Bosch BCA Series User manual

Installation Instructions
Split System Heat Pump
Bosch BCA Series
Ceiling Mounted Air Handler Units | 1.5-3 Ton Capacity | R410A
BTC 761703106 A / 03.2023

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
Table of Contents
1 Key to Symbols and Safety Instructions 4
1.1 Key to Symbols 4
1.2 Safety 4
2 General 5
3 Dimensional Data 6
3.1 Uncased Unit Dimensions 6
3.2 Cased Unit Dimensions 7
4 Mounting 8
5 Electrical wiring 8
5.1 Power Wiring 8
5.2 Control Wiring 8
5.3 Grounding 8
5.4 Electrical Data 8
6 Airow Performance 9
6.1 Uncased Unit 9
6.2 Cased Unit 10
6.3 Required Airflow Range for Normal Operation 11
7 Ductwork 12
8 Refrigerant Connections 13
8.1 Condensate Drain Connection 13
9 Air Filter (Not Factory-Installed) 14
10 Maintenance 15
10.1 Cleaning Precautions 15
10.2 Regular Maintenance 15
11 Wiring Diagrams 16
11.1 Unit Wiring 17

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
1 Key to Symbols and Safety Instructions
1.1 Key to Symbols
Warnings
Warnings in this document are identified by a warning triangle
printed against a grey background.
Keywords at the start of a warning indicate the type and seriousness
of the ensuing risk if measures to prevent the risk are not taken.
The following keywords are defined and can be used in this document:
fDANGER: indicates a hazardous situation which, if not avoided, will result
in death or serious injury.
fWARNING: indicates a hazardous situation which, if not avoided, could
result in death or serious injury.
fCAUTION: indicates a hazardous situation which, if not avoided, could
result in minor to moderate injury.
fNOTICE: is used to address practices not related to personal injury.
Important information
This symbol indicates important information where there is no risk to
people or property.
1.2 Safety
Please read before proceeding
WARNING:
These instructions are intended as an aid to qualified, licensed
service personnel for proper installation, adjustment and
operation of this unit. Read these instructions thoroughly
before attempting installation or operation. Failure to follow
these instruction may lead to improper installation, adjustment,
service or maintenance possibly resulting in fire, electrical shock,
property damage, personal injury or death.
This document is customer property and is to remain with this unit.
These instructions do not cover all the different variations of systems nor
does it provide for every possible contingency to be met in connection
with installation.
WARNING: FIRE, ELECTRICAL SHOCK, PROPERTY DAMAGE,
PERSONAL INJURY, OR DEATH
All phases of this installation must comply with NATIONAL, STATE
AND LOCAL CODES. If additional information is required please
contact your local distributor.
WARNING: ELECTRICAL SHOCK
Disconnect all power to unit before installing or servicing. More
than one disconnect switch may be required to deenergize the
equipment. Hazardous voltage can cause severe personal injury or
death.
WARNING: ELECTRICAL SHOCK
If removal of the blower assembly is required, all disconnect
switches supplying power to the equipment must be deenergized
and locked (if not in sight of unit) so the field power wires can be
safely removed from the blower assembly. Failure to do so can
cause electrical shock resulting in personal injury or death.
WARNING: FIRE, ELECTRICAL SHOCK, PROPERTY DAMAGE,
PERSONAL INJURY, OR DEATH
Because of possible damage to equipment or personal injury,
installation, service, and maintenance should be performed
by trained, qualified service personnel. Consumer service is
recommended only for filter cleaning / replacement. Never operate
the unit with the access panels removed.

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
WARNING:
This product can expose you to chemicals including Lead and Lead
components, which are known to the State of California to cause
cancer and birth defects or other reproductive harm. For more
information go to www.P65Warnings.ca.gov.
WARNING: ELECTRICAL SHOCK
The unit must be permanently grounded. Failure to do so can
result in electrical shock causing personal injury or death.
CAUTION: FIRE HAZARD
The material of plenum and ductwork must meet the latest edition
of the NFPA 90B standard.
2 General
The unit is designed for horizontal orientation and is suitable for ceiling installations
in conditioned space and are paired with IDS Light Condensers. The units have a
factory−installed TXV and are available in 18,000 through 36,000 Btuh nominal
cooling capacities.
The unit is equipped with sweat−type connections and is vapor−charged with dry
nitrogen. Units are designed for horizontal applications only. Local codes may limit
this free−air−return type unit to installation in single−level applications.
NOTICE:
The installed unit must have the required clearances as shown
in Section 3. Failure to follow these instructions may result in
equipment damage and/or premature equipment failure.
WARNING: FIRE HAZARD
Keep flammable material and vapors, such as gasoline, away from
the air handler. Failure to follow these instructions can result in
death, explosion, or fire.

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
3 Dimensional Data
3.1 Uncased Unit Dimensions
Figure 1
F
C
E
BD
Top
Back
Right
Left
Uncased unit dimensions
Model
Size
Dimensions Inch [mm]
Unit Length
A
Unit Height
B
Unit Width
C
Supply Air Height
D
Supply Air Length
E
Mounting
F
Liquid Line/
Vapor Line
18 37-1/4 [946] 37-1/4 [946] 37-1/4 [946] 6-1/2 [165] 30 [762] 34-11/16 [881] 3/8/ 3/4 [9.5/ 19]
24 37-1/4 [946] 37-1/4 [946] 37-1/4 [946] 6-1/2 [165] 30 [762] 34-11/16 [881] 3/8/ 3/4 [9.5/ 19]
30 49-1/4 [1251] 49-1/4 [1251] 49-1/4 [1251] 6-1/2 [165] 42 [1067] 46-11/16 [1186] 3/8/ 3/4 [9.5/ 19]
36 49-1/4 [1251] 49-1/4 [1251] 49-1/4 [1251] 6-1/2 [165] 42 [1067] 46-11/16 [1186] 3/8/ 3/4 [9.5/ 19]
Table 1

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
3.2 Cased Unit Dimensions
Figure 2
E
C
A
F
D
B
G
H
Left
Right
Cased unit dimensions
Casings are sold separately as an accessory.
Model
Size
Dimensions Inch [mm]
Unit
Length
A
Unit
Height
B
Unit
Width
C
Supply Air
Height
D
Supply Air
Length
E
Mounting
F
Return Air
Cutout
Length
G
Return Air
Cutout
Height
H
Max Filter
Length
J
Max Filter
Width
K
Liquid Line/
Vapor Line
18 43-3/8 [1102] 11-1/8 [283] 28-3/8 [720] 6-7/8 [174] 30-3/8 [771] 41-5/16 [1050] 28 [711] 7 [178] 39 [990] 15-9/16 [395] 3/8/ 3/4 [9.5/ 19]
24 43-3/8 [1102] 11-1/8 [283] 28-3/8 [720] 6-7/8 [174] 30-3/8 [771] 41-5/16 [1050] 28 [711] 7 [178] 39 [990] 15-9/16 [395] 3/8/ 3/4 [9.5/ 19]
30 55-3/8 [1407] 11-1/8 [283] 28-3/8 [720] 6-7/8 [174] 42-3/16 [1071] 53-5/16 [1354] 40 [1016] 7 [178] 51 [1295] 15-9/16 [395] 3/8/ 3/4 [9.5/ 19]
36 55-3/8 [1407] 11-1/8 [283] 28-3/8 [720] 6-7/8 [174] 42-3/16 [1071] 53-5/16 [1354] 40 [1016] 7 [178] 51 [1295] 15-9/16 [395] 3/8/ 3/4 [9.5/ 19]
Table 2

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
4 Mounting
Mounting slots on the top of the unit are provided for attachment of the unit to
supporting structure. The supporting structure must be designed to safely support
the full weight of the unit. Field supplied washers and bolts capable of supporting
the unit load should be used to secure the unit to the supporting structure at the
mounting slots.
The unit must be mounted level to ensure proper drainage of condensate. If the
supporting structure is not level at the mounting attachment, then spacers must be
used to level the unit.
5 Electrical wiring
Field wiring must comply with the National Electric Code (C.E.C. in Canada) and
any applicable local ordinances.
WARNING: ELECTRICAL SHOCK
Disconnect all power to unit before installing or servicing. More
than one disconnect switch may be required to deenergize the
equipment. Hazardous voltage can cause severe personal injury or
death.
5.1 Power Wiring
It is important that proper electrical power is available for connection to the unit
being installed. See the unit nameplate, wiring diagram, and electrical data in the
installation instructions for more detailed requirements.
fIf required, install a branch circuit disconnect of adequate size, located
within sight, and readily accessible from the unit.
fSupply circuit power wiring must be 221°F minimum copper conductors
only. See Electrical Data In this section for ampacity, wire size and circuit
protector requirements. Supply circuit protection devices may be either
fuses or “HACR” type circuit breakers.
fHigh voltage wiring must be connected to the red and black wiring in the
control section of the air handler.
5.2 Control Wiring
Low voltage control wiring should not be run in conduit with high voltage
wiring. Keep distance between the two conduits per local codes.
f18 AWG. color-coded low voltage wire should be used for lengths less than
100ft. For wire lengths longer than 100 ft., 16 AWG. wire should be used.
fFor low voltage wire connection location, see Figures 1 and 2.
fSee wiring diagram located on the bottom of air handler for proper wiring
instruction.
fAfter installation, ensure separation of low voltage and high voltage wiring
is maintained.
5.3 Grounding
DANGER: ELECTRICAL SHOCK
The unit must be permanently grounded. Failure to do so can
result in electrical shock causing personal injury or death.
fThe ground may consist of electrical wire or metal conduit when installed
in accordance with existing electrical codes.
fGrounding may also be accomplished by attaching ground wire(s) to
ground lug provided in the unit wiring compartment.
fUse of multiple supply circuits require grounding of each circuit to lug
provided in unit.
fGround lug is located on the upper right side of the cabinet.
5.4 Electrical Data
Model Voltage Hertz HP Speeds
Blower
Motor
FLA
Maximum
Circuit
Protector
18 208/230 60 1/3 5 2.6 15(A)
24 208/230 60 1/3 5 2.6 15(A)
30 208/230 60 1/3 5 2.6 15(A)
36 208/230 60 1/3 5 2.6 15(A)
Table 3

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
6 Airow Performance
Airflow performance data is based on cooling performance with a coil and no filter
in place. Check the performance table for appropriate unit size selection.
External static pressure should stay within the minimum and maximum limits
shown in the table below in order to ensure proper operation of both cooling,
heating, and electric heating operation.
6.1 Uncased Unit
Model Motor Speed
SCFM, Uncased
External Static Pressure-Inches W.C. [kPa]
0[0] 0.1[.025] 0.15[.0375] 0.2[.050] 0.3[.075] 0.4[.100] 0.5[.125] 0.6[.150]
18
1741 670 638 612 545 470 403 336
2 925 860 819 788 727 655 588 500
3 1069 1005 973 941 886 826 683 550
4 1193 1140 1106 1071 970 850 700 560
51288 1221 1177 1133 1024 895 745 575
24
1741 670 638 612 545 470 403 336
2925 860 819 788 727 655 588 500
3 1069 1005 973 941 886 826 683 550
4 1193 1140 1106 1071 970 850 700 560
51288 1221 1177 1133 1024 895 745 575
30
1800 691 647 602 530 460 380 300
21025 921 871 820 723 628 536 448
31203 1106 1059 1011 916 822 729 636
4 1339 1266 1224 1181 1085 978 859 729
5 1468 1399 1361 1323 1253 1061 900 760
36
1800 691 647 602 530 460 380 300
21025 921 871 820 723 628 536 448
3 1203 1106 1059 1011 916 822 729 636
41339 1266 1224 1181 1085 978 859 729
51468 1399 1361 1323 1253 1061 900 760
Table 4 Air performance - uncased unit
Bold outlined areas represent airow outside of the required 300-450 cfm/ton
range.
NOTES:
1. Airflow data is without filter or electric heat. Electric Heater adds 0.05 in.
static pressure.
2. Use wet coil data for determining cooling airflow.
3. Bottom louver panel adds 0.05 in. static pressure.

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
6.2 Cased Unit
Model Motor Speed
SCFM, Cased, Back Return
External Static Pressure-Inches W.C. [kPa]
0[0] 0.1[.025] 0.15[.0375] 0.2[.050] 0.3[.075] 0.4[.100] 0.5[.125] 0.55[.1375]
18
1753 655 609 564 481 407 340 309
2 913 828 787 746 666 588 513 476
3 1044 982 945 904 810 700 575 500
4 1153 1058 1007 953 837 711 578 503
51163 1068 1017 963 847 719 580 506
24
1753 655 609 564 481 407 340 309
2913 828 787 746 666 588 513 476
3 1044 982 945 904 810 700 575 500
4 1153 1058 1007 953 837 711 578 503
51163 1068 1017 963 847 719 580 506
30
1801 700 651 602 508 418 331 288
21015 916 869 822 731 645 562 523
31177 1107 1069 1029 943 848 745 670
4 1327 1279 1245 1203 1098 963 795 692
5 1493 1404 1350 1289 1150 987 798 695
36
1801 700 651 602 508 418 331 288
21015 916 869 822 731 645 562 523
3 1177 1107 1069 1029 943 848 745 670
41327 1279 1245 1203 1098 963 795 692
51493 1404 1350 1289 1150 987 798 695
Table 5 Air performance - cased unit, back return
Bold outlined areas represent airow outside of the required 300-450 cfm/ton
range.
NOTES:
1. Airflow data is without filter or electric heat. Electric Heater adds 0.05 in.
static pressure.
2. Use wet coil data for determining cooling airflow.
3. Bottom louver panel adds 0.05 in. static pressure.

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
Model Motor Speed
SCFM without Filter or Electric Heat, Cased, Bottom Return
External Static Pressure-Inches W.C. [kPa]
0[0] 0.1[.025] 0.15[.0375] 0.2[.050] 0.3[.075] 0.4[.100] 0.5[.125] 0.55[.1375]
18
1756 658 611 566 480 400 325 290
2 946 855 810 766 675 591 506 464
3 1035 965 926 883 788 681 561 497
4 1208 1110 1056 999 874 736 585 504
51225 1132 1079 1023 898 758 602 518
24
1756 658 611 566 480 400 325 290
2946 855 810 766 678 591 506 464
3 1035 965 926 883 788 681 561 497
4 1208 1110 1056 999 874 736 585 504
51225 1132 1079 1023 898 758 602 518
30
1796 712 670 626 537 445 351 302
21012 901 850 801 709 627 555 522
31156 1083 1044 1002 911 811 702 616
4 1310 1197 1150 1101 980 850 708 626
5 1469 1328 1256 1182 1031 875 714 632
36
1796 712 670 626 537 445 351 302
21012 901 850 801 709 627 555 522
3 1156 1083 1044 1002 911 811 702 616
41310 1197 1150 1101 980 850 708 626
51469 1328 1256 1182 1031 875 714 632
Table 6 Air performance without lter/electric heat - cased unit, bottom return
Bold outlined areas represent airow outside of the required 300-450 cfm/ton
range.
NOTES:
1. Airflow data is without filter or electric heat. Electric Heater adds 0.05 in.
static pressure.
2. Use wet coil data for determining cooling airflow.
3. Bottom louver panel adds 0.05 in. static pressure.
6.3 Required Airow Range for Normal Operation
Model SCFM
Min Max
18 450 675
24 600 900
30 750 1125
36 900 1350
Table 7 Airow range for normal operation

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
7 Ductwork
Field ductwork must comply with the National Fire Protection Association NFPA
90A, NFPA 90B and any applicable local ordinance(s).
WARNING: FIRE HAZARD AND CARBON MONOXIDE
Do not, under any circumstances, connect return ductwork
to any other heat producing device such as fireplace insert,
stove, etc. Unauthorized use of such devices may result in
fire, carbon monoxide poisoning, explosion, personal injury
or property damage.
Sheet metal ductwork run in unconditioned spaces must be insulated and covered
with a vapor barrier. Fibrous ductwork may be used if constructed and installed
in accordance with SMACNA Construction Standard on Fibrous Glass Ducts.
Ductwork must comply with National Fire Protection Association as tested by
U/L Standard 181 for Class I Air Ducts. Check local codes for requirements on
ductwork and insulation.
fDuct system must be designed within the range of external static pressure
the unit is designed to operate against. It is important that the system
airflow be adequate. Make sure supply and return ductwork, grills, special
filters, accessories, etc. are accounted for in total resistance. See airflow
performance tables in Section 5 of this manual.
fDesign the duct system in accordance with “ACCA” Manual “D” Design
for Residential Winter and Summer Air Conditioning and Equipment
Selection. Latest editions are available from: “ACCA” Air Conditioning
Contractors of America, 1513 16th Street, N.W., Washington, D.C.
20036. If duct system incorporates flexible air duct, be sure pressure
drop information (straight length plus all turns) shown in “ACCA” Manual
“D” is accounted for in system.
If an elbow is included in the plenum close to the unit, it must not be
smaller than the dimensions of the supply duct flange on the unit.
fSecure the supply and return ductwork to the unit flanges, using proper
fasteners for the type of duct used and tape the duct-to-unit joint as
required to prevent air leaks.

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
8 Refrigerant Connections
Keep the coil connections sealed until refrigerant connections are made. Refer to
the Bosch IDS Condenser Section Installation, Operation, and Maintenance Manual
for details on line sizing, tubing installation, and charging information.
Coil is factory charged with Nitrogen. Evacuate the system before charging with
refrigerant.
Install refrigerant lines so that they do not block service access to the unit.
Nitrogen should flow through the refrigerant lines while brazing.
Use a brazing shield to protect the cabinet and a wet rag to protect the rubber
grommet and input pipe’s piston seal ring from being damaged by torch flames.
Use a wet rag or an approved heat paste to protect the TXV sensing bulb during the
brazing process.
After the refrigerant line connections are made, seal the gap around the
connections with pressure sensitive gasket.
After the brazing work is finished, make sure to check that there is no refrigerant
leakage. After checking for vapor leaks, be sure to insulate the pipe connections,
refer to Figure 3.
Figure 3
Do not leave a gap
Do not leave a gap
Vapor line
Piping heat insulation
material
Liquid line
Air
handler
Insulation of pipe connections
8.1 Condensate Drain Connection
Consult local codes for specific requirements.
Refer to Figure 4 and the information below for required condensate drain trap
installation.
Figure 4
When making drain fitting connections to the drain pan, use a thin
layer of Teflon paste, silicone or Teflon tape and install by hand
tightening.
When making drain fi tting connections to drain pan, do not
overtighten. Over tightening fi ttings can split pipe connections on the
drain pan.
Condensate pan has primary and secondary drain connections to meet FHA
requirements. These connections have 3/4" (19 mm) male pipe threads.
All condensate drain line sizes should be a minimum of 7/8" (22 mm) OD. Drain
lines from condensate pan to exterior of unit must be plastic pipe.
The condensate drain line should be tilted downward at a slope of 1 inch per 10 ft
(25 mm per 3 m).
Additional mounting holes are available if more slope is desired by installer. See
figure 4 for drain pan alternate mounting hole locations.
If coil is located in or above a living space where damage may result from
condensate overflow, a separate 3/4" (19 mm) drain must be provided from
secondary drain connection. Run this drain to a place in compliance with local
installation codes where it will be noticed when unit is operational.
Condensate flow from secondary drain indicates a plugged primary drain. Install
a 2" (51 mm) trap in condensate drain line as close to the unit as possible. Make
sure that the top of trap is below connection to drain pan to prevent condensate
from overflowing.
Prime all traps, test for leaks, and insulate in areas where sweating of the traps and
drain lines could potentially cause water damage.
Refer to local code requirements for usage of auxiliary drain pan and
condensate overflow switch.

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
9 Air Filter (Not Factory-Installed)
Filters are not included with the unit and must be field supplied.
All return air must be filtered. The unit can be installed with or without a return-air
duct. When installed as a ducted return, an insulated cover for the bottom casing
opening must be field supplied. When installed without return-air duct (free return
application), the space housing of the unit must be fully sealed except for the the
return air connection to the conditioned space. Air filters should be located at the
return air openings to the unit.
If adding high efficiency filters or electronic air filtration systems, it is very
important that the air flow is not reduced. If air flow is reduced the overall
performance and efficiency of the unit will be reduced. It is strongly recommended
that a professional installation technician is contacted to ensure such filtration
systems are installed correctly.
Do not double filter the return air duct system. Do not filter the supply
air duct system. This will change the performance of the unit and reduce
airflow.
WARNING: FIRE HAZARD
Do not operate the system without filters. A portion of the dust
suspended in the air may temporarily lodge in the duct runs and at
the supply registers. Any circulated dust particles could be heated
and charred by contact with the air handler elements. This residue
could soil ceilings, walls, drapes, carpets and other articles in the
house. Soot damage may occur with filters in place, when certain
types of candles, oil lamps or standing pilots are burned.

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
10 Maintenance
For continuing high performance and to minimize possible equipment
failure, annual maintenance must be performed on this equipment.
10.1 Cleaning Precautions
WARNING: PERSONAL INJURY, PRODUCT DAMAGE
Any unit repairs must be performed by qualified service personnel
only.
WARNING: ELECTRICAL SHOCK
Always turn off your heat pump and disconnect its power supply
before cleaning or maintenance.
WARNING: FIRE HAZARD
Do not use chemicals or chemically treated cloths to clean the
unit.
Do not use benzene, paint thinner, polishing powder or other
solvents to clean the unit.
Do not operate the system without a filter in place
CAUTION: PERSONAL INJURY
When removing filter, do not touch metal parts in the unit.
The sharp metal edges can cut you.
10.2 Regular Maintenance
Your heat pump must be inspected annually by a qualified service technician. Your
annual system inspection must include:
1. Inspect the air filter every thirty days or as often as needed. If blocked or
obstructed, clean or replace at once.
2. Inspection and/or cleaning of the blower wheel housing and motor. The
blower motor is permanently lubricated for normal operating conditions.
3. Inspection and cleaning of indoor and outdoor coils as required.
4. Inspection and/or cleaning of the indoor coil drain pan and drain lines, as
well as auxiliary drain pan and lines.
5. Check all electrical wiring and connections. Correct as needed, referring to
the wiring diagram.
6. Inspect outdoor unit to make sure that no debris or vegetation is within the
required clearance distances.

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
11 Wiring Diagrams
WARNING: ELECTRICAL SHOCK
Disconnect all power before servicing or installing this unit.
Multiple power sources may be present. Failure to do so may
cause property damage, personal injury or death.
DANGER: ELECTRICAL SHOCK
This unit must be properly grounded and protected by a circuit
breaker or fuse.
WARNING: ELECTRICAL SHOCK
These units must be wired and installed in accordance with all
National and Local Safety Codes.
fTo avoid electrical shock, please ensure:
—The heat pump is properly grounded
—The main power plug to the heat pump has been joined with the
ground wiring (DO NOT ALTER THIS).
fDo not strain the power wiring.
For thermostat wiring please refer to the Owner’s Manual of the
thermostat.
Figure 5
YW2
W1C GCYBW
INDOOR UNIT OUTDOOR UNIT
THERMOSTAT
Y
R
G
YELLOW BROWN/BLACK GREEN
RED
BROWN/BLACK
YELLOW
BLUE
C
For single-stage auxiliary heating
(supported by 2H thermostat), jump W1
and W2.
W2
O/B
R
W/E
Wiring for 3H and 1C thermostat
Thermostat wiring diagram for BOVA 15 with BCA series
Electric wiring gauge for H/P systems
Model(Btu/h) 18 24 30 36
Power
Phase Single
Voltage/frequency 208/230VAC, 60Hz
Line Gauge
Input Current Fuse Indoor unit (A) 15A 15A 15A 15A
Indoor Unit
Power Line
Line Quantity 3 3 3 3
Line Diameter (AWG) 14 14 14 14
Outdoor Unit
Power Line
Line Quantity 3 3 3 3
Line Diameter (AWG) 14 14 12 12
Outdoor -Indoor
Signal Line
Line Quantity 4444
Line Diameter (AWG) 18 18 18 18
Thermostat
Signal Line
Line Quantity 5 5 5 5
Line Diameter (AWG) 18 18 18 18
Table 8

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Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
11.1 Unit Wiring
For 24/36k Model
Figure 6
287387 9
a
9$
W
1
G
R
BLK
GRN
COM
240V
208V
TFMR
YEL
RED
GND
BRN
COMPONENT ARRANGEMENT
9
a
COM
240V
208V
TFMR
RED
SEE NOTE 5
SEE NOTE 3
GND
BLK
BLK/WHT
C
TO THERMOSTAT
BRN
YEL
WHT
PUR
BLK
RED
PLUG
PLUG
1
2
3
4
5
61
2
RED
BLK
L1
L2
1
2
TFMR TRANSFORMER
TB TERMINAL BLOCK
FM FAN MOTOR
GND GROUND
COMPONENT ARRANGEMENT
SEE NOTE 1 AND NOTE 2
GND
Y
0
W
0
Y
1
BRN BLK
TB
GND
TB
WHT
GRN
FM
(2)
Y/G-GND
(4)
(N)
C
(L)
(3)
(5)
(1)
( )
SPEED TAP SELECTION
NOTES:
1: Use copper wire(75°C min) only between disconnect switch and unit, To be wired in accordance with N.E.C. and local codes. Fan coils equipped
with electric heater connect power supply to terminal block. Cooling controls wiring not used with electric heaters.
2: If any of the original wire as supplied must be replaced, use the same or equivalent type wire.
3: Remove the red lead from 240V terminal and then connect the red lead to 208V terminal on the transformer for 208 volts.
4: To Change Speed Tap, Move green Wire To Desired Terminal 1 Through 5.
5:Connect R to R, G to G, etc. See outdoor or indoor instructions for details.
6:See Airflow Tables For Tap Usage.
7:N.E.C.Class 2,24volts.
8: The fuse model is 32V/ 3A.Fuse Manufacturer: Littelfuse, fuse part number: 0257003.
1 LOW
2 MEDIUM LOW
3 MEDIUM
4 MEDIUM HIGH
5 HIGH
SEE NOTE 6
16023000008021
FUSE
3A
SEE NOTE 8
ELECTRIC HEAT WIRING
CONNECTION (WHEN APPLIED)
SCHEMATIC DIAGRAM CAUTION:
NOT SUITABLE FOR USE ON SYSTEMS EXCEEDING 150V TO GROUND
ATTENTION:
NE CONVIENT PAS AUXINSTALLATIONS DE PLUS DE 150V ALA TERRE
FIELD POWER WIRING
SEE RATING PLATE FOR VOLTS&HERTZ
TO THERMOSTAT TO OUTDOOR UNIT
W1WHITEW
0BLACK/WHITE
Y1YELLOW
Y0PURPLE
RRED
CBROWN
GGREEN
CAP AND SEAL THE UNUSED WIRE
Red shrinkable tube
Indoor Unit Wiring Diagram for 24/36k Models

18 |
Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
For 18/30k Model
Figure 7
287387 9
a
9$
BLK
COM
240V
208V
TFMR
RED
SEE NOTE 3
TFMR TRANSFORMER
TB TERMINAL BLOCK
FM FAN MOTOR
GND GROUND
GND
NOTES:
1: Use copper wire(75°C min) only between disconnect switch and unit, To be wired in accordance with N.E.C. and local codes. Fan coils equipped
with electric heater connect power supply to terminal block. Cooling controls wiring not used with electric heaters.
2: If any of the original wire as supplied must be replaced, use the same or equivalent type wire.
3: Remove the red lead from 240V terminal and then connect the red lead to 208V terminal on the transformer for 208 volts.
4: To Change Speed Tap, Move green Wire To Desired Terminal 1 Through 5.
5:Connect R to R, G to G, etc. See outdoor or indoor instructions for details.
6:See Airflow Tables For Tap Usage.
7:N.E.C.Class 2,24volts.
8: The fuse model is 32V/ 3A.Fuse Manufacturer: Littelfuse, fuse part number: 0257003.
SEE NOTE 6
16023000008026
Red shrinkable tube
W
1
G
R
GRN
YEL
RED
GND
BRN
COMPONENT ARRANGEMENT
9
a
COM
240V
208V
TFMR
SEE NOTE 5
GND
BLK
BLK/WHT
C
TO THERMOSTAT
BRN
YEL
WHT
PUR
BLK
RED
PLUG
PLUG
1
2
3
4
5
61
2
RED
BLK
L1
L2
1
2
COMPONENT ARRANGEMENT
SEE NOTE 1 AND NOTE 2
GND
Y
0
W
0
Y
1
BRN BLK
TB
TB
WHT
GRN
FM
(2)
Y/G-GND
(4)
(N)
C
(L)
(3)
(5)
(1)
( )
63(('7 $ 36(/(&7,21
1 LOW
2 MEDIUM LOW
3 MEDIUM
4 MEDIUM HIGH
5 HIGH
ELECTRIC HEAT WIRING
CONNECTION (WHEN APPLIED)
SCHEMATIC DIAGRAM CAUTION:
NOT SUITABLE FOR USE ON SYSTEMS EXCEEDING 150V TO GROUND
ATTENTION:
NE CONVIENT PAS AUXINSTALLATIONS DE PLUS DE 150V ALA TERRE
FIELD POWER WIRING
SEE RATING PLATE FOR VOLTS&HERTZ
FUSE
3A
SEE NOTE 8
TO THERMOSTAT TOOUTDOOR UNIT
W
1WHITE
W
0BLACK/WHITE
Y1YELLOWY
0PURPLE
RRED
CBROWN
GGREEN
CAP AND SEAL THE UNUSED WIRE
Indoor Unit Wiring Diagram for 18/30k Models

| 19
Installation Instructions
Bosch BCA Series Air Handler - BTC 761703106 A (03.2023)
Figure 8
CLGN
1 2 3 4 5
Ceiling mounted AHU ECM motor speed taps
Tap Delay - Off Time(s) 18 24 30 36
Tap 1 90 Default — — —
Tap 2 90 — Default — —
Tap 3 90 — — Default —
Tap 4 90 — — — Default
Tap 5 90 — — — —
Table 9 ECM motor speed taps
To Change the Fan Speed Tap:
At the motor connection plug, connect the green wire into the desired
Fan Speed Tap where indicated on the Blower Motor Plug.
The blower motor is equipped with a Time Delay Board (TDB). There
is a 90 second Fan-off delay when G is de-energized on the thermostat
terminal. This setting cannnot be changed.
Online Help Resources
Alternatively, please visit our Service & Support webpage to find FAQs, videos,
service bulletins, and more; www.boschheatingcooling.com/service or use your
cellphone to scan the code below.
Figure 9

United States and Canada
Bosch Thermotechnology Corp.
65 Grove St.
Watertown, MA 02472
Tel: [phone]
Fax: [phone]
www.bosch-thermotechnology.us
BTC 761703106 A / 03.2023
Bosch Thermotechnology Corp. reserves the right
to make changes without notice due to continuing
engineering and technological advances.