Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The CU3A-94 and CU3A-125 are the two smallest floor-standing Vitocrossal 300 models and share the compact 26 x 27-inch footprint at 95% AFUE. The 125 fires higher at both ends — 25,000 to 125,000 BTU (7.3 to 36.6 kW) against the 94's 19,000 to 94,000 BTU (5.6 to 27.5 kW) — and weighs 275 lb (125 kg) against 269 lb (122 kg), so the 94's lower minimum fire is its main argument in low-load homes.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Viessmann Vitocrossal 300 CU3A-94 | Viessmann Vitocrossal 300 CU3A-125 |
|---|---|---|
| Input, minimum | 19 MBH | 25 MBH |
| Input, maximum | 94 MBH | 125 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| Weight | 269 lb | 275 lb |
| Width | 26 in | 26 in |
| Depth | 27 in | 27 in |
| Height | 61.5 in | 61.5 in |
Both models are floor-standing condensing boilers on the same CU3A platform: 95% AFUE, a stainless steel Inox-Crossal heat exchanger, a MatriX dome gas burner with Lambda Pro control and a 5:1 turndown ratio. The published difference is input range: 19,000 to 94,000 BTU (5.6 to 27.5 kW) for the 94, and 25,000 to 125,000 BTU (7.3 to 36.6 kW) for the 125.
The minimum fire rates matter in mild climates: the 94 drops to 19,000 BTU and the 125 only to 25,000 BTU. In a home whose load sits low for much of the year the 94 can track shoulder-season demand more closely, while the 125's extra 31 MBH of ceiling serves larger loads and faster indirect-tank recovery.
The cabinets are nearly identical: both are 26 inches (660 mm) wide and 27 inches (684 mm) deep and stand 61.5 inches (1562 mm) with the control closed, while weight steps from 269 lb (122 kg) on the 94 to 275 lb (125 kg) on the 125. Neither model is a combi, and both operate up to 194°F (90°C) and 10,000 ft (3,000 m) of altitude per the page.
Viessmann
The Vitocrossal 300 CU3A-94 is the smallest of Viessmann Canada's floor-standing CU3A models: 19,000 to 94,000 BTU (5.6 to 27.5 kW) of input at 95% AFUE, weighing 269 lb (122 kg), with an Inox-Crossal stainless steel heat exchanger.
Viessmann
The Vitocrossal 300 CU3A-125 is the mid-size model of Viessmann Canada's floor-standing CU3A line: 25,000 to 125,000 BTU (7.3 to 36.6 kW) of input at 95% AFUE, weighing 275 lb (125 kg) in the compact floor-standing cabinet.
Nearly. Both share the 26 x 27 inch (660 x 684 mm) footprint and 61.5-inch height; the 125 weighs 275 lb (125 kg) against 269 lb (122 kg) for the 94, per Viessmann Canada.
The 94 fires 19,000 to 94,000 BTU (5.6 to 27.5 kW) and the 125 fires 25,000 to 125,000 BTU (7.3 to 36.6 kW), both rated 95% AFUE.
When the heat-loss calculation plus hot-water recovery demand exceeds the 94's ceiling. Below that, the 94's lower 19,000 BTU minimum fire matches low loads more closely.
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 8, 2026. Last updated September 8, 2026. Technical reviewer: not yet assigned.