Model Numbers Pertaining to the Bosch Greenstar Combi and Straight Boilers

Below is a table describing the model numbers that pertain to the Bosch Greenstar gas-fired wall-hung boilers and combination boilers.

Z - Central heating appliance
W - DHW heating
B - Condensing technology
R - Constant temperature control
16 - Output up to 54,600 BTU/hr (16 kW)
21 - Output and DHW output up to 71,600 BTU/hr (21 kW)
28 - Output and DHW output up to 95,500 BTU/hr (28 kW)
35 - Output and DHW output up to 119,400 BTU/hr (35 kW)
42 - Output and DHW output up to 143,300 BTU/hr (42 kW)
-3 - Version
A - Fan-supported appliance
23 - Natural gas (NG) conversion to Liquid Propane (LP) comes with boiler

So if you wanted to reference model number "ZWB42-3" this would be the model number for the Bosch Combi 151 Gas-Fired Wall-Hung Boiler for space heating and domestic hot water (DHW).
Z - Central heating appliance
W - DHW heating
B - Condensing technology
42 - Output and DHW output up to 143,300 BTU/hr (42 kW)
-3 - Version

All Greenstar boilers and Combi units are fan assisted "A" and they all come preset for Natural Gas NG "23" but also come with the conversion kit for Liquid Propane LP.

Conversion:
Model #               Description
ZBR16-3             Bosch Greenstar Wall-Hung 57 Boiler
ZBR21-3             Bosch Greenstar Wall-Hung 79 Boiler
ZBR28-3             Bosch Greenstar Wall-Hung 100 Boiler
ZBR35-3             Bosch Greenstar Wall-Hung 131 Boiler
ZBR42-3             Bosch Greenstar Wall-Hung 151 Boiler
ZWB28-3            Bosch Greenstar Wall-Hung Combi 100 Boiler
ZWB35-3            Bosch Greenstar Wall-Hung Combi 131 Boiler
ZWB42-3            Bosch Greenstar Wall-Hung Combi 151 Boiler

New Bosch Greenstar 79 Gas-Fired Wall-Hung Condensing Boiler

Bosch has just introduced a new Greenstar 79 Gas-Fired Wall-Hung Condensing Boiler and it is very efficient and simple to set and operate.  Space heating boiler for connection to a hot water tank with unsurpassed performance and control. With special insulation to ensure ultra quiet operation and the exclusive keypad safety lock feature to prevent unwanted tampering with heating controls, this unit is the ideal "green" upgrade for detached & terraced houses and is also suitable for apartments.

The Greenstar 79 is simple to operate and some of the specifications include:

79,000 BTU 

AFUE rating of 95%

1" main heating connections

Can be vented with 2" or 3" PVC

3" PVC concentric vent kit available for vertical or horizontal installation

Telescopic Concentric Up and out vent kit available for horizontal installation 

The energy-savings and environmental features are:

Aluminum-Silicon heat exchanger delivers high efficiency with low temperature applications

Low NOx emissions ahead of 2012 SCAQMD regulations

Simple, intelligent control options optimize efficiency and fuel consumption

Low electrical consumption when the boiler is in standby mode

Electronic ignition

Anti-cycle and modulation control

This Greenstar 79 condensing space heating boiler can be used for either Natural Gas or Liquid Propane installations.   The heater comes preset for Natural Gas (NG), but can be converted to Liquid Propane (LP).  A gas conversion kit is included.

The Greenstar boiler comes with a temperature control FW 200 that can either be mounted to the heater or mounted to the wall beside the heater.  This module allows the heater to be set for different temperatures, zones and the time of day the heater comes on and goes off.  The FW 200 control also comes with a temperature probe that goes to the outside and detects and monitors the outside temperature and then allows the heater to remember the coldest and warmest times of the day and year.

The Greenstar condensing space heating boiler is specifically designed for space heating only but can also be used for Domestic Hot Water (DHW) when it is piped to an indirect tank and using a pump, aquastat and check valves.

New Bosch Greenstar Combi 131 Gas Fired Wall Hung Boiler

Bosch has just introduced a new Greenstar Combi 131 Gas-Fired Wall-Hung Condensing Boiler for space heating and DHW.  "Combi" (combination) unit with space heating and integrated water heating in one highly efficient, compact unit. With special insulation to ensure ultra quiet operation and the exclusive keypad safety lock feature to prevent unwanted tampering with heating controls, this unit is the ideal "green" upgrade for detached & terraced houses and is also suitable for apartments.

The Greenstar Combi 131 is simple to operate and some of the specifications include:

131.9K BTU 

AFUE rating of 95%

Delivers 3.2 GPM at 72 degree rise

3/4" Water connections

1" main heating connections

Can be vented with 2" or 3" PVC

3" PVC concentric vent kit available for vertical or horizontal installation

Telescopic Concentric Up and out vent kit available for horizontal installation 

The energy-savings and environmental features are:

Aluminum-Silicon heat exchanger delivers high efficiency with low temperature applications

Low NOx emissions ahead of 2012 SCAQMD regulations

Simple, intelligent control options optimize efficiency and fuel consumption

Low electrical consumption when the boiler is in standby mode

Electronic ignition

Anti-cycle and modulation control

These Greenstar Combi 131 condensing space heating boiler can be used for either Natural Gas or Liquid Propane installations.   The Greenstar units come preset for Natural Gas (NG), but can be converted to Liquid Propane (LP).  A gas conversion kit is included.

The Greenstar Combi units come with a temperature control FW 200 that can either be mounted to the heater or mounted to the wall beside the heater.  This module allows the heater to be set for different temperatures, zones and the time of day the heater comes on and goes off.  The FW 200 control also comes with a temperature probe that goes to the outside and detects and monitors the outside temperature and then allows the heater to remember the coldest and warmest times of the day and year.

All Greenstar Combi boilers are equipped with a high-strength stainless steel secondary exchanger and burner with double passage - ensuring consistent temperature output based on demand. The DHW hot water temperature control limit of 140°F helps prevent scale build-up within the heat exchanger.

Discrepancy in Dimensions for Bosch Therm 520HN & 520PN

There was recently a discrepancy found in the dimensions (HxDxW) for the Bosch Therm 520 series gas tankless water heaters in the product selection guide.  The discrepancy has been corrected.   Please always follow the instructions in the installation manual for a safe and proper installation of the gas tankless water heater.  The dimensions in the installation manual for the Bosch Therm 520 series heaters is correct and is:  H 25.75 x D 8.66 x W 16.73.

Service Bulletins for Bosch Therm Gas Tankless Water Heaters

Bosch has a series of service bulletins for the new model Bosch Therm tankless water heaters.  These service bulletins can be very helpful with installation questions and when having an issue to troubleshoot the heater.

Please remember to be safe when working on a gas fired appliance.  Service bulletins are helpful but you can also contact Bosch technical support for help at 800-642-3111.

Link to:
Service Bulletins for Bosch Therm Units