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Bosch Thermotechnology · Series
The Greenstar Combi 100 p and 151 p are the wall-hung combi models Bosch Canada documents in the 'Greenstar Combi 100P and 151P' I&O manual (doc 6721853953, 11.2025): the ZWB 28-3A and ZWB 42-3A, which heat space and produce domestic hot water from the same 110.2 lb wall-hung cabinet.
Series facts
Bosch's CA product pages market 95% AFUE efficiency for the Greenstar family; the 11.2025 I&O manual technical tables do not print an AFUE row (the AFUE figure is published in the AHRI directory).
Bosch's CA manual library titles this pair 'Greenstar Combi 100P and 151P', and the I&O manual (6721853953, 11.2025) maps the two names to engineering codes: the combi 100 p is the ZWB 28-3A and the combi 151 p is the ZWB 42-3A. Both are wall-hung condensing combis — space heating and on-demand domestic hot water from one appliance — and Bosch's Greenstar pages market the family at 95% AFUE with 'available in both heating-only and combi versions'.
The 100 p fires 24,600 to 100,000 BTU/hr input on natural gas and the 151 p 36,000 to 151,600 BTU/hr; on the DHW side the manuals publish maximum DHW flow of 2.64 GPM (combi 100 p) and 3.963 GPM (combi 151 p), with nominal flow at a 140 °F outlet of 2.03 and 3.61 GPM respectively. The model naming only partially lines up with the Greenstar Wall manual, which also lists the ZWB 35-3A combi: the 35-3A has no 100p/151p manual coverage and is documented by Boilers.ca under the Greenstar Wall series.
The combi control uses the same Heatronic two-character fault-code family as the wall models — codes such as A7, EA and F0 appear in Table 33 'Faults shown on the display' of this I&O manual — so owners read codes against this 11.2025 manual. Boilers.ca's Greenstar pages carry a note that some technical figures differ slightly between the Wall and the Combi-100p/151p manual editions for the same size.
Highlights
Models
One canonical page per model with input, output and efficiency kept separate.
Bosch Thermotechnology
The Greenstar Combi 100p is the ZWB 28-3A wall-hung combi: 24,600 to 100,000 BTU/hr heating input with DHW output to 91,400 BTU/hr at a 140 °F outlet and 2.03 GPM nominal DHW flow, documented in the Combi 100P/151P I&O manual (6721853953).
Bosch Thermotechnology
The Greenstar Combi 151p is the ZWB 42-3A wall-hung combi — the largest Greenstar combi: 36,000 to 151,600 BTU/hr heating input, DHW output to 135,800 BTU/hr at a 140 °F outlet and 3.61 GPM nominal DHW flow, covered by the Combi 100P/151P I&O manual.
| Specification | Bosch Greenstar Combi 100p (ZWB 28-3A) | Bosch Greenstar Combi 151p (ZWB 42-3A) |
|---|---|---|
| Input rate, minimum | 24.6 MBH | 36 MBH |
| Input rate, maximum | 100 MBH | 151.6 MBH |
| Output rate, maximum (104/86 °F) | 93.8 MBH | 137.5 MBH |
| afue | — | — |
| turndown | — | — |
| vent-max-3 | — | — |
| vent-max-2 | — | — |
| Weight (without packaging) | 110.2 lb | 110.2 lb |
Read the full comparison: Bosch Greenstar Combi 100p (ZWB 28-3A) vs Combi 151p (ZWB 42-3A) →
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Manuals
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Services for Bosch Thermotechnology boilers
Bosch's Greenstar Wall I&O (6721853955) and Greenstar Combi 100P/151P I&O (6721853953) both list the ZWB 28-3A and ZWB 42-3A combi models. Bosch's CA manual library keeps two titles, and Boilers.ca keeps the records under the Combi (100p/151p) series with the Wall manual cited as the second reference.
No. The combi-100p/151p manual covers only the ZWB 28-3A and ZWB 42-3A. The ZWB 35-3A is documented only in the Greenstar Wall I&O manual, which is why Boilers.ca files it under the Greenstar Wall series.
Neither — both are combis. They combine space heating with on-demand domestic hot water in the one wall-hung appliance, which is what the integrated DHW heat exchanger, three-way valve and flow meter in the manual's product description are for.
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Sources and verification
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.