Bosch Greenstar FS User manual

6720810589 (2021/01) CA/US
Operating instructions
Residential Gas Condensing Boiler
Greenstar FS/Combi FS
6720810589-00.2Wo
KBR21/28-/35/42-3A | KWB28/35/42-3A

Contents
Greenstar FS/Combi FS – 6720810589 (2021/01)
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Contents
1 Explanation of symbols and safety instructions . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Explanation of symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Information about the appliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
2.1 Certifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
2.2 Proper use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
2.3 Overview of boiler types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3 Prepare for operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.1 Checking the boiler water pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
3.2 Topping up the heating system water . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
4 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
4.1 Overview of controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
4.2 Switching the appliance ON/OFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.3 Turning the space heating ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.4 Programming the heating control unit. . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.5 KBR..-3A appliances with DHW tank:
Setting the DHW temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
4.6 KWB..-3A appliances (combi boilers):
Setting the DHW temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.7 Setting manual summer mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
4.8 Setting frost protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
4.9 Activating the key pad lock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
4.10 Display codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
5 Thermal disinfection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

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Greenstar FS/Combi FS – 6720810589 (2021/01)
Contents
6 Energy saving tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
9 Environmental protection and disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.1 Environmental protection and disposal . . . . . . . . . . . . . . . . . . . . . . . . . 31
10 Quick reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Explanation of symbols and safety instructions
Greenstar FS/Combi FS – 6720810589 (2021/01)
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1 Explanation of symbols and safety instructions
1.1 Explanation of symbols
Warnings
In warnings, signal words at the beginning of a warning are used to indicate the type
and seriousness of the ensuing risk if measures for minimizing danger are not taken.
The following keywords are defined and can be used in this document:
DANGER
DANGER indicates that severe or life-threatening personal injury will occur.
WARNING
WARNING indicates that severe to life-threatening personal injury may occur.
CAUTION
CAUTION indicates a hazardous situation which, if not avoided, could result in minor
to moderate injury.
NOTICE
NOTICE is used to address practices not related to personal injury.
Important Information
The info symbol indicates important information where there is no risk to people or
property.

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Greenstar FS/Combi FS – 6720810589 (2021/01)
Explanation of symbols and safety instructions
Additional symbols
Symbol Explanation
▶Sequence of steps
Cross-reference to another part of the document
•Listing/list entry
– Listing/list entry (2nd level)
Table 1
1.2 Safety instructions
HGeneral information
This manual is available in English and French.
▶ Keep this manual for future use.
▶ Observe the safety instructions of this manual
before putting the heating appliance into operation.
Iftheinformationinthismanualisnotfollowed exactly,
a fire or explosion may result causing property
damage, personal injury or loss of life.
▶ Do not store or use gasoline or other flammable
vapors and liquids in the vicinity of this or any other
appliance.

Explanation of symbols and safety instructions
Greenstar FS/Combi FS – 6720810589 (2021/01)
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▶ 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.
▶ Installation and service must be performed by a
trained and certified heating contractor, service
agency or the gas supplier.
HIf you smell gas
▶ Turn off the gas shut-off valve.
▶ Open windows and doors.
▶ Do not touch any electrical switch, telephone, and
do not use outlets.
▶ Extinguish all open flames.
▶ Do not smoke!
▶ Do not use lighters!
▶ Warn all occupants of the building, but do not ring
any bell.

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Greenstar FS/Combi FS – 6720810589 (2021/01)
Explanation of symbols and safety instructions
▶ From outside the building, call the gas supply
company and a trained and certified installer or
service company.
HIf you smell flue gas
▶ Switch OFF the appliance (page 15).
▶ Open windows and doors.
▶ Inform a trained and certified heating contractor.
HFor appliances operating on room air:
Danger of flue gas poisoning if supply of
combustion air is insufficient
▶ Safeguard supply of combustion air.
▶ Do not cover or reduce the size of ventilation
openings in doors, windows and walls.
▶ Safeguard sufficient supply of combustion air also
for appliances installed at a later date, e.g. kitchen
exhaust fans, clothes dryers, and air conditioning
units with vent to the outside.
▶ Never operate the appliance if the supply of
combustion air is insufficient.
HDanger of explosion of flammable gases
▶ Only employ a trained and certified contractor to
carry out work on the gas train.

Explanation of symbols and safety instructions
Greenstar FS/Combi FS – 6720810589 (2021/01)
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HRisk of scalding
▶ If running at DHW temperatures above 104 °F
(40
°C) ask a trained and certified heating
contractor to install a tempering valve to prevent
scalding.
▶ When the thermal disinfection function is
enabled, DHW temperatures above 140
°F (60 °C)
can occur.
HRisk of damage due to operator error
Operator errors can result in personal injury and
damage to property.
▶ Ensure that children never operate this appliance
unsupervised or play with it.
▶ Ensure that only people who know to operate this
appliance correctly have access to it.
HInstallation, conversion
Only have the appliance installed or modified by a
trained and certified heating contractor.
Never modify any parts that carry flue gas.
Never close the outlet of safety valves. Water may be
expelled from any safety valve during heat-up.

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Greenstar FS/Combi FS – 6720810589 (2021/01)
Explanation of symbols and safety instructions
HInspection and maintenance
The operator is responsible for safety and
environmental compliance of the heating system.
Sign a maintenance and inspection contract with a
trained and certified contractor, covering an annual
inspection and demand-dependent maintenance.
This guarantees high efficiency and environmentally
sound combustion.
HExplosive and easily combustible materials
Never use or store easily combustible materials
(paper, thinners, paints, etc.) near the appliance.
HCombustion air / room air
To prevent corrosion, keep the supply of
combustion
air / room air free of corrosive substances
(e.g. halogenated hydrocarbons that contain chlorine
or fluorine compounds).
HOverheating of the appliance
Should overheating occur or the gas supply fail to shut
off, do not turn off or disconnect the electrical supply
to the pump. Instead, shut off the gas supply at a
location outside of the appliance.

Information about the appliance
Greenstar FS/Combi FS – 6720810589 (2021/01)
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HIn case of water damage
Do not use this boiler if any part has been under water.
Immediately call a trained and certified service
technician to inspect the boiler and to replace any part
of the control system and any gas control which has
been under water.
2 Information about the appliance
2.1 Certifications
This product has been tested and certified for the US and the
Canadian market and complies with all applicable standards
required for the US and the Canadian market.
2.2 Proper use
The appliance may only be installed in closed loop hot water central heating systems.
Any other purpose is considered improper use. Any resulting damage is excluded
from the manufacturer's warranty.
The commercial and industrial use of the appliance for generating process heat is not
permitted.