Viessmann · Vitocrossal (legacy CA3/CT3 and earlier CM2 generations)
Viessmann Vitocrossal 300 CT3-37
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.
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 CT3-37 in practice
The CT3-37 is rated 1389 MBH (407 kW) input and 1350 MBH (396 kW) output at 97.2% combustion and thermal efficiency. It is the first CT3 size on the wider 800 mm shell with a 10 in. (251 mm) internal vent pipe, and it weighs 1,671 lb (758 kg) as a shell and 1,962 lb (890 kg) complete.
Boiler water content steps up to 129.5 USG (490 L) and the unit measures 1,751 x 800 x 2,023 mm (69 x 31½ x 79⅝ in) as shipped. The 30 psig maximum operating pressure and 210°F maximum supply temperature are shared across the CT3 range.
Best suited to
- Existing CT3-37 installations needing printed ratings
- Commercial loads crossing the 1,300 MBH mark on the wide CT3 chassis
- Documentation for the first 10 in. vent CT3 size
Applicability and support
- Model number
- CT3-37
- 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 | 1,389 MBH | 407 kW, per the technical data manual |
| Output | ||
| Output | 1,350 MBH | 396 kW; tested to AHRI BTS-2000. |
| Efficiency | ||
| Combustion efficiency | 97.2 % | Per the printed rating table. |
| Thermal efficiency | 97.2 % | Per the printed rating table. |
| Venting and air | ||
| Vent pipe internal diameter | 10 in | 251 mm per the technical data manual. |
| Physical and connections | ||
| Weight, boiler shell | 1,671 lb | 758 kg |
| Overall weight (with insulation and control, less burner) | 1,962 lb | 890 kg |
| Boiler length as shipped (door removed) | 1,751 mm | Printed as 69 in |
| Width 1 (maximum shell width) | 800 mm | Printed as 31½ in |
| Maximum height | 2,023 mm | Printed as 79⅝ 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 | 129.5 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 CT3-37 rated at?
1389 MBH (407 kW) input and 1350 MBH (396 kW) output, with 97.2% combustion efficiency and 97.2% thermal efficiency.
What changed on the CT3-37 versus the CT3-28?
The shell widens to 800 mm, the vent pipe grows from 8 to 10 in., weight rises from 1,202 to 1,671 lb as a shell, and water content from 87.2 to 129.5 USG.
How much does the CT3-37 weigh complete?
1,962 lb (890 kg) with insulation and control, less burner, per the technical data manual.
Questions about the Viessmann Vitocrossal 300 CT3-37?
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
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- Viessmann Vitocrossal 300 CT3-28Same series
- Viessmann Vitocrossal 300 CT3-46Same series
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- 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.