Bosch BWA Series User manual

Installation Instructions
Split System Heat Pump
Bosch BWA Series
Wall Mounted Air Handler Units | 1.5-3 Ton Capacity | R410A
BTC 761703105 A / 03.2023

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 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 6
2.1 Installations in High Humidity Environments 6
3 Dimensional Data 7
3.1 Unit Dimensions 7
3.2 Unit Back Dimensions 8
4 Applications 9
4.1 Wall Mount 9
4.2 Frame Mount 10
4.3 Return Air Panel Configuration 11
5 Electrical wiring 11
5.1 Power Wiring 11
5.2 Control Wiring 12
5.3 Grounding 12
5.4 Electrical Data 12
5.5 Electric Heat Kit MCA/MOP Data 13
5.5.1 EHK Without Unit 13
5.5.2 EHK With Unit 13
6 Airow Performance 14
7 Ductwork 15
8 Refrigerant Connections 16
8.1 Condensate Drain Connection 16
9 Air Filter (Not Factory-Installed) 17
10 Filter Installation Dimensions 17
11 Maintenance 18
11.1 Cleaning Precautions 18
11.2 Regular Maintenance 18
12 Wiring Diagrams 19
12.1 Unit Wiring 20
12.2 Electric Heat Kit Wiring 22

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 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 BWA Series Air Handler - BTC 761703105 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.
NOTICE:
Make sure the blower motor support is tight (3-motor mounting
bolts - Fig. 1). Then check if wheel is tightly secured to motor shaft
before operating unit.
Figure 1
Blower Motor
Mounting Bolt

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
2 General
The unit is intended to be paired with IDS Light BOVA15 Condensers. The unit
can be positioned for front return or converted to bottom air return in the upflow
position only.
Adjust the motor speed by adjusting the motor wiring at the blower motor plug.
Select correct air flow according to airflow performance table in Section 6. Please
refer to wiring diagram for motor speed selection instructions.
Please refer to Figure 2 for high and low voltage wiring connections.
To ensure the proper installation, select a solid and level site. Ensure enough
clearance is maintained for installation and maintenance.
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.
2.1 Installations in High Humidity Environments
When the unit is installed in a hot and humid place, if the humidity inside the
installation space exceeds 86°F and RH 80%, it is recommended to insulate the
cabinet exterior. Use glass wool or polyethylene foam as insulation; the thickness
should be more than 2 in. and it must fit inside the installation space opening.
Condensation may come from the surface of the insulation. Be sure to use insulation
that is designed for use with HVAC Systems. Condensation may be produced on
surface during cooling operation. It is also recommended to use auxiliary drain pan
and secure the unit firmly to prevent it from falling.
Refer to local code requirements for usage of auxiliary drain pans.

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
3 Dimensional Data
3.1 Unit Dimensions
Figure 2
Low voltage
connection
Breaker switch
(for electric heater only)
D1
D
W1
W
H
Return air opening
High voltage connection
7/8" dia knock outs
Vapor line connection
copper (sweat)(3/4"dia pipe)
Liquid line connection
copper (sweat)(3/8"dia pipe)
All units are configured for vertical upflow.
Units cannot be installed in any other configuration.
Front return shown. Units may
also be installed as bottom
return. See the applications
section for more detail.
Primary drain conncetion 3/4"
female pipe thread (NPT)
Auxiliary drain connection 3/4"
female pipe thread (NPT)
NOTE:Hand tighten only
Unit dimensions
Model Size Dimensions Inch [mm]
Unit Height "H" Unit Width "W" Unit Length "D" Supply Duct Width "W1" Supply Duct Length "D1" Liquid Line/ Vapor Line
18 36-1/2 (928) 20-1/2 (521) 15 (381) 17-2/5 (442) 9-1/2 (242) 3/8 / 3/4 (9.5) / (19)
24 36-1/2 (928) 20-1/2 (521) 15 (381) 17-2/5 (442) 9-1/2 (242) 3/8 / 3/4 (9.5) / (19)
30 39-1/2 (1004) 22 (559) 19 (483) 18-4/5 (478) 9-1/2 (242) 3/8 / 3/4 (9.5) / (19)
36 39-1/2 (1004) 22 (559) 19 (483) 18-4/5 (478) 9-1/2 (242) 3/8 / 3/4 (9.5) / (19)
Table 1

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
3.2 Unit Back Dimensions
Figure 3
ABC
Unit back dimensions
Model Size Dimensions Inch [mm]
A B C
18 24-9/10" [150] 10-1/8"[61] 119-1/20" [717]
24 24-9/10" [150] 10-1/8"[61] 119-1/20" [717]
30 24-9/10" [150] 10-1/8"[61] 132" [795]
36 24-9/10" [150] 10-1/8"[61] 132" [795]
Table 2

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
4 Applications
The small air handler should be centrally located and may be installed in a closet,
alcove, utility room, or basement. Minimum clearances must be met.
The air handler comes standard with two different options for mounting, wall mount
or frame mount. Both mounting options require the unit to be level from side to
side and from front to back in order to allow condensate to properly drain from the
unit. Failure to do this will result in condensate leaking out from the unit, potentially
causing structural damage to the surrounding support structures, dry wall, carpet,
etc. Also, both mounting structures require the ability to accommodate a minimum
of 150 lb load. Failure to do this will cause damage to the support structure and
potentially damage the unit.
4.1 Wall Mount
The air handler comes standard with a wall mounting bracket and air handler
mounting bracket. Reference Figures 4 & 5 for more detail.
1. Remove lower wall mounting bracket from the back of the unit by removing
one screw which attaches the bracket to the air handler. Note: Discard the
screw after you have removed the wall mounting bracket.
2. Install bracket on the wall by using 3 wood screws (not provided). Make
sure the bracket is level in order to provided proper drainage from the
unit. Note: Do not attach the wall mounting bracket into unsupported dry
wall. Make sure that the wood screws are going into a structure that can
suppport a minimum load of 150 lb.
3. Lift the air handler above the wall mounting bracket and attach the unit to
the installed bracket. Reference Figures 4 & 5. Install the additional bottom
plate for extra support for this type mounting (see Figure 5).
The additional plate is shipped in the bottom of the shipping carton.
Figure 4
WALL STRUTURE
WOOD SCREWS
WOOD SCREWS
PROVIDED WALL
MOUNT BRACKET
NOTE: MOUNTING WALLAND SUPPORTING
STRUCTURE MUST BE ABLE TO SUPPORT A
MINIMUM OF 150 LBS.
PROVIDED AIR HANDLER
MOUNTING BRACKET
NOTE:
IN ORDER TO PREVENT
AIR LEAKAGE,THE TABS
AND SCREW HOLES
NEED TO BE SEALED
UP WHEN THEYARE
NOT TO BE USED.
Wall Mounting Side View
Figure 5
PROVIDED WALL
MOUNT BRACKET
WALLMOUNT BRACKET
WOOD SCREWS
SUPPORTING
2˝X 4˝
STRUCTURE
WOOD SCREWS
OFFSET HANGING
BRACKET
(ONLY FOR 30K/36K)
Wall Mounting

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
4.2 Frame Mount
The air handler comes with 6 clearance holes (3 on each side). These holes are
used to mount the air handler inside of a frame structure (see Figure 6). When
mounting in this fashion, make sure that the wood screws are mounted from within
the air handler and not from outside the unit in order to avoid damaging the coil. If
the frame does not provide support in the front of the unit and additional support
is needed, open up the tabs and fix the unit to the frame or other support structure
with screws. Select a solid and level site to ensure proper installation of the frame
mount. Verify that there is sufficient space for installation and maintenance (see
Figure 7).
CAUTION: PERSONAL INJURY,PRODUCT DAMAGE,
PROPERTY DAMAGE
The (6) wood screws are not provided with the unit.
#12 x 1 ½˝ wood screws are recommended. When the unit is
installed on a wood frame, the screws should be used to fix the unit
to the studs. If they are not used, the unit may fall down or cause
other damage. See Figure 6 for frame mount installation.
Figure 6
WALL STRUCTURE
SUPPORTING
2˝X4˝ STRUCTURE
WOOD SCREWS
SUPPORTING 2˝X 4˝
STRUCTURE
STUD ATTACHMENT
HOLES
THE TABS
BRACKET PLACEMENT
FOR HANGING
IN A CLOSET
Frame Mount
Figure 7
≥0"
Top view of the indoor unit clearance(including air duct).
≥ 20"
≥0"
≥24"
≥0"
Front of unit
AIRFLOW
Space for frame mount
The installed unit must have the required clearances as shown in
Figure 7. Failure to follow these instructions may result in equipment
damage and/or premature equipment failure.

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
4.3 Return Air Panel Conguration
Figure 8
REMOVE BOTTOM
COIL PANEL OFF PLATE
INSTALL
FRONT
COIL PANEL
Different return air conguration
Bottom Return Conversion:
Divert the return air from the factory standard front return to a bottom return.
Remove the cross brace when converting cabinet to bottom return.
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.
When the Electric Heater is installed, units may be equipped with one 60
amp. circuit breaker. These breaker(s) protect the internal wiring in
the event of a short circuit and serve as a disconnect. Circuit breakers
installed within the unit do not provide over-current protection of the
supply wiring and therefore may be sized larger than the branch circuit
protection.
fSupply circuit power wiring must be 167°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 may be run through knockout holes on the right, left or
top of the unit.
fTwo 7/8" dia. concentric knockouts are provided for running high voltage
wiring to the unit. Refer to Figure 2 for High Voltage knock out locations.
fHigh voltage wiring must be connected to the red and black wiring in the
control section of the air handler.

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
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.
fLow voltage wire connections are made to low voltage pigtails extending
from top of air handler (see Figure 2). Connections for control wiring are
made with wire nuts. Control wiring knockouts (7/8˝) are also provided on
the right and left side of the unit for side connection.
fSee wiring diagram located on inside of blower access panel 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 lugs are located close to wire entrance on left side of unit. Lugs
may be moved to marked locations near wire entrance on right side of unit
if alternate location is more convenient.
5.4 Electrical Data
Model Voltage Hertz HP Speeds
Blower
Motor
FLA
Maximum
Circuit
Protector
18 208/230 60 1/3 5 1.9 15(A)
24 208/230 60 1/3 5 1.9 15(A)
30 208/230 60 1/2 5 2.7 15(A)
36 208/230 60 1/2 5 2.7 15(A)
Table 3

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
5.5 Electric Heat Kit MCA/MOP Data
5.5.1 EHK Without Unit
Heat Kit
Model
Air Handler
Model
Electric Heat
(kW)
Heat kit
FLA (A)
MIN.Circuit
Ampacity (A)
MAX.Fuse or Breaker
(HACR) Ampacity Fan speed
208 VAC 240 VAC 208 VAC 240 VAC 208 VAC 240 VAC 12345
EHK-05W
18/24/30/36
5 18.1 20.8 23 26 25 30 
EHK-08W 7.5 27.1 31.3 34 40 35 40 X X 
EHK-10W 10 36.1 41.7 46 53 50 60 X X 
Table 4 Suitable heat kits for AHU installation
[ means available, X means not available ]
5.5.2 EHK With Unit
Heat Kit
Model
Air Handler
Model
Unit Motor
FLA
(A)
Electric Heat
(kW)
Heat kit
FLA (A)
MIN.Circuit
Ampacity (A)
MAX.Fuse or Breaker
(HACR) Ampacity
208 VAC 240 VAC 208 VAC 240 VAC 208 VAC 240 VAC
EHK-05W
18 1.9
5 18.1 20.8 25 29 25 30
EHK-08W 7.5 27.1 31.3 37 42 40 45
EHK-10W 10 36.1 41.7 48 55 50 60
EHK-05W
24 1.9
5 18.1 20.8 25 29 25 30
EHK-08W 7.5 27.1 31.3 37 42 40 45
EHK-10W 10 36.1 41.7 48 55 50 60
EHK-05W
30 2.7
5 18.1 20.8 26 30 30 30
EHK-08W 7.5 27.1 31.3 38 43 40 45
EHK-10W 10 36.1 41.7 49 56 50 60
EHK-05W
36 2.7
5 18.1 20.8 26 30 30 30
EHK-08W 7.5 27.1 31.3 38 43 40 45
EHK-10W 10 36.1 41.7 49 56 50 60
Table 5 Suitable heat kits for AHU installation
—Heat pump systems require a specified airflow. Each ton of cooling
requires between 350 and 450 cubic feet of air per minute (CFM),
or 400 CFM nominally
—All electric heat kits include breaker(s) for each heater element for
short circuit protection
—EHK-05W, EHK-08W, and EHK-10W are single circuit (contain 1
heater element)
—Blower motor load is included in MCA and MAX Fuse/Breaker size
Heater Kit Accessories
Model Description 18 24 30 36
EHK-05W 5 kW Heat Kit, Double Pole Breaker 
EHK-08W 7.5 kW Heat Kit, Double Pole Breaker 
EHK-10W 10 kW Heat Kit, Double Pole Breaker 
Table 6
[ means available, X means not available ]

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 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.
MODEL
SIZE
BLOWER
SPEEDS
SCFM
EXTERNAL STATIC PRESSURE-Inches w.c.[kPa]
0[0] 0.1[.02] 0.18[.04] 0.2[.05] 0.3[.07] 0.4[.10] 0.5[.12] 0.6[.15] 0.7[.17] 0.8[.20]
18
Tap(5) 913 881 848 848 818 792 763 731 691 650
Tap(4) 825 787 756 753 717 682 650 617 580 540
Tap(3) 737 700 666 663 630 589 550 511 474 436
Tap(2)-Factory 675 632 598 596 555 521 480 440 399 366
Tap(1) 590 548 512 499 455 430 368 338 309 263
24
Tap(5) 913 881 848 848 818 792 763 731 691 650
Tap(4)-Factory 825 787 756 753 717 682 650 617 580 540
Tap(3) 737 700 666 663 630 589 550 511 474 436
Tap(2) 675 632 598 596 555 521 480 440 399 366
Tap(1) 590 548 512 499 455 430 368 338 309 263
30
Tap(5) 1362 1325 1280 1266 1238 1197 1159 1119 1080 1040
Tap(4) 1282 1242 1195 1176 1151 1111 1071 1028 975 936
Tap(3) 1267 1225 1178 1143 1120 1078 1036 993 942 897
Tap(2)-Factory 1157 1111 1061 1052 1016 971 929 884 842 802
Tap(1) 1077 1028 978 965 932 886 850 804 768 732
36
Tap(5) 1362 1325 1280 1266 1238 1197 1159 1119 1080 1040
Tap(4)-Factory 1282 1242 1195 1176 1151 1111 1071 1028 975 936
Tap(3) 1267 1225 1178 1143 1120 1078 1036 993 942 897
Tap(2) 1157 1111 1061 1052 1016 971 929 884 842 802
Tap(1) 1077 1028 978 965 932 886 850 804 768 732
Table 7 Air Performance
Bold outlined areas represent airow outside of the required 300-450 cfm/ton
range.
NOTES:
1. Airflow based upon dry coil at 230V with no electric heat, no filter. For
24,30 and 36 sizes, airflow at 208V is approximately the same as 230V
because the multi-tap ECM motor is a constant torque motor. The torque
doesn't drop off at the speeds in which the motor operates.
2. Airflow is equivalent for front or bottom return configurations.
3. SCFM is nearly the same with cooling performance airflow, the gap is in the
1 to 2%.

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 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 6 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.
fSupply plenum should be attached to the 3/4” duct flanges supplied with
the unit. Attach flanges around the blower outlet.
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.
The front flange on the return duct (if connected to the blower casing
must not be screwed into the area where the power wiring is located.
Drills or sharp screw points can damage insulation on wires located
inside 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 BWA Series Air Handler - BTC 761703105 A (03.2023)
8 Refrigerant Connections
fKeep 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.
fCoil is factory charged with Nitrogen. Evacuate the system before charging
with refrigerant.
fInstall refrigerant lines so that they do not block service access to the front
of the unit.
fNitrogen should flow through the refrigerant lines while brazing.
fUse a brazing shield to protect the cabinet’s paint 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. Refer to Figure 9.
fAfter the refrigerant line connections are made, seal the gap around the
connections with pressure sensitive gasket.
Figure 9
Vapor line
Liquid line
Wet rag
Use a wet rag to protect the sealing rings in the
input pipe from being damaged by torch flames
while brazing.
Protection during the brazing process
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 10.
Figure 10
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
The unit is supplied with primary and auxiliary condensate drains that have 3/4”
NPT connections. Both drains must be trapped outside the unit and piped in
accordance with applicable materials and building codes. Do not reduce the drain
line size less than the connection size on the drain pan. Condensate should be
piped to an open drain or to the outside. All drains must pitch downward away from
the unit a minimum of 1/4” per foot of line to ensure proper drainage. Insulate the
primary drain line to prevent sweating where dew point temperatures may be met.
(Insulation is optional depending on climate and application needs.)
If cleanout tee is used, standpipe must be sealed/capped.

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Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
9 Air Filter (Not Factory-Installed)
Filters are not included with the unit and must be field supplied.
An air filter must be installed before air enters the evaporator coil in order to protect
the coil, blower, and other internal parts from excessive dirt and dust. Consult the
filter manufacturer for proper sizing and maximum velocity requirements.
Filter application and placement are critical to airflow, which may affect the heating
and cooling system performance. Reduced airflow can shorten the life of the
system’s major components, such as motor, elements, heat relays, evaporator coil
or compressor. Consequently, we recommend that the return air duct system have
only one filter location. For systems without a return air filter grill, multiple filter
grills can be installed at each of the return air openings.
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.
10 Filter Installation Dimensions
Filters are not included with the unit and must be field supplied.
Dimensional data
Model Filter Size
In. [mm]
18/24 16x20 [406x508]
30/36 20x20 [508x508]
Table 8
Air lter removal / installation
fHold the edge of the air filter and pull out.
fInstall new filter so that the arrow on the filter is in the same direction as
airflow.
fIf reusable filter is being used, please clean according to the
manufacturer's specification prior to re-installation.

18 |
Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
11 Maintenance
For continuing high performance and to minimize possible equipment
failure, annual maintenance must be performed on this equipment.
11.1 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.
11.2 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.

| 19
Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
12 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.
Dashed lines in the following thermostat wiring diagrams refer to optional
wiring (wiring for Electric Heat). For thermostat wiring please refer to the
Owner’s Manual of the thermostat.
Figure 11
YW2
W1C GCYBW
INDOOR UNIT OUTDOOR UNIT
THERMOSTAT
Y
R
G
YELLOW BROWN/BLACK GREEN
RED
WHITE
WHITE/BLACK
BROWN/BLACK
YELLOW
BLUE
WHITE
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 BWA
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 9

20 |
Installation Instructions
Bosch BWA Series Air Handler - BTC 761703105 A (03.2023)
12.1 Unit Wiring
For 24/36k Models
Figure 12
NOTES:
1. Use copper wire (75°C Min) only between disconnect switch and unit.
2. To be wired in accordance with NEC and local codes.
3. If any of the original wire, as supplied, must be replaced. Use the same or
equivalent type wire.
4. Connect R to R, G to G, etc. See outdoor instructions for details.
5. To change speed tap, move green wire to desired terminal1 through 5.
6. See Airflow tables for tap usage.
7. Do not use red wire from motor.
8. Taps 2 & 4 have a 90s delay off, taps.
COMPONENTARRANGEMENT
F M
NOT SUITABLE FOR USEON SYSTEMS EXCEEDING 150VTO GROUND
CAUTION:
Indoor Unit Wiring Diagram for 24k and 36k Models
Tap Delay - Off Time(s) 18 24 30 36
Tap 1 30 — — — —
Tap 2 90 Default — Default —
Tap 3 30 — — — —
Tap 4 90 — Default — Default
Tap 5 30 — — — —
Table 10 Blower Motor Speed Taps