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Viessmann · Series
This hub documents the discontinued Vitocrossal generations whose manuals Viessmann Canada keeps under its Historic manuals downloads: the Vitocrossal 200 CM2 with GC1/GW2 control (186–311) and with GW5B control (400–620), and the Vitocrossal 300 CA3 (single-fuel and dual-fuel) and CT3 — including eight CT3 model records from the printed rating table, CT3-17 to CT3-89.
Series facts
Viessmann Canada's Historic manuals page documents the earlier Vitocrossal generations alongside the current catalogue, which is the Vitocrossal 200 CI2 and CM2 (GW6B) and the Vitocrossal 300 CA3B (GW6C/HI932). The historic families are the Vitocrossal 200 CM2 boilers of two earlier control generations and the Vitocrossal 300 CA3 and CT3 ranges — all superseded floor-standing commercial condensing boilers whose installation, service, operating and technical data documents remain downloadable.
The CT3 range is documented on Boilers.ca with eight model records taken from its printed rating table: CT3-17, CT3-22, CT3-28, CT3-37, CT3-46, CT3-57, CT3-72 and CT3-89, covering 638 to 3361 MBH (187 to 985 kW) input at 96.7-98.3% combustion efficiency and 96.7-98.1% thermal efficiency, with 30 psig maximum operating pressure. The CT3 technical data manual (doc 5285 871 - 05, 01/2016) also prints boiler output at three return-temperature conditions, standby losses, weights, water content and flue-connection sizes for each size. The CA3 range (single-fuel and dual-fuel) remains documented at the series level on this hub.
The CM2 entries split by size range and control generation. 'Main Boiler Documentation — CM2 Boiler with GC1/GW2 Control' covers the CM2-186 to CM2-311 models (technical data manual rev 02 06/2014, installation instructions 06 12/2015, service instructions 04 10/2014) with Vitotronic 100 GC1, Vitotronic 300 GW2 and Vitocontrol-S controls. 'Main Boiler Documentation — CM2 Boiler with GW5B Control' covers the CM2-400 to CM2-620 models (technical data manual rev 03 06/2014, installation instructions 05 12/2015, service instructions 04 07/2014) with Vitotronic 300 GW5B and Vitotronic 300-K MW1B controls.
The Vitocrossal 300 family is covered by two historic entries: the CA3 range, the predecessor of today's CA3B, in its single-fuel ('Boiler Documentation (Single Fuel CA3)') and dual-fuel ('Boiler Documentation (Dual Fuel CA3)') versions with 03/2025 revisions and Vitotronic 300 GW6C wiring diagrams for the 2.5–6.0 sizes; and the older CT3 generation with its own technical data manual (rev 05 01/2016), installation instructions (03 10/2015) and service instructions (04 01/2016), documented with GC1/GC1B, GW2/GW2B and Vitocontrol-S CT3 controls. An owner of any of these units can still pull the document set that matches the generation shown on the rating plate.
Highlights
Models
One canonical page per model with input, output and efficiency kept separate.
Viessmann
The Vitocrossal 300 CT3-17 is the smallest CT3 commercial condensing boiler: 638 MBH input (187 kW), 626 MBH output, 98.3% combustion and 98.1% thermal efficiency at 30 psig.
Viessmann
The Vitocrossal 300 CT3-22 steps the CT3 range to 846 MBH input (248 kW) with 827 MBH output at 97.8% combustion and 97.7% thermal efficiency.
Viessmann
The Vitocrossal 300 CT3-28 is the largest CT3 model on the small chassis: 1071 MBH input (314 kW), 1044 MBH output and 97.4% combustion and thermal efficiency.
Viessmann
The Vitocrossal 300 CT3-37 opens the CT3 wide chassis: 1389 MBH input (407 kW), 1350 MBH output, 97.2% combustion and thermal efficiency and a 10 in. vent pipe.
Viessmann
The Vitocrossal 300 CT3-46 is the mid-size CT3 wide-chassis model: 1726 MBH input (506 kW), 1675 MBH output and 97.1% combustion and thermal efficiency.
Viessmann
The Vitocrossal 300 CT3-57 is the largest CT3 model on the 800 mm shell: 2160 MBH input (633 kW), 2094 MBH output and 96.9% combustion and thermal efficiency.
Viessmann
The Vitocrossal 300 CT3-72 opens the CT3 largest chassis: 2702 MBH input (792 kW), 2616 MBH output, 96.8% combustion and thermal efficiency and a 12 in. vent pipe.
Viessmann
The Vitocrossal 300 CT3-89 is the largest CT3 boiler: 3361 MBH input (985 kW), 3252 MBH output and 96.7% combustion and thermal efficiency — the top of the range.
| Specification | Viessmann Vitocrossal 300 CT3-17 | Viessmann Vitocrossal 300 CT3-22 | Viessmann Vitocrossal 300 CT3-28 | Viessmann Vitocrossal 300 CT3-37 | Viessmann Vitocrossal 300 CT3-46 | Viessmann Vitocrossal 300 CT3-57 | Viessmann Vitocrossal 300 CT3-72 | Viessmann Vitocrossal 300 CT3-89 |
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| input-min | — | — | — | — | — | — | — | — |
| input-max | — | — | — | — | — | — | — | — |
| output-max | — | — | — | — | — | — | — | — |
| afue | — | — | — | — | — | — | — | — |
| turndown | — | — | — | — | — | — | — | — |
| vent-max-3 | — | — | — | — | — | — | — | — |
| vent-max-2 | — | — | — | — | — | — | — | — |
| weight | — | — | — | — | — | — | — | — |
Read the full comparison: Viessmann Vitocrossal 300 CT3-17 vs CT3-22 →
Read the full comparison: Viessmann Vitocrossal 300 CT3-37 vs CT3-46 →
Read the full comparison: Viessmann Vitocrossal 300 CT3-57 vs CT3-72 →
Read the full comparison: Viessmann Vitocrossal 300 CT3-72 vs CT3-89 →
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 Viessmann boilers
The earlier CM2 generations (186–311 with GC1/GW2 control, 400–620 with GW5B control), the Vitocrossal 300 CA3 in single-fuel and dual-fuel versions, and the older Vitocrossal 300 CT3 — all documented under Viessmann Canada's Historic manuals downloads.
Yes. Viessmann Canada keeps the technical data, installation, service, operating and wiring documents for the CM2 GC1/GW2 and GW5B generations, CA3 and CT3 available under its Historic manuals page, so owners and servicers can match documents to the generation on the rating plate.
Per the historic-page layout, the current Vitocrossal catalogue is the Vitocrossal 200 CI2 and CM2 (GW6B control) and the Vitocrossal 300 CA3B (GW6C control with the HI932 user interface on current units).
Describe what the boiler is doing and get a straight answer about the next step.
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.