Viessmann · Vitocrossal 300 (CA3B)
Viessmann Vitocrossal 300 CA3B 3.5
The Vitocrossal 300 CA3B 3.5 is the 3500 MBH size of the CA3B range: 300,000 to 3,500,000 BTU (88 to 1026 kW) of natural-gas input at 96.1% thermal efficiency, rated for 160 psi, weighing 4696 lb (2130 kg).
Key figures
- Max input
- 3,500 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- 300 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Viessmann Vitocrossal 300 CA3B 3.5 in practice
The CA3B 3.5 lifts the CA3B range's maximum input to 3,500,000 BTU (1026 kW) — 3500 MBH — while keeping the 300,000 BTU (88 kW) natural-gas minimum fire it shares with the CA3B 3.0.
It is the first CA3B size to leave the entry chassis: single-fuel weight steps up to 4696 lb (2130 kg), 463 lb heavier than the CA3B 2.5/3.0 pair. The 160 psi pressure rating and 96.1% thermal-efficiency row are unchanged across the range.
Common CA3B platform features apply: SA240 316Ti Inox-Lamellar heat exchanger, fully modulating pre-mix cylinder burners, Vitotronic 300 GW6C control with cascade primary/secondary control, common venting of up to four boilers, dual-fuel (NG/LP) models with key changeover and altitude operation to 10,000 ft.
Best suited to
- Plants whose design load approaches 3500 MBH of input
- Loads that outgrow the 4233 lb CA3B entry chassis
- High-pressure commercial systems on the 160 psi CA3B platform
Applicability and support
- Model number
- CA3B 3.5
- 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) | 300 MBH | 300,000 BTU (88 kW), per the product page |
| Maximum input (natural gas) | 3,500 MBH | 3,500,000 BTU (1026 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 | 4,696 lb | 2130 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 3.5?
Natural-gas input from 300,000 BTU (88 kW) minimum to 3,500,000 BTU (1026 kW) maximum, per the product page; maximum input is 3500 MBH.
How heavy is the CA3B 3.5?
4696 lb (2130 kg) as a single-fuel unit per the product page — the first CA3B size above the 4233 lb entry chassis.
What efficiency does the CA3B 3.5 print?
96.1% thermal efficiency, printed for every CA3B model, alongside the range's 160 psi maximum operating pressure.
Questions about the Viessmann Vitocrossal 300 CA3B 3.5?
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 CA3B 3.0 vs CA3B 3.5Comparison
- Viessmann Vitocrossal 300 CA3B 3.5 vs CA3B 4.0Comparison
- Viessmann Vitocrossal 300 CA3B 2.5Same series
- Viessmann Vitocrossal 300 CA3B 3.0Same series
- Viessmann Vitocrossal 300 CA3B 4.0Same series
- Viessmann Vitocrossal 300 CA3B 5.0Same series
- Viessmann Vitocrossal 300 CA3B 6.0Same series
- Vitocrossal 300 (CA3B) series hub
- Buying guide
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.