Viessmann · Vitocrossal (legacy CA3/CT3 and earlier CM2 generations)
Viessmann Vitocrossal 300 CT3-72
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.
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 CT3-72 in practice
The CT3-72 is rated 2702 MBH (792 kW) input and 2616 MBH (767 kW) output at 96.8% combustion and thermal efficiency. It is the first CT3 size on the 951 mm shell with a 12 in. (301 mm) internal vent pipe and a taller 2,235 mm (88 in) shipping height.
The boiler shell weighs 2,706 lb (1,230 kg) and the complete unit 3,014 lb (1,370 kg), with 199.2 USG (754 L) of boiler water — the second-highest water content in the range after the CT3-89. It measures 2,095 x 951 x 2,235 mm (82⅛ x 37½ x 88 in) as shipped.
Best suited to
- Existing CT3-72 installations needing printed ratings
- Large commercial loads crossing the 2,700 MBH mark
- Documentation for the first 12 in. vent CT3 size
Applicability and support
- Model number
- CT3-72
- 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 | 2,702 MBH | 792 kW, per the technical data manual |
| Output | ||
| Output | 2,616 MBH | 767 kW; tested to AHRI BTS-2000. |
| Efficiency | ||
| Combustion efficiency | 96.8 % | Per the printed rating table. |
| Thermal efficiency | 96.8 % | Per the printed rating table. |
| Venting and air | ||
| Vent pipe internal diameter | 12 in | 301 mm per the technical data manual. |
| Physical and connections | ||
| Weight, boiler shell | 2,706 lb | 1230 kg |
| Overall weight (with insulation and control, less burner) | 3,014 lb | 1370 kg |
| Boiler length as shipped (door removed) | 2,095 mm | Printed as 82⅛ in |
| Width 1 (maximum shell width) | 951 mm | Printed as 37½ in |
| Maximum height | 2,235 mm | Printed as 88 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 | 199.2 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 CT3-72 rated at?
2702 MBH (792 kW) input and 2616 MBH (767 kW) output, with 96.8% combustion efficiency and 96.8% thermal efficiency.
What changed on the CT3-72 versus the CT3-57?
The shell widens to 951 mm, the vent pipe grows to 12 in., height increases to 2,235 mm and water content rises from 150.6 to 199.2 USG.
How much does the CT3-72 weigh?
2,706 lb (1,230 kg) as a shell and 3,014 lb (1,370 kg) complete, per the technical data manual.
Questions about the Viessmann Vitocrossal 300 CT3-72?
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 CT3-57 vs CT3-72Comparison
- Viessmann Vitocrossal 300 CT3-72 vs CT3-89Comparison
- Viessmann Vitocrossal 300 CT3-17Same series
- Viessmann Vitocrossal 300 CT3-22Same series
- Viessmann Vitocrossal 300 CT3-28Same series
- Viessmann Vitocrossal 300 CT3-37Same series
- Viessmann Vitocrossal 300 CT3-46Same series
- Viessmann Vitocrossal 300 CT3-57Same 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.