Viessmann · Vitocrossal (legacy CA3/CT3 and earlier CM2 generations)
Viessmann Vitocrossal 300 CT3-28
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.
Key figures
- Max input
- —
- Max CSA output
- —
- AFUE
- —
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Viessmann Vitocrossal 300 CT3-28 in practice
The CT3-28 is rated 1071 MBH (314 kW) input and 1044 MBH (306 kW) output with 97.4% combustion efficiency and 97.4% thermal efficiency. It is the last CT3 size before the line steps to the wider chassis used by the 37 to 89 models.
The boiler shell weighs 1,202 lb (545 kg) and the complete unit 1,455 lb (660 kg), holding 87.2 USG (330 L) of boiler water. It measures 1,675 x 684 x 1,811 mm (66 x 27 x 71⅛ in) as shipped, with the 8 in. (201 mm) internal vent pipe and 30 psig maximum operating pressure.
Best suited to
- Existing CT3-28 installations needing printed ratings
- Commercial loads up to about 1071 MBH on the small CT3 chassis
- Documentation for the last small-chassis CT3 size
Applicability and support
- Model number
- CT3-28
- Canadian availability
- historical
- Production status
- discontinued
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Not verified
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.
Specifications
Published specifications
Values as published by Viessmann. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Input | 1,071 MBH | 314 kW, per the technical data manual |
| Output | ||
| Output | 1,044 MBH | 306 kW; tested to AHRI BTS-2000. |
| Efficiency | ||
| Combustion efficiency | 97.4 % | Per the printed rating table. |
| Thermal efficiency | 97.4 % | Per the printed rating table. |
| Venting and air | ||
| Vent pipe internal diameter | 8 in | 201 mm per the technical data manual. |
| Physical and connections | ||
| Weight, boiler shell | 1,202 lb | 545 kg |
| Overall weight (with insulation and control, less burner) | 1,455 lb | 660 kg |
| Boiler length as shipped (door removed) | 1,675 mm | Printed as 66 in |
| Width 1 (maximum shell width) | 684 mm | Printed as 27 in |
| Maximum height | 1,811 mm | Printed as 71⅛ in |
| Operating limits and other | ||
| Fuel | Natural gas or liquid propane | Gas-fired condensing boiler; maximum supply temperature 210°F (99°C). |
| Boiler water content | 87.2 USG | Per the technical data manual. |
| Maximum operating pressure | 30 psig | 207 kPa; maximum operating temperature 210°F (99°C). |
| Boiler supply / return | Per model | Supply and return connections 2½ to 5 in. depending on size; boiler drain 1 in. |
Manuals
- Technical Data Manual — Vitocrossal 300 CT3 Series, doc 5285 871 - 055285 871 - 05 · 2016-01
- Installation Instructions — Vitocrossal 300 CT3, rev 0303 · 2015-10
- Service Instructions — Vitocrossal 300 CT3, rev 0404 · 2016-01
- Operating Instructions — Vitocrossal 300 CT3, rev 0202 · 2015-10
Alerts documented for this model
None documented yet.
Frequently asked questions
What is the CT3-28 rated at?
1071 MBH (314 kW) input and 1044 MBH (306 kW) output, with 97.4% combustion efficiency and 97.4% thermal efficiency.
Is the CT3-28 the largest small-chassis model?
Yes — the CT3-37 steps up to the wider 800 mm shell with a 10 in. vent pipe; the 17, 22 and 28 share the 684 mm shell and 8 in. vent.
What is the CT3-28 water content?
87.2 USG (330 L) of boiler water per the technical data manual.
Questions about the Viessmann Vitocrossal 300 CT3-28?
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.
Compare and explore
- Viessmann Vitocrossal 300 CT3-17Same series
- Viessmann Vitocrossal 300 CT3-22Same series
- Viessmann Vitocrossal 300 CT3-37Same series
- Viessmann Vitocrossal 300 CT3-46Same series
- Viessmann Vitocrossal 300 CT3-57Same series
- Viessmann Vitocrossal 300 CT3-72Same series
- Viessmann Vitocrossal 300 CT3-89Same series
- Vitocrossal (legacy CA3/CT3 and earlier CM2 generations) series hub
- Buying guide
Sources and verification
- Technical Data Manual — Vitocrossal 300 CT3 Series, doc 5285 871 - 05 · 5285 871 - 05 · accessed September 9, 2026
- Viessmann Canada — Historic manuals · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.