Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The CM2-500 and CM2-620 are the two largest Vitocrossal 200 CM2 models and the top of the series: both print 95.1% combustion efficiency with 5:1 turndown. The 620 fires to 2245 MBH against the 500's 1800 MBH, from a 450 MBH minimum against 358, and weighs 1929 lb against 1662 lb — the size behind the series' 2245 MBH single-boiler ceiling.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Viessmann Vitocrossal 200 CM2-500 | Viessmann Vitocrossal 200 CM2-620 |
|---|---|---|
| Input, minimum (natural gas) | 358 MBH | 450 MBH |
| Input, maximum (natural gas) | 1,800 MBH | 2,245 MBH |
| Combustion efficiency | 95.1 % | 95.1 % |
| Turndown ratio | 5:1 | 5:1 |
| Weight | 1,662 lb | 1,929 lb |
Both models top the large CM2 chassis documented by service manual doc 5546 489 - 15, with identical printed efficiency figures: 95.1% combustion efficiency and a 5:1 turndown. The CM2-620 carries the series' single-boiler maximum of 2,245,000 BTU (658 kW) against the 500's 1,800,000 BTU (527 kW).
The extra 445 MBH of ceiling comes with a higher floor: the 620's minimum fire is 450,000 BTU (132 kW) against the 500's 358,000 BTU (105 kW), so plants whose loads rarely approach the 620's ceiling will see it idle higher in part-load conditions. Weight steps from 1662 lb (754 kg) to 1929 lb (875 kg), the heaviest figure in the CM2 range.
Both share the Inox-Crossal stainless steel heat exchanger, pre-mix cylinder burner, natural-gas or propane operation with simple electronic conversion and the Vitotronic 300 GW6B control with cascade control of up to eight boilers. The 620 earns its place when the design load genuinely approaches 2245 MBH — the top of the CM2 single-boiler range before cascading.
Viessmann
The Vitocrossal 200 CM2-500 is the mid-size model of the large CM2 (GW6B) chassis: 358 to 1800 MBH natural-gas input (105 to 527 kW) at 95.1% combustion efficiency and 5:1 turndown, weighing 1662 lb (754 kg).
Viessmann
The Vitocrossal 200 CM2-620 is the top of the CM2 (GW6B) line: 450 to 2245 MBH natural-gas input (132 to 658 kW) at 95.1% combustion efficiency and 5:1 turndown, weighing 1929 lb (875 kg).
The 500 fires 358 to 1800 MBH and the 620 fires 450 to 2245 MBH of natural-gas input, per the product page.
1929 lb (875 kg) per the product page — the heaviest model in the CM2 range, against 1662 lb (754 kg) for the CM2-500.
When the design load approaches the series' 2245 MBH single-boiler ceiling. Below about 1800 MBH the 500 delivers the same efficiency with a lower minimum fire and 267 lb less weight.
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.