Carrier CAS181 Series Dimensions and installation guide

CAS-181-303-01SI 2-23
Installation, Start-Up and Service Instructions
CONTENTS
Page
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . 1
INSTALLATION GUIDELINES . . . . . . . . . . . . . . 2
Replacement/Retrofit —
R-22 to R-410A Refrigerant . . . . . . . . . . . . . . 2
Rated Indoor Airflow (cfm) . . . . . . . . . . . . . . . . . 2
Identify Factory Options . . . . . . . . . . . . . . . . . . 3
Matching CAS Model to Evaporator Coil . . . . . 3
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Jobsite Survey . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Step 1 — Plan for Unit Location . . . . . . . . . . . . 8
Step 2 — Complete Pre-Installation Checks . . 8
Step 3 — Prepare Unit Mounting Support . . . . 8
Step 4 — Rig and Mount the Unit . . . . . . . . . . . 8
Step 5 — Determine Refrigerant Line Sizes . . . 9
Suction Riser . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Step 6 — Complete Refrigerant Piping
Connections . . . . . . . . . . . . . . . . . . . . . . . . . 12
Step 7 — Install Accessories . . . . . . . . . . . . . . 16
Step 8 — Complete Electrical Connections . . 16
Step 9 — Wind Baffles for Low Ambient
Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
PRE-START-UP . . . . . . . . . . . . . . . . . . . . . . . . . 22
System Check . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Turn On Crankcase Heater . . . . . . . . . . . . . . . 22
Preliminary Charge . . . . . . . . . . . . . . . . . . . . . . 22
START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Preliminary Checks . . . . . . . . . . . . . . . . . . . . . 23
Start Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
OPERATING SEQUENCE . . . . . . . . . . . . . . . . . 29
Base Unit Controls . . . . . . . . . . . . . . . . . . . . . . 29
All Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . 30
Quarterly Inspection
(and 30 days after initial start) . . . . . . . . . . . 30
Seasonal Maintenance . . . . . . . . . . . . . . . . . . . 30
SERVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Refrigeration System . . . . . . . . . . . . . . . . . . . . 31
Comfort Alert Diagnostic Module . . . . . . . . . . 31
Compressor Protection . . . . . . . . . . . . . . . . . . 38
Routine Cleaning of Round-Tube Plate Fin
(RTPF) Coils . . . . . . . . . . . . . . . . . . . . . . . . . 38
Fastener Torque Values . . . . . . . . . . . . . . . . . . 39
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . 39
APPENDIX A — AIR CONDITIONER AND HEAT
PUMP WITH R-410A — QUICK REFERENCE
GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
APPENDIX B — WIRING DIAGRAMS . . . . . . . 42
APPENDIX C — LOW AMBIENT OPTION . . . . 58
START-UP CHECKLIST . . . . . . . . . . . . . . . . . CL-1
SAFETY CONSIDERATIONS
Improper installation, adjustment, alteration, service,
maintenance, or use can cause explosion, fire, electrical
shock or other conditions which may cause personal injury
or property damage. Consult a qualified installer, service
agency, or your distributor or branch for information or
assistance. The qualified installer or agency must use
factory-authorized kits or accessories when modifying this
product. Refer to the individual instructions packaged with
the kits or accessories when installing.
Follow all safety codes. Wear safety glasses and work
gloves. Use quenching cloths for brazing operations and
have a fire extinguisher available. Read these instructions
thoroughly and follow all warnings or cautions attached to
the unit. Consult local building codes and appropriate
national electrical codes (in U.S.A., ANSI/NFPA70, National
Electrical Code (NEC); in Canada, CSA C22.1) for special
requirements.
It is important to recognize safety information. This is the
safety-alert symbol . When you see this symbol on the
unit and in instructions or manuals, be alert to the potential
for personal injury.
Understand the signal words DANGER, WARNING,
CAUTION, and NOTE. These words are used with the
safety-alert symbol. DANGER identifies the most serious
hazards which will result in severe personal injury or death.
WARNING signifies hazards which could result in personal
injury or death. CAUTION is used to identify unsafe
practices, which may result in minor personal injury or
product and property damage. NOTE is used to highlight
suggestions which will result in enhanced installation,
reliability, or operation.
DANGER
ELECTRICAL SHOCK HAZARD
Failure to follow this warning will result in personal injury
or death.
Before performing service or maintenance operations
on unit, turn off main power switch to unit and install
lock(s) and lockout tag(s). Ensure electrical service to
rooftop unit agrees with voltage and amperage listed on
the unit rating plate. Unit may have more than one
power switch.
WARNING
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal
injury, death and/or equipment damage.
R-410A refrigerant systems operate at higher pressures
than standard R-22 systems. Do not use R-22 service
equipment or components on R-410A refrigerant
equipment.
CAS181-303
Air-Cooled Condensing Units
with R-410A Refrigerant

2Specifications subject to change without notice. CAS-181-303-01SI
INSTALLATION GUIDELINES
Replacement/Retrofit —
R-22 to R-410A Refrigerant
Replacement/retrofit installations require change-out of out-
door unit, metering device, and filter driers. Change-out of
indoor coil (evaporator) and interconnecting tubing is
recommended.
EXISTING EVAPORATOR COIL
If the existing evaporator coil may be re-used, check with
the coil manufacturer to verify the coil construction is suit-
able for operation with the higher pressures of R-410A re-
frigerant (R-410A). Also determine if the existing TXV valve
is compatible with R-410A, replace if necessary. The mini-
mum factory test pressure rating must be 250 psig
(1725 kPa). Existing coil will need to be purged with Nitro-
gen to remove as much mineral oil as possible to eliminate
cross contamination of oils.
ACID TEST
If the existing system is being replaced because of a com-
pressor electrical failure, assume acid is in system. If sys-
tem is being replaced for any other reason, use an ap-
proved acid test kit to determine acid level. If even low lev-
els of acid are detected, install a 100 percent activated
alumina suction-line filter drier in addition to the replacement
liquid-line filter drier. Remove the suction line filter drier as
soon as possible, with a maximum of 72 hr of operation.
Recommendation: Install a ball valve in the liquid line at the
filter drier location when installing a suction filter in the suc-
tion line.
EXISTING REFRIGERATION PIPING
Reuse of existing refrigerant piping involves three issues:
quality (strength) of existing tubing, cleanliness and tube
size. Inspect all tube segments and joints for signs of dam-
age, corrosion or poor brazing. Flush the interconnecting
piping system with dry Nitrogen to eliminate as much trace
of mineral oil as possible.
Same tube sizes are capable of handling higher flow rates
(expressed as tons of cooling capacity) with R-410A refrig-
erant compared to R-22 at constant pressure drops. For ex-
ample, a 1/2-inch OD liquid line is rated at 33% higher tons
with R-410A than with R-22 (at 5°F pressure drop). A
1-1/8 inch OD suction line is rated at 53% higher tons with
R-410A than with R-22 (at 2°F pressure drop). Refrigeration
lines selected for R-22 use are typically oversized for
R-410A applications. Carefully check the existing suction
line size against the table for maximum size; replace vertical
riser segments if necessary. Check existing liquid line size
against sizing data in Tables 7 and 8 or; replace with smaller
lines when feasible.
INSTALLATION
1. Remove the existing evaporator coil or fan coil and
install the replacement coil when appropriate.
2. Drain oil from low points and traps in suction line tub-
ing and evaporator if they were not replaced. Remov-
ing oil from evaporator coil may require purging of
the tubing with dry nitrogen.
3. Unless indoor unit is equipped with an R-410A
approved metering device, change the metering
device to a thermal expansion valve (TXV) designed
for R-410A refrigerant.
4. Remove the existing outdoor unit. Install the new out-
door unit according to these installation instructions.
5. Install a new field-supplied liquid-line filter drier at the
indoor coil just upstream of the TXV or fix orifice
metering device.
6. If a suction line filter drier is also to be installed,
install suction line drier downstream of suction line
service valve at condensing unit.
7. If required, install a 100% activated alumina suction
line filter drier at the outdoor unit.
8. Evacuate and charge the system according to the
instructions in this installation manual.
9. Operate the system for 10 hr. Monitor the pressure
drop across the suction line filter drier. If pressure
drop exceeds 3 psig (21 kPa), replace suction-line
and liquid-line filter driers. Be sure to purge system
with dry nitrogen and evacuate when replacing filter
driers. Continue to monitor the pressure drop across
suction-line filter drier. Repeat filter changes if neces-
sary. Never leave suction-line filter drier in system
longer than 72 hr (actual time).
Rated Indoor Airflow (cfm)
Tables 1 and 2 lists the rated indoor airflow used for the
AHRI efficiency rating for the units covered in this
document.
WARNING
PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to follow this warning could cause personal injury
or death.
Relieve pressure and recover all refrigerant before
system repair or final unit disposal.
Wear safety glasses and gloves when handling
refrigerants. Keep torches and other ignition sources
away from refrigerants and oils.
CAUTION
PERSONAL INJURY HAZARD
Failure to follow this caution may result in
personal injury.
Sheet metal parts may have sharp edges or burrs. Use
care and wear appropriate protective clothing, safety
glasses and gloves when handling parts and servicing
air conditioning equipment.
CAUTION
EQUIPMENT DAMAGE
Failure to follow this caution can result in equipment
damage.
Do not install a suction-line filter drier in liquid line. A
liquid-line filter drier designed for use with R-410A
refrigerant is required on every unit.
Table 1 — CAS181/241*A/B with FAS
MODEL NUMBERS FULL LOAD AIRFLOW (CFM)
CAS181*A/B 6000
CAS241*A/B 8300
Table 2 — CAS183/243/303*T/U with FAS
MODEL NUMBERS FULL LOAD AIRFLOW (CFM)
CAS183*T/U 5625
CAS243*T/U 8000
CAS303*T/U 9375

CAS-181-303-01SI Specifications subject to change without notice. 3
Identify Factory Options
Factory options will affect CAS unit pipe sizing selections.
Coil type impacts liquid lift limits; Check this unit’s Model
Number against the Model Number Nomenclature, Fig. 1.
Determine the significance of this unit’s values in Position 9
(coil options).
Matching CAS Model to Evaporator Coil
The Model CAS181/241*A/B is a single-circuit unit design,
requiring one set of refrigeration piping. This model can be
connected to an evaporator coil with one circuit or with two
circuits (by manifolding the evaporator connections into a
single piping system).
The Model CAS183/243/303*T/U is a dual-circuit unit de-
sign that requires two sets of refrigeration piping between
the outdoor unit and the evaporator coil (or coils). This mod-
el can only be connected to an evaporator coil that has two
refrigeration circuits (or to two separate evaporator coils).
The Model CAS183/243/303*T/U CANNOT be connected
to a single-circuit evaporator coil. The Model
CAS183/243/303*T/U CANNOT be field-converted to a
single-circuit design. See Table 3.
Before unpacking this new CAS model, compare the evapo-
rator coil design to the CAS model.
General
For unit dimensions and corner weights see Fig. 2 and 3.
For physical data see Tables 4 and 5.
Table 3 — Evaporator Coil Connections
EVAPORATOR
COIL HAS
CONNECT TO
MODEL NOTES
Single Circuit CAS181/241*A/B
ONLY —
Two Circuits
CAS181/241*A/B Manifold evaporator circuits
into single piping system.
CAS183/243/303*T/U Use two separate piping
systems

4Specifications subject to change without notice. CAS-181-303-01SI
Fig. 1 — Model Number Nomenclature
MODEL SERIES
CAS181HAA0A0 0A
Position Number 1234567891011121314
C = R-410A Condensing Unit
A = Air Conditioning (Cooling Only) Type
S = Standard ASHRAE 90.1-2016 Efficiency
181 = 180,000 BTUH = 15 Tons (1 circuit)
183 = 180,000 BTUH = 15 Tons (2 circuit)
241 = 240,000 BTUH = 20 Tons (1 circuit)
243 = 240,000 BTUH = 20 Tons (2 circuit)
303 = 300,000 BTUH = 25 Tons (2 circuit) Nominal
Cooling Capacity
H = 208/230-3-60
L = 460-3-60
S = 575-3-60 Voltage
A = Single Circuit¹
B = Single Circuit with Low Ambient Control¹
T = Dual Circuit, 3 Stage²
U = Dual Circuit, 3 Stage with Low Ambient Control² Refrigerant System
Options
A = Al/Cu Round Tube Plate Fin (RTPF) Coil
B = Pre-Coat Al/Cu RTPF Coil
C = E-Coat Al/Cu RTPF Coil
E = Cu/Cu RTPF Coil
M = Al/Cu RTPF Coil with Louvered Hail Guards
N = Pre-Coat Al/Cu RTPF Coil with Louvered Hail Guards
P = E-Coat Al/Cu RTPF Coil with Louvered Hail Guards
R = Cu/Cu RTPF Coil with Louvered Hail Guards Condenser Coil Options
0 = None
1 = Non-powered 115v Convenience Outlet
2 = Powered Convenience Outlet Service Options
A = None
C = Non-Fused Disconnect Switch Electrical Options
0 = Standard Electromechanical Controls Base Unit Controls
0 = No options, reserved for future use Future Use
A = Standard
B = LTL Packaging
¹ Only available on sizes 181 and 241.
² Only available on sizes 183, 243, and 303.

CAS-181-303-01SI Specifications subject to change without notice. 5
NOTE: Dimensions and drawings for size 180 also apply to 181/183 and those for refrigerant option D also apply to option T.
Fig. 2 — CAS181/183 Base Unit Dimensions

6Specifications subject to change without notice. CAS-181-303-01SI
NOTE: Dimensions and drawings for size 240 also apply to 241/243 and those for refrigerant option D also apply to option T.
Fig. 3 — CAS241*A/B / CAS243/303*T/U Base Unit Dimensions

CAS-181-303-01SI Specifications subject to change without notice. 7
Table 4 — CAS181/241*A/B Physical Data
UNIT CAS181*A/B CAS241*A/B
NOMINAL CAPACITY (TONS) 15 20
OPERATING WEIGHT (lb) 731 978
REFRIGERATION SYSTEM
No. Circuits / No. Comp. / Type 1 / 2 / Scroll 1 / 2 / Scroll
Refrigerant Type R-410A R-410A
R-410A Shipping Charge A/B (lb) 9.0 9.0
System Charge w/ Fan Coila43.0 38.0
Metering Device TXV TXV
High-press. Trip / Reset (psig) 630 / 505 630 / 505
Low-press. Trip / Reset (psig) 54 / 117 54 / 117
COMPRESSOR
Oil Charge A/B (oz) 60 / 60 110 / 110
Speed (rpm, 60/50 Hz) 3500 3500
CONDENSER COIL
Material Al/Cu Al/Cu
Coil Type RTPF RTPF
Rows / FPI 2 / 17 2 / 17
Total Face Area (ft2)23.5 x 2 25.0 x 2
CONDENSER FAN / MOTOR
Qty / Motor Drive Type 3 / direct 4 / direct
Motor HP / rpm 1/4 / 1100 1/4 / 1100
Fan Diameter (in.) 22 22
Nominal Airflow (cfm) 9,000 12,000
Watts (total) 970 1150
PIPING CONNECTIONS
Qty / Suction (in. ODS) 1 / 1-3/8 1 / 1-5/8
Qty / Liquid (in. ODS) 1 / 5/8 1 / 5/8
NOTE(S):
a Approximate system charge with about 25 ft piping of sizes indicated with matched FAS.
Table 5 — CAS183/243/303*T/U Physical Data
UNIT CAS183*T/U CAS243*T/U CAS303*T/U
NOMINAL CAPACITY (TONS) 15 20 25
OPERATING WEIGHT (lb) 731 978 978
REFRIGERATION SYSTEM
No. Circuits / No. Comp. / Type 2 / 2 / Scroll 2 / 2 / Scroll 2 / 2 / Scroll
Refrigerant Type R-410A R-410A R-410A
R-410A Shipping Charge A/B (lb) 9.0 / 9.0 9.0 / 9.0 9.0 / 9.0
System Charge w/ Fan Coila20.4 / 22.4 20.90 / 20.55 24.17 / 25.80
Metering Device TXV TXV TXV
High-press. Trip / Reset (psig) 630 / 505 630 / 505 630 / 505
Low-press. Trip / Reset (psig) 54 / 117 54 / 117 54 / 117
COMPRESSOR
Oil Charge A/B (oz) 60 / 60 110 / 110 110 / 110
Speed (rpm, 60/50 Hz) 3500 / 2900 3500 / 2900 3500 / 2900
CONDENSER COIL
Material Al/Cu Al/Cu Al/Cu
Coil Type RTPF RTPF RTPF
Rows / FPI 2 / 17 2 / 17 2 / 17
Total Face Area (ft2)23.5 x 2 25.0 x 2 25.0 x 2
CONDENSER FAN / MOTOR
Qty / Motor Drive Type 3 / direct 4 / direct 4 / direct
Motor HP / rpm 1/4 / 1100 1/4 / 1100 1/4 / 1100
Fan Diameter (in.) 22 22 22
Nominal Airflow (cfm) 9,000 12,000 12,000
Watts (total) 970 1150 1150
PIPING CONNECTIONS
Qty / Suction (in. ODS) 2 / 1-3/8 2 / 1-3/8 2 / 1-3/8
Qty / Liquid (in. ODS) 2 / 1/2 2 / 1/2 2 / 1/2
NOTE(S):
a Approximate system charge with about 25 ft piping of sizes indicated with matched FAS.

8Specifications subject to change without notice. CAS-181-303-01SI
INSTALLATION
Jobsite Survey
Complete the following checks before installation.
1. Consult local building codes and the NEC (National Elec-
trical Code) ANSI/NFPA 70 for special installation
requirements.
2. Determine unit location (from project plans) or select
unit location.
3. Check for possible overhead obstructions which may
interfere with unit lifting or rigging.
Step 1 — Plan for Unit Location
The CAS units are designed and approved for outdoor in-
stallation only. Do not locate these units indoors. Do not add
ducting to unit fan system.
Select a location for the unit and its support system (pad,
rails or other) that provides for the minimum clearances re-
quired for safety. This includes the clearance to combustible
surfaces, unit performance and service access below,
around and above unit as specified in unit drawings. See
Fig. 4.
NOTE: Local codes may require different clearances than
specified in Fig. 4. It is the responsibility of installers to be
knowledgeable in local codes and to modify the recom-
mended clearances to satisfy local codes.
NOTE: Consider also the effect of adjacent units on airflow
performance and control box safety clearance.
Do not install the outdoor unit in an area where fresh air
supply to the outdoor coil may be restricted or when recircu-
lation from the condenser fan discharge is possible. Do not
locate the unit in a well or next to high walls.
Fig. 4 — Service Clearance Dimensional Drawing
Evaluate the path and required line length for interconnect-
ing refrigeration piping, including suction riser requirements
(outdoor unit above indoor unit) and liquid line lift (outdoor
unit below indoor unit) Relocate sections to minimize the
length of interconnecting tubing.
Although unit is weatherproof, avoid locations that permit
water from higher level runoff and overhangs to fall onto the
unit.
Step 2 — Complete Pre-Installation Checks
CHECK UNIT ELECTRICAL CHARACTERISTICS
Confirm before installation of unit that voltage, amperage
and circuit protection requirements listed on unit data plate
agree with power supply provided.
UN-CRATE UNIT
Remove unit packaging except for the top skid assembly,
which should be left in place until after the unit is rigged into
its final location.
INSPECT SHIPMENT
File a claim with shipping company if the shipment is dam-
aged or incomplete.
CONSIDER SYSTEM REQUIREMENTS
Consult local building codes and National Electrical Code
(NEC, U.S.A.) for special installation requirements.
Allow sufficient space for airflow clearance, wiring, refriger-
ant piping, and servicing unit. See Fig. 2 and 3 for unit di-
mensions and weight distribution data.
Locate the unit so that the outdoor coil (condenser) airflow is
unrestricted on all sides and above.
The unit may be mounted on a level pad directly on the
base channels or mounted on raised pads at support points.
See Fig. 2 and 3 for weight distribution based on recom-
mended support points.
NOTE: If vibration isolators are required for a particular in-
stallation, use the weight distribution data in Fig. 2 and 3 to
make the proper selection.
Step 3 — Prepare Unit Mounting Support
SLAB MOUNT
Provide a level concrete slab that extends a minimum of
6 in. (150 mm) beyond unit cabinet. Install a gravel apron in
front of condenser coil air inlet to prevent grass and foliage
from obstructing airflow.
Step 4 — Rig and Mount the Unit
RIGGING
These units are designed for overhead rigging. Refer to the
rigging label for preferred rigging method. Spreader bars are
not required if top crating is left on the unit. All panels must
be in place when rigging. As further protection for coil faces,
plywood sheets may be placed against the sides of the unit,
behind cables. Run cables to a central suspension point so
that the angle from the horizontal is not less than
45 degrees. Raise and set the unit down carefully.
If it is necessary to roll the unit into position, mount the unit
on longitudinal rails, using a minimum of 3 rollers. Apply
force to the rails, not the unit. If the unit is to be skidded into
position, place it on a large pad and drag it by the pad. Do
not apply any force to the unit.
Raise from above to lift the unit from the rails or pad when
unit is in its final position.
After the unit is in position, remove all shipping materials
and top crating.
IMPORTANT: DO NOT BURY REFRIGERANT LINES.
LEFT:
Min 18" (457 mm)
required for service
RIGHT:
Min 18" (457 mm)
required for service
REAR:
Min 18" (457 mm)
required for service
NOTE: Observe requirements for 39" (914 mm) operating clearance
on either Left or Rear coil opening.
FRONT:
42" (1067 mm)
required for service
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
All panels must be in place when rigging. Unit is not
designed for handling by fork truck when packaging
is removed.
If using top crate as spreader bar, once unit is set,
carefully lower wooden crate off building roof top to
ground. Ensure that no people or obstructions are below
prior to lowering the crate.

CAS-181-303-01SI Specifications subject to change without notice. 9
Step 5 — Determine Refrigerant Line Sizes
Select the recommended line sizes for CAS181/241*A/B
and CAS183/243/303*T/U unit from the appropriate tables.
Determine the linear length of interconnecting piping re-
quired between the outdoor unit and indoor unit (evapora-
tor). Consider and identify also the arrangement of the tub-
ing path (quantity and type of elbows in both lines), liquid
line solenoid size, filter drier and any other refrigeration
specialties located in the liquid line. Refer to the indoor unit
installation instructions for additional details on refrigera-
tion specialties devices.
Determine equivalent line length adjustments for path and
components and add to linear line lengths. See Table 6,
Equivalent Lengths for Common Fittings, for usual fitting
types. Also identify adjustments for refrigeration specialties.
NOTE: Equivalent line lengths will vary based on tube diam-
eter. Calculate equivalent line length for each pipe by add-
ing equivalent length adjustments to linear lengths for each
pipe.
Enter the appropriate table to select the recommended line
sizes.
LIQUID LIFT
A liquid lift condition exists when the outdoor unit is located
below the indoor (evaporator) unit and liquid flows vertically
up in a portion of the liquid line. The vertical column of liquid
reduces the available state point sub-cooling at the evapo-
rator coil’s thermal expansion valve. This effect reduces the
length of liquid lift (feet of elevation) that a liquid line size can
accommodate. Longer linear tube lengths will also reduce
the amount of liquid lift possible.
Check Tables 7 (CAS181/241*A/B) and 8 (CAS183/
243/303*T/U), for maximum liquid lift capabilities for line
sizes. Note for size 181/183 that condenser coil type also
effects maximum liquid lift; ensure the lines for this unit’s
specific coil type are being used.
Reselect the liquid line tube size if necessary. If maximum
available tube size cannot provide the required lift distance
on this installation, relocate the outdoor unit to reduce the
equivalent line length or the lift requirement.
Table 6 — Equivalent Lengths for Common Fittings (ft)
NOMINAL
TUBE OD
(in.)
ELBOWS
90° Std 90° Lrad 90° Street 90° Std 90° Street
3/8 1.3 0.8 2.2 0.6 1.0
1/2 1.4 0.9 2.3 0.7 1.1
5/8 1.6 1.0 2.5 0.8 1.3
3/4 1.8 1.2 2.9 0.9 1.5
7/8 2.0 1.4 3.2 0.9 1.6
1-1/8 2.6 1.7 4.1 1.3 2.1
1-3/8 3.3 2.3 5.6 1.7 3.0
1-5/8 4.0 2.6 6.3 2.1 3.4
2-1/8 5.0 3.3 8.2 2.6 4.5
NOMINAL
TUBE OD
(in.)
TEES
Branch
Flow
Straight-Thru
No Reduct Reduce 25% Reduce 50%
3/8 2.6 0.8 1.1 1.3
1/2 2.7 0.9 1.2 1.4
5/8 3.0 1.0 1.4 1.6
3/4 3.5 1.2 1.7 1.8
7/8 4.0 1.4 1.9 2.0
1-1/8 5.0 1.7 2.3 2.6
1-3/8 7.0 2.3 3.1 3.3
1-5/8 8.0 2.6 3.7 4.0
2-1/8 10.0 3.3 4.7 5.0
MODEL NUMBER
POSITION NO. 8 TABLE QUANTITY OF LINE SETS
CAS181/241*A/B 71
CAS183/243/303*T/U 82

10 Specifications subject to change without notice. CAS-181-303-01SI
Table 7 — CAS181/241*A/B Piping Recommendations (Single-Circuit)
MODEL AND
NOMINAL
CAPACITY
LINEAR LINE (FT) 0-24 25-49 50-74 75-99 100-124 125-149 150-174 175-200
EQUIV. LINE (FT) 0-37 38-74 75-112 113-149 150-187 188-224 225-262 263-300
CAS181*A/B
TC 185.7,
SC 18.4°F
Liquid Line Size (in.) 5/8 5/8 5/8 5/8 5/8 5/8 5/8 3/4 5/8 3/4
Liquid PD (F) 0.7 1.3 2.0 2.7 3.4 4.0 4.7 2.5 5.4 2.8
Max Lift (ft) 25 50 75 100 125 150 153 175 145 175
Max Lift PD (F) 2.8 5.65 8.5 11.3 14.1 16.9 17.9 17.5 17.9 17.9
Suction Line Size (in.) 1-3/8 1-3/8 1-3/8 1-3/8 1-3/8 1-5/8 1-3/8 1-5/8 1-3/8 1-5/8 1-3/8 1-5/8
Suction Line PD (F)
(Cap Red) 1.4 1.0 1.5 2.0 2 . 5 (–0.9%) 1.1 3 (–1.8%) 1.3 3 . 5 (–2.7%) 1.5 4 (–3.6%) 1.7
Charge (lb) 35.1 38.1 41.2 44.2 47.3 48.4 50.4 51.7 53.4 63.7 56.5 68.3
No./TR 2.9 3.11 3.36 3.61 3.86 3.95 4.11 4.22 4.36 5.20 4.61 5.57
CAS241*A/B
TC 233.3,
SC 13.0°F
Liquid Line Size (in.) 5/8 5/8 5/8 5/8 5/8 3/4 5/8 3/4 5/8 3/4 5/8 3/4
Liquid PD (F) 1.1 2.1 3.2 4.3 5.4 2.8 6.4 3.3 7.5 3.9 8.6 4.4
Max Lift (ft) 25 50 93 98 85 116 71 108 59 102 46 95
Max Lift PD (F) 3.2 6.4 9.6 12.5 12.5 12.5 12.4 12.5 12.5 12.5 12.5 12.5
Suction Line Size (in.) 1-3/8 1-3/8 1-3/8 1-5/8 1-3/8 1-5/8 1-3/8 1-5/8 1-5/8 2-1/8 1-5/8 2-1/8 1-5/8 2-1/8
Suction Line PD (F)
(Cap Red) 0.8 1.6 2 . 4
(–0.8%) 1.0 3 . 3 .
(–2.2%) 1.4 4
(–3.6%) 1.7 2.0 0.4 2 . 4
(–0.7%) 0.5 2 . 7
(–1.2%) 0.6
Charge (lb) 31.1 34.1 37.2 37.9 40.2 41.1 43.3 50.7 47.7 58.5 51.0 63.6 54.3 68.7
No./TR 2.52 2.77 3.02 3.07 3.26 3.34 3.51 4.11 3.87 4.75 4.13 5.16 4.40 5.57
LEGEND
No./TR — Charge to unit capacity ratio, lb per ton (at 45°F SST, 95°F OAT)
Cap Red — Capacity reduction caused by suction line pressure drop > 2°F
Liquid PD (F) — Liquid line pressure drop, saturated temperature, °F
Max Lift — Maximum liquid lift (Indoor unit ABOVE outdoor unit only), at maximum permitted pressure drop.
Max Lift PD (F) — Pressure drop including Maximum liquid lift value
SC — Sub-cooling, °F (at liquid line valve)
Suction Line PD (F) — Suction line pressure drop, saturated temperature, °F
TC — Total Capacity, MBH (at 45°F Saturated suction, 95°F outdoor air temperature)

CAS-181-303-01SI Specifications subject to change without notice. 11
Table 8 — CAS183/243/303*T/U Piping Recommendations (Dual-Circuit)a
NOTE(S):
a CAS183/243/303*T/U units require TWO sets of refrigeration piping.
MODEL AND
NOMINAL
CAPACITY
LINEAR LINE (FT) 0-24 25-49 50-74 75-99 100-124 125-149 150-174 175-200
EQUIV. LINE (FT) 0-37 38-74 75-112 113-149 150-187 188-224 225-262 263-300
CAS183*T/U
TC 92.9
Each,
SC 15.1°F
Liquid Line Size (in.) 3/8 3/8 3/8 1/2 1/2 1/2 1/2 5/8 1/2 5/8 1/2 5/8
Liquid PD (F) 3.4 6.9 10.3 1.9 2.6 3.2 3.9 1.0 4.5 1.2 5.1 1.4
Max Lift (ft) 25 50 32 75 144 125 127 150 121 159 112 157
Max Lift PD (F) 5.5 11.1 13.0 8.2 10.9 13.7 14.5 13.6 14.5 14.5 14.5 14.5
Suction Line size (in.) 1-3/8 1-3/8 1-1/8 1-1/8 1-1/8 1-3/8 1-1/8 1-3/8 1-1/8 1-3/8 1-1/8
Suction Line PD (F)
(Cap Red) 0.5 0.1 1.2 1.6 2 (–0.1%) 0.7 2.5 (–0.8%) 0.8 2.9 (–1.5%) 1.0 3.3 (–2.2%) 1.1
Charge (lb) 22.6 23.9 19.5 21.8 23.7 25.7 26.6 27.6 34.4 29.5 37.4 31.5 40.5
No./TR 1.42 1.50 1.55 1.73 1.89 2.04 2.11 2.19 2.73 2.35 2.97 2.50 3.22
CAS243*T/U
TC 121.2
Each,
SC 10.6°F
Liquid Line Size (in.) 3/8 1/2 1/2 5/8 1/2 5/8 1/2 5/8 1/2 5/8 5/8 5/8 3/4
Liquid PD (F) 5.6 2.2 3.3 0.9 4.3 1.2 5.4 1.5 6.5 1.8 2.1 2.4 1.3
Max Lift (ft) 25 50 64 75 70 108 55 104 42 100 97 92 107
Max Lift PD (F) 7.7 6.3 8.5 7.1 10.0 9.4 9.9 10.0 10.0 10.0 10.0 9.9 10.0
Suction Line Size (in.) 1-1/8 1-1/8 1-1/8 1-3/8 1-1/8 1-3/8 1-1/8 1-3/8 1-3/8 1-3/8 1-3/8
Suction Line PD (F)
(Cap Red) 0.7 1.3 2.0 0.7 2.7 (–1.2%) 1.0 3.4 (–2.4%) 1.2 1.4 1.7 1.9
Charge (lb) 15.2 17.9 19.8 23.2 21.7 26.2 23.7 29.3 26.7 32.4 35.4 38.5 48.5
No./TR 1.20 1.41 1.56 1.83 1.72 2.07 1.87 2.31 2.11 2.56 2.80 3.04 3.83
CAS303*T/U
TC 281.9
Each,
SC 13.9°F
Liquid Line Size (in.) 1/2 1/2 5/8 5/8 3/4 5/8 3/4 5/8 3/4 3/4 7/8 3/4 7/8 3/4 7/8
Liquid PD (F) 4.2 8.5 3.0 4.6 2.4 6.1 3.2 7.7 4.0 4.8 1.5 5.6 1.8 6.4 2.1
Max Lift (ft) 25 14 50 48 75 42 79 23 69 59 99 49 96 39 93
Max Lift PD (F) 6.3 9.6 7.1 8.4 8.4 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5
Suction Line Size (in.) 1-1/8 1-3/8 1-5/8 1-3/8 1-5/8 1-5/8 1-5/8 1-5/8 1-5/8 2-1/8
Suction Line PD (F)
(Cap Red)
4.2
(–4.0%)
2.8
(–1.6%) 1.2 4.3 (–4.2%) 1.8 2.4 3.0 (–1.9%)
3.6
(–2.9%)
4.2
(–4.0%) 1.9
Charge (lb) 25.8 28.1 30.4 33.7 39.1 39.2 44.2 43.1 49.3 54.4 63.3 59.5 69.8 64.6 76.4
No./TR 1.10 1.20 1.30 1.44 1.67 1.67 1.88 1.83 2.10 2.32 2.69 2.53 2.97 2.75 3.25
LEGEND
No./TR — Charge to unit capacity ratio, lb per ton (at 45°F SST, 95°F OAT)
Cap Red — Capacity reduction caused by suction line pressure drop > 2°F
Liquid PD (F) — Liquid line pressure drop, saturated temperature, °F
Max Lift — Maximum liquid lift (Indoor unit ABOVE outdoor unit only), at maximum permitted pressure drop.
Max Lift PD (F) — Pressure drop including Maximum liquid lift value
SC — Sub-cooling, °F (at liquid line valve)
Suction Line PD (F) — Suction line pressure drop, saturated temperature, °F
TC — Total Capacity, MBH (at 45°F Saturated suction, 95°F outdoor air temperature)

12 Specifications subject to change without notice. CAS-181-303-01SI
Suction Riser
A suction riser condition exists when the outdoor unit is lo-
cated above the indoor (evaporator) unit and suction vapor
must flow vertically up to return to the compressor. Oil return
is a concern when the suction tube size is too large to pro-
duce the minimum refrigerant velocity to ensure oil return at
minimum load conditions.
CAS181/241*A/B AND CAS183/243/303*T/U
Check Table 9 for maximum suction tube size for CAS units
at minimum load conditions. Consider suction speed riser
(reduced tube size for vertical segment only) or double suc-
tion riser arrangement if the planned suction tube size does
not provide necessary minimum flow-rates for this riser.
Outdoor Unit ABOVE Evaporator Coil
This installation will have at least one suction riser segment.
If the vertical elevation difference is less than 20-ft (6.1 m)
linear feet and requires only one or two segments, consider
a speed riser selection for Circuit 1; use the line marked
VAPOR RISER REQUIRED; NOT GREATER THAN 20 FT
(6.1 M). See Fig. 5. Tube S is the horizontal line size; tube A
is the reduced diameter riser size.
If the vertical elevation difference is greater than 20-ft
(6.1-m) linear feet or requires more than two short lift seg-
ments, select the Circuit 1 suction line size from Double
Suction Riser lines data under VAPOR RISER GREATER
THAN 20 FT (6.1 M). See Fig. 6. Tube S is the horizontal
line size. Tube A is the reduced diameter riser size without
bottom trap; Tube B is the parallel riser size with bottom oil
trap.
Outdoor Unit BELOW Evaporator Coil and No
Vertical Riser Segments
Select Circuit 1 suction line size from NO VAPOR RISER
line.
Circuit 2 Suction Line
No special riser selections are necessary.
Vertical Separation (outdoor unit above indoor unit)
Vertical elevation difference of 200 ft (60 m) is permitted
when the outdoor unit (CAS181/241*A/B or
CAS183/243/303*T/U) is located above the indoor unit.
Fig. 5 — Suction Line Piping - Speed Riser
Fig. 6 — Suction Line Piping - Double Riser
Step 6 — Complete Refrigerant Piping
Connections
PROVIDE SAFETY RELIEF
If local codes dictate an additional safety relief device, pur-
chase locally and install locally. Installation will require the
recovery of the factory shipping charge before the factory
tubing can be cut and the supplemental relief device is
installed.
Model CAS183/243/303*T/U has two separate refrigeration
systems. If required, each circuit will require a field-
supplied/installed supplemental relief device.
CHECK CAS MODEL WITH EVAPORATOR COIL
CONNECTIONS
Confirm before installation of unit that the evaporator coil
connections are consistent with this CAS model. See
Table 3 on page 3.
INSULATE SUCTION LINES
Apply closed-cell tubular insulation to all suction lines be-
tween evaporator coil connection and CAS unit’s suction
service valve.
CAS183/243/303*T/U PIPING CONNECTIONS
The CAS183/243/303*T/U unit’s two circuits are designated
Circuit 1 and Circuit 2. Circuit 1 is controlled by the thermo-
stat’s Y1 (or TC1) contact and will be the first circuit on and
last circuit off. Circuit 2 is controlled by the thermostat’s Y2
(or TC2) contact and this circuit is always the “lag” circuit.
See Fig. 7 for location of Circuit 1 and Circuit 2 service
valves and field piping connections. Circuit 1 is on the right-
hand side of the service valve compartment; Circuit 2 is on
the left.
Table 9 — CAS Maximum Suction Pipe Size
MODEL UNIT SIZE MAXIMUM TUBE SIZE (in.)
CAS****A/B 181/241 1-5/8
CAS****T/U 183/243/303 1-5/8
Condensing
Unit
20-ft (6.1 m)
max
A
A - Suction Riser With Trap
LEGEND
S - Suction Line to Condensing Unit
S
IMPORTANT: DO NOT BURY REFRIGERANT LINES.
IMPORTANT: A refrigerant receiver is not provided with
the unit. Do not install a receiver.
From
Evaporator
A
A - Suction Riser Without Trap
B - Suction Riser With Trap
S - Suction Line to Condensing Unit
LEGEND
B
S
S

CAS-181-303-01SI Specifications subject to change without notice. 13
Fig. 7 — CAS183/243/303*T/U Service Valve
Locations
When a single piece evaporator coil with two separate cir-
cuits is connected to a CAS183/243/303*T/U, the lower coil
circuit should be connected to the CAS183/243/303*T/U
unit’s Circuit 1 so that the evaporator’s lower coil segment is
first-on/last-off (to avoid re-evaporation of condensate on
dry lower coil segments).
Plan the Circuit 1 and Circuit 2 tubing segments carefully,
mark each segment and check constantly as piping sys-
tems are assembled to avoid piping errors.
The CAS183/243/303*T/U unit cannot be field-piped as a
single-circuit/tandem system.
FINAL TUBING CHECK — CAS183/243/303*T/U
Before completing the field piping connections to the
CAS183/243/303*T/U unit service valves, confirm that the
suction line to the indoor coil’s first-on/last-off circuit (and
its companion liquid line) are correctly identified as Circuit
1 use for the CAS183/243/303*T/U unit. If a suction riser is
required, it must be in Circuit 1.
Connecting FAS to CAS183/243/303*T/U
The FAS fan coil in sizes 180, 240 and 300 is a face-split
coil design that also has its circuits designated as 1 and 2.
See Table 10 and Fig. 8. Note that the lower coil segment
changes as the arrangement of the FAS changes. In a verti-
cal arrangement, the FAS unit’s lower coil segment is seg-
ment 2; this segment should be connected to the
CAS183/243/303*T/U unit’s Circuit 1. In a horizontal ar-
rangement, the FAS unit’s lower segment is now
segment 1; this segment should be connected to the
CAS183/243/303*T/U unit’s Circuit 1.
Note that refrigerant suction piping should be insulated.
Fig. 8 — Typical Evaporator Coil Connections (FAS)
INSTALL FILTER DRIER(S) AND MOISTURE
INDICATOR(S)
Every unit MUST have a filter drier in the liquid line.
CAS183/243/303*T/U models require two filter driers (one
in each liquid line). Locate the filter drier(s) at the indoor unit,
close to the evaporator coil’s thermal expansion valve (TXV)
inlets.
The CAS units include one (CAS181/241*A/B) or two
(CAS183/243/303*T/U) R-410A-duty filter drier(s), shipped
in cartons attached to the unit basepan (see Table 11). Re-
move the filter drier(s) and prepare to install in the liquid
line(s) at the evaporator coil. Do not remove connection fit-
ting plugs until ready to connect and braze the filter drier into
the liquid line position.
Installation of liquid line moisture indicating sight glass in
each circuit is recommended. Locate the sight glass(es) be-
tween the outlet of the filter drier and the TXV inlet.
Refer to Table 12 for recommendations on refrigeration
specialties.
Table 10 — FAS Arrangement Details
FAS
ARRANGEMENT
COOLING
STAGE
FAS COIL
SEGMENT
CONNECT TO
CAS183/243/
303*T/U
Vertical Y1 2 Circuit 1
Y2 1 Circuit 2
Horizontal Y1 1 Circuit 1
Y2 2 Circuit 2
Circuit 1
Connections
Circuit 2
Connections
CKT
1
CKT
1
CKT
2
CKT
2
Table 11 — R-410A Filter Drier(s)
MODEL SIZE QTY
LIQUID
LINE OD
(in.)
DESICCANT
VOLUME
PART
NUMBER
REF.
CAS181*A/B 1 5/8 30 cu in. 1192274
CAS241*A/B 1 5/8 30 cu in. 1192274
CAS183*T/U 2 1/2 8 cu in. 1191316
CAS243*T/U 2 1/2 16 cu in. 1191316
CAS303*T/U 1 1/2 16 cu in. 1191316
Condensate Drain Connection
Condensate Drain
Connection
Suction-Vapor
Connection
Liquid Line
Connection
Horizontal Installation
Coil Segment 1
Coil Segment 2
First On/Last Off = 2
Coil Segment 2
Coil Segment 1
First On/Last Off = 1
Vertical Installation

14 Specifications subject to change without notice. CAS-181-303-01SI
In some applications, depending on space and convenience
requirements, it may be desirable to install 2 filter driers and
sight glasses in a single circuit application. One filter drier
and sight glass may be installed at A locations (see Fig. 9)
or 2 filter driers and sight glasses may be installed at B loca-
tions (see Fig. 9 and 10).
Select the filter drier for maximum unit capacity and mini-
mum pressure drop. Complete the refrigerant piping from
the indoor unit to the outdoor unit before opening the liquid
and suction lines at the outdoor unit.
INSTALL LIQUID LINE SOLENOID VALVE
It is recommended that a solenoid valve be placed in the
main liquid line (see Fig. 9 and 10) between the condensing
unit and the evaporator coil. Locate the solenoid valve at the
outlet end of the liquid line, near the evaporator coil connec-
tions, with flow direction arrow pointed at the evaporator
coil. Refer to Table 12. (A liquid line solenoid valve is re-
quired when the liquid line length exceeds 75 ft [23 m].) This
valve prevents refrigerant migration (which causes oil dilu-
tion) to the compressor during the off cycle, at low outdoor
ambient temperatures. Wire the solenoid in parallel with the
compressor contactor coil (see Fig. 9 and 10). This means
of electrical control is referred to as solenoid drop control.
Fig. 9 — Location of Sight Glass(es) and Filter Driers
Typical CAS181/241*A/B Systems
Fig. 10 — Location of Sight Glasses and Filter Driers
Typical CAS183/243/303*T/U Systems
Solenoid Drop Control Wiring
Control the power to the liquid line solenoid through a Sole-
noid Valve Relay (SVR) in all units. Use part number
1178205 (field-supplied, installed). CAS181/241*A/B unit re-
quires one SVR; CAS183/243/303*T/U unit requires two
relays.
A unit with two liquid line solenoid valves also requires a
separate control power transformer for the liquid solenoid
valve loads. Select TRAN3 transformer part number ac-
cording to unit power supply.
Mount the SVR (and transformer TRAN3 when used) in unit
control box. Connect per wiring schematic label on unit.
Evaporator Capacity Control Liquid Line Solenoid
Valve
Many older unit designs included automatic capacity con-
trols that sensed changes in suction pressure and could in-
crease or decrease compressor capacity automatically as
the evaporator load changed. Control systems were used
on these units that had the thermostat’s second stage con-
tacts control a capacity control liquid line solenoid valve to
open or shutoff a portion of the evaporator surface without
any direct connection to the compressor circuit.
Table 12 — Refrigerant Specialties Part Numbers
MODEL SIZES LIQUID LINE
SIZE (in.)
LIQUID LINE
SOLENOID VALVE (LLSV) LLSV COIL SIGHT GLASS FILTER DRIER
CAS****T/Ua
NOTE(S):
a CAS183/243/303*T/U units require TWO sets of parts.
183/243/303 1/2 1179872 1179874 1179877 Provided with unit,
see Table 11
5/8 1179873 1179874 1179878
CAS****A/B 181/241 5/8 1179873 1179874 1179878
INDOOR
COIL CKT 2
AIRFLOW
INDOOR
COIL CKT 1
AIRFLOW
15 DIAMS
MIN 10
DIAMS
8 DIAMS
MIN
TXV
SENSING
BULB
EQUALIZER LINE
SIGHT GLASS
A LOCATION
SIGHT
GLASSES
B LOCATION
TXV
CKT 2
FILTER DRIER
A LOCATION
FILTER
DRIERS
B LOCATION
FLOW
TXV
SENSING
BULB
TXV
CKT 1
8 DIAMS
MIN
15 DIAMS
MIN 10
DIAMS
Single Circuit Coil Piping Configuration
For Single Compressor Condensing Units
Dual Circuit Coil Piping Configuration
For Single Compressor Condensing Units
15 DIAMS
MIN 10
DIAMS
8 DIAMS
MIN
INDOOR
COIL CKT
AIRFLOW
TXV
SENSING
BULB
EQUALIZER LINE
SIGHT GLASS
A LOCATION
TXV
FILTER DRIER
A LOCATION
LIQUID LINE
SOLENOID
VALVE
FLOW
LIQUID LINE
SOLENOID
VALVE
MODEL QTY
LSV
RELAY SVR
QTY —
PART
NUMBER
TRAN3 PRIMARY V:
PART NUMBER
CAS181/241*A/B 1 1 — 1178205 N/R
2 2 — 1178205 208/230V: HT01BD202
CAS183/243/303*T/U 2 2 — 1178205 460V: HT01BD702
575V: HT01BD902
LEGEND
LSV — Liquid Solenoid Valve
SVR — Solenoid Valve Relay
N/R — Not Required
AIRFLOW
SUCTION
CIRCUIT 2
SUCTION
CIRCUIT 1
AIRFLOW
15 DIAMS
MIN 10
DIAMS
8 DIAMS
MIN
TXV
SENSING
BULB
EQUALIZER LINE
SIGHT
GLASSES
TXV
CKT 2
FILTER
DRIERS
LIQUID LINE
SOLENOID VALVE
CIRCUIT 2
FLOW
LIQUID LINE
SOLENOID VALVE
CIRCUIT 1
FLOW
TXV
SENSING
BULB
TXV
CKT 1
8 DIAMS
MIN
15 DIAMS
MIN 10
DIAMS
Dual Circuit Coil Piping Configuration
For Two Circuit Condensing Units

CAS-181-303-01SI Specifications subject to change without notice. 15
This form of system capacity staging control is not possi-
ble with CAS models. If this installation is a retrofit for a
unit that included automatic pressure-operated unload-
ing, check the existing thermostat and liquid solenoid
valve. When found, convert the evaporator second stage
solenoid control into a drop-solenoid control. Use the two
SVR relays and transformer as required on
CAS183/243/303*T/U models (above); wire the SVRs
and transformer per two solenoid valve systems.
SELECTING AN ACCUMULATOR
Because all CAS models use scroll compressors, an accu-
mulator is not required. If an accumulator is to be added,
check the accumulator manufacturer’s literature carefully
for indication of its suitability for use with R-410A; look for
minimum working pressure of 200 psig (1380 kPa). Select
the accumulator first on the basis of its cataloged minimum
capacity (tons) to ensure oil return from the accumulator,
then on tube size or holding capacity.
MAKE PIPING CONNECTIONS
Piping connections at the CAS unit are ball valves with
stub tube extensions. Do not open the unit service valves
until all interconnecting tube brazing has been complet-
ed. The stub tube connections include 1/4-in. SAE ser-
vice fittings with Schrader valve cores (see Fig. 11). Be-
fore making any brazed connections to the unit service
valves, remove both Schrader valve caps and cores and
save for re-installation. Connect a source for nitrogen to
one of these service fittings during tube brazing to pre-
vent the formation of copper oxides inside the tubes at
brazed joints.
When connecting the field tubing to the CAS service
valves, wrap the valves in wet rags to prevent overheat-
ing.
Pressure-test all joints from outdoor unit connections
over to the evaporator coil, using nitrogen as pressure
and with soap-and-bubbles.
When pressure-testing is completed, remove the nitro-
gen source at the outdoor unit service valves and re-
install the two Schrader valve cores. Torque the cores to
2 to 3 in.-lb (23 to 34 N-cm).
Fig. 11 — Typical Piping Connection Assembly
EVACUATION/DEHYDRATION
Evacuate and dehydrate the connected refrigeration sys-
tem(s) (excluding the CAS unit) to 500 microns using a two-
stage vacuum pump attached to the service ports outside
the CAS service valves, following description in GTAC II,
Module 4, System Dehydration.
This unit is designed for use with R-410A refrigerant. Do not
use any other refrigerant in this system.
R-410A refrigerant is provided in pink (rose) colored cylin-
ders. These cylinders are available with and without dip
tubes; cylinders with dip tubes will have a label indicating
this feature. For a cylinder with a dip tube, place the cylinder
in the upright position (access valve at the top) when remov-
ing liquid refrigerant for charging. For a cylinder without a
dip tube, invert the cylinder (access valve on the bottom)
when removing liquid refrigerant.
Because R-410A refrigerant is a blend, it is strongly rec-
ommended that refrigerant always be removed from the
cylinder as a liquid. Admit liquid refrigerant into the system
in the discharge line. If adding refrigerant into the suction
line, use a commercial metering/expansion device at the
gauge manifold; remove liquid from the cylinder, pass it
through the metering device at the gauge set and then
pass it into the suction line as a vapor. Do not remove
R-410A refrigerant from the cylinder as a vapor.
WARNING
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal
injury, death and/or equipment damage.
R-410A refrigerant systems operate at higher pressures
than standard R-22 systems. Do not use R-22 service
equipment or components on R-410A refrigerant
equipment.
Factory
High-Flow
Access Port
Service Valve
with Stem Cap
Field Service
Access Port
(Schrader core)
Sweat
Connection

16 Specifications subject to change without notice. CAS-181-303-01SI
PRELIMINARY CHARGE
Before starting the unit, charge R-410A liquid refrigerant into
the high side of each CAS circuit through the liquid service
valve(s). The amount of refrigerant added must be at least
80% of the operating charge listed in Tables 4 or 5 for LIN-
EAR line length LESS the factory charge quantity (if factory
shipping charge has not been removed). See example be-
low.
NOTE: See “Adjust Refrigerant Charge” on page 23 for de-
tails on refrigerant charge adjustment. Be sure that all con-
denser fans are operating while charging the unit.
Allow high and low side pressures to equalize. If pres-
sures do not equalize readily, charge R-410A vapor (us-
ing special service manifold with expansion device) into
the suction line service port for the low side of system to
assure charge in the evaporator. Refer to GTAC II, Mod-
ule 5, Charging, Recover, Recycling, and Reclamation for
liquid charging procedures.
Example:
CAS241*A/B
60-ft (18.3 m) linear line length
Equivalent line length 90-ft (27.4 m)
Liquid Lift: 20-ft (6.1 m)
Select line sizes from Table 8 (CAS183/243/303*T/U):
Liquid 1/2 in.
Suction 1-1/8 in.
Charge
Circuit 1: 23.1 lb (at 75-ft linear length)
Circuit 2: 22.0 lb
80% of Operating Charge:
Circuit 1: 0.80 x 23.0 = 18.4 lb
Circuit 2: 0.80 x 22.0 = 17.6 lb
Factory Shipping Charge: 15 lb
Field-Charge
Circuit 1: 18.4 - 15.0 = 3.4 lb
Circuit 2: 17.6 - 15.0 = 2.6 lb
For linear line lengths longer than 125 ft (38 m), contact
your local representative for system charge value.
Step 7 — Install Accessories
Accessories requiring modifications to unit wiring should be
completed now. These accessories may include Winter
Start controls and Low Ambient controls. Refer to the in-
structions shipped with the accessory.
Step 8 — Complete Electrical Connections
NOTE: Check all factory and field electrical connections for
tightness. Field-supplied wiring shall conform with the limita-
tions of 63°F (33°C) rise.
FIELD POWER SUPPLY
If equipped with optional Powered Convenience Outlet: The
power source leads to the convenience outlet’s transformer
primary are not factory connected. Installer must connect
these leads according to required operation of the conve-
nience outlet. If an always-energized convenience outlet op-
eration is desired, connect the source leads to the line side
of the unit-mounted disconnect. (Check with local codes to
ensure this method is acceptable in your area.) If a de-
energize via unit disconnect switch operation of the conve-
nience outlet is desired, connect the source leads to the
load side of the unit disconnect. On a unit without a unit-
mounted disconnect, connect the source leads to compres-
sor contactor C and indoor fan contactor IFC pressure lugs
with unit field power leads.
Field power wires are connected to the unit at line-side
pressure lugs on compressor contactor C and TB1 (see wir-
ing diagram label for control box component arrangement)
or at factory-installed option non-fused disconnect switch.
Max wire size is no. 4 AWG (copper only).
NOTE: TEST LEADS — Unit may be equipped with short
leads (pigtails) on the field line connection points on contac-
tor C or optional disconnect switch. These leads are for fac-
tory run-test purposes only; remove and discard before con-
necting field power wires to unit connection points. Make
field power connections directly to line connection pressure
lugs only.
Fig. 12 — Disconnect Switch and Unit
UNITS WITH FACTORY-INSTALLED NON-FUSED
DISCONNECT
The factory-installed option disconnect switch is located in a
weatherproof enclosure located under the main control box.
The manual switch handle is accessible through an opening
in the access panel.
UNITS WITHOUT FACTORY-INSTALLED NON-FUSED
DISCONNECT
When installing units, provide a disconnect switch per NEC
(National Electrical Code) of adequate size. Disconnect siz-
ing data is provided on the unit informative plate. Locate on
unit cabinet or within sight of the unit per national or local
codes. Do not cover unit informative plate if mounting the
disconnect on the unit cabinet.
WARNING
ELECTRIC SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Unit cabinet must have an uninterrupted, unbroken
electrical ground to minimize the possibility of personal
injury if an electrical fault should occur. This ground may
consist of electrical wire connected to unit ground lug in
control compartment, or conduit approved for electrical
ground when installed in accordance with NEC;
ANSI/NFPA 70, latest edition (in Canada, Canadian
Electrical Code CSA [Canadian Standards Association]
C22.1), and local electrical codes.
WARNING
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
Do not connect aluminum wire between disconnect
switch and unit. Use only copper wire. (See Fig. 12.)
Copper
Wire Only
Electric
Disconnect
Switch
Aluminum
Wire

CAS-181-303-01SI Specifications subject to change without notice. 17
ALL UNITS
All field wiring must comply with NEC and all local codes.
Size wire based on MCA (Minimum Circuit Amps) on the
unit informative plate. See Fig. 13 for power wiring connec-
tions to the unit contactor and terminal block and equipment
ground.
Fig. 13 — Power Wiring Connections
Provide a ground-fault and short-circuit over-current protec-
tion device (fuse or breaker) per NEC Article 440 (or local
codes). Refer to unit informative data plate for MOCP (Max-
imum Over-current Protection) device size.
All units except 208/230-v units are factory wired for the
voltage shown on the nameplate. If the 208/230-v unit is to
be connected to a 208-v power supply, the control trans-
former must be rewired by moving the black wire with the
1/4-in. female spade connector from the 230-v connection
and moving it to the 208-v 1/4-in. male terminal on the pri-
mary side of the transformer. Refer to unit label diagram for
line-side information.
Affix the crankcase heater warning sticker to the unit discon-
nect switch.
CONVENIENCE OUTLETS
Two types of convenience outlets are offered on CAS mod-
els: Non-powered and unit-powered. Both types provide a
125-volt GFCI (ground-fault circuit-interrupter) duplex re-
ceptacle rated at 15-A behind a hinged waterproof access
cover, located on the end panel of the unit. See Fig. 14.
Non-Powered Type
This type requires the field installation of a general-purpose
125-volt 15-A circuit powered from a source elsewhere in
the building. Observe national and local codes when select-
ing wire size, fuse or breaker requirements and disconnect
switch size and location. Route 125-v power supply conduc-
tors into the bottom of the utility box containing the duplex
receptacle. Maximum continuous current for this type of
convenience outlet (non-unit powered) must not exceed
8Amps.
Unit-Powered Type
A unit-mounted transformer is factory-installed to step down
the main power supply voltage to the unit to 115-v at the du-
plex receptacle. This option also includes a manual switch
with fuse, located in a utility box and mounted on a bracket
behind the convenience outlet; access is through the unit’s
control box access panel. See Fig. 14.
Fig. 14 — Convenience Outlet Location
The primary leads to the convenience outlet transformer are
not factory-connected. Selection of primary power source is
a customer-option. If local codes permit, the transformer pri-
mary leads can be connected at the line-side terminals on
the unit-mounted non-fused disconnect switch; this will pro-
vide service power to the unit when the unit disconnect
switch is open. Other connection methods will result in the
convenience outlet circuit being de-energized when the unit
disconnect switch is open. See Fig. 15.
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Units with convenience outlet circuits may use multiple
disconnects. Check convenience outlet for power status
before opening unit for service. Locate its disconnect
switch, if appropriate, and open it. Lock-out and tag-out
this switch, if necessary.
11 13
L1 L2 L3
C TB1
208/230-3-60
460-3-60
575-3-60
Units Without Disconnect Option
Units With Disconnect Option
2
4
6
1
3
5
L1
L2
L3
Optional
Disconnect
Switch
Disconnect factory test leads; discard.
Factory
Wiring
Disconnect
per
NEC
Control Box
Access Panel
Pwd-CO
Transformer
Convenience
Outlet
GFCI
Pwd-CO
Fuse
Switch

18 Specifications subject to change without notice. CAS-181-303-01SI
Fig. 15 — Powered Convenience Outlet Wiring
The unit-powered convenience outlet has a 1000 VA rated
transformer. Maximum continuous current must not exceed
8Amps.
Test the GFCI receptacle by pressing the TEST button on
the face of the receptacle to trip and open the receptacle.
Check for proper grounding wires and power line phasing
if the GFCI receptacle does not trip as required. Press the
RESET button to clear the tripped condition.
Fuse on power type: The factory fuse is a Bussman™1
“Fusetron™”1T-15, non-renewable screw-in (Edison base)
type plug fuse.
Installing Weatherproof Cover
A weatherproof while in use cover for the factory installed
convenience outlets is now required by UL standards. This
cover cannot be factory mounted due its depth; it must be
installed at unit installation. For shipment, the convenience
outlet is covered with a blank cover plate.
The weatherproof cover kit is shipped in the unit’s control
box. The kit includes the hinged cover, a backing plate and
gasket.
DISCONNECT ALL POWER TO UNIT AND CONVE-
NIENCE OUTLET.
Remove the blank cover plate at the convenience outlet;
discard the blank cover.
Loosen the two screws at the GFCI duplex outlet, until ap-
proximately 1/2-in. (13 mm) under screw heads are ex-
posed. Press the gasket over the screw heads. Slip the
backing plate over the screw heads at the keyhole slots and
align with the gasket; tighten the two screws until snug (do
not overtighten).
Mount the weatherproof cover to the backing plate as
shown in Fig. 16. Remove two slot fillers in the bottom of the
cover to permit service tool cords to exit the cover. Check
for full closing and latching.
Fig. 16 — Weatherproof Cover Installation
ALL UNITS
Voltage to compressor terminals during operation must be
within voltage range indicated on unit nameplate. See
Tables 13 and 14 (on page 21). On 3-phase units, voltages
between phases must be balanced within 2% and the cur-
rent within 10%. Use the formula shown in the legend for
Table 13, Note 5 (see page 22) to determine the percent of
voltage imbalance. Operation on improper line voltage or
excessive phase imbalance constitutes abuse and may
cause damage to electrical components. Such operation
would invalidate any applicable unit warranty.
FIELD CONTROL WIRING
The CAS unit control voltage is 24 v. See Appendix B Wiring
Diagrams (on pages 42-57) for typical field control connec-
tions and the unit’s label diagram for field-supplied wiring
details. Route control wires to the CAS unit through the
opening in unit’s end panel to the connections terminal
board in the unit’s control box.
Remainder of the system controls connection will vary ac-
cording to the specific construction details of the indoor
section (air handler or packaged fan coil). Figures 17
(CAS181/241*A/B) and 18 (CAS183/243/303*T/U) depict
typical connections to a FAS fan coil unit. Plan for field
connections carefully and install control wiring correctly
per the project plan. Additional components and supple-
mental transformer accessory may be required.
The CAS unit requires an external temperature control de-
vice. This device can be a thermostat (field-supplied).
1. Third-party trademarks and logos are the property of their respective
owners.
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Using unit-mounted convenience outlets: Units with unit-
mounted convenience outlet circuits will often require
that two disconnects be opened to de-energize all power
to the unit. Treat all units as electrically energized until
the convenience outlet power is also checked and de-
energization is confirmed. Observe National Electrical
Code Article 210, Branch Circuits, for use of
convenience outlets.
PRIMARY
CONNECTIONS
UNIT
VOLTAGE
208, 230
460
575
CONNECT
AS
240
480
600
L1: RED + YEL
L2: BLU + GRA
L1: RED
Splice BLU + YEL
L2: GRA
L1: RED
L2: GRA
TRANSFORMER
TERMINALS
H1 + H3
H2 + H4
H1
H2 + H3
H4
H1
H2
Cover — While-In-Use
Weatherproof
Baseplate For
GFCI Receptacle
Gasket
GFCI Receptacle
Not Included
TOP
TOP
TOP
WET LOCA
TIONS
WETLOCATIONS

CAS-181-303-01SI Specifications subject to change without notice. 19
THERMOSTAT
Install a field-installed accessory thermostat according to
installation instructions included with the accessory. For
typical thermostat connections see Fig. 17 (CAS181/241
*A/B) and 18 (CAS183/243/303*T/U). Locate the field-
installed thermostat accessory on a solid wall in the con-
ditioned space to sense average temperature in accor-
dance with the thermostat installation instructions.
Fig. 17 — Typical Remote Thermostat Connections
— CAS181/241*A/B
Fig. 18 — Typical Remote Thermostat Connections
— CAS183/243/303*T/U
The CAS181/241*A/B is a single-circuit, two-stage cooling
unit. Select a two-stage cooling thermostat, with or without
supplemental heating as needed.
The CAS183/243/303*T/U is a dual-circuit, three-stage
cooling unit. Select a three-stage cooling thermostat, with or
without supplemental heating as needed.
Select a thermostat cable or equivalent single leads of dif-
ferent colors with minimum of five leads for
CAS181/241*A/B or six leads for CAS183/243/303*T/U
unit. Check the thermostat installation instructions for addi-
tional features which might require additional conductors in
the cable.
For wire runs up to 50 ft (15 m), use no. 18 AWG (American
Wire Gauge) insulated wire (35°C minimum). For 50 to 75 ft
(15 to 23 m), use no. 16 AWG insulated wire (35°C mini-
mum). For over 75 ft (23 m), use no. 14 AWG insulated wire
(35°C minimum). All wire sizes larger than no. 18 AWG can-
not be directly connected to the thermostat and will require
a junction box and splice at the thermostat.
NOTES:
1. Connect only if thermostat requires 24-vac power source.
2. Connect W1 and W2 if supplemental heaters are installed.
3. Y2 connection for Single Circuit/2-Stage units only.
Field Wiring
(Note 1)
(Note 2)
(Note 3)
(Note 2)
LEGEND
(Note 1)
(Note 2)
(Note 3)
(Note 3)
1. Typical multi-function marking. Follow manufacturer’s configuration instructions to select Y2.
2. Connect only if thermostat requires 24-vac power source.
3. Connect W1and W2 if supplemental heaters are installed.
Field Wiring
LEGEND
NOTES:

20 Specifications subject to change without notice. CAS-181-303-01SI
CONTROL CIRCUIT WIRING
Control voltage is 24 v. See Fig. 13 and the unit’s label dia-
gram for field-supplied wiring details. Route control wires
through the opening in unit’s end panel to the connection in
the unit’s control box.
CONTROL TRANSFORMER WIRING
On multi voltage units, check the transformer primary wiring
connections. See Fig. 19 or refer to the unit’s label diagram.
If the unit will be operating at 208-3-60 power, remove the
black wire (BLK) from the transformer primary connection
labeled “230” and move it to the connection labeled “208.”
See Fig. 19.
Fig. 19 — Control Transformer Wiring
EXTERNAL DEVICES
The CAS control transformers provide 24-v NEC Class 2
power sources to energize external control devices. These
devices will include the indoor fan motor contactor (or con-
trol relay). These devices may also include liquid line sole-
noid valve (two on CAS183/243/303*T/U model), economiz-
er control relay, supplemental electric heater contactors or
control relays and other devices selected by system
designer.
Control transformer TRAN1 provides control power through
terminal R to C on the field connection terminal strip TB for
supply fan motor interlock. This source may also be used to
energize economizer control relay and electric heater con-
tactors or relays. Maximum available power is 20 va. Check
concurrent loadings by external control devices. If the maxi-
mum concurrent loading exceeds 20 va, purchase and in-
stall the accessory Transformer-Relay package (available
for 208/230 and 460-v units).
CAS183/243/303*T/U Only
Control transformer TRAN3 provides control power through
terminals A1 (9) and A2 (10) to C for liquid line solenoids.
Maximum available power is 75 va. These outputs are
switched ON/OFF by the Solenoid Valve Relays.