Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The CM2-400 and CM2-500 are the two smallest models of the large Vitocrossal 200 CM2 chassis and share its printed figures: 95.1% combustion efficiency and a 5:1 turndown. The 500 fires to 1800 MBH against the 400's 1445 MBH, from a higher 358 MBH minimum (against 287), and weighs 1662 lb against 1495 lb.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Viessmann Vitocrossal 200 CM2-400 | Viessmann Vitocrossal 200 CM2-500 |
|---|---|---|
| Input, minimum (natural gas) | 287 MBH | 358 MBH |
| Input, maximum (natural gas) | 1,445 MBH | 1,800 MBH |
| Combustion efficiency | 95.1 % | 95.1 % |
| Turndown ratio | 5:1 | 5:1 |
| Weight | 1,495 lb | 1,662 lb |
Both models sit on the large CM2 chassis documented by service manual doc 5546 489 - 15 (CM2-400/500/620), sharing the 95.1% combustion-efficiency row and 5:1 turndown of the large size range. The comparison is therefore capacity and minimum fire.
The 500 fires from a 358,000 BTU (105 kW) minimum up to 1,800,000 BTU (527 kW) maximum, against the 400's 287,000 to 1,445,000 BTU (84 to 423 kW). The extra 355 MBH of ceiling costs a 71,000 BTU higher minimum fire, so a plant whose load hovers near the 400's ceiling will see the 500 idle higher in part-load conditions.
Weight steps from 1495 lb (678 kg) on the 400 to 1662 lb (754 kg) on the 500. Both run natural gas or propane with simple electronic conversion on the Inox-Crossal heat exchanger and pre-mix cylinder burner platform, with the Vitotronic 300 GW6B control supporting cascades of up to eight boilers and common venting of up to four.
Viessmann
The Vitocrossal 200 CM2-400 opens the large CM2 (GW6B) chassis: 287 to 1445 MBH natural-gas input (84 to 423 kW) at 95.1% combustion efficiency and 5:1 turndown, weighing 1495 lb (678 kg).
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).
The 400 fires 287 to 1445 MBH and the 500 fires 358 to 1800 MBH of natural-gas input, per the product page.
They share the large chassis, but the printed weights differ: 1495 lb (678 kg) for the 400 against 1662 lb (754 kg) for the 500.
Neither — both print 95.1% combustion efficiency with a 5:1 turndown, the figures shared by the CM2-400, CM2-500 and CM2-620.
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.