Bosch Singular 4000 User manual

Installation Instructions
Gas Condensing Combi Boilers
Singular
Singular 4000 | Singular 5200
BTC 439003301 B / 07.2021
WARNING:
If the information in these instructions are not followed exactly, a fire or explo-
sion may result causing property damage, personal injury or death.
WARNING:
Do not store or use gasoline or other flammable vapors and liquids in the vicinity
of this or any other appliance.
WHAT TO DO IF YOU SMELL GAS
—Do not try to light any appliance.
—Do not touch any electrical switch; do not use any phone in your building.
—Immediately call your gas supplier from a neighbor’s phone. Follow the gas
supplier’s instructions.
—If you cannot reach your gas supplier, call the fire department.
WARNING:
Improper installation, adjustment, alteration, service or maintenance can cause
property damage, personal injury (exposure to hazardous materials)* or loss of
life. Refer to the user's information manual provided with this boiler. Installation
and service must be performed by a qualified installer, service agency or the gas
supplier who must read and follow the supplied instructions before installing,
servicing, or removing this boiler. This boiler contains materials that have been
identified as carcinogenic, or possibly carcinogenic, to humans.
This boiler must be installed in accordance with local, state, and federal codes.
In the absence of such requirements, then to the latest edition of the National
Fuel Gas Code, ANSI Z223.1./NFPA 54. In Canada, installation must be in
accordance with the requirements of CAN/CSA B149.1, Natural Gas and
Propane Installation Code.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
Table of Contents
1 Key to Symbols and Safety Instructions 4
1.1 Key to Symbols 4
1.2 Safety 4
2 General Information 7
2.1 Included Items 7
2.2 Optional Accessories 7
2.3 Specifications 8
2.4 Rating Plate 9
2.4 Dimensions 10
2.5 Components 11
3 Boiler Installation 13
3.1 Installer Qualifications 13
3.2 Compliance Requirements 13
3.3 Location 13
3.3.1 Access to Utilities 13
3.3.2 Humidity and Contact with Water 13
3.3.3 Drainage 13
3.3.4 Venting and Ventilation 13
3.3.5 Clearances 14
3.3.6 Clean, Debris and Chemical-Free Combustion Air 14
3.3.7 Position 14
3.4 Mounting to the Wall 15
4 System Piping 16
4.1 Installing a Space Heating System 16
4.1.1 Guidelines for a Space Heating System 16
4.1.2 Essential Elements in a Space Heating System 16
4.1.3 Space Heating Piping 17
4.2 Installing a Domestic Hot Water(DHW) System 17
4.2.1 Guidelines for a DHW System 17
4.2.2 Essential Elements in a DHW System 18
4.2.3 DHW System Piping 18
4.3 Connecting the Condensate Drain 19
4.3.1 Filling the Condensate Trap 20
4.4 System Filling 20
4.4.1 Built-In Water Filling 20
4.4.2 External Water Fill Connection 20
4.5 Test the Water System 21
4.5.1 External Water Fill Connection 21
4.6 Examples of System Applications 22
4.6.1 System Application – Zone System with Zone Valves 22
4.6.2 System Application – Single Zone System 23
4.6.3 System Application – Zone System with Circulators 24
5 Connecting the Gas Supply 25
5.1 Gas Pipe Sizing Tables 25
5.2 Gas Piping 26
5.3 Inlet Gas Pressure 27
6 Installing a Vent 29
6.1 Vent Type 29
6.1.1 Direct Venting 29
6.1.2 Non- Direct Venting 31
6.2 Vent Pipe Materials 33
6.3 Vent Length 34
6.4 Connecting the Vent Clip 34
6.5 Vent Termination 35
6.5.1 Single-Pipe Sidewall Venting 35
6.5.2 Two-Pipe Sidewall Venting 35
6.5.3 Snorkel Flue 36
6.5.4 Non-Concentric Sidewall Venting 36
6.5.5 Concentric Sidewall Venting 36
6.5.6 Two-Pipe Vertical Venting 37
6.5.7 Concentric Roof Venting 37
7 Setting the DIP Switches 38
8 Connecting the Power Supply 39
9 Installation Checklist 40
10 Operating the Boiler 42
10.1 Turning the Boiler On or Off 42
10.2 Checking the Ignition System 42
10.3 Setting the Space Heating Temperature 42
10.4 Setting the DHW (Domestic Hot Water) Temperature 43
10.5 Viewing Basic Information 43
10.5.1 H0 mode 44
10.5.2 H1 mode 44
10.5.3 H2 mode 44
10.5.4 H3 mode 44
10.5.5 H4 mode 45
10.5.6 H5 mode 45
10.5.7 H6 mode 45
10.5.8 H7 mode 45
10.5.9 H8 mode 46
10.5.10 H9 mode 46
10.5.11 HA mode 46
10.5.12 HB mode 46
10.5.13 Cd mode 47
10.6 Setting the Heat Load for The Outdoor Reset Control Mode 47
10.7 Altitude Adjustment 49
11 Gas Conversion 50
11.1 Combustion Analysis 52
12 Wiring Diagram 54
13 Ladder Diagram 55
14 Normal Operating Sequence 56
15 Outdoor Temperature Sensor 58
15.1 Outdoor Temperature Sensor Installation (Optional) 58
15.2 Outdoor Temperature Sensor Installation Guidelines 58
15.3 Outdoor Reset Control 59
16 Inspection and Maintenance 60
16.1 Draining the Boiler 60
16.2 Cleaning the Cold Water Inlet Filter 62
16.3 Cleaning the Air Intake Filter 62
16.4 Protecting the Boiler from Freezing 63
16.5 Maintenance Schedules 63
16.5.1 Owner Maintenance 63
16.5.2 Service Technician Maintenance 63
17 Troubleshooting 65
17.1 Basic Problems 65
17.2 Error Codes 66

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
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:
DANGER indicates a hazardous situation which, if not avoided, will result
in death or serious injury.
WARNING indicates a hazardous situation which, if not avoided, could
result in death or serious injury.
CAUTION indicates a hazardous situation which, if not avoided, could
result in minor to moderate injury.
NOTICE 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:FIRE,EXPLOSION
Vapors from flammable liquids can explode and/or catch fire
causing death or severe burns.
Keep flammable products far away from the boiler and store
them in approved containers. Keep the containers tightly
closed and out of the reach of children.
The boiler has a main burner flame that can come on at any
time and will ignite flammable vapors.
Vapors cannot be seen and are heavier than air. They can
travel long distances along the ground and can be carried
from other rooms to the boiler’s main burner flame by air
current.
WARNING:SCALDHAZARD
Water temperature over 125°F can cause severe burns or
death from scalding.
If it is necessary to set the water temperature above 125°F
(52°C), consider installing a thermostatically-controlled
mixing valve. Contact a licensed plumber or your local
plumbing authority for more information.
Children, the disabled and the elderly are at highest risk of
being scalded.
Test water before bathing or showering.
Temperature TimetoProduceSerious Burn
120 °F (48 °C) More than 5 minutes
125 °F (51 °C) 1.5 to 2 minutes
130 °F (54 °C) Approx. 30 seconds
135 °F (57 °C) Approx. 10 seconds
140 °F (60 °C) Less than 5 seconds
145 °F (62 °C) Less than 3 seconds
150 °F (65 °C) Approx. 1.5 seconds
155 °F (68 °C) Approx. 1 second
Table 1
WARNING: RISKOFPERSONAL INJURYORDEATHFROMEXPLOSION!
Work on gas components may only be carried out by a
trained and certified installer or service company.
Appliance installation, the connection of gas and vent
piping, initial commissioning, electrical connections, and
service and maintenance must only be carried out by a
trained and certified installer or service company.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
WARNING:FIRE,EXPLOSION
Do not store combustibles, such as papers or laundry, near
the boiler or venting system.
Do not store or use gasoline or other flammable liquids near
this boiler.
Do not store or use compressed gases, such as hair sprays
or spray paints, near the boiler or venting system, including
the vent termination.
WARNING:HAZARDOUSVOLTAGE
Do not remove the front cover unless the power to the boiler
is turned off or disconnected.
Do not touch the internal components of the boiler or the
power cord with wet hands.
WARNING:FIRE,CARBONMONOXIDE
Do not operate the boiler with the front cover opened.
Do not operate the boiler without proper venting.
Do not place anything in or around the vent terminals that
could obstruct the air flow in or out of the boiler.
WARNING:FIRE,EXPLOSION
Have your installer or plumber show you the location of the
gas shut off valve and demonstrate how to close the valve. If
the boiler is damaged as a result of overheating, fire, flood,
or any other reason, close the manual shut off valve and do
not operate the boiler again until it has been inspected by a
qualified technician.
WARNING:FIRE,EXPLOSION
Should overheating occur or if the gas supply fails to shut
off, turn off the manual gas shut off valve.
WARNING:PERSONALINJURY,PROPERTY DAMAGE
Do not allow children to operate or have access to the boiler.
WARNING:IMPROPEROR DANGEROUSOPERATION
Immediately call a qualified service technician to inspect the
appliance and replace any part of the control system and/or
any gas control which has been immersed in water.
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:FIRE,CARBONMONOXIDE
After replacement of a gas related component, where a
gasket of seal has been disturbed or replaced, check for gas
tightness using a gas detector / analyzer.
On re-assembly check all affected seals for cracks hardness
and deterioration. If damaged or in any doubt the seal must
be replaced.
CAUTION:INTENDEDUSE
Do not use the boiler for anything other than its intended
purpose, as described in this manual.
CAUTION:IMPROPERORDANGEROUSOPERATION
Do not use unapproved replacement or accessory parts.
When servicing the controls, label all wires prior to
disconnecting them to prevent wiring errors.
Do not attempt to repair or replace any part of the boiler,
unless it is specifically recommended in this manual. For all
other service, contact an authorized technician or licensed
professional. Improper adjustments, alterations, service, or
maintenance may lead to property damage, personal injury,
or death and will void your warranty.
NOTICE:BOILERDAMAGE
Do not turn on the boiler unless the water and gas supplies
are fully opened. Failure to do so may damage the boiler.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
1.3 Important Note for the State of Massachusetts
NOTICE BEFORE INSTALLATION
This appliance must be installed by a licensed plumber or gas fitter in accordance
with the Massachusetts Plumbing and Fuel Gas Code 248 CMR Sections 4.00 and
5.00.
IMPORTANT: In the State of Massachusetts (248 CMR 4.00 & 5.00)
For all side wall horizontally vented gas fueled equipment installed in every
dwelling, building or structure used in whole or in part for residential purposes,
including those owned or operated by the Commonwealth and where the side wall
exhaust vent termination is less than seven (7) feet above finished grade in the
area of the venting, including but not limited to decks and porches, the following
requirements shall be satisfied.
1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At the time of
installation of the side wall horizontal vented gas fueled equipment, the
installing plumber or gasfitter shall observe that a hard wired carbon
monoxide detector with an alarm and battery back-up is installed on the floor
level where the gas equipment is to be installed. In addition, the installing
plumber or gasfitter shall observe that a battery operated or hard wired
carbon monoxide detector with an alarm is installed on each additional level
of the dwelling, building or structure served by the side wall horizontal vented
gas fueled equipment. It shall be the responsibility of the property owner to
secure the services of qualified licensed professionals for the installation of
hard wired carbon monoxide detectors
a. In the event that the side wall horizontally vented gas fueled equipment
is installed in a crawl space or an attic, the hard wired carbon monoxide
detector with alarm and battery back-up may be installed on the next
adjacent floor level.
b. In the event that the requirements of this subdivision cannot be met
at the time of completion of installation, the owner shall have a period
of thirty (30) days to comply with the above requirements; provided,
however, that during said thirty (30) day period, a battery operated
carbon monoxide detector with an alarm shall be installed.
2. APPROVED CARBON MONOXIDE DETECTORS. Each carbon monoxide
detector as required in accordance with the above provisions shall comply
with NFPA 720 and be ANSI/UL 2034 listed and IAS certified.
3. SIGNAGE. A metal or plastic identification plate shall be permanently
mounted to the exterior of the building at a minimum height of eight (8)
feet above grade directly in line with the exhaust vent terminal for the
horizontally vented gas fueled heating appliance or equipment. The sign
shall read, in print size no less than one half (1/2) inch in size, “GAS VENT
DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS”.
4. INSPECTION. The state or local gas inspector of the side wall horizontally
vented gas fueled equipment shall not approve the installation unless, upon
inspection, the inspector observes carbon monoxide detectors and signage
installed in accordance with the provisions of 248 CMR 5.08(2)(a)1 through
4.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
2 General Information
2.1 Included Items
The following items are included with the boiler. Check each of the following items
before installation.
Figure 1
Wall mounting bracket Tapping screws & anchors
Installation and
User manual
Vent clip
Gas conversion kit
Spare parts
Pressure Relief Valve
2" Vent termination cap &
Wall ange
If there is a missing item, please contact Technical Support at
1-866-642-3198.
2.2 Optional Accessories
The following optional accessory is not included with the boiler, but may be
necessary for the installation. Check the need for the following optional accessory
before installation.
Figure 2
Outdoor temperature sensor
WARNING:
Installing the appliance and/or any accessories for the
appliance may only be carried out by a qualified service
technician and must conform to the requirements of the
authority having jurisdiction or, in the absence of such
requirements, to the latest edition of the National Fuel
Gas Code, ANSI Z223.1./NFPA 54. In Canada, installation
must be in accordance with the requirements of CAN/CSA
B149.1, Natural Gas and Propane Installation Code.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
2.3 Specifications
The following table shows the specifications for the boiler. Additional specifications
about water, gas, electric, and air supplies (venting) appear in each installation
section.
Singular4000 Singular 5200
Heat Capacity (Input) Space Heating 19,900–80,000 BTU/H 19,900–140,000 BTU/H
Domestic Hot Water 19,900–155,000 BTU/H 19,900–199,000 BTU/H
Flow Rate (DHW) 45°F (25°C) Temp Rise 6.0GPM (23LPM) 7.7GPM (29LPM)
67°F (37°C) Temp Rise 4.0GPM (15LPM) 5.2GPM (20LPM)
AFUE Natural Gas (propane) 95.0% (95.0%) 95.0% (95.0%)
Dimensions (W x D x H) 18.1“ x 27.6” x 11.6“ (460 mm x 700 mm x 295 mm)
Installation Type Indoor wall-hung
Venting Type Forced draft direct vent
Ignition Electronic ignition
Water Pressure(Hydronic/DHW) 12~30psi /15~150 psi
Supply Pressure Natural Gas 3.5" – 10.5" WC
Propane 8" – 13" WC
Temperature Range Space Heating 82°F – 180°F(27°C – 82°C)
DHW 86°F – 140°F(31°C – 60°C)
Minimum Flow Rate (DHW) 0.5GPM(2.0LPM)
Power Supply Main Supply 120V AC, 60 Hz / uses less than 5 AMP
Connection Sizes
Space heating Supply/Return 1" NPT
Cold water Inlet 3/4" NPT
Hot Water Outlet 3/4" NPT
Gas Inlet 3/4" NPT
Materials Primary Heat Exchanger Stainless steel
Secondary Heat Exchanger Stainless steel
Venting
Exhaust/Intake "2"" or 3"" PVC, CPVC, Polypropylene
2"" or 3"" Special gas vent type BH (Class II, A/B/C)"
Length 2" 60ft(18.3m)
3" 150ft(45.7m)
Vent Clearances 0" to combustibles
Safety Devices Flame rod, APS, Over heat preventer, Low water cut off switch,
Exhaust temperature high limit sensor, Power surge fuse
Table 2

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
2.4 Rating Plate
WARNING:FIRE,EXPLOSION
The gas type and electricity voltage must match the rating
plate. Using a different gas type and electricity voltage will
cause the boiler to malfunction.
Before the installation, check the rating plate located on the side of the boiler to
ensure that the boiler matches the gas type, gas pressure, water pressure, and
electrical supply available in the installation location. If the boiler does not match
each of these ratings, do not install the boiler. If the gas conversion is required, the
included gas conversion kit must be used.
Figure 3
Natural Gas
0.
Certied to
NSF/ANSI 372
Combination Boiler and Space Heater / Combiné Chaudière et Chaue-Espace
For either direct vent installation or for installation using indoor combustion air .
/Pour une installation à évacuation directe ou pour une installation utilisant de l'air de combustion à l'intérieur .
Natural Gas
Heating Capacity
Capacité de chauffage
3.5~10.5
210
Edition of the standard : ANSI Z21.13-2017. CSA 4.9-2017, Low Pressure Boiler
Orices necessary for LP conversion are provided.
Les injectures nécessaires à la conversion au GPL sont fournis.
For installation on noncombustible oors only . /Pour l'installation sur des sols incombustibles uniquement.
Water temperature limit
limite de température de l'eau
M/C No. 271266
of
This boiler must be installed in accordance with local codes, if any; if not, follow the National Fuel Gas Code , ANSI
Z223.1/NFP A 54, or the Natural Gas and Propane Installation Code , CAN/CSA B149.1, as applicable.
Cette chaudière doit être installée conformément aux codes locaux, le cas échéant. Sinon, respectez le code national de gaz
combustible, ANSI Z223.1 / NFPA 54, ou le code d'installation de gaz naturel et propane, CAN/CSA B149.1, selon le cas.
This boiler must be installed with vent the vent-air intake system as specied and installed in accordance with the
Cette chaudière doit être installée de manière à purger le système d’admission d’air-air comme spécifié et installée
manufacturer ’s installation instructions.
conformément aux instructions d’installation du fabricant.
When reinstalling the appliance, check the sealing on the exhaust & air intake vent system.
Lors de la réinstallation de l'appareil, vérifiez l'étanchéité du système de ventilation d'échappement et d'admission d'air.
50 W entworth Ave, Londonderry , NH 03053
~
Bosch
Bosch Thermotechnology Corporation
-866-642-3198
The pressure relief valve provided by the manufacturer shall
Valve shall be placed in suitable area where it will not cause
doit
damage.
(La vanne doit être placée dans un endroit approprié où
elle ne causera pas de dommages.)
Bosch.
Bosch.
en haute de
Corée du Sud

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
2.4 Dimensions
Figure 4
2.80"
(71.1 mm) 0.36" (9.2 mm)
18.11" (460 mm)
5.57"
(141.5 mm)
5.26"
(133.5 mm)
11.61" (295 mm)
G
H
4.0"
(101.6 mm)
3.6"
(91.4 mm)
2.7"
(68.6 mm)
1.6" (40.6 mm)6.1"
(154.9 mm)
2.8"
(71.1 mm)
3.4"
(86.4 mm)
4.7" (119.4 mm)
2.2"
(55.9 mm)
8.0" (203.2 mm)
A B C D E F 1.8"
(45.7 mm)
27.56" (700 mm)
31.87" (809.5 mm)
Position Description Diameter
A Space heating Return 1" NPT
B Cold water inlet 3/4" NPT
C Condensate Outlet 1/2" NPT
D Hot water Outlet 3/4" NPT
E Space heating Supply 1" NPT
F Gas Inlet 3/4" NPT
G Exhaust Vent 2"
H Air inlet 2"
Table 3

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
2.5 Components
Figure 5
Air intake connector
Gas connector
Gas valve
3-way valve
Pressure sensor
Space heating supply
Gas inlet
Hot water outlet
Burner hood
Heat Exchanger Cover
Pump
Air vent
Condensate drain
Space heating return
Cold water inlet
Exhaust temperature
sensor
Flue connector

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
Figure 6
Ignition transformer
PCB assembly
Front panel
Secondary heat
exchanger
Primary heat
exchanger
Flow sensor
Air Pressure Sensor
TDR damper
Water Pressure Sensor
Turbo fan assembly

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
3 Boiler Installation
3.1 Installer Qualifications
A licensed professional must install and inspect the appliance. A
licensed professional is a person who is licensed for the following:
Connecting gas lines, water lines, valves, electricity
Vent installation through walls and roofs
Applicable of local, state, and national codes
3.2 Compliance Requirements
National electrical code.
National fuel gas code, ANSI Z223.1/NFPA 54 and/or CSA B149.1,
natural gas and propane installation codes.
Local, state, provincial, and national codes, laws, regulations, and
ordinances.
For Canada only: B149.1 installation Code, CSA C22.1 Canadian
Electricity supply enters the building.
3.3 Location
For installation:
Observe the current national and local codes and regulations.
Observe country-specific requirements.
Observe installation instructions of the venting system accessories and
their clearances.
When considering a location for installation, the installer, must ensure the
following:
Access to utilities
Humidity and contact with water
Water quality
Drainage
Venting and ventilation
Proximity to fixtures and appliances
Clearances
Clean, debris and chemical-free combustion air
High elevation Installations
3.3.1 Access to Utilities
Electricity – Close to where the electrical supply enters the building
Water – Close to where the domestic water supply enters the building
Gas – Close to where the gas supply enters the building
3.3.2 Humidity and Contact with Water
Avoid places with excessive humidity. The boiler has electric gas ignition
components. If water gets inside the boiler, the ignition system can be damaged.
The boiler must be installed in such a way as to ensure that the gas ignition system
components are protected from water (dripping, spraying, rain, etc.) during
operation and service.
3.3.3 Drainage
A significant amount of condensate is produced during the boiler operation.
Install the boiler near a suitable drain and where damage from a possible leak will
be minimal. Installing the boiler without a drain will void the warranty. For more
information about condensate drainage, refer to "Connecting the Condensate
Drain" on page 19.
The Boiler must be located in an area where leakage of the unit or connections will
not result in damage to the area adjacent to the appliance or to lower floors of the
structure. When such locations cannot be found, installation of an adequately-
draining drain pan under the boiler is recommended. When installing the drain pan,
ensure that the installation does not restrict combustion air flow.
3.3.4 Venting and Ventilation
Consider venting restrictions caused by windows, doors, air intakes, gas meters,
foliage and other buildings, and select a location that requires minimal venting.
When considering an adequate venting and ventilation, ensure the following:
Maintain a minimum clearance of 4 feet (1.2 meters) from heating and
cooling vents
Maintain proper clearances from any openings in the building
Install the boiler vent termination with a minimum clearance of 12 inches
(300 mm) above an exterior grade or as required by local codes
Install the exhaust vent in an area that is free from obstructions and does
not allow the exhaust to accumulate
Do not enclose the vent termination
Do not install the boiler where moisture from the exhaust may discolor or
damage walls
Do not install the boiler in bathrooms, bedrooms, or any other occupied
rooms that is normally kept closed or that is not adequately ventilated
For more information about venting, refer to "Installing a Vent" on page 29.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
3.3.5 Clearances
The boiler should be installed in an area that allows for service and maintenance
access to utility connections, piping, filters, and traps. Ensure the following
clearances are maintained:
Figure 7
Side Side
Front
Back
Top
Bottom
ClearanceFrom Wall Mounting
Top 12 inches (305 mm) min.
Back 0.6 inches (15 mm) min.
Front 6 inches (152 mm) min.
Sides 3 inches (76 mm) min.
Bottom 12 inches (300 mm) min.
Table 4
WARNING:FIRE
Do not install the boiler on carpeting.
3.3.6 Clean, Debris and Chemical-Free Combustion Air
Do not install the boiler in areas where dust and debris may accumulate or
where combustion air can be contaminated.
Do not install the boiler in areas with greasy fumes or heavy amounts of
steam, if necessary, take measures to prevent fumes and steam from
entering the boiler.
Chemicals that are corrosive in nature should not be stored or used near
the boiler.
3.3.7 Position
WARNING:FIRE,EXPLOSION,PROPERTY DAMAGE
Do not mount the boiler to dry wall that has not been
reinforced.
The boiler can be mounted to the wall. For easy installation, use the mounting
bracket to mount the boiler to standard wall studs. If the strength of the wall is
insufficient and or if the framing is non-standard or uneven, reinforce the area
before installation. Avoid installation in unstable locations as the boiler will make
some operational noises while it is running.
Consider vent length and surrounding circumstances when mounting the
boiler.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
3.4 Mounting to the Wall
To mount the boiler to the wall:
1. Check that the wall is level and can support the weight of the boiler.
2. Affix the mounting bracket securely to the wall.
Figure 8
3. Align the grooves on the back of the boiler with the tongues on the mounting
bracket and hang the boiler from the bracket.
Figure 9
CAUTION:BODILYINJURY, PRODUCTDAMAGE
The boiler is heavy. Always lift the unit with assistance. Be
careful not to drop the boiler while lifting or handling it to
avoid bodily injury or damage to the unit.
NOTICE:PRODUCT DAMAGE
Do not rest the bolier on the bottom end after removing it
from the shipping carton. Doing so may result in excessive
pressure on protruding pipes and cause product damage.
If you must put the boiler down, lay it on its back or put it
inside the protective shipping base.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
4 System Piping
Before connecting the pipes to the boiler, clean all systems to remove sediment,
flux, solder, scale, debris, or other impurities that may be harmful to the boiler
system. It is important to maintain the inside of the pipes free of debris, copper
dust, sand, and dirt while installing the heating system.
When installing the Singular boiler and keeping the existing pipes, all pipes
including the radiator should be cleaned.
NOTICE:PRODUCT DAMAGE
If you fail to remove the above-mentioned contaminants
from the heating system, your warranty will be void, the heat
exchange will break down faster than normal, and property
damage may occur as a result.
4.1 Installing a Space Heating System
The primary heat exchanger and secondary heat exchanger of Singular boiler are
designed optimally to obtain high thermal efficiency. The primary heat exchanger
is configured in the finned tube method and the secondary heat exchanger is
configured in the plate to plate method, maximizing the heating surface area to
achieve high thermal efficiency. In order to allow the heat exchanger to operate
effectively over time without trouble, it is important to follow the rules and
guidelines mentioned in this section.
WARNING:FIRE,PERSONAL INJURY,PROPERTYDAMAGE
If you fail to follow the guidelines provided in this section,
your warranty will be void and property damage, fire,
serious injury, or death may occur as a result.
4.1.1 Guidelines for a Space Heating System
Read the guidelines below for installing the boiler heating system safely and
properly.
Freeze Protection for the Space Heating System
Freeze protection products may be used to prevent the
space heating system from becoming frozen. A specially manufactured
glycol is necessary for preventing a new or existing piping system from
becoming frozen. This glycol should include inhibitors not harmful to
metallic system components.
Before using freeze protection products, it is necessary
to check if the amount of glycol use in the space heating water is
appropriate and if the inhibitor level in such glycol
is appropriate. Bosch recommends against exceeding a 35%
concentration of glycol.
If freeze protection products are used, the system should be tested at
least once a year.
When using the freeze protection products, allowance should be made for
expansion of the glycol solution.
Freeze damage is not covered by the warranty.
NOTICE:PRODUCT DAMAGE
For a system requiring freeze protection, use only inhibited
propylene glycol, specially formulated for hydronic heating
systems; use of other types of antifreeze may be harmful to
the system and will void the warranty.
System Pressure
Singular boiler is intended solely for use in a pressurized closed loop
heating system operating with 12-30psi water pressure at the boiler
outlet. To obtain the minimum system design pressure, comply with the
piping diagram in this section.
The space heating system of Singular boiler is not approved to operate
as an “open system”, and thus cannot be used for direct potable water
heating or to process heating of any kind.
Air Elimination
This boiler can be installed only in a pressurized closed-loop heating system free of
air and other impurities.
Install a proper-sized air-purging device at a proper position to eliminate air from
the entire heating system.
4.1.2 Essential Elements in a Space Heating System
Low Water Cut Off (LWCO) Device
Internal LWCO - The Singular boiler is equipped with a factory-installed,
pressure-sensing type low water cutoff (LWCO) device. The minimum
operating pressure of this device is 7.1psig.
Refer to local codes to determine if a LWCO device is required for your system
and ensure that the built-in device meets the requirements.
External LWCO - Install LWCO if it is required by local code.
The following figure shows an example of general LWCO installation.
Figure 10
External LWCO
Space heating
return
Space heating
supply
NOTE: LWCO installed outside
should be installed at least
6 inches (150mm) or more
away from the end of the
heat exchanger.
Backflow Preventer
When filling the device with water, install a backflow preventer if it is required by
local code.

| 17
Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
Expansion Tank
The expansion tank should be installed in the system pipes in order to prevent
excessive pressure in the heating pipes.
When installing the expansion tank, follow the guidelines below.
If the air separator is located on the suction side of the system circulator,
connect the air separator to the expansion tank.
Singular boiler has a connection (water fill connection) for additional
water. Therefore, in most cases, an additional water fill connection is not
necessary.
If an additional water fill connection is necessary for special use, install
the water fill connection at the same location as the expansion tank’s
connection to the system.
When replacing the expansion tank, refer to the literature of the expansion
tank manufacturer for selecting the proper size.
When installing the diaphragm expansion tank, always install an automatic
air vent at the top of the air separator in order to remove residual air in the
system.
Isolation Valves and Unions
This boiler system requires a full port ball valve. If a full port ball valve is
not used, water may flow at a limited flow rate through the boiler.
It is recommended to use unions for the serviceability of the device.
Pressure Relief Valve
This boiler comes with an ASME-approved pressure relief valve to install space
heating. To complete the installation of the boiler, you must install an approved
3/4", maximum 30 PSI (for space heating).
WARNING:PERSONALINJURY,PROPERTY DAMAGE
Improper installation of the pressure relief valve may result
in property damage, personal injury, or death. Follow all
instructions and guidelines when installing the pressure
relief valve. Only a licensed professional should install the
valve.
CAUTION:PERSONALINJURY,PROPERTY DAMAGE
Install the pressure relief valve as close to the boiler as
possible. No valve should be installed between the pressure
relief valve and the boiler.
Figure 11
Pressure relief valve
Space heating return Space heating supply
4.1.3 Space Heating Piping
When connecting the space heating system, follow these guidelines.
Tighten the connection valves carefully in order to avoid damage.
After installing the boiler, check if the space heating water flows smoothly
and if there is a water leak. Inform the boiler owner of the fact that the
strainer should be cleaned periodically to maintain the smooth flow of
space heating water. (The strainer is located on the side of the space
heating return.)
NOTICE:PRODUCT DAMAGE
Bosch suggests the installation of a dirt/magnetic separator
(boiler filter) on the system return line to help eliminate
sludge and particles from entering and damaging the boiler
components.
4.2 Installing a Domestic Hot Water(DHW) System
The boiler can supply domestic hot water continuously when the flow rate is
detected by the flow switch. This is the most appropriate way to minimize standby
losses and improve the combustion efficiency.
4.2.1 Guidelines for a DHW System
The boiler is designed to provide space heating and domestic hot water.
This boiler is equipped with the flow switch, and when approximately 0.5GPM or
more water flows, the flow switch will sense such water flow. The boiler will then
switch to the DHW mode immediately regardless of the space heating system's
status.
Read and follow the guidelines stated below for the safety and proper installation of
DHW system.
Scald Hazard
The hotter the water, the higher the risk of burns. If the DHW temperature is set too
high, there is a risk of burns from domestic hot water. Make sure to follow the usage
guidelines in the user manual.
Water Quality
If the quality of water cannot meet the EPA standard, appropriate boiler
maintenance is required. Any damage resulting from bad quality of water voids the
warranty. The following table shows the permitted maximum contaminant levels
based on the EPA National Secondary Drinking Water Regulations (40 CFR Part
143.3).
Contaminant MaximumAllowable Level
Total Hardness 200 mg/l (12 grains/gallon)
Aluminum 0.05 – 0.2 mg/l
Chloride 250 mg/l
Copper 1.0 mg/l
Iron 0.3 mg/l
Manganese 0.05 mg/l
pH 6.5 – 8.5
Sulfate 250 mg/l
Total Dissolved Solids (TDS) 500 mg/l
Zinc 5 mg/l
Table 5

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
Bosch is not responsible for the blockage of the domestic system due to the
accumulation of foreign matters or scaling.
The installer or the user should take appropriate measures in order to avoid any
problem related to the quality of water.
Freeze Protection
Bosch recommends insulating the DHW pipes. The pipes can be covered using
heat-insulating materials. Freeze damage voids the warranty.
4.2.2 Essential Elements in a DHW System
Drain and Isolation Valves
Install drain and isolation valves on the inlet and outlet of the DHW heat exchanger,
so it can be flushed free of possible build-up caused by dirt or hard water.
DHW Filter
Singular boiler has a filter on its cold water inlet nipple. Clean the filter periodically
to prevent the interruption of water flow by foreign matters.
If such foreign substances adhere to the flow switch, the boiler may malfunction.
Pressure Relief Valve for DHW
To complete the installation of the DHW system, you must install the approved ¾”,
maximum 150psi pressure relief valve on the hot water outlet.
The DHW pressure relief valve is not provided together with the product. However,
it is necessary to install such a valve.
WARNING:PERSONALINJURY,PROPERTY DAMAGE
Improper installation of the pressure relief valve may result
in property damage, personal injury, or death.
Follow all instructions and guidelines when installing the
pressure relief valve. Only a licensed professional should
install the valve.
CAUTION:PERSONALINJURY,PROPERTY DAMAGE
Install the pressure relief valve as close to the boiler as
possible. No valve should be installed between the pressure
relief valve and the boiler.
When installing the pressure relief valve, follow the guidelines below.
The discharge capacity of the valve should be greater than or equal to the
maximum pressure rating of the DHW system in the boiler.
The maximum Btu/h rating of the pressure relief valve should be greater
than or equal to the maximum input Btu/h rating of the boiler.
If the pressure relief valve operates, discharging domestic hot water may
scatter or splash onto other equipment around. Connect the pressure
relief valve to the DHW outlet pipe.
When installing the discharge piping line, do not install a coupling whose
internal diameter decreases or has other restrictions.
If the pressure relief valve discharges hot water periodically, it may be caused by
thermal expansion of the closed water system. The suggested method of controlling
thermal expansion is to install an expansion tank in the cold water line between
the boiler and the check valve. Contact the water supplier or a local plumbing
contractor. Do not plug the pressure relief valve.
4.2.3 DHW System Piping
CAUTION:PERSONALINJURY,PROPERTY DAMAGE
In order to meet the requirements of ASME or CRN, an
additional high temperature limitation device may be
required. Refer to the requirements of the local code for
whether this device is required.
Figure 12
Cold
water
supply
DHW
supply
When installing the DHW system, follow the guidelines below.
Only use permitted pipes, valves and other parts such as a solder for the
potable water system.
Tighten the connection valves carefully in order to avoid damage.
Bosch recommends the use of unions and manual shut-off valves for the
cold water inlet and DHW outlet.
Keep the hot water piping system as short as possible, to deliver hot water
to the fixtures more quickly.
When installing a mixing valve on the DHW piping, ensure that the cold
water pressure does not exceed the hot water pressure.
To conserve water and energy, insulate the DHW supply and DHW
recirculation lines (if applicable). Do not cover the drains or pressure relief
valves.
After installing the boiler, clean the cold water inlet filter. Then, check
if domestic water flows properly and check for water leaks. Inform
boiler owner that the filter should be cleaned periodically to ensure that
domestic hot water flows smoothly.

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Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
4.3 Connecting the Condensate Drain
NOTICE:BOILERDAMAGE,PROPERTY DAMAGE
All condensate must drain and be disposed of according to
local codes.
Do not cap or plug the integrated condensate line. If
prevented from draining, condensate can damage the boiler.
The condensate line must have a negative slope to drain
properly.
Do not run drain outdoors. Freezing of condensate can
cause property damage.
Do not connect the condensate drain line directly to the rain
sewer
Do not connect the condensate drain line with an air
conditioning evaporator coil drain.
Use only corrosion resistant materials for the condensate
drain lines such as PVC pipe or plastic hose.
The end of the condensate drain pipe should be open to the
atmosphere. The end should not be under water or other
substances.
The boiler creates condensation when it operates. This condensation has an acidic
pH of 3-5. Follow all local codes and regulations when disposing of condensate
from the boiler.
Disposal:
Dispose of condensate from the boiler, through a neutralizing agent, and
then into an external drain using an air gap.
NOTICE:
If necessary, a condensate pump can be used when there is
an uphill pipe run and/or a long distance between the boiler
and the disposal point.
NOTICE:
The neutralizing agent must be replaced periodically.
Depletion of the neutralizing agent will vary, based on the
usage rate of the boiler. During the first year of operation,
the neutralizer should be checked every few months for
depletion and replaced as needed.
Figure 13
External drain
neutralizer
condensate pump
(if necessary)
air gap
To connect the condensate drain:
1. Connect a drain line to the boiler.
NOTICE:
Use only corrosion-resistant material for the drain line, such
as PVC or CPVC. Do not reduce the size of this ftting or the
drain line to less than 1/2".
Figure 14
NPT 1/2 in.

20 |
Installation Instructions
Singular Combi Boiler - BTC 439003301 B (2021/07)
2. Place the free end of the drain line into an appropriate drain.
NOTICE:
If you are using a condensate pump, ensure that the pump
allows for up to 2 GPH of drainage for each boiler in the
system.
If you are not using a condensate pump, ensure that the
drain line is pitched downward at a minimum slope of 1/4"
per foot.
4.3.1 Filling the Condensate Trap
Before operating the boiler, fill the condensate trap with water through the flue
connector. The boiler may be severely damaged unless filled with water prior to
operation. Pour more than 0.1 gallon (400 ml) of water into the exhaust duct. Open
air vent cap sufficiently or equip the air vent with an outlet pipe prior to filling the
condensate trap with water (there must be no air inside the heat exchanger).
Figure 15
4.4 System Filling
4.4.1 Built-In Water Filling
The boiler is designed to fill the system with water. Therefore, additional water fill
connection is not necessary in most cases. Filling the system with water should be
carried out after all space heating pipes and DHW pipes are connected.
The procedure is as follows.
When you turn the makeup water feeding valve shown in the figure below
counterclockwise, the space heating system will be filed with water.
When filling with water after installing it for the first time, it may operate
and stop repeatedly due to the presence of air. Allow sufficient time to
remove air from the pipes completely.
After filling with water completely and removing air completely, close the
makeup water feeding valve by turning it clockwise.
Fill the system with water to a level at which the pressure inside the
system does not exceed 30psi.
Figure 16
4.4.2 External Water Fill Connection
External water fill connection may be installed on the system piping if it is required
for specific applications. See the following figure for an example of external water
fill installation on the system piping.
Figure 17
Circulator
To System
Air Separator
Make-up water
ExpansionTank
From
System