Viessmann · Vitocrossal 300 (CA3B)
Viessmann Vitocrossal 300 CA3B 6.0
The Vitocrossal 300 CA3B 6.0 tops the CA3B range at 6000 MBH: 400,000 to 6,000,000 BTU (117 to 1758 kW) of natural-gas input at 96.1% thermal efficiency, rated for 160 psi, in the range's heaviest 6894 lb (3127 kg) unit.
Key figures
- Max input
- 6,000 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- 400 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Viessmann Vitocrossal 300 CA3B 6.0 in practice
The CA3B 6.0 is the largest of the six Vitocrossal 300 CA3B sizes and the reason the page prints maximum inputs of 2500 to 6000 MBH. Its natural-gas input runs from a 400,000 BTU (117 kW) minimum up to 6,000,000 BTU (1758 kW) — 6000 MBH — per the product page.
At 6894 lb (3127 kg) as a single-fuel unit it is the heaviest boiler in the range, sharing the largest chassis with the CA3B 5.0. It carries the range's 96.1% thermal-efficiency row and 160 psi maximum operating pressure, with a 210°F high limit in the printed data.
The full CA3B platform applies: SA240 316Ti Inox-Lamellar heat exchanger, up to three fully modulating pre-mix cylinder burners, Vitotronic 300 GW6C control, common venting of up to four boilers, sealed-combustion or room-air-dependent venting, dual-fuel (NG/LP) availability with key changeover and altitude operation to 10,000 ft.
Best suited to
- The largest single-boiler commercial loads — up to 6000 MBH of input
- Plants where one CA3B 6.0 replaces several smaller boilers
- High-pressure hydronic systems needing maximum per-boiler capacity
Applicability and support
- Model number
- CA3B 6.0
- Canadian availability
- available
- Production status
- current
- 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 | ||
| Minimum input (natural gas) | 400 MBH | 400,000 BTU (117 kW), per the product page |
| Maximum input (natural gas) | 6,000 MBH | 6,000,000 BTU (1758 kW), per the product page |
| Efficiency | ||
| Thermal efficiency | 96.1 % | 96.1% on all CA3B models (page/TDM: AHRI 1500 / DOE / ANSI Z21.13-CSA 4.9 / BTS-2000). |
| Physical and connections | ||
| Weight, single fuel | 6,894 lb | 3127 kg |
| Operating limits and other | ||
| Maximum operating pressure | 160 psig | 160 psi per the product page; the printed data lists a 210°F high limit. |
Manuals
Alerts documented for this model
None documented yet.
Frequently asked questions
What is the firing range of the CA3B 6.0?
Natural-gas input from 400,000 BTU (117 kW) minimum to 6,000,000 BTU (1758 kW) maximum, per the product page — the top of the CA3B single-boiler range at 6000 MBH.
How big is the CA3B 6.0?
6894 lb (3127 kg) as a single-fuel unit per the product page, the heaviest figure printed in the CA3B range.
How efficient is the CA3B 6.0?
96.1% thermal efficiency like every CA3B model (AHRI 1500 / DOE / ANSI Z21.13-CSA 4.9 / BTS-2000), on the range's 160 psi rating.
Questions about the Viessmann Vitocrossal 300 CA3B 6.0?
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
- Viessmann Canada — Vitocrossal 300 CA3B product page · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.