Bosch ZWB28-3A User manual

6720872363 (2017/04) US/CA
Operating Instructions
Residential Gas Condensing Boiler
Greenstar combi 100 p / 151 p
ZWB28-3A... | ZWB42-3A...

2| Contents
6720872363 (2017/04)Greenstar combi 100 p / 151 p
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 Preparing the appliance for operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.1 Checking the boiler water pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.2 Topping up the heating system water . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
4 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
4.1 Overview of controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
4.2 Switching the appliance ON/OFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.3 Turning the space heating ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.4 Programming the heating control unit. . . . . . . . . . . . . . . . . . . . . . . . . . . .18
4.5 Setting the DHW temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
4.6 Setting manual summer mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.7 Setting frost protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
4.8 Activating the key pad lock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
4.9 Display codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
5 Energy saving tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
6 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
7 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Contents | 3
6720872363 (2017/04) Greenstar combi 100 p / 151 p
8 Environmental protection and disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9 Quick reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4| Explanation of symbols and safety instructions
6720872363 (2017/04)Greenstar combi 100 p / 151 p
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 a hazardous situation which, if not avoided, could result in death
or serious injury.
WARNING:
WARNING indicates a hazardous situation which, if not avoided, could result in
death or serious injury.
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.

Explanation of symbols and safety instructions | 5
6720872363 (2017/04) Greenstar combi 100 p / 151 p
Important Information
The info symbol indicates important information where there is no risk to people or
property.
Additional symbols
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.
If the information in this manual is not followed 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.
Symbol Explanation
▶ Sequence of steps
Cross-reference to another part of the document
• Listing/list entry
– Listing/list entry (2nd level)

6| Explanation of symbols and safety instructions
6720872363 (2017/04)Greenstar combi 100 p / 151 p
▶ 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.

Explanation of symbols and safety instructions | 7
6720872363 (2017/04) Greenstar combi 100 p / 151 p
▶ 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 16).
▶ 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.

8| Explanation of symbols and safety instructions
6720872363 (2017/04)Greenstar combi 100 p / 151 p
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.

Explanation of symbols and safety instructions | 9
6720872363 (2017/04) Greenstar combi 100 p / 151 p
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.

10 | Information about the appliance
6720872363 (2017/04)Greenstar combi 100 p / 151 p
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.

Preparing the appliance for operation | 11
6720872363 (2017/04) Greenstar combi 100 p / 151 p
2.3 Overview of boiler types
Table 2 Appliance types
Z Central heating appliance
W DHW heating
B Condensing technology
28 Output and DHW output up to 95,500 BTU/hr (28 kW)
42 Output and DHW output up to 143,300 BTU/hr (42 kW)
-3 Version
A Fan-supported appliance
23 Natural gas (NG)
3 Preparing the appliance for operation
▶ If existing, open the heating supply valve and the heating return valve.
▶ If existing, open the cold water valve and the DHW valve.
▶ Open the gas cock.
▶ Open the control panel cover.
3.1 Checking the boiler water pressure
The standard boiler water pressure is 14.5 - 21.75 psi (1 - 1.5 bar).
Should a higher boiler water pressure be required, refer to a trained and certified
heating contractor.
ZWB28-3 A 23 Greenstar combi 100 p
ZWB42-3 A 23 Greenstar combi 151 p

12 | Operation
6720872363 (2017/04)Greenstar combi 100 p / 151 p
Fig. 1
3.2 Topping up the heating system water
Topping up the heating system water is different on every system. Therefore, you
should ask a trained and certified heating contractor to show you how it is done.
Maximum pressure of 30 psi (2.07 bar) at maximum heating water temperature
must not be exceeded (safety valve will spill).
4 Operation
These operating instructions apply only to the boiler.
Depending on the heating control unit used, some functions may vary.
The following options for controlling the heating system are available:
• Room thermostat
• RRC Room thermostat with outdoor reset
• Third party system control unit
6 720 641 934-04.2O
1
0
2
3
4
bar
psi
15
3045

Operation | 13
6720872363 (2017/04) Greenstar combi 100 p / 151 p
Therefore, please read the operating instructions for the heating control unit used.
Page 27 contains a quick reference. You can fold this outward and keep these
operating instructions in the control panel cover.
Fig. 2
6 720 614 235-04.1O
max
1
2
34
5
6

14 | Operation
6720872363 (2017/04)Greenstar combi 100 p / 151 p
4.1 Overview of controls
Fig. 3
1 2 3 4 5 6 7 8
10
9
11
12
14
15
1718 13
6 720 641 934-01.3O
16
eco
reset

Operation | 15
6720872363 (2017/04) Greenstar combi 100 p / 151 p
[1] Emission test button for contractors (see installation instructions)
[2] Service button for contractors (see installation instructions)
[3] Burner ON indicator lamp
[4] ON/OFF switch
[5] Key pad lock
[6] ECO button
[7] Reset button
[8] Display
[9] Boiler water pressure gauge
[10] DHW thermostat
[11] Safety relief valve discharge hose
[12] Condensate drain hose
[13] Heating return pipe
[14] Cold water pipe
[15] Gas pipe
[16] DHW pipe
[17] Supply pipe
[18] Boiler high limit dial

16 | Operation
6720872363 (2017/04)Greenstar combi 100 p / 151 p
4.2 Switching the appliance ON/OFF
Startup
▶ Switch the appliance ON using the ON/OFF switch.
The display shows the supply temperature.
Fig. 4
If the display shows in alternation with the supply temperature, the appliance
operates at its lowest output for 15 minutes per the initial startup sequence.
Shutdown
▶ Switch the appliance OFF using the ON/OFF switch.
The display goes out.
▶ If the appliance is taken out of service for a longer period: observe frost
protection (Section 4.7).
4.3 Turning the space heating ON
The maximum supply temperature can be set from 95 °F (35 °C) up to approx. 194 °F
(90 °C). The current supply temperature is shown on the display.
With radiant floor heating, limit the maximum permissible supply temperature.
max
1
2
34
5
6
6 720 613 896-05.1O

Operation | 17
6720872363 (2017/04) Greenstar combi 100 p / 151 p
▶ Adjusting the supply temperature with the boiler high limit dial :
– Radiant floor heating: e.g. setting 3(approx. 122 °F (50 °C))
– Panel or cast iron radiator heating: setting 6(approx. 167 °F (75 °C))
– Heating with supply temperatures up to 194 °F (90 °C): setting max
Fig. 5
The burner ON indicator lamp lights up if the burner is operating.
Table 3 Typical supply temperatures
Boiler high limit dial Typical supply
temperatures
Sample application
1 approx. 95 °F (35 °C) Frost protection
2 approx. 109 °F (43 °C)
3 approx. 122 °F (50 °C) Radiant floor heating system
4 approx. 140 °F (60 °C)
5 approx. 153 °F (67 °C)
6 approx. 167 °F (75 °C) Radiator heating system
max approx. 187 °F (86 °C) Convector heating
eco
reset
6 720 641 933-53.1O
max
1
2
34
5
6
max
1
2
34
e
6
min

18 | Operation
6720872363 (2017/04)Greenstar combi 100 p / 151 p
4.4 Programming the heating control unit
Observe the operating instructions for the heating control unit included in the scope
of delivery. There you can read:
▶ How to set the operating mode
▶ How to adjust the room temperature
▶ How to heat economically and save energy
4.5 Setting the DHW temperature
▶ Set the DHW temperature on the DHW thermostat .
The set DHW temperature flashes on the display for 30 seconds.
Fig. 6
Table 4
DHW thermostat Typical DHW temperatures
min approx. 104 °F (40 °C)
e approx. 122 °F (50 °C)
max approx. 140 °F (60 °C)
6 720 641 933-55.1O
max
1
2
34
5
6
reset
eco
max
1
2
34
e
6

Operation | 19
6720872363 (2017/04) Greenstar combi 100 p / 151 p
ECO button
Pressing and holding the ECO button until it lights up switches between Comfort
mode and Economy mode.
•Comfort mode (default setting)
The appliance is continually maintained at the set temperature. Consequently,
DHW draws are immediate, however the appliance may run even if no DHW is
being drawn.
•Economy mode, ECO button lights up
– DHW is only generated when DHW is drawn.
–On demand: Quickly open and close a DHW tap to signal the appliance to
heat to the selected temperature. After a short wait DHW will be available.
The DHW on demand signal allows maximum gas and water savings.
4.6 Setting manual summer mode
In summer mode or warm weather shut down (WWSD), the heating zone pump and
consequently central heating are switched off. DHW generation remains active
following the DHW program.
NOTICE:
Material damage due to frost!
Heating system at risk of freezing. In manual summer mode, only the appliance is
protected from freezing.
▶ Observe frost protection measures where there is a risk of freezing.
▶ Make a note of the setting of the boiler high limit dial .

20 | Operation
6720872363 (2017/04)Greenstar combi 100 p / 151 p
▶ Turn the boiler high limit dial counterclockwise to .
Fig. 7
For further information, see the operating instructions for the heating control unit
included in the scope of delivery.
4.7 Setting frost protection
Frost protection of the heating system:
▶ Leave the appliance switched ON; turn the boiler high limit dial at least to
position 1.
Fig. 8
For further information, see the operating instructions for the heating control unit
included in the scope of delivery.
6 720 641 933-82.1O
eco
reset
max
1
2
3
5
6
maxmin
1
2
34
e
6
eco
reset
max
1
2
3
5
6
max
1
2
34
e
6
6 720 641 933-68.1O
min