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