Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Viessmann Vitocrossal 300 CA3B 3.0 and Viessmann Vitocrossal 300 CA3B 3.5 are both condensing boilers in the Viessmann Vitocrossal 300 (CA3B) line. The Viessmann Vitocrossal 300 CA3B 3.0 is rated 300–3,000 MBH input and 96.1% thermal efficiency, and the Viessmann Vitocrossal 300 CA3B 3.5 is rated 300–3,500 MBH input and 96.1% thermal efficiency. Viessmann Vitocrossal 300 CA3B 3.5 lists 500 MBH more input than Viessmann Vitocrossal 300 CA3B 3.0 (3,500 MBH against 3,000 MBH). Both list the same published thermal efficiency of 96.1%. Viessmann Vitocrossal 300 CA3B 3.5 lists 463 lb more shipping weight than Viessmann Vitocrossal 300 CA3B 3.0 (4,696 lb against 4,233 lb).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Viessmann Vitocrossal 300 CA3B 3.0 | Viessmann Vitocrossal 300 CA3B 3.5 |
|---|---|---|
| Minimum input (natural gas) | 300 MBH | 300 MBH |
| Maximum input (natural gas) | 3,000 MBH | 3,500 MBH |
| Thermal efficiency | 96.1 % | 96.1 % |
| Weight, single fuel | 4,233 lb | 4,696 lb |
| Maximum operating pressure | 160 psig | 160 psig |
Published ratings: the Viessmann Vitocrossal 300 CA3B 3.0 is rated 300–3,000 MBH input and 96.1% thermal efficiency; the Viessmann Vitocrossal 300 CA3B 3.5 is rated 300–3,500 MBH input and 96.1% thermal efficiency. Viessmann Vitocrossal 300 CA3B 3.5 lists 500 MBH more input than Viessmann Vitocrossal 300 CA3B 3.0 (3,500 MBH against 3,000 MBH). Both list the same published thermal efficiency of 96.1%.
Viessmann Vitocrossal 300 CA3B 3.5 lists 463 lb more shipping weight than Viessmann Vitocrossal 300 CA3B 3.0 (4,696 lb against 4,233 lb).
Both records print the same input (300 MBH), thermal efficiency (96.1%) and maximum operating pressure (160 psig), per the cited sources.
Viessmann
The Vitocrossal 300 CA3B 3.0 is the 3000 MBH size of the CA3B range: 300,000 to 3,000,000 BTU (88 to 879 kW) of natural-gas input at 96.1% thermal efficiency, rated for 160 psi, in the same 4233 lb (1920 kg) unit as the CA3B 2.5.
Viessmann
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).
The Viessmann Vitocrossal 300 CA3B 3.5 lists 3,500 MBH, against 3,000 MBH on the Viessmann Vitocrossal 300 CA3B 3.0, per the cited documentation.
Both list the same thermal efficiency of 96.1%.
It ships at 4,696 lb against 4,233 lb for the Viessmann Vitocrossal 300 CA3B 3.0, per the cited sources.
A consultation includes a heat-loss review so the size is right the first time.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.