•
Run Test Report and Installation Manual
Included in Controls Compartment
•
Color-Coded Wiring and Wiring
Diagrams
•
Factory Installed Convenience Outlet
•
Service Access Lights
•
Remote Start/Stop Terminals
•
Liquid Line Sight Glass
•
Compressor Isolation Valves
System Integration
•
Complete Split System with AAON DX
Air Handling Units
•
Single Point Non-Fused Disconnect
Power Switch
•
Labeled Split System Piping Stub Outs
with Shut-Off Valves
•
Flooded Condenser 0°F Low Ambient
Controls
•
Terminal Block for Thermostat with
Isolation Relays
•
Constant Air Volume (CAV), Makeup
Air (MUA), Variable Air Volume
(VAV), and Single Zone Variable Air
Volume (SZ VAV)
Environmentally Friendly
•
R-410A Refrigerant
Extended Life
•
Optional 5 Year Compressor Warranty
•
G90 Galvanized Steel Construction
•
2,500 Hour Salt Spray Tested Exterior
Corrosion Protection
•
6,000 Hour Salt Spray Tested Polymer
E-Coated Condenser Coils
•
Copper Fin and Stainless Steel Casing
Coils
•
Condenser Coil Guards
servicing, shut off all electrical power
to
the
unit,
including
remote
disconnects, to avoid shock hazard
or injury from rotating parts. Follow
proper Lockout-Tagout procedures.
WARNING
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.
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
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.
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
Unit contains fans with moving parts
that can cause serious injury. Do not
remove grill containing fans until the
power
to
the
unit
has
been
disconnected and fan has stopped
rotating.
WARNING
LIVE ELECTRICAL
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
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
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
VARIABLE FREQUENCY DRIVES
Do not leave VFDs unattended in
hand
mode or
manual
bypass.
Damage to personnel or equipment
can occur if left unattended. When in
hand mode or manual bypass mode
VFDs will not respond to controls or
alarms.
WARNING
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
VARIABLE FREQUENCY DRIVES
Electric motor over-current protection
and overload protection may be a
function of the Variable Frequency
Drive to which the motors are wired.
Never defeat the VFD motor overload
feature. The overload ampere setting
must not exceed 115% of the electric
motors FLA rating as shown on the
motor nameplate.
CAUTION
PVC PIPING
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.
CAUTION
3-PHASE ROTATION
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
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
DOOR LATCHES
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. If the shipping hardware is
not replaced with a pad lock, always
re-install the nut and bolt after closing
the door to maintain tooled access.
CAUTION
Do not work in an enclosed area
where refrigerant or nitrogen gases
may be leaking. A sufficient quantity
of vapors may be present and cause
injury or death.
WARNING
COMPRESSOR LUBRICANT
Polyolester (POE) and Polyvinylether
(PVE) oils are two types of lubricants
used in hydrofluorocarbon (HFC)
refrigeration systems. Refer to the
compressor label for the proper
compressor lubricant type.
CAUTION
COIL CLEANERS
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
COIL CLEANERS
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.
WARNING
COIL CLEANING
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.
CAUTION
CONVENIENCE OUTLETS
Factory installed convenience outlets
are not intended for use while the unit
is operating.
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
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
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.
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
CF Series Feature String Nomenclature
Model Options
:
Unit Feature Options
GEN
MJREV
SIZE
SERIES
MNREV
VLT
A1
A2
A3
A4
A5
1
2A
2B
3A
3B
4
5
6A
6B
6C
7
8A
8B
8C
8D
9
10
11
12
13
14
15
CF A - 015 - B - A - 3 - D C 0 0 K : 0 - A 0 - E 0 - C 0 - A N 0 - B - D E 0 0 - 0 0 A 0 E 0 0
0 0 0 0 0 D B
16
17
18
19
20
21
22
11
CF Series Feature String Nomenclature
MODEL OPTIONS
Series and Generation
CF
Major Revision
A
Unit Size
002 = 2 ton Capacity
003 = 3 ton Capacity
004 = 4 ton Capacity
005 = 5 ton Capacity
006 = 6 ton Capacity
007 = 7 ton Capacity
009 = 9 ton Capacity
011 = 11 ton Capacity
013 = 13 ton Capacity
015 = 15 ton Capacity
016 = 16 ton Capacity
018 = 18 ton Capacity
020 = 20 ton Capacity
025 = 25 ton Capacity
026 = 26 ton Capacity
030 = 30 ton Capacity
031 = 31 ton Capacity
040 = 40 ton Capacity
050 = 50 ton Capacity
060 = 60 ton Capacity
070 = 70 ton Capacity
Series
A = 2-7 ton units
B = 9-15 ton units
C = 16-25 & 30 ton units
D = 26 & 31-70 ton units
Minor Revision
A
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
A1: Compressor Style
0 = Air-Cooled Condenser - No Compressors
(1 Circuit)
A = R-410A Scroll Compressors
B = R-410A Two Step Capacity Scroll Compressors
D = R-410A Variable Capacity Scroll Compressors
E = R-410A Tandem Scroll Compressors
G = R-410A Tandem Variable Capacity Scroll
Compressors
P = Air-Cooled Condenser - No Compressors
(2 Circuits)
Q = Air-Cooled Condenser - No Compressors
(4 Circuits)
A2: Condenser Style
C = Air-Cooled Condenser
J = Air-Source Heat Pump
A3: Configuration
0 = Standard
A4: Coating
0 = Standard
E = Polymer E-Coated Condenser Coil
G = Copper Fin + Stainless Steel Casing - Condenser
Coil
A5: Staging
0 = No Cooling
G = 1 On/Off Refrigeration System
H = 1 Variable Capacity Refrigeration System
J = 2 On/Off Refrigeration Systems
K = 1 Variable Capacity Refrigeration System + 1
On/Off Refrigeration System
L = 2 Variable Capacity Refrigeration System
R = 4 On/Off Refrigeration Systems
T = 2 Variable Capacity Refrigeration Systems + 2
On/Off Refrigeration Systems
U = 4 Variable Capacity Refrigeration Systems
CF Series Feature String Nomenclature
Model Options
:
Unit Feature Options
GEN
MJREV
SIZE
SERIES
MNREV
VLT
A1
A2
A3
A4
A5
1
2A
2B
3A
3B
4
5
6A
6B
6C
7
8A
8B
8C
8D
9
10
11
12
13
14
15
CF A - 015 - B - A - 3 - D C 0 0 K : 0 - A 0 - E 0 - C 0 - A N 0 - B - D E 0 0 - 0 0 A 0 E 0 0
0 0 0 0 0 D B
16
17
18
19
20
21
22
12
UNIT FEATURE OPTIONS
1: Unit Orientation
0 = Vertical Condenser Discharge - Standard Access
A = Horizontal Condenser Discharge - Standard
Access
2A: Refrigeration Control
0 = Standard
A = 5 Minute Compressor Off Timer + 20 Second
Compressor Stage Delay
C = Adjustable Fan Cycling
D = Adjustable Compressor Lockout
G = Option A + Adjustable Fan Cycling
H = Option A + Adjustable Compressor Lockout
M = Adjustable Fan Cycling + Adjustable
Compressor Lockout
W = Option A + Adjustable Fan Cycling +
Adjustable Compressor Lockout
2B: Blank
0 = Standard
3A: Refrigeration Options
0 = Standard
A = Hot Gas Bypass Lead Stage [HGB]
B = HGB Lead + HGB Lag
D = Hot Gas Bypass Non-Variable Capacity
Refrigeration Systems [HGBNV]
E = Modulating Hot Gas Reheat [MHGR]
H = HGB + MHGR
J = HGB Lead + HGB Lag + MHGR
L = HGBNV + MHGR
3B: Blank
0 = Standard
4: Refrigeration Accessories
0 = Standard
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 + D
4: Refrigeration Accessories Continued
H = Flooded Condenser 0°F Low Ambient Controls-
Two Circuits
J = Options A + H
K = Options B + H
L = Options A + B + H
R = Flooded Condenser 0°F Low Ambient Controls –
Four Circuits
S = Options A + R
T = Options B + R
U = Options A + B + R
5: Blank
0 = Standard
6A: Unit Disconnect Type
0 = Single Point Power Block
A = Single Point Power Non-Fused Disconnect
6B: Disconnect 1 Size
0 = Standard
N = 100 amps
R = 150 amps
V = 250 amps
Z = 400 amps
6C: Blank
0 = Standard
7: Accessories
0 = Standard
B = Phase & Brown Out Protection
D = Suction Pressure Transducer on Each
Refrigeration Circuit
E = Compressor Sound Blanket
L = Options B + D
M = Options B + E
Q = Options D + E
1 = Options B + D + E
CF Series Feature String Nomenclature
Model Options
:
Unit Feature Options
GEN
MJREV
SIZE
SERIES
MNREV
VLT
A1
A2
A3
A4
A5
1
2A
2B
3A
3B
4
5
6A
6B
6C
7
8A
8B
8C
8D
9
10
11
12
13
14
15
CF A - 015 - B - A - 3 - D C 0 0 K : 0 - A 0 - E 0 - C 0 - A N 0 - B - D E 0 0 - 0 0 A 0 E 0 0
0 0 0 0 0 D B
16
17
18
19
20
21
22
13
8A: Control Sequence
A = Terminal Block for Thermostat w/ Isolation
Relays
D = VAV Unit Controller - VAV Cool + CAV Heat
E = CAV Unit Controller
F = Makeup Air Unit Controller - CAV Cool + CAV
Heat
H = Constant Volume HP Unit Controller - CAV
Cool + CAV Heat
J = Makeup Air HP Unit Controller - CAV Cool +
CAV Heat
N = Field Installed DDC Controls by Others with
Isolation Relays
8B: Control Suppliers
0 = Standard
E = WattMaster VCC-X (Main Controller in Air
Handling Unit)
H = AAON Touchscreen Controller (Main Controller
in Air Handling Unit)
8C: Control Supplier Options
0 = Standard
8D: BMS Connection & Diagnostics
0 = Standard
9: Blank
0 = Standard
10: Blank
0 = Standard
11: Maintenance Accessories
0 = Standard
A = Factory Wired 115VAC Convenience Outlet
B = Field Wired 115VAC Convenience Outlet
C = Service Lights
E = Remote Unit Start/Stop Terminals
F = Options A + C
H = Options A + E
J = Options B + C
L = Options B + E
N = Options C + E
R = Options A + C + E
U = Options B + C + E
12: Code Options
0 = Standard ETL USA Listing
B = ETL USA + Canada Listing
13: Air-Cooled Condenser Accessories
0 = Standard
A = Condenser Coil Guard
C = ECM Condenser Fan Head Pressure Control
E = VFD Condenser Fan Head Pressure Control
G = Options A + C
J = Options A + E
14: Blank
0 = Standard
15: Blank
0 = Standard
16: Electrical Options
0 = Standard
17: Shipping Options
0 = Standard
A = Crating
B = Export Crating
18: Blank
0 = Standard
19: Blank
0 = Standard
20: Cabinet Material
0 = Galvanized Steel Cabinet
21: Warranty
0 = Standard
D = Compressor Warranty - Years 2-5
22: Type
B = Premium AAON Gray Paint Exterior
E = Premium AAON Gray Paint Ext + Shrink Wrap
X = SPA + Premium AAON Gray Paint Exterior
1 = SPA + Premium AAON Gray Paint Exterior +
Shrink Wrap
AAON CF Series air-cooled condensers and
condensing units have been designed for
outdoor
use
only.
They
are
factory
assembled, wired, charged, and run-tested.
Codes and Ordinances
CF Series units have been tested and
certified, by ETL, in accordance with UL
Safety Standard 1995/CSA C22.2 No. 236.
System should be sized in accordance with
the
American
Society
of
Heating,
Refrigeration
and
Air
Conditioning
Engineers Handbook.
Installation of CF Series units must conform
to the ICC standards of the International
Mechanical Code, the International Building
Code, and local building, plumbing and
electrical 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.
If repairs must be made to damaged goods,
then the factory should be notified before
any repair action is taken in order to protect
the warranty. Certain equipment alteration,
repair, and manipulation of equipment
without the manufacturer’s consent may
void the product warranty. Contact AAON
Warranty Department for assistance with
handling damaged goods, repairs, and
freight claims: (903) 236-4403.
NOTE: Upon receipt check shipment for
items that ship loose. Consult order and
shipment documentation to identify potential
loose-shipped items. Loose-shipped items
may have been placed inside the unit cabinet
SHARP EDGES
Coils and sheet metal surfaces
present sharp edges and care must
be
taken
when
working
with
equipment.
WARNING
QUALIFIED INSTALLER
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 Factory Trained
Service Technician.
WARNING
Failure to observe the following
instructions will result in premature
failure of your system and possible
voiding of the warranty.
WARNING
for security. Installers and owners should
secure all doors with locks or nuts and bolts
to prevent unauthorized access.
The warranty card must be completed in full
and returned to AAON not more than 3
months after the 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.
Failure to observe the following instructions
will result in premature failure of your
system, and possible voiding of the
warranty.
Never turn 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. The compressor is designed to
pump refrigerant gas and damage may occur
if liquid enters the compressor 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 control
panel, never at the main power supply
(except for emergency or for complete
shutdown of the system).
CLEAN AIR ACT
The Clean Air Act of 1990 bans the
intentional ven ting of refrigerant as
of July 1, 1992. Approved methods of
recovery, recycling, or reclaiming
must be followed.
CAUTION
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
3-PHASE ROTATION
Rotation must be checked on all
MOTORS AND COMPRESSORS of
three phase units. All motors, to
include and not be limited to pump
motors and 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.
CAUTION
The standard compressors must be on a
minimum of 5 minutes and off for a
minimum of 5 minutes. The cycle rate must
be no more than 6 starts per hour.
The variable capacity compressors must be
on a minimum of 3 minutes and off for a
minimum of 3 minutes. The cycle rate must
be no more than 6 starts per hour.
The 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
diagram in point-to-point form is laminated
in plastic and located inside the control
compartment door.
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 condensing unit.
This includes reading and recording suction
pressures and checking for normal sub-
cooling and superheat.
COMPRESSOR ROTATION
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.
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
CAUTION
Forklifting the Unit
CF Series condensing unit sizes 2-25 & 30
tons can be lifted using a forklift. 2-7 ton
units must have forks at least 48” in length.
9-25 & 30 ton units must have forks 72” in
length, or the forks must have 72” fork
extensions. Standard units can be lifted from
all sides except the condenser coil side. CF
Series condensing unit sizes 26 & 31-70
tons cannot be lifted using a forklift. They
can be lifted as shown in Figure 3.
Forks must be perpendicular to the unit and
they must be in far enough that the back of
the forks are no more than 6” away from the
edge of the unit.
Figure 1 - Forklifting a CF Series A Cabinet
Figure 2 - Forklifting a CF Series B and C
Cabinet
FORKLIFTING
2-7 TON UNITS
Forks or Fork Extensions must be at
least 48” in length.
CAUTION
FORKLIFTING
9-25 & 30 TON UNITS
Forks or Fork Extensions must be at
least 72” in length.
CAUTION
Lifting the Unit
If cables or chains are used to hoist the unit
they must be the same length. Minimum
cable length is 99” for CF Series 9-70 ton
units. CF Series 2-7 ton units do not include
factory installed lifting lugs and should be
lifted by forklift only. Care should be taken
to prevent damage to the cabinet, coils, and
condenser fans.
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.
Figure 3 – Lifting Details and Orientation of
a CF Series 9-70 ton Condensing Unit
Locating the Unit
The CF Series condenser and condensing
unit 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
one-piece concrete slab should be used with
footings that extend below the frost line.
Also with ground level installation, care
must be taken to protect the coil fins from
damage due to vandalism or other causes.
The first clearance table below gives the
clearance values for proper unit operation.
The second clearance table gives the
clearance necessary for removing the coil
without disassembling a large part of the
condensing unit. For ease of removing the
condenser coil, use the second table
clearances for the right hand side of the unit.
Table 1 –Clearances for Proper Operation
Location
Unit Size
2-7 tons
9-70 tons
Front -
(Controls
Side)
Unobstructed
36”
Left Side
6”
30”
Right Side
6”
36”
Top
3”
Unobstructed
Back
18”
6”
Table 2 – Clearances for Coil Pull
Unit Size
Right Hand Side
2-7 tons
42”
9-15 tons
42”
16-25 & 30 tons
54”
26 & 31-70 tons
66”
Figure 4 - Orientation of Series 2-7 ton
Condensing Unit
The placement relative to the building air
intakes and other structures must be
carefully selected. Airflow to and from the
condenser or condensing unit must not be
restricted
to
prevent
a
decrease
in
performance and efficiency.
The installation position for 9-70 ton units
must provide at least 30” of left and right
side clearance for proper airflow to the
condenser coils. When units are mounted
adjacent to each other, the minimum right
and left side clearance required between the
units is 60” or 5 feet. Similarly, when 2-7
ton units are mounted adjacent to each other,
the minimum clearance required between
the back side of the units is 36” or 3 feet.
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 5 feet (3 feet for 2-7tons).
CF Series condensers and condensing units
that have a vertical air discharge must have
no obstruction above the equipment. Do not
place the unit under an overhang. CF Series
condensers and condensing units that have a
horizontal
discharge
must
have
no
obstruction in front of the unit.
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.
Mounting Isolation
For roof mounted applications or anytime
vibration transmission is a factor, vibration
isolators may be used.
Access Doors
Access doors are provided to the compressor
and electrical compartment.
Low Ambient Operation
During low ambient temperatures, the vapor
refrigerant will migrate to the cold part of
the system and condense into liquid. All CF
Series compressors are provided with
factory installed crankcase heaters to help
prevent liquid refrigerant from slugging the
compressors during startup in low ambient
conditions. The condenser or condensing
unit must have continuous power 24 hours
prior to startup. This ensures the compressor
will receive sufficient refrigerant vapor at
startup. Standard units can operate down to
55°F ambient temperature.
AAON head pressure control units can
operate down to 35°F ambient temperature.
Three different head pressure control
options available are adjustable fan cycling,
ECM condenser fan, or VFD controlled
condenser fans. See detailed information
following.
The AAON low ambient (condenser flood-
back) system is used to operate a refrigerant
PVC PIPING
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.
CAUTION
system down to 0°F outside air temperature.
See detailed information following.
Fan Cycling Low Ambient
Adjustable fan cycling is a low ambient
head pressure control option that cycles the
condenser fans to maintain refrigerant
circuit head pressures at acceptable levels
during cooling operation. The head pressure
set point (100-470 psi) and pressure
differential (35-200 psi) can be field
adjusted using a flathead screwdriver. For
example, if the head pressure is set to
300psi, and the differential is set to 100psi,
then fans will cut in at 300psi and cut out at
200psi. Fan cycling and variable speed
condenser fan head pressure control options
allow mechanical cooling with ambient
temperatures down to 35°F.
Figure 5 - Adjustable Fan Cycling Switch
Variable Speed Low Ambient
Variable speed condenser fan head pressure
control is a low ambient head pressure
control option that sends a variable signal in
relation to the refrigerant circuit head
pressure of the system to an electronically
commutated motor or VFD. The motor
either speeds up or slows down air flow
accordingly in order to maintain constant
head pressure. Fan cycling and variable
speed condenser fan head pressure control
options allow mechanical cooling with
ambient temperatures down to 35°F.
Flooded Condenser Low Ambient
Flooded condenser low ambient control
maintains normal head pressure during
periods of low ambient. When the ambient
temperature
drops,
the
condensing
temperature and therefore pressure drops.
Without ambient control, the system would
shut down on low discharge pressure. The
flooded condenser method of low ambient
control fills the condenser coil with liquid
refrigerant, decreasing the heat transfer
capacity of the coil, which allows the coil to
operate at an acceptable discharge pressure.
The condenser coil will not be flooded
during summer ambient temperatures, so a
receiver is included to store the additional
liquid refrigerant required to flood the
condenser coil in low ambient.
The 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 reduces liquid
refrigerant
flow
from
the
condenser,
reducing its effective surface area, which 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. CF Series
condensers and condensing units use an
LAC valve for low ambient operation.
LAC Valve
The Low Ambient Control (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 6 - Piping Schematic of Example System using the LAC Valve
Condenser Flooding
In order to maintain head pressure in the
refrigeration system, liquid refrigerant is
kept in the condenser coil to reduce
condenser coil surface. The following chart
shows the percentage that a condenser coil
must be flooded in order to function
properly at the given ambient temperature.
During higher ambient temperatures the
entire condenser coil 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 is factory-sized to
contain all of the flooded volume. Without a
receiver there would be high head pressures
during higher ambient conditions.
Table 3 - Condenser Flooding
PERCENTAGE OF CONDENSER TO BE
FLOODED
Ambient
Temperature
(°F)
Evaporating Temperature (°F)
0° 10° 20° 30° 35° 40° 45° 50°
70°
40 24
0
0
0
0
0
0
60°
60 47
33
17
26
20
10
4
50°
70 60
50
38
45
40
33
28
40°
76 68
60
50
56
52
46
42
30°
80 73
66
59
64
60
55
51
20°
86 77
72
65
69
66
62
59
0°
87 83
78
73
76
73
70
68
(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 CF 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 installation.
Piping should conform to generally accepted
practices and codes.
Care must be taken not to cross the circuits
on multiple circuit systems.
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.
Determining Refrigerant Line Size
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 decrease, pressure drop increases.
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 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.
REFRIGERANT PIPING
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
REFRIGERANT PIPING
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, Inc. is not responsible for
interconnecting
refrigerant
piping.
Consult
ASHRAE
Handbook
–
Refrigeration and ASME Standards.
CAUTION
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 up vertical risers or in
excessively long line runs. AAON does not
recommend
running
underground
refrigerant lines.
Liquid Line
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
sub-
cooling 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, with the liquid line
flowing down, 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.
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
In cooling only systems, 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 through heat gain.
In heat pump systems, when the liquid line
is routed through regions where temperature
losses are expected (all lines exposed to
outside air conditions), insulate with a
minimum 1 inch thick Armaflex insulation,
as this will prevent capacity loss during
heating mode of operation.
Liquid Line Guidelines
In order to ensure liquid at the TXV, the
sum of frictional losses and pressure loss
due to vertical rise 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. An
additional recommendation is that the sum
of frictional losses (including valve losses,
filter drier losses, other accessories, and line
losses) and pressure loss due to vertical rise
should not exceed 8°F if the available sub-
cooling is 10°F.
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 to
discourage fluid backup, and 500 fpm from
receiver tank to the evaporator (300 fpm if
the line includes an electric valve to
minimize valve induced liquid hammer).
Liquid Line Accessories
Liquid line shut off valves and filter driers
are factory provided. 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.
A liquid line receiver is factory installed on
units with modulating hot gas reheat, units
with low ambient control flooded condenser,
and units with heat pump.
Suction Line
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
For cooling only systems, pitch the suction
line in the direction of flow (about 1 inch
per 20 feet of length) to maintain oil flow
towards the compressor, and keep it from
flooding back into the evaporator.
For heat pump systems, do not pitch lines
since they will be flowing in one direction in
cooling mode and the opposite direction in
heating mode.
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.
For difficult line routing applications, 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.
Figure 7 - Double Suction Riser
Construction
A double riser can also be used for heat
pump operation. The specific volume
(ft3/lb) of refrigerant at the discharge
temperature and pressure (heating mode line
conditions) is significantly lower than the
specific volume at the suction temperature
and pressure (cooling mode line conditions).
To compound the issue, the capacity in
heating mode is lower than the capacity in
cooling mode. The discharge velocity in the
riser during heating mode is much lower
than the suction velocity during cooling
mode. Often, a double riser is necessary to
get acceptable velocities for the discharge
mode and acceptable velocities for the
suction mode. In the example diagrams (See
Figure 8 & Figure 9), the cooling mode will
use both lines, and the heating mode will use
only one.
Suction Line Traps
Include a trap immediately after the
evaporator coil outlet to protect the TXV
bulb from liquid refrigerant.
Include traps every 20 feet in vertical
suction riser sections.
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. This line should still be insulated in
heat pump systems even though it acts as
both a discharge and suction line.
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.
When suction flow is up, variable capacity
compressors require a minimum velocity of
1,500 fpm at full load.
Tandem compressors must be considered for
full load operation (both compressors
operating) and at partial load (only one
compressor operating). When suction flow
is up, and the tandem has a variable capacity
compressor, the velocity for only one
compressor in operation must be greater
than 1,500 fpm. For on/off compressors, the
velocity must be greater than the minimum
velocity required to return oil.
Heat pump vapor lines must be checked for
suction flow (cooling mode operation) and
discharge flow (heating mode operation).
The same line must be used for both modes
of operation.
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.
For split system piping with long horizontal
runs and short vertical risers, a smaller pipe
size can be used to provide sufficient
velocity to return oil in vertical risers at part
loads, and a larger size pipe can be used on
the horizontal runs and vertical drop
sections. This helps with oil return, yet
keeps the pressure drop to a minimum.
Suction Line Accessories
If the job requirements specify suction
accumulators, they must be separately
purchased and field installed. Heat pump
units will include a factory installed suction
accumulator.
Discharge Line
The discharge line is similar to the suction
line from a design and construction
standpoint. 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.
Pressure loss in the discharge line has less of
an impact on capacity than pressure loss in
the suction line. Pressure loss in the
discharge line causes the compressors to
work harder and thus use more power.
Discharge Line Routing
For cooling only remote condenser systems,
pitch the discharge line in the direction of
flow (about 1 inch per 20 feet of length) to
maintain oil flow towards the compressor.
In a heat pump system, the field installed
suction line is also used as a discharge line
in the heating mode of operation so the line
must be sized to meet both the suction line
conditions in cooling mode and the
discharge line conditions in heating mode.
Because it is used in both directions for a
heat pump unit, the line should be installed
level, not pitched, to facilitate oil return in
both modes of operation.
It is important to consider part load
operation when sizing discharge 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.
For difficult line routing applications, a
double discharge riser can be applied to the
situation of part load operation with a
discharge riser. A double discharge riser is
designed to return oil at minimum load
while not incurring excessive frictional
losses at full load. A double discharge 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.
SUCTION RISER TRAPS
Circuits require suction riser traps
every 20 feet.
CAUTION
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. (See
the Double Suction Riser Construction
Figure 7)
A double riser can also be used for heat
pump operation. The specific volume
(ft3/lb) of refrigerant at the discharge
temperature and pressure (heating mode line
conditions) is significantly lower than the
specific volume at the suction temperature
and pressure (cooling mode line conditions).
To compound the issue, the capacity in
heating mode is lower than the capacity in
cooling mode. The discharge velocity in the
riser during heating mode is much lower
than the suction velocity during cooling
mode. Often, a double riser is necessary to
get acceptable velocities for the discharge
mode and acceptable velocities for the
suction mode. In the example diagrams, the
cooling mode will use both lines, and the
heating mode will use only one. See the
following schematics that illustrate how the
double discharge riser can work for heat
pump applications.
Figure 8 – Heat Pump Piping Schematic of
Cooling Mode in Double Riser
Figure 9 – Heat Pump Piping Schematic of
Heating Mode in Double Riser
Discharge Line Traps
Include traps every 12 feet in vertical
discharge riser sections.
Discharge Line Insulation
Although a typical discharge line does not
need to be insulated, the suction line does.
Since the same line is used for both, the line
must be insulated as described in the Suction
Line Insulation section.
Discharge Line Guidelines
For proper performance, discharge line
velocities less than a 3,500 fpm maximum
are recommended. The minimum velocity
required to return oil is dependent on the
pipe diameter, however, a general guideline
of 900 fpm minimum may be applied.
When discharge flow is up, variable
capacity compressors require a minimum
velocity of 900 fpm at full load.
Tandem compressors must be considered for
full load operation (both compressors
operating) and at partial load (only one
compressor operating). When discharge
flow is up, and the tandem has a variable
capacity compressor, the velocity for only
one compressor in operation must be greater
than 900 fpm. For on/off compressors, the
velocity must be greater than the minimum
velocity required to return oil.
Heat pump vapor lines must be checked for
suction flow (cooling mode operation) and
discharge flow (heating mode operation).
The same line must be used for both modes
of operation.
In a fashion similar to the suction 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.
For split system piping with long horizontal
runs and short vertical risers, a smaller pipe
size can be used to provide sufficient
velocity to return oil in vertical risers at part
loads, and a larger size pipe can be used on
the horizontal runs and vertical drop
sections. This helps with oil return, yet
keeps the pressure drop to a minimum.
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.
Hot Gas Bypass Piping Considerations
Pitch the hot gas bypass (HGB) line
downward in the direction of refrigerant
flow, toward the evaporator.
DISCHARGE RISER TRAPS
Circuits require discharge riser traps
every 12 feet.
CAUTION
When installing vertical hot gas bypass
lines, 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 hot gas bypass line
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.
Figure 10 – Oil Return 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 Line Guidelines
Choose a small size line to ensure oil return,
and minimize refrigerant charge.
Maintain velocities below a maximum of
3,500 fpm. A general minimum velocity
guideline to use is approximately 2,000 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 vertical hot gas reheat lines,
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 an oil return line,
using 1/8 inch capillary tube, 10 feet in
length, from the hot gas reheat line 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. (See
Oil Return Line Figure 10)
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.
The single point electrical power connections
are
made
in
the
electrical
control
compartment.
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.
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.
Size supply conductors based on the unit
MCA rating. Supply conductors must be rated
a minimum of 167°F (75°C).
Route power and control wiring, separately,
through the utility entry. Do not run power
and signal wires in the same conduit.
Protect the branch circuit in accordance with
code requirements. The unit 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.
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 affecting the unit's
agency/safety certification.
Three phase voltage imbalance will cause
motor overheating and premature failure. The
maximum allowable imbalance is 5%.
Voltage imbalance is defined as 100 times the
maximum deviation from the average voltage
divided by the average voltage.
Example:
(218V+237V+235V)/3
=
230V,
then
100*(230V-218V)/230V
=
5.2%,
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.
3-PHASE ROTATION
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. Variable frequency drives
are programmed to automatically
rotate the fan in the correct rotation.
Do not rely on fans with variable
frequency drives for compressor
rotation.
CAUTION
ELECTRIC SHOCK
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
NOTE: 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.
Wire control signals to the unit’s low voltage
terminal block located in the controls
compartment.
If any factory installed wiring must be
replaced, use a minimum 221°F (105°C) type
AWM insulated conductors.
SEALING ELECTRICAL ENTRIES
Installing Contractor is responsible
for proper sealing of the electrical
entries into the unit. Failure to seal
the entries may result in damage to
the unit and property.
CAUTION
(See back of the manual for startup form.)
Before startup of the condenser or condensing
unit, make sure that the following items have
been checked.
1. Verify that electrical power is available to
the unit.
2. Verify that any remote stop/start device
connected to the unit controller is
requesting the unit to start.
Cycle through all the compressors to confirm
that all are operating within tolerance.
While performing the check, use the 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.
Compressor Operation
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
cause undue stress and wear.
3-PHASE ROTATION
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. Variable frequency drives
are programmed to automatically
rotate the fan in the correct rotation.
Do not rely on fans with variable
frequency drives for compressor
rotation.
CAUTION
ELECTRIC SHOCK
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
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.
WARNING
Before
completing
installation,
a
complete operating cycle should be
observed
to
verify
that
all
components are functioning properly.
CAUTION
Variable Capacity Compressor Controller
Units
with
variable
capacity
scroll
compressors may include a 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.
Figure 11 - Variable Capacity Compressor
Controller
Note: When using field controls any variable
capacity compressors should run at 100% for 1
minute when starting.
Low Voltage Terminals
24COM
Module Common
24VAC
Module Power
C1
Demand Input -
C2
Demand Input +
P1
Pressure Common
P2
Pressure Input
P3
Pressure Power 5VDC
P4
Pressure Shield
P5
Pressure Output -
P6
Pressure Output +
T1 & T2
Discharge Temperature Sensor
High Voltage Terminals
A1 & A2
Alarm Relay Out
M1 & M2
Contactor
L1
Control Voltage N
L2
Control Voltage L
U1 & U2
Variable Capacity 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 5 for the
relationship between thermistor temperature
readings and resistance values.
COMPRESSOR CONTROLLER
To avoid damaging the compressor
controller, DO NOT connect wires to
terminals C3, C4, T3, T4, T5, or T6.
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
Table 4 - Demand Signal vs. Compressor Capacity Modulation
Figure 12 - Compressor Controller Flash Code Details
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%
Table 5 - Thermistor Temperature vs. Resistance Values
°C
°F
kΩ
°C
°F
kΩ
-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
Compressor Lockouts
Some units include adjustable compressor
lockouts. The compressor lockout in the
picture below can be set to any temperature
between -10°F and 70°F. The ambient
temperature sensor hangs right outside the
unit with a cover.
Figure 13 - Adjustable compressor lockout
Heat pump units include a non-adjustable
compressor lockout for the cooling mode set
to 55°F, and an adjustable compressor
lockout for the heating mode that can be set
between 20°F to 95°F. If a heat pump is
selected with the compressor lockout
feature, the adjustable compressor lockout
will change to the -10°F to 70°F range.
Figure 14 - Ambient sensor cover
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.
Compressors
The scroll compressors are fully hermetic
and require no maintenance except keeping
the shell clean.
Refrigerant Filter Driers
Each refrigerant circuit contains a filter
drier. Replacement is recommended when
there is excessive pressure drop across the
assembly or moisture is indicated in a liquid
line sight glass.
Table 6 - Max Filter Drier Pressure Drops
Circuit Loading
Max. Pressure Drop
100%
10 psig
50%
5 psig
Adjusting Refrigerant Charge
All AAON CF Series condensers and
condensing units are shipped with a factory
holding charge. The factory charge is
different depending on the unit size and
system (heat pump, modulating hot gas
reheat, LAC). The factory charge per circuit
is shown on the unit nameplate. Adjusting
the charge of the system will be required
during installation.
Adjusting the charge of 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
which refrigerant must be used to charge the
system.
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 charging,
unit
should
be
operated
in
reheat
(dehumidification) mode to check for
correct operation.
Units equipped with heat pump options
should be charged in cooling mode to get the
COMPRESSOR LUBRICANT
Polyolester (POE) and Polyvinylether
(PVE) oils are two types of lubricants
used in hydrofluorocarbon (HFC)
refrigeration systems. Refer to the
compressor label for the proper
compressor lubricant type.
CAUTION
CLEAN AIR ACT
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
proper charge. After charging, unit should
be operated in heating mode to check for
correct charge. Charge may need to be
adjusted for heating mode. If adjustments
are made in the heating mode, cooling mode
must be rerun to verify proper 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
7
when
determining the proper sub-cooling.
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.
Convert the pressure obtained to a saturated
temperature using the appropriate refrigerant
temperature-pressure chart.
Subtract
the
measured
liquid
line
temperature from the saturated temperature
to determine the liquid sub-cooling.
Compare calculated sub-cooling to Table 7
for the appropriate unit type and options.
Table 7 - Acceptable Refrigeration Circuit
Values
Cooling
Mode
Liquid Sub-
Cooling
Values
Cooling Only Unit4
8-15°F
Cooling Only Unit with Hot
Gas Reheat1,4
5-15°F
Heat PumpUnit2,4
2-4°F
Heat Pump Unit with Hot
Gas Reheat3,4
2-6°F
Cooling Only Unit with
LAC4
8-15°F
Cooling Only Unit with Hot
Gas Reheat & LAC4
8-15°F
Notes:
1.
Must be charged with the hot gas valve closed. After
charging, unit should be operated in reheat
(dehumidification) mode to check for correct
operation.
2.
The sub-cooling value in this table is for the unit
running in cooling mode of operation. After charging,
unit should be operated in heating mode to check for
correct operation.
3.
The sub-cooling value in this table is for the unit
running in cooling mode of operation and the hot gas
valve closed. After charging, unit should be operated
in reheat (dehumidification) mode to check for correct
operation and then in heating mode to check for
correct operation.
4.
Sub-cooling must be increased by 1°F per 10 feet of
vertical liquid line rise for R-410A (AHU above CU).
For example, a cooling only unit with hot gas reheat
and a vertical liquid drop can charge to a sub-cooling
value of 5-15°F, but a cooling only unit with hot gas
reheat and a vertical liquid rise of 30 ft must charge to
a sub-cooling value of at least 8-15°F.
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.
Subtract the saturated temperature from the
measured
suction
line
temperature
to
determine the evaporator superheat.
For refrigeration systems with tandem
compressors, it is critical that the suction
superheat setpoint on the TXV is set with
one compressor running. The suction
superheat should be 10-13°F with one
compressor running. The suction superheat
will increase with both compressors in a
tandem
running.
Inadequate
suction
superheat can allow liquid refrigerant to
return to the compressors which will wash
the oil out of the compressor. Lack of oil
lubrication will destroy a compressor.
Liquid sub-cooling should be measured with
both compressors in a refrigeration system
running.
Compare
calculated
superheat
to
the
acceptable cooling mode superheat values of
8-15°F for all system types. 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 compared to Table 7
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 of 8-15°F
(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 the superheat
is too high and 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.
DO NOT OVERCHARGE!
Refrigerant overcharging leads to
excess refrigerant in the condenser
coils resulting in elevated compressor
discharge pressure.
CAUTION
EXPANSION VALVE ADJUSTMENT
Thermal expansion valves must be
adjusted to approximately 8-15°F of
suction superheat. Failure to have
sufficient superheat will damage the
compressor and void the warranty.
CAUTION
Special Low Ambient Option Charging
Instructions
For units equipped with low ambient control
(LAC) refrigerant flood back option being
charged 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
when the ambient temperature is cold:
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.
The unit will have to be checked for proper
operation once the ambient temperature is
above 80°F.
Oil Level
It is critical that the refrigerant line piping is
designed to maintain proper oil return to the
compressors. Some systems may require oil
to be added in addition to what is provided
in the compressors. The oil is a PVE type
and
is
available
from
your
AAON
Representative under part number V41850.
Proper oil level should be observed under
minimum load conditions. On units
equipped with tandem compressors, all oil is
returned to the lead compressor in each
tandem pair. When only the lead
compressor is running, the oil level should
be a minimum of ⅜ from the bottom of the
sight glass. With both compressors running,
the level in the lead compressor should drop
to the bottom of the sight glass and the level
in the second compressor should be a
minimum of ⅜, from the bottom of its sight
glass.
Table 8 - 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
Lubrication
All original motors and bearings are
furnished with an original factory charge of
lubrication. Certain applications require
bearings be re-lubricated periodically. The
schedule will vary depending on operating
duty, temperature variations, or severe
atmospheric conditions.
Bearings should be re-lubricated at normal
operating temperatures, but not when
running.
Condenser Tube Inspection
The coils are leak tested at 650 psig, 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.
Maintenance Recommendations
Fan Motor Maintenance
Cleaning - Remove oil, dust, water, and
chemicals from exterior of motor. Keep
motor air inlet and outlet open. Blow out
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.
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.
Propeller Fans and Motors
The fans are directly mounted on the motor
shafts and the assemblies require minimal
maintenance except to assure 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.
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 condenser coils should be inspected
annually 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
tubes.
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
used. In either case, the tool should be
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.
ELECTRIC SHOCK
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
WARNING
PRESSURE CLEANING
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
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 less than 100 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 approved coil cleaner as
mentioned in the next section. 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
(4:1 condensers & 8:1 evaporators) 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 H-
EC01.
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 to the
substrate. For the effective use of this
product, the product must be in contact with
the salts. These salts may be beneath any
soils, grease or dirt; therefore, these barriers
must be removed prior to application of this
product.
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,
COIL CLEANERS
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
the salts will be soluble and is now only
necessary to rinse the salts off.
Rinse - It is highly recommended that a hose
be used. A pressure washer on a high
pressure setting 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.
Service
If the unit will not operate correctly and a
service company is required, only a
company with service technicians qualified
and experienced in both refrigerant chillers
and air conditioning are permitted to service
the systems to keep warranties in effect. If
assistance is required, the service technician
must contact AAON.
Warranties
Please refer to the limitation of warranties in
effect at the time of purchase.
Replacement Parts
Parts for AAON equipment may be obtained
by
contacting
your
local
AAON
representative.
When
ordering
parts,
reference the serial number and part number
located on the external or internal nameplate
of the unit.
AAON - Longview Warranty, Service,
and Parts Department
203 Gum Springs Rd.
Longview, TX 75602
Ph: 903-236-4403
Fax: 903-236-4463
www.aaon.com
NOTE: Before calling, technician should
have model and serial number of the unit
available
for
the
customer
service
department
to
help
answer
questions
regarding the unit.
Figure 27 - A/C with Modulating Hot Gas Reheat and Hot Gas Bypass Split System Piping,
Suction Down
Figure 28 - A/C with Modulating Hot Gas Reheat and Hot Gas Bypass Split System Piping,
Suction Up
Figure 29 - A/C with Modulating Hot Gas Reheat and Hot Gas Bypass + LAC Split System
Piping, Suction Down
Figure 30 - A/C with Modulating Hot Gas Reheat and Hot Gas Bypass + LAC Split System
Piping, Suction Up
Figure 37 – Heat Pump with Modulating Hot Gas Reheat and Hot Gas Bypass Split System
Piping, Suction Down
Figure 38 – Heat Pump with Modulating Hot Gas Reheat and Hot Gas Bypass Split System
Piping, Suction Up
CF Series Startup Form
Job Name:_______________________________________________
Date:______________
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 rotate freely?
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
N/A
N/A
Suction
N/A
Liquid
N/A
Refrigeration System 2 - Cooling Mode
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
N/A
N/A
Suction
N/A
Liquid
N/A
Refrigeration System 3 - Cooling Mode
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
N/A
N/A
Suction
N/A
Liquid
N/A
Refrigeration System 4 - Cooling Mode
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
N/A
N/A
Suction
N/A
Liquid
N/A
Refrigeration System 1 - Heating Mode (Heat Pump Only)
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
N/A
N/A
Suction
N/A
Liquid
N/A
Refrigeration System 2 - Heating Mode (Heat Pump Only)
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
N/A
N/A
Suction
N/A
Liquid
N/A
Refrigeration System 3 - Heating Mode (Heat Pump Only)
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
N/A
N/A
Suction
N/A
Liquid
N/A
Refrigeration System 4 - Heating Mode (Heat Pump Only)
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
N/A
N/A
Suction
N/A
Liquid
N/A
Condenser Fans
Alignment
Check Rotation
Nameplate Amps________
Number
hp
L1
L2
L3
1
2
3
4
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
July 2015
Initial version
March 2016
Clarified forklift instructions and removed wording about curb mounting.
June 2016
Updated CF Series Features and Options Introduction. Added Feature 17 Shipping Options in
the Feature String Nomenclature. Added Storage information. Added Table for Service
Clearances. Clarified Low Ambient section and added a picture of an adjustable fan cycle
switch. Added guidelines for variable capacity compressors and tandem compressors in the line
sizing section. Added double riser schematics and discussion for heat pump operation. Added a
section on compressor lockouts. Included heat pump charging guidelines in the Acceptable
Refrigeration Circuit Values Table. Added Special Low Ambient Option Charging Instructions.
Added A/C with LAC Piping to show low ambient piping which is internal to the condensing
unit.
March 2017
Updated Piping Diagrams because receivers are now factory installed in CF 2-7 tons.
April 2017
Updated service clearances tables and added a table for coil pull. Updated orientation of the CF
9-70 ton. Added a note that AAON does not recommend underground refrigerant lines. Added
clarification to the liquid line solenoid valve recommendation. Added a double suction risers
figure. Removed solenoid valve recommendation on the heat pump double risers and updated
the figures. Added a suction line traps section. Changed the suction flow minimum velocity for
variable compressors. Changed the caution note by removing the variable capacity compressor
wording. Added discharge line sizing guidelines. Removed the hot gas bypass piping
considerations for evaporator below condensing unit since they are the same as for evaporator
above condensing unit. Added a figure for oil return line. Changed the maximum hot gas
maximum velocity from 4,000 fpm to 3,500 fpm. Changed the sub-cooling values in the
Acceptable Refrigeration Circuit Values table. Updated heat pump piping diagrams to include
suction/discharge line traps in suction down diagrams. Added all the LAC piping diagrams.
October 2017
Updated digital compressor discharge up minimum velocity. Updated charge information.
Updated phase imbalance example. Added Air Cooled Condenser Option in A1 Compressor
Style. Added No Cooling Option in A5 Staging. Added WattMaster VCCX.
March 2018
Added AAON Touchscreen Controller feature 8B. Updated Refrigerant Piping section to match
the DX Handbook. Added note about running variable capacity compressors at 100% for 1
minute when starting. Updated Acceptable Refrigeration Circuit Values Table and notes.
Updated piping diagrams with 3-way reheat valve.
203 Gum Spring Rd.
Longview, TX 75602-1721
Phone: 903-236-4403
Fax: 903-236-4463
www.aaon.com
CF Series
Installation, Operation, &
Maintenance
V45040 · Rev. A · 180319
(ACP J00424)
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.