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Bosch Thermotechnology · Series
The Buderus GC124 II is a discontinued atmospheric cast-iron gas boiler sold in three sizes (18/3, 25/4, 32/5) at 74,000, 103,000 and 132,500 BTU/hr input. Its manuals sit in Bosch's US discontinued Buderus products library.
Series facts
The Logano GC 124 II is described in its manual as an atmospheric gas boiler with a cast-iron heat exchanger, intended to heat water for single or multiple-occupancy buildings. The dimensions/specs table lists three sizes - 18/3 (74,000 BTU/hr), 25/4 (103,000 BTU/hr) and 32/5 (132,500 BTU/hr) - with dry weights of 228, 287 and 349.5 lb, water contents of 2.4, 2.9 and 3.4 US gallons and 5", 5" and 6" vent connections.
The GC124 II is not in Bosch's current Canadian or US catalogs. Its installation/service manual, user manual and propane conversion instructions are published from the US 'Discontinued Buderus Products' documentation library. Boilers.ca documents it as a historical model for owners and service techs. The manual has no electronic fault-code table because the boiler uses a mechanical ignition module and adjustable temperature controller rather than a code-displaying control.
Highlights
Models
One canonical page per model with input, output and efficiency kept separate.
Bosch Thermotechnology
The Buderus GC124 II 18/3 is a discontinued atmospheric cast-iron gas boiler rated 74,000 BTU/hr input with a 228 lb dry weight and 2.4 US gal water volume.
Bosch Thermotechnology
The Buderus GC124 II 25/4 is a discontinued atmospheric cast-iron gas boiler rated 103,000 BTU/hr input with a 287 lb dry weight and 2.9 US gal water volume.
Bosch Thermotechnology
The Buderus GC124 II 32/5 is a discontinued atmospheric cast-iron gas boiler rated 132,500 BTU/hr input with a 349.5 lb dry weight and 3.4 US gal water volume.
| Specification | Buderus GC124 II 18/3 | Buderus GC124 II 25/4 | Buderus GC124 II 32/5 |
|---|---|---|---|
| input-min | — | — | — |
| Boiler input | 74 MBH | 103 MBH | 132.5 MBH |
| output-max | — | — | — |
| afue | — | — | — |
| turndown | — | — | — |
| vent-max-3 | — | — | — |
| vent-max-2 | — | — | — |
| weight | — | — | — |
Read the full comparison: Buderus GC124 II 18/3 vs 32/5 →
Read the full comparison: Buderus GC124 II 18/3 vs II 25/4 →
Read the full comparison: Buderus GC124 II 25/4 vs II 32/5 →
Error codes and alerts
No alerts documented for this series yet.
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
They are closely related Buderus atmospheric cast-iron boilers with the same three sizes and ratings, but they are documented in different manuals: the GC124 II in 6 720 804 440 (2012/11) and the GC 144 II in 6 720 808 893 (2018/02). Boilers.ca keeps separate records for each.
Bosch's US 'Discontinued Buderus Products' documentation library still serves the installation and service instructions, user manual and propane conversion instructions. Boilers.ca links the live PDFs on each model record.
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On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.