Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other appliance.
WARNING
If the information in this manual is not
followed exactly, a fire or explosion
may result causing property damage,
personal injury or loss of life.
WARNING
QUALIFIED INSTALLER
Improper installation, adjustment,
alteration, service or maintenance
can cause property damage,
personal injury or loss of life. Startup
and service must be performed by a
Factory Trained Service Technician.
A copy of this IOM should be kept
with the unit.
Figure 5– A/C only piping, AHU above CU ................................................................................ 31
Figure 6 – A/C only piping, AHU below CU ............................................................................... 32
Figure 7 – Modulating hot gas reheat piping, AHU above CU .................................................... 33
Figure 8 – Modulating hot gas reheat piping, AHU below CU .................................................... 34
Figure 9 – Hot gas bypass piping, AHU above CU ...................................................................... 35
Figure 10 – Hot gas bypass piping, AHU below CU .................................................................... 36
Figure 11 – Modulating hot gas reheat with hot gas bypass piping, AHU above CU .................. 37
Figure 12 – Modulating hot gas reheat with hot gas bypass piping, AHU below CU .................. 38
Figure 13 – Heat pump piping, AHU above CU .......................................................................... 39
Figure 14 – Heat pump piping, AHU below CU .......................................................................... 40
Figure 15 – Heat pump with modulating hot gas reheat piping, AHU above CU ........................ 41
Figure 16 – Heat pump with modulating hot gas reheat, AHU below CU ................................... 42
R57611 · Rev. - · 130603
(ACP J00187)
5
Safety
Attention should be paid to the following statements:
NOTE - Notes are intended to clarify the unit installation, operation and maintenance.
CAUTION - Caution statements are given to prevent actions that may result in
equipment damage, property damage, or personal injury.
WARNING - Warning statements are given to prevent actions that could result in
equipment damage, property damage, personal injury or death.
DANGER - Danger statements are given to prevent actions that will result in equipment
damage, property damage, severe personal injury or death.
ELECTRIC SHOCK, FIRE OR
EXPLOSION HAZARD
Failure to follow safety warnings
exactly could result in dangerous
operation, serious injury, death or
property damage.
Improper servicing could result in
dangerous operation, serious injury,
death or property damage.
Before servicing, disconnect all
electrical power to the unit. More
than one disconnect may be
provided.
When servicing controls, label all
wires prior to disconnecting.
Reconnect wires correctly.
Verify proper operation after
servicing. Secure all doors with
key-lock or nut and bolt.
WARNING
Electric shock hazard. Before
servicing, disconnect all electrical
power to the unit, including remote
disconnects, to avoid shock hazard
or injury from rotating parts. Follow
proper Lockout-Tagout procedures.
WARNING
FIRE, EXPLOSION OR CARBON
MONOXIDE POISONING HAZARD
Failure to replace proper controls
could result in fire, explosion or
carbon monoxide poisoning. Failure
to follow safety warnings exactly
could result in serious injury, death or
property damage. Do not store or use
gasoline or other flammable vapors
and liquids in the vicinity of this
appliance.
WARNING
6
GROUNDING REQUIRED
All field installed wiring must be
completed by qualified personnel.
Field installed wiring must comply
with NEC/CEC, local and state
electrical code requirements. Failure
to follow code requirements could
result in serious injury or death.
Provide proper unit ground in
accordance with these code
requirements.
WARNING
During installation, testing, servicing
and troubleshooting of the equipment
it may be necessary to work with live
electrical components. Only a
qualified licensed electrician or
individual properly trained in handling
live electrical components shall
perform these tasks.
Standard NFPA-70E, an OSHA
regulation requiring an Arc Flash
Boundary to be field established and
marked for identification of where
appropriate Personal Protective
Equipment (PPE) be worn, should be
followed.
WARNING
UNIT HANDLING
To prevent injury or death lifting
equipment capacity shall exceed unit
weight by an adequate safety factor.
Always test-lift unit not more than 24
inches high to verify proper center of
gravity lift point to avoid unit damage,
injury or death.
WARNING
ROTATING COMPONENTS
Unit contains fans with moving parts
that can cause serious injury. Do not
open door containing fans until the
power to the unit has been
disconnected and fan has stopped
rotating.
WARNING
Compartments containing hazardous
voltage or rotating parts are equipped
with a panel requiring tooled access.
Always re-install screws on the panel
after installation or service is
completed.
CAUTION
Rotation must be checked on all
MOTORS AND COMPRESSORS of
3 phase units at startup by a qualified
service technician. Scroll
compressors are directional and can
be damaged if rotated in the wrong
direction. Compressor rotation must
be checked using suction and
discharge gauges. Fan motor rotation
should be checked for proper
operation. Alterations should only be
made at the unit power connection
CAUTION
7
Do not clean DX refrigerant coils with
hot water or steam. The use of hot
water or steam on refrigerant coils
will cause high pressure inside the
coil tubing and damage to the coil.
Some chemical coil cleaning
compounds are caustic or toxic. Use
these substances only in accordance
with the manufacturer’s usage
instructions. Failure to follow
instructions may result in equipment
damage, injury or death.
WARNING
To prevent damage to the unit, do not
use acidic chemical coil cleaners. Do
not use alkaline chemical coil
cleaners with a pH value greater than
8.5, after mixing, without first using
an aluminum corrosion inhibitor in the
cleaning solution.
CAUTION
CAUTION
Do not use oxygen, acetylene or air
in place of refrigerant and dry
nitrogen for leak testing. A violent
explosion may result causing injury or
death.
WARNING
Do not work in a closed area where
refrigerant or nitrogen gases may be
leaking. A sufficient quantity of
vapors may be present and cause
injury or death.
WARNING
COMPRESSOR CYCLING
5 MINUTE MINIMUM OFF TIME
To prevent motor overheating
compressors must cycle off for a
minimum of 5 minutes.
5 MINUTE MINIMUM ON TIME
To maintain the proper oil level
compressors must cycle on for a
minimum of 5 minutes.
The cycle rate must not exceed 6
starts per hour.
WARNING
1. Startup and service must be performed
by a Factory Trained Service
Technician.
2. The unit is for outdoor use only. See
General Information section for more
unit information.
3. Every unit has a unique equipment
nameplate with electrical, operational
and unit clearance specifications.
Always refer to the unit nameplate for
specific ratings unique to the model you
have purchased.
4. READ THE ENTIRE INSTALLATION,
OPERATION AND MAINTENANCE
MANUAL. OTHER IMPORTANT
SAFETY PRECAUTIONS ARE
PROVIDED THROUGHOUT THIS
MANUAL.
5. Keep this manual and all literature
safeguarded near or on the unit.
8
CB Base Model and Features Description
CB - B - 060 - 3 - B - 1 : A D 0 0 0 A 0
Series and
Generation
Design
Sequence
Unit
Size
Voltage
Compressor
Type
Number
of
Circuits
1 2 3 4 5 6
7
BASE MODEL
SERIES AND GENERATION
CB
REVISION
B = Design Sequence
UNIT SIZE
024 = 24 MBH - 2 Ton - Vertical Discharge
036 = 36 MBH - 3 Ton - Vertical Discharge
048 = 48 MBH - 4 Ton - Vertical Discharge
060 = 60 MBH - 5 Ton - Vertical Discharge
B = R-410A Two Step Scroll Compressor
D = R-410A Variable Capacity Scroll Compressor
F = R-410A Two Step Scroll Compressor with Sound
Blanket
H = R-410A Variable Capacity Scroll Compressor
with Sound Blanket
NUMBER OF CIRCUITS
1 = One Circuit
FEATURE 1: AMBIENT CONTROL
0 = Standard (55°F Ambient)
B = Adjustable Fan Cycling (35°F Ambient)
D = Modulating Fan Pressure Control (35°F
Ambient)
F = Flooded Condenser Ambient Controls +
Option B
G = Flooded Condenser Ambient Controls +
Option D
FEATURE 2: REFRIGERATION
OPTIONS
0 = Standard - Split System Air Conditioner
A = External Hot Gas Bypass
B = Split System Heat Pump
D = Modulating Hot Gas Reheat
F = Options A + D
G = Options B + D
FEATURE 3: CONTROLS
0 = Standard - Terminal Block
A = Suction Pressure Transducer (F1- Wattmaster
Reheat)
H = Control Circuit Transformer
J = Variable Capacity Compressor Integrated
Controls
S = Suction Pressure Transducer (Not F1 Wattmaster Controls)
T = Control Circuit Transformer w/ Suction Pressure
Transducer
W = Wattmaster CB/F1 Controller
FEATURE 4: COIL PROTECTION
0 = Standard
A = Polymer E-Coated Coil
FEATURE 5: CABINET OPTIONS
0 = Standard – Louvered Panels
A = Wire Grille
D = Corrosion Protection Paint
G = Options A + D
FEATURE 6: WARRANTY
0 = Standard
A = Second to Fifth Year Extended Compressor
Warranty
FEATURE 7: TYPE
0 = Standard
X = Special Pricing Authorization
9
General Description
Improper installation, adjustment,
alteration, service or maintenance
can cause property damage,
personal injury or loss of life. Startup
and service must be performed by a
Factory Trained Service Technician.
WARNING
Coils and sheet metal surfaces
present sharp edges and care must
be taken when working with
equipment.
WARNING
The Clean Air Act of 1990 bans the
intentional venting of refrigerant as of
July 1, 1992. Approved methods of
recovery, recycling, or reclaiming
must be followed.
CAUTION
Failure to observe the following
instructions will result in premature
failure of your system and possible
voiding of the warranty.
WARNING
AAON® CB Series condensing units have
been designed for outdoor installation only.
Startup and service must be performed by a
Factory Trained Service Technician.
Codes and Ordinances
System should be sized in accordance with
the American Society of Heating,
Refrigeration and Air Conditioning
Engineers Handbook.
Installation of CB Series units must conform
to the ICC standards of the International
Mechanical Code, the International Building
Code, and local building, plumbing and
waste water codes. All appliances must be
electrically grounded in accordance with
local codes, or in the absence of local codes,
the current National Electric Code,
ANSI/NFPA 70 or the current Canadian
Electrical Code CSA C22.1.
Receiving Unit
When received, the unit should be checked
for damage that might have occurred in
transit. If damage is found it should be noted
on the carrier’s Freight Bill. A request for
inspection by carrier’s agent should be made
in writing at once.
Nameplate should be checked to ensure the
correct model sizes and voltages have been
received to match the job requirements.
The warranty card must be completed in full
and returned to AAON not more than 3
months after unit is delivered.
Storage
If installation will not occur immediately
following delivery, store equipment in a dry
protected area away from construction
traffic and in the proper orientation as
marked on the packaging with all internal
packaging in place. Secure all loose-shipped
items.
10
Direct Expansion (DX) Condensing Units
CRANKCASE HEATER
OPERATION
Units are equipped with compressor
crankcase heaters, which should be
energized at least 24 hours prior to
cooling operation, to clear any liquid
refrigerant from the compressors.
CAUTION
CB Series condensing units are factory
assembled and wired, including a full charge
of R-410A refrigerant for up to 25 feet of
line set. Systems with the modulating hot
gas reheat option will require refrigerant to
be field added because of the additional
refrigerant components and piping
associated with the system.
Refrigeration system includes factory
provided liquid line filter drier and fully
hermetic scroll compressor with a positive
pressure forced lubrication system.
Never cut off the main power supply to the
unit, except for servicing, emergency, or
complete shutdown of the unit. When power
is cut off from the unit, compressors using
crankcase heaters cannot prevent refrigerant
migration. This means the compressor may
cool down and liquid refrigerant may
accumulate in the compressor. Since the
compressor is designed to pump refrigerant
gas, damage may occur when power is
restored.
If power to the unit must be off for more
than an hour, turn the thermostat system
switch to “Off”, or turn the unit off at the
control panel, and then cut off the main
power supply. Leave the unit off until the
main power supply has been turned on again
for at least 24 hours. This will give the
crankcase heater time to clear any liquid
accumulation out of the compressor before it
is required to run.
Always control the system from the
thermostat, or control panel, never at the
main power supply, except for servicing,
emergency, or complete shutdown of the
unit.
Note: Low Ambient Operation
Units without a low ambient option, such as
condenser fan cycling or the 0°F low
ambient option, will not operate in the
cooling mode of operation properly when
the outdoor temperature is below 55°F. Low
ambient and/or air handling unit economizer
options are recommended if cooling
operation below 55°F is expected.
Note: Multiple Systems with Multiple
Thermostats
When several heating and cooling split
systems are used to condition a space all
thermostat switches must be set in either
heating mode, cooling mode or off. Do not
leave part of the systems switched to the
opposite mode. Cooling only systems should
be switched off at the thermostat during the
heating season.
Wiring Diagrams
Unit specific wiring diagram is laminated in
plastic and located inside the controls
compartment door.
11
Installation
AAON equipment has been designed for
quick and easy installation.
Locating Unit
CB Series condensing units are designed for
outdoor application and placement at ground
level or on a rooftop. Units must be placed
on a level and solid foundation that can
support the unit’s weight.
When rooftop mounted, a steel frame must
be provided that will support the unit above
the roof itself for load distribution.
When installed at ground level, a one-piece
concrete slab or composite condenser pad
should be used with footings that extend
below the frost line (a substantial base that
will not settle). Slab should be surrounded
by a graveled area for proper drainage and
should not adjoin the building as sound and
vibration may be transmitted to the
structure. Care must also be taken to protect
the coils and fins from damage due to
vandalism or other hazards.
Airflow to and from the condensing unit
must not be restricted. Coils and fans must
be free of any obstructions and debris in
order to start and operate properly with a
correct amount of airflow. Obstruction to air
flow will result in decreased performance
and efficiency.
The installation position must provide at
least one foot of clearance from the wall for
proper air flow to the coils. When multiple
units are mounted adjacent to each other, the
clearance required between them is three
feet.
Service compartment must be accessible for
periodic servicing of controls, safety
devices, and refrigerant service/shutoff
valves. At least two feet of clearance on this
corner of the unit is recommended for
service.
Figure 1 – Condensing Unit Clearances
Condensing units should not be installed in
an enclosure or pit that is deeper than the
height of the unit. When recessed
installation is necessary, the clearance to
maintain proper airflow is at least three feet.
CB Series condensing units are single
circuited with vertical air discharge. There
must be no obstruction above the equipment.
Do not place the unit under an overhang.
Placement relative to the building air intakes
and other structures must be carefully
selected. Consider the effects of outdoor fan
noise on conditioned space and any adjacent
occupied space. It is recommended that the
unit be placed so that discharge does not
12
blow toward windows less than 25 feet
Design
Temperature
Suggest Minimum
Elevation
+15 F and above
3”
-5 F to +17 F
8”
Below -5 F
12”
Incorrect lifting can cause damage to
the unit.
CAUTION
Electric shock hazard. Before
attempting to perform any installation,
service, or maintenance, shut off all
electrical power to the unit at the
disconnect switches. Unit may have
multiple power supplies. Failure to
disconnect power could result in
dangerous operation, serious injury,
death or property damage.
WARNING
away.
Heat pumps require special location
consideration in areas where snow
accumulation can become an obstruction
and in areas with prolonged continuous
subfreezing temperatures. Heat pump unit
bases are cutout under the outdoor coil to
permit drainage of frost accumulation. The
unit must be situated to permit free
unobstructed drainage of the defrost water
and ice. A minimum 3 inches clearance
under the outdoor coil is required in the
milder climates. In more severe weather
locations, it is recommended that the unit be
elevated to allow unobstructed drainage and
airflow.
Table 1 - Recommended Elevation
Minimums
Lifting the Unit
CB Series condensing units have channels
underneath the base which provide lifting
access to the underside of the equipment and
allow moving and placement without
physical damage.
Dollies and/or carts are recommended to lift
and place the unit to prevent damage to the
equipment and injury to the installer.
Care should be taken if using spreader bars,
blocking, or other lifting devices to prevent
any damage to the cabinet, coil or
condensing fans.
Before lifting unit, be sure that all shipping
material has been removed from unit.
Hoist unit to a point directly above the
condenser pad, and lower unit into the
proper place. Unit may also be positioned
with a dolly. When the unit is in place,
remove the dolly or lifting device. Make
sure the unit is properly seated and level.
Electrical
Verify the unit nameplate agrees with the
power supply. Connect power and control
field wiring as shown on the unit wiring
diagram provided with the unit.
Route power and control wiring through the
utility entries on the unit. It is recommended
not to run power and control signal wires in
the same conduit. If the control wires are to
run inside the same conduit, 600 volt wires
should be used, or as required by applicable
codes.
Size supply conductors based on the unit
MCA rating. Supply conductors must be
rated a minimum of 75°C.
Protect the branch circuit in accordance with
code requirements. The unit must be
13
electrically grounded in accordance with
Scroll compressors are directional
and will be damaged by operation in
the wrong direction. Low pressure
switches on compressors have been
disconnected after factory testing.
Rotation should be checked by a
qualified service technician at startup
using suction and discharge pressure
gauges and any wiring alteration
should only be made at the unit
power connection.
Three phase voltage imbalance will
cause motor overheating and
premature failure.
CAUTION
Rotation must be checked on all
MOTORS AND COMPRESSORS of
three phase units. Condenser fan
motors should be checked by a
qualified service technician at startup
and any wiring alteration should only
be made at the unit power
connection.
CAUTION
CAUTION
local codes, or in the absence of local codes,
the current National Electric Code,
ANSI/NFPA 70 or the current Canadian
Electrical Code CSA C22.1.
Note: Units are factory wired for 208V,
230V, 460V or 575V. In some units, the
208V and 230V options may also be
provided in single or three phase
configurations. The transformer
configuration must be checked by a
qualified technician prior to startup.
Wire power leads to the unit terminal block
or compressor contactor. All wiring beyond
this point has been done by the manufacturer
and cannot be modified without effecting the
unit's agency/safety certification.
All units require field supplied electrical
overcurrent and short circuit protection.
Device must not be sized larger than the
Maximum Overcurrent Protection (MOP)
shown on the unit nameplate.
Codes may require a disconnect switch be
within sight of the unit.
It is recommended that the field installed
overcurrent protection or disconnect switch
not be installed on the unit.
Supply voltage must be within the min/max
range shown on the unit nameplate.
Available short circuit current should not
exceed the short circuit current rating
(SCCR) shown on the unit nameplate.
Three phase voltage imbalance will cause
motor overheating and premature failure.
The maximum allowable imbalance is 2.0%.
Voltage imbalance is defined as 100 times
the maximum deviation from the average
voltage divided by the average voltage.
Example:
(221V+230V+227V)/3 = 226V, then
100*(226V-221V)/226V = 2.2%, which
exceeds the allowable imbalance.
Check voltage imbalance at the unit
disconnect switch and at the compressor
terminal. Contact your local power company
for line voltage corrections.
Installing contractor must check for proper
motor rotation and check blower motor
amperage listed on the motor nameplate is
not exceeded.
14
Wire control signals to the unit’s low
This section is for information only
and is not intended to provide all
details required by the designer or
installer of the refrigerant piping
between the condenser or
condensing unit and the air handling
unit. AAON is not responsible for
interconnecting refrigerant piping.
Consult ASHRAE Handbook –
Refrigeration and ASME Standards.
CAUTION
voltage terminal block located in the
controls compartment.
If any factory installed wiring must be
replaced, use a minimum 105°C type AWM
insulated conductors.
Thermostat
If a thermostat is used for unit control,
thermostat should be located on an inside
wall 4-5 feet above the floor where it will
not be subjected to drafts, sun exposure, or
heat from electrical fixtures or appliances.
Follow thermostat manufacturer’s
instructions for general installation
procedure.
Thermostat control wiring size must be large
enough to prevent excess voltage drop and
ensure proper operation.
All external devices must be powered via a
separate external power supply.
Units with the modulating hot gas reheat
dehumidification feature must use a
humidistat or a thermostat with a normally
closed (NC) dehumidification option. The
following thermostats have been approved
for usage with the dehumidification feature,
Robertshaw® 9825i2 Thermostat
Honeywell VisionPRO® IAQ Thermostat
AAON Mini Controller
Refrigerant Piping
(See back of the manual for refrigerant
piping diagrams.)
General
Piping from the condensing unit to the air
handler is the responsibility of the installing
contractor.
Use only clean type “ACR” copper tubing
that has been joined with high temperature
brazing alloy.
The pipe or line sizes must be selected to
meet the actual installation conditions and
not simply based on the connection sizes at
the condensing unit or air handler.
All CB Series condensing units are provided
with in-line shutoff valves on both the liquid
and suction lines. These should remain
closed until the system is ready for start-up
after piping and vacuuming.
Piping should conform to generally accepted
practices and codes.
Upon completion of piping connection, the
interconnecting piping and air handler
MUST BE evacuated to 500 microns or less;
leak checked and charged with refrigerant.
15
Determining Refrigerant Line Size
Line sizes must be selected to meet
actual installation conditions, not
simply based on the connection sizes
at the condensing unit or air handling
unit.
CAUTION
The piping between the condenser and low
side must ensure:
1. Minimum pressure drop, and
2. Continuous oil return, and
3. Prevention of liquid refrigerant slugging,
or carryover
Minimizing the refrigerant line size is
favorable from an economic perspective,
reducing installation costs, and reducing the
potential for leakage. However, as pipe
diameters narrow, pressure-reducing
frictional forces increase.
Excessive suction line pressure drop causes
loss of compressor capacity and increased
power usage resulting in reduced system
efficiency. Excessive pressure drops in the
liquid line can cause the liquid refrigerant to
flash, resulting in faulty Thermal Expansion
Valve (TXV) operation and improper
system performance. In order to operate
efficiently and cost effectively, while
avoiding malfunction, refrigeration systems
must be designed to minimize both cost and
pressure loss.
Equivalent Line Length
All line lengths discussed in this manual,
unless specifically stated otherwise, are
Equivalent Line Lengths. The frictional
pressure drop through valves, fittings, and
accessories is determined by establishing the
equivalent length of straight pipe of the
same diameter. Always use equivalent line lengths when calculating pressure drop.
Special piping provisions must be taken
when lines are run underground, up vertical
risers, or in excessively long line runs.
Liquid Line Sizing
When sizing the liquid line, it is important to
minimize the refrigerant charge to reduce
installation costs and improve system
reliability. This can be achieved by
minimizing the liquid line diameter.
However, reducing the pipe diameter will
increase the velocity of the liquid refrigerant
which increases the frictional pressure drop
in the liquid line, and causes other
undesirable effects such as noise.
Maintaining the pressure in the liquid line is
critical to ensuring sufficient saturation
temperature, avoiding flashing upstream of
the TXV, and maintaining system
efficiency. Pressure losses through the
liquid line due to frictional contact, installed
accessories, and vertical risers are
inevitable. Maintaining adequate subcooling at the condenser to overcome these
losses is the only method to ensure that
liquid refrigerant reaches the TXV.
Liquid refrigerant traveling upwards in a
riser loses head pressure. If the evaporator is
below the condenser, and the liquid line
does not include risers, the gravitational
force will increase the pressure of the liquid
refrigerant. This will allow the refrigerant to
withstand greater frictional losses without
the occurrence of flashing prior to the TXV.
A moisture-indicating sight glass may be
field installed in the liquid line to indicate
the occurrence of premature flashing or
moisture in the line. The sight glass should
not be used to determine if the system is
properly charged. Use temperature and
pressure measurements to determine
liquid sub-cooling, not the sight glass.
16
Liquid Line Routing
Circuits with variable capacity scroll
compressors require suction riser
traps every 10 feet.
CAUTION
Care should be taken with vertical risers.
When the system is shut down, gravity will
pull liquid down the vertical column, and
back to the condenser when it is below the
evaporator. This could potentially result in
compressor flooding. A check valve can be
installed in the liquid line where the liquid
column rises above the condenser to prevent
this. The liquid line is typically pitched
along with the suction line, or hot gas line,
to minimize the complexity of the
configuration.
Liquid Line Insulation
When the liquid line is routed through
regions where temperature losses are
expected, no insulation is required, as this
may provide additional sub-cooling to the
refrigerant. When routing the liquid line
through high temperature areas, insulation of
the line is appropriate to avoid loss of subcooling through heat gain.
Liquid Line Guidelines
In order to ensure liquid at the TXV,
frictional losses must not exceed available
sub-cooling. A commonly used guideline to
consider is a system design with pressure
losses due to friction through the line not to
exceed a corresponding 1-2°F change in
saturation temperature.
If the velocity of refrigerant in the liquid line
is too great, it could cause excessive noise or
piping erosion. The recommended
maximum velocities for liquid lines are 100
fpm from the condenser to a receiver tank to
discourage fluid backup, and 300 fpm from
receiver tank to the evaporator to minimize
valve induced liquid hammer.
Liquid Line Accessories
Liquid line shut off valves and filter driers
are factory provided. Filter driers must be
field installed. The total length equivalent of
pressure losses through valves, elbows and
fittings must be considered when adding
additional components in the field. It is a
good practice to utilize the fewest elbows
that will allow the mating units to be
successfully joined.
Suction Line Sizing
The suction line is more critical than the
liquid line from a design and construction
standpoint. More care must be taken to
ensure that adequate velocity is achieved to
return oil to the compressor at minimum
loading conditions. However, reducing the
piping diameter to increase the velocity at
minimal load can result in excessive
pressure losses, capacity reduction, and
noise at full load.
Suction Line Routing
Pitch the suction line in the direction of flow
(about 1 foot per 120 feet of length) to
maintain oil flow towards the compressor,
and keep it from flooding back into the
evaporator. Crankcase heaters are provided
to keep any condensed refrigerant that
collects in the compressor from causing
damage or wear. Make sure to provide
support to maintain suction line positioning,
and insulate completely between the
evaporator and condensing unit.
It is important to consider part load
operation when sizing suction lines. At
minimum capacity, refrigerant velocity may
not be adequate to return oil up the vertical
riser. Decreasing the diameter of the vertical
riser will increase the velocity, but also the
frictional loss.
17
A double suction riser can be applied to the
situation of part load operation with a
suction riser. A double suction riser is
designed to return oil at minimum load
while not incurring excessive frictional
losses at full load. A double suction riser
consists of a small diameter riser in parallel
with a larger diameter riser, and a trap at the
base of the large riser. At minimum
capacity, refrigerant velocity is not sufficient
to carry oil up both risers, and it collects in
the trap, effectively closing off the larger
diameter riser, and diverting refrigerant up
the small riser where velocity of the
refrigerant is sufficient to maintain oil flow.
At full load, the mass flow clears the trap of
oil, and refrigerant is carried through both
risers. The smaller diameter pipe should be
sized to return oil at minimum load, while
the larger diameter pipe should be sized so
that flow through both pipes provides
acceptable pressure drop at full load.
Suction Line Insulation
The entire suction line should be insulated
with a minimum 1 inch thick Armaflex
insulation. This prevents condensation from
forming on the line, and reduces any
potential loss in capacity associated with
heat gain placing additional load on the
system.
Suction Line Guidelines
For proper performance, suction line
velocities less than a 4,000 fpm maximum
are recommended. The minimum velocity
required to return oil is dependent on the
pipe diameter, however, a general guideline
of 1,000 fpm minimum may be applied.
In a fashion similar to the liquid line, a
common guideline to consider is a system
design with pressure losses due to friction
through the line not to exceed a
corresponding 1-2°F change in saturation
temperature.
At points where small pipe size can be used
to provide sufficient velocity to return oil in
vertical risers at part loads, greater pressure
losses are incurred at full loads. This can be
compensated for by over sizing the
horizontal runs and vertical drop sections.
This will however require additional
refrigerant charge.
Circuits with variable capacity scroll
compressors require suction riser traps every
10 feet.
Suction Line Accessories
If the job requirements specify suction
accumulators, they must be separately
purchased and field installed.
Hot Gas Bypass Line
Hot Gas Bypass (HGB) is available for use
with DX systems that may experience low
suction pressure during the operating cycle.
This may be due to varying load conditions
associated with VAV applications or units
supplying a large percentage of outside air.
The system is designed to divert refrigerant
from the compressor discharge to the low
pressure side of the system in order to keep
the evaporator from freezing and to maintain
adequate refrigerant velocity for oil return at
minimum load.
Hot discharge gas is redirected to the
evaporator inlet via an auxiliary side
connector (ASC) to false load the evaporator
when reduced suction pressure is sensed.
Field piping between the condensing unit
and the evaporator is required.
Hot Gas Bypass Piping Considerations for
Evaporator above Condensing Unit
Pitch the hot gas bypass line downward in
the direction of refrigerant flow, toward the
evaporator.
18
When installing hot gas bypass risers, an oil
drip line must be provided at the lowest
point in the system. The oil drip line must be
vertical, its diameter should be the same as
the diameter of the riser, and it should be 1
foot long. Install a sight glass in the oil drip
line for observation. Run an oil return line,
using 1/8 inch capillary tube, 10 feet in
length, from the oil drip line to the suction
line. Connect the oil return line below the
sight glass and 1 inch above the bottom of
the oil drip line.
HGB valves are adjustable. Factory HGB
valve settings will be sufficient for most
applications, but may require slight
adjustments for some applications, including
some make up air applications.
Insulate the entire length of the HGB line
with a minimum 1 inch thick Armaflex
insulation.
Hot Gas Bypass Piping Considerations for
Evaporator Below Condensing Unit
The line must slope downward from the
HGB valve toward the evaporator.
Hot Gas Bypass Line Guidelines
Choose a small size line to ensure oil return,
and minimize refrigerant charge.
Maintain velocities below a maximum of
4,000 fpm. A general minimum velocity
guideline to use is approximately 1,000 fpm.
Hot Gas Reheat
The AAON modulating hot gas reheat
system diverts hot discharge gas from the
condenser to the air handling unit through
the hot gas line. Field piping between the
condensing unit and the air handler is
required.
The line delivers the hot discharge gas to the
reheat coil and/or the hot gas bypass valve,
so it is sized as a discharge line.
Discharge lines should be sized to ensure
adequate velocity of refrigerant to ensure oil
return, avoid excessive noise associated with
velocities that are too high, and to minimize
efficiency losses associated with friction.
Pitch the hot gas line in the direction of flow
for oil return.
When installing hot gas reheat risers, an oil
drip line must be provided at the lowest
point in the system. The oil drip line must be
vertical, its diameter should be the same as
the diameter of the riser, and it should be 1
foot long. Run a drip line, using 1/8 inch
capillary tube, 10 feet in length, from the oil
drip line to the suction line. Connect the oil
return line below the sight glass and 1 inch
above the bottom of the oil drip line.
Insulate the entire length of the hot gas line
with a minimum 1 inch thick Armaflex
insulation.
Hot Gas Reheat Guidelines
Maintain velocities below a maximum of
3,500 fpm. A general minimum velocity
guideline is 2,000 fpm.
Predetermined Line Sizes
To aid in line sizing and selection, AAON
has predetermined line sizes for the liquid,
suction, and hot gas lines in comfort cooling
applications.
In order to generate this information, the
following cycle assumptions are made:
Saturated suction temperature = 50°F,
Saturated condensing temperature = 125°F,
Sub-cooling = 10°F, Superheat = 15°F.
19
The liquid lines have been chosen to
Before using this table read the
When to Use Predetermined Line
Sizes section. Do not assume that
these line sizes are appropriate for
every case. Consult ASHRAE
Handbook – Refrigeration for
generally accepted system piping
practices. The AAON Refrigerant Piping Calculator in Ecat32 can be
used for job specific line sizing.
CAUTION
maintain velocities between 100 and 350
fpm. The suction line diameters are selected
to limit velocities to a 4,000 fpm maximum,
while a minimum velocity restriction is
imposed by the ability to entrain oil up
vertical suction risers (ASHRAE Handbook
- Refrigeration).
Acceptable pressure loss criteria are applied
to each of the lines: The total equivalent
length of the liquid line available is
determined such that 3°F of liquid subcooling remain at the TXV. This includes
the pressure losses in horizontal and vertical
sections, accessories, elbows, etc.
Recall that the available sub-cooling for the
cycle is assumed as 10°F. To maintain at
least 3°F sub-cooling as a factor of safety to
avoid flashing at the TXV, we consider a
maximum pressure loss equivalent to a 7°F
change in saturation temperature. Pressure
losses in the suction line are not to exceed
2°F.
When to Use Predetermined Line Sizing
The line sizes presented are not the only
acceptable pipe diameters, they are however
appropriate for general comfort cooling
applications, and satisfy common job
requirements. Examine the conditions,
assumptions, and constraints used in the
generation of the predetermined pipe
diameters to ensure that this method is
applicable to a particular case. Do not
assume that these line sizes are appropriate
for every case. Consult ASHRAE
Handbook – Refrigeration for generally
accepted system piping practices.
How to Use Predetermined Line Sizing
First, read the previous section, When to Use
Predetermined Line Sizing, to decide if this
method is applicable. Next, consult Table 2
below for pipe diameters.
Examine Figure 2 below to determine the
acceptable line dimensions associated with
the pipe diameters determined in Table 2
below. The figure is shown as total available
riser height versus total equivalent line
length for the liquid line. The curve
identifies a region of acceptable piping
configuration when the predetermined line
sizes are selected for any model in the table.
A piping configuration above the curve falls
outside the assumptions used to determine
the line size and will result in a loss of subcooling, and additional pressure losses in the
suction and hot gas lines.
The total equivalent line length definition
includes the height of vertical rise, pressure
drop through elbows and accessories, and
horizontal line length, so elbows,
accessories, and vertical rise must be
considered when determining horizontal
length available from the total equivalent
line length.
The figure below is presented in terms of the
liquid line, but it assumes that the suction
line length is similar, as these lines are
commonly routed together to minimize the
space and cost required for split system
installation.
20
Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A
Model
Connection Sizes
Predetermined Line Size
Liquid
Suction
Hot Gas
Liquid
Suction
HGBP*
HGRH**
CB-024
3/8”
3/4”
3/8”
3/8”
3/4”
3/8”
3/8”
CB-036
3/8”
3/4”
3/8”
3/8”
3/4”
3/8”
1/2”
CB-048
3/8”
7/8”
1/2”
1/2”
7/8”
1/2”
1/2”
CB-060
3/8”
7/8”
1/2”
1/2”
7/8”
1/2”
1/2”
Total Equivalent Line Length in this
figure is limited to 160 equivalent
feet.
CAUTION
* Hot Gas Bypass line
** Hot Gas Reheat line
Figure 2 - Riser height versus total equivalent line length
Note: Figure 2 is for R-410A split system applications with two step compressor CB-024
through CB-060 units. The region of acceptable riser height is the lighter area. Select the
corresponding predetermined line size from Table 2 above.
21
Startup
Rotation must be checked on all
MOTORS AND COMPRESSORS of
three phase units. Condenser fan
motors should all be checked by a
qualified service technician at startup
and any wiring alteration should only
be made at the unit power
connection.
Improper installation, adjustment,
alteration, service or maintenance
can cause property damage,
personal injury or loss of life.
Installation and service must be
performed by a trained, qualified
installer.
WARNING
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
WARNING
CAUTION
Scroll compressors are directional
and will be damaged by operation in
the wrong direction. Low pressure
switches on compressors have been
disconnected after factory testing.
Rotation should be checked by a
qualified service technician at startup
using suction and discharge pressure
gauges and any wiring alteration
should only be made at the unit
power connection.
CAUTION
The Clean Air Act of 1990 bans the
intentional venting of refrigerant
(CFC’s and HCFC’s) as of July 1,
1992. Approved methods of recovery,
recycling or reclaiming must be
followed. Fines and/or incarceration
may be levied for non-compliance.
CAUTION
(See back of the manual for startup form.)
Compressors
All compressors are equipped with
crankcase heaters, which should be
energized at least 24 hours prior to cooling
operation of the compressor.
The unit comes with full charge based on a
25 foot line set. Charging a system in the
field must be based on determination of
liquid sub-cooling and evaporator superheat.
On a system with a TXV, liquid sub-cooling
is more representative of the charge than
evaporator superheat but both measurements
must be taken.
Before Charging
Unit being charged must be at or near full
load conditions before adjusting the charge.
Units equipped with hot gas bypass must
have the hot gas bypass valve closed to get
the proper charge.
22
Units equipped with hot gas reheat must be
Air-Cooled Condenser
Sub-Cooling*
12-18°F
Sub-Cooling with
Hot Gas Reheat*
15-22°F
Superheat**
8-15°F
Air-Source Heat Pump
Sub-Cooling*
2-4°F
Sub-Cooling with
Hot Gas Reheat*
15-22°F
Superheat**
16-22°F
charged with the hot gas valves closed while
the unit is in cooling mode. After charging,
unit should be operated in reheat
(dehumidification) mode to check for
correct operation.
After adding or removing charge the system
must be allowed to stabilize, typically 10-15
minutes, before making any other
adjustments.
The type of unit and options determine the
ranges for liquid sub-cooling and evaporator
superheat. Refer to Table 3 below when
determining the proper sub-cooling.
The vertical rise of the liquid line must be
known in order to adjust the sub-cooling
range for proper charge.
Checking Liquid Sub-cooling
Measure the temperature of the liquid line as
it leaves the condenser coil.
Read the gauge pressure reading of the
liquid line close to the point where the
temperature was taken. You must use liquid
line pressure as it will vary from discharge
pressure due to condenser coil pressure
drop.
Convert the pressure obtained to a saturated
temperature using the appropriate refrigerant
temperature-pressure chart or Table 5 below.
Subtract the measured liquid line
temperature from the saturated temperature
to determine the liquid sub-cooling.
Compare calculated sub-cooling to Table 3
below for the appropriate unit type and
options.
Checking Evaporator Superheat
Measure the temperature of the suction line
close to the compressor.
Read gauge pressure at the suction line close
to the compressor.
Convert the pressure obtained to a saturated
temperature using the appropriate refrigerant
temperature-pressure chart or Table 5 below.
Subtract the saturated temperature from the
measured suction line temperature to
determine the evaporator superheat.
Compare calculated superheat to Table 3
below for the appropriate unit type and
options.
Table 3 - Sub-cooling and Superheat
* Sub-cooling must be increased by 2°F per
20 feet of vertical liquid line rise for R-410A
** Superheat will increase with long suction
line runs.
Adjusting Sub-cooling and Superheat
Temperatures
The system is overcharged if the sub-cooling
temperature is too high and the evaporator is
fully loaded (low loads on the evaporator
result in increased sub-cooling) and the
evaporator superheat is within the
temperature range as shown in Table 3
above (high superheat results in increased
sub-cooling)
23
Correct an overcharged system by reducing
Model
Cooling Stage 2
(cfm)
Cooling Stage 1
(cfm)
Heating Stage 2
(cfm)
Heating Stage 1
(cfm)
CB-B-024-*-*-1
885
663.75
885
796.5
CB-B-036-*-*-1
1250
937.5
1250
1125
CB-B-048-*-*-1
1500
1125
1500
1350
CB-B-060-*-*-1
1545
1158.75
1545
1390.5
DO NOT OVERCHARGE!
Refrigerant overcharging leads to
excess refrigerant in the condenser
coils resulting in elevated compressor
discharge pressure.
CAUTION
Before completing startup and
leaving the unit a complete operating
cycle should be observed to verify
that all components are functioning
properly.
CAUTION
the amount of refrigerant in the system to
lower the sub-cooling.
The system is undercharged if the superheat
is too high and the sub-cooling is too low
Air Flow
Table 4 - Performance Testing Air Flow Setpoints
Correct an undercharged system by adding
refrigerant to the system to reduce superheat
and raise sub-cooling.
If the sub-cooling is correct and the
superheat is too high, the TXV may need
adjustment to correct the superheat.
5 MINUTE MINIMUM OFF TIME
To prevent motor overheating
compressors must cycle off for a
minimum of 5 minutes.
5 MINUTE MINIMUM ON TIME
To maintain the proper oil level
compressors must cycle on for a
minimum of 5 minutes.
The cycle rate must not exceed 6
starts per hour.
WARNING
Unit operations should be controlled with
thermostat, or unit controller, never at the
main power supply, except for emergency,
servicing, or complete shutdown of the unit.
Thermostat Operation
Heating
Thermostat system switch - "Heat"
Thermostat fan switch - "Auto" or "On"
Thermostat temperature set to desired point.
Cooling
Thermostat system switch - "Cool"
Thermostat fan switch - "Auto" or "On"
Thermostat temperature set to desired point.
Air Circulation
Thermostat system switch - "Off"
Thermostat fan switch - "Auto" or "On"
No change of the thermostat temperature.
With these settings, the air handler’s supply
fan will run continuously but the supply air
will not be heated, cooled, or dehumidified.
System Off
Thermostat system switch - "Off"
Thermostat fan switch - "Auto"
No change of the thermostat temperature.
With these settings, the system is shut down,
with the exception of the control system
power (24 VAC), and the crankcase heaters
(about 60 watts/compressor).
Night and Weekend Unoccupied Operation
To reduce the operating time of the unit
when the space is unoccupied, such as nights
and weekends, it is recommended that the
temperature setting be raised about 5°F
while unoccupied during the cooling season
and lowered about 10°F during the heating
season.
Compressor
The compressors must be off for a minimum
of 5 minutes and on for a minimum of 5
minutes. Short cycling of the compressors
can causes undue stress and wear.
Variable Capacity Compressor
Controller
Units with variable capacity scroll
compressors may include variable capacity
compressor controller. The following is an
explanation of the terminals and
troubleshooting of the alert flash codes on
the controller. For more information on the
compressor controller, see Emerson Climate
Bulletin AE8-1328.
26
Figure 3 - Variable Capacity Compressor
Demand
Signal (VDC)
Loaded %
Unloaded %
Time Loaded
Time
Unloaded
% Compressor
Capacity
1.00
Off
Off
Off
Off
0%
1.44
10%
90%
1.5 sec
13.5 sec
10%
3.00
50%
50%
7.5 sec
7.5 sec
50%
4.20
80%
20%
12 sec
3 sec
80%
5.00
100%
0%
15 sec
0 sec
100%
To avoid damaging the compressor
controller, DO NOT connect wires to
terminals C3, C4, T3, T4, T5, or T6.
WARNING
Controller
Low Voltage Terminals
24COM Module Common
24VAC Module Power
C1 & C2 Demand Input
P1 Pressure Common
P2 Pressure Input
P3 Pressure Power 5VDC
P4 Pressure Shield
P5 & P6 Pressure Output
T1 & T2 Discharge Temperature Sensor
Table 6 - Demand Signal vs. Compressor Capacity Modulation
High Voltage Terminals
A1 & A2 Alarm Relay Out
M1 & M2 Contactor
L1 Control Voltage N
L2 Control Voltage L
U1 & U2 Digital Unloader Solenoid
V1 & V2 Vapor Injection Solenoid
The compressor controller modulates the
compressor unloader solenoid in an on/off
pattern according the capacity demand
signal of the system. The following table
shows the linear relationship between the
demand signal and compressor capacity
modulation. The compressor controller also
protects the compressor against high
discharge temperature. Refer to Table 7 for
the relationship between thermistor
temperature readings and resistance values.
Table 7 - Thermistor Temperature vs. Resistance Values
28
Low Ambient Options
Improper installation, adjustment,
alteration, service or maintenance
can cause property damage,
personal injury or loss of life.
Installation and service must be
performed by a trained, qualified
installer.
WARNING
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
WARNING
The condenser fan cycling option is used to
operate a refrigerant system down to 35°F
outside air temperature. As the ambient
temperature drops, the condenser becomes
more effective therefore lowering the head
pressure. When the head pressure gets too
low there will be insufficient pressure to
operate the expansion valve properly.
During low ambient temperatures, it is
difficult to start a system because the
refrigerant will migrate to the cold part of
the system (condenser) and make it difficult
for refrigerant to flow.
The AAON 0°F low ambient system
maintains normal head pressure during
periods of low ambient by effectively
reducing the heat transfer surface area,
reducing capacity and increasing condensing
pressure, allowing the system to operate
properly. During periods with higher
ambient temperatures the entire condenser is
required to condense refrigerant.
Maintenance
(See back of the manual for maintenance
log.)
At least once each year, a qualified service
technician should check out the unit. This
includes reading and recording suction
pressures and checking for normal subcooling and superheat.
Only trained and qualified service
technicians experienced in both condensing
units and air conditioning are permitted to
service the CB Series units to keep
warranties in effect.
Coils
The condenser coils should be inspected
yearly to ensure unrestricted airflow. If the
coils contain a large amount of airborne dust
or other material, they should be cleaned.
Care must be taken to prevent bending of the
aluminum fins on the coils.
Before attempting to clean the coils; set
thermostat to the "OFF" position; turn the
electrical power to the unit to the "OFF"
position at the disconnect switch. The
condenser coil can be cleaned by washing
from the inside out with water and a coil
cleaner. If coil is extremely dirty with
clogged fins, a service professional
specializing in coil cleaning should be
called.
E-Coated Coil Cleaning
Documented routine cleaning of e-coated
coils is required to maintain coating
warranty coverage.
Surface loaded fibers or dirt should be
removed prior to water rinse to prevent
restriction of airflow. If unable to back wash
the side of the coil opposite of the coils
entering air side, then surface loaded fibers
or dirt should be removed with a vacuum
cleaner. If a vacuum cleaner is not available,
a soft non-metallic bristle brush may be
29
used. In either case, the tool should be
High velocity water from a pressure
washer or compressed air should
only be used at a very low pressure
to prevent fin and/or coil damages.
The force of the water or air jet may
bend the fin edges and increase
airside pressure drop. Reduced unit
performance or nuisance unit
shutdowns may occur.
CAUTION
Harsh chemicals, household bleach,
or acid cleaners should not be used
to clean outdoor or indoor e-coated
coils. These cleaners can be very
difficult to rinse out of the coil and
can accelerate corrosion and attack
the e-coating. If there is dirt below the
surface of the coil, use the
recommended coil cleaners.
CAUTION
applied in the direction of the fins. Coil
surfaces can be easily damaged (fin edges
bent over) if the tool is applied across the
fins.
Use of a water stream, such as a garden
hose, against a surface loaded coil will drive
the fibers and dirt into the coil. This will
make cleaning efforts more difficult. Surface
loaded fibers must be completely removed
prior to using low velocity clean water rinse.
A monthly clean water rinse is
recommended for coils that are applied in
coastal or industrial environments to help to
remove chlorides, dirt, and debris. It is very
important when rinsing, that water
temperature is less than 130°F and pressure
is than 900 psig to avoid damaging the fin
edges. An elevated water temperature (not to
exceed 130°F) will reduce surface tension,
increasing the ability to remove chlorides
and dirt.
Quarterly cleaning is essential to extend
the life of an e-coated coil and is required
to maintain coating warranty coverage.
Coil cleaning shall be part of the unit’s
regularly scheduled maintenance
procedures. Failure to clean an e-coated coil
will void the warranty and may result in
reduced efficiency and durability.
For routine quarterly cleaning, first clean the
coil with the below approved coil
cleaner. After cleaning the coils with the
approved cleaning agent, use the approved
chloride remover to remove soluble salts and
revitalize the unit.
Recommended Coil Cleaner
The following cleaning agent, assuming it is
used in accordance with the manufacturer’s
directions on the container for proper mixing
and cleaning, has been approved for use on
e-coated coils to remove mold, mildew,
dust, soot, greasy residue, lint, and other
particulate:
Enviro-Coil Concentrate, Part Number HEC01.
Recommended Chloride Remover
CHLOR*RID DTS™ should be used to
remove soluble salts from the e-coated coil,
but the directions must be followed closely.
This product is not intended for use as a
degreaser. Any grease or oil film should first
be removed with the approved cleaning
agent.
Remove Barrier - Soluble salts adhere
themselves to the substrate. For the effective
use of this product, the product must be able
to come in contact with the salts. These salts
30
may be beneath any soils, grease or dirt;
therefore, these barriers must be removed
prior to application of this product. As in all
surface preparation, the best work yields the
best results.
Apply CHLOR*RID DTS - Apply directly
onto the substrate. Sufficient product must
be applied uniformly across the substrate to
thoroughly wet out surface, with no areas
missed. This may be accomplished by use of
a pump-up sprayer or conventional spray
gun. The method does not matter, as long as
the entire area to be cleaned is wetted. After
the substrate has been thoroughly wetted,
the salts will be soluble and is now only
necessary to rinse them off.
Rinse - It is highly recommended that a hose
be used, as a pressure washer will damage
the fins. The water to be used for the rinse is
recommended to be of potable quality,
though a lesser quality of water may be used
if a small amount of CHLOR*RID DTS is
added. Check with CHLOR*RID
International, Inc. for recommendations on
lesser quality rinse water.
DX Cooling
Set unit controls to cooling mode of
operation with supply fans on. Check
compressor operation, rotation, amperage
and voltage to the unit nameplate (check the
amperage on the load side of the compressor
contactor).
The scroll compressors are fully hermetic
and require no maintenance except for
keeping the shell clean.
Refrigerant circuit includes factory provided
and field installed line filter drier. The unit
does not include a liquid line solenoid valve.
This must be field furnished and installed if
required by job conditions.
Condenser Fan Motor
All original motors and bearings are
furnished with factory lubrication. They
require no lubrication.
The electrically commutated condenser fan
motor (ECM) is factory preprogrammed and
requires no maintenance.
Replacement Parts
Parts for AAON equipment may be obtained
from AAON at www.aaonparts.com. When
ordering parts, reference the unit serial
number and part number.
AAON – Longview
Warranty, Service, and Parts Department
Note: Before calling, technician should have
model and serial number of the unit
available for the service department to help
answer questions regarding the unit.
31
Refrigerant Piping Diagrams
Figure 5– A/C only piping, AHU above CU
32
Figure 6 – A/C only piping, AHU below CU
33
Figure 7 – Modulating hot gas reheat piping, AHU above CU
34
Figure 8 – Modulating hot gas reheat piping, AHU below CU
35
Figure 9 – Hot gas bypass piping, AHU above CU
36
Figure 10 – Hot gas bypass piping, AHU below CU
37
Figure 11 – Modulating hot gas reheat with hot gas bypass piping, AHU above CU
38
Figure 12 – Modulating hot gas reheat with hot gas bypass piping, AHU below CU
39
Figure 13 – Heat pump piping, AHU above CU
40
Figure 14 – Heat pump piping, AHU below CU
41
Figure 15 – Heat pump with modulating hot gas reheat piping, AHU above CU
42
Figure 16 – Heat pump with modulating hot gas reheat, AHU below CU
Installing contractor should verify the following items.
1. Is there any visible shipping damage?
Yes
No
2. Is the unit level?
Yes
No
3. Are the unit clearances adequate for service and operation?
Yes
No
4. Do all access doors open freely and are the handles operational?
Yes
No
5. Have all shipping braces been removed?
Yes
No
6. Have all electrical connections been tested for tightness?
Yes
No
7. Does the electrical service correspond to the unit nameplate?
Yes
No
8. On 208/230V units, has transformer tap been checked?
Yes
No
9. Has overcurrent protection been installed to match the unit nameplate
requirement?
Yes
No
10. Have all set screws on the fans been tightened?
Yes
No
11. Do all fans and pumps rotate freely?
Yes
No
12. Is all copper tubing isolated so that it does not rub?
Yes
No
Ambient Temperature
Ambient Dry Bulb Temperature ________°F
Ambient Wet Bulb Temperature ________°F
Refrigeration System 1 - Cooling Mode
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
Suction
Liquid
CB Series Startup Form
Refrigeration System 1 - Heating Mode (Heat Pump Only)
Pressure
Saturated
Temperature
Line
Temperature
Sub-cooling
Superheat
Discharge
Suction
Liquid
Air-Cooled Condenser Fan
Alignment_____
Check Rotation_____
Nameplate Amps________
Number
hp
L1
L2
L3
1
Entry Date
Action Taken
Name/Tel.
Maintenance Log
This log must be kept with the unit. It is the responsibility of the owner and/or
maintenance/service contractor to document any service, repair or adjustments. AAON Service
and Warranty Departments are available to advise and provide phone help for proper operation
and replacement parts. The responsibility for proper start-up, maintenance and servicing of the
equipment falls to the owner and qualified licensed technician.
Literature Change History
June 2013
New installation and operation manual
AAON
2425 South Yukon Ave.
Tulsa, OK 74107-2728
Phone: 918-583-2266
Fax: 918-583-6094
www.aaon.com
CB Series
Installation, Operation &
Maintenance
R57611 · Rev. - · 130603
(ACP J00187)
It is the intent of AAON to provide accurate and current product information. However, in the
interest of product improvement, AAON reserves the right to change pricing, specifications,
and/or design of its product without notice, obligation, or liability.