Viessmann · Vitocrossal 300 (CU3A)
Viessmann Vitocrossal 300 CU3A-94
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.
Key figures
- Max input
- 94 MBH
- Max CSA output
- —
- AFUE
- 95 %
- Min input
- 19 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Viessmann Vitocrossal 300 CU3A-94 in practice
The CU3A-94 is the entry size of the floor-standing Vitocrossal 300 line. It fires from a 19,000 BTU (5.6 kW) minimum input up to 94,000 BTU (27.5 kW) maximum, is rated 95% AFUE like every CU3A model, and weighs 269 lb (122 kg) in the 26-inch-wide (660 mm), 27-inch-deep (684 mm) cabinet it shares with the CU3A-125.
The boiler pairs a vertical stainless steel Inox-Crossal heat exchanger with a MatriX dome gas burner and Lambda Pro combustion control, per Viessmann Canada. The page cites a 5:1 turndown ratio, operating temperature up to 194°F (90°C), high-altitude operation up to 10,000 ft (3,000 m), and no dedicated boiler pump required.
Viessmann positions the CU3A for new construction and retrofits, including homes with high-mass cast iron radiators and high DHW requirements. The service instructions (doc 5673 649 - 20, dated 03/2025) cover the Canadian CU3A models including the CU3A-94.
Best suited to
- Retrofits and new construction with heat loads up to about 94 MBH
- Homes with high-mass cast iron radiators that suit a floor-standing boiler
- Basement mechanical rooms with the 61½-inch (1562 mm) headroom for the cabinet
Applicability and support
- Model number
- CU3A-94
- 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 | ||
| Input, minimum | 19 MBH | 19,000 BTU (5.6 kW), per the Canadian product page |
| Input, maximum | 94 MBH | 94,000 BTU (27.5 kW), per the Canadian product page |
| Efficiency | ||
| Efficiency (AFUE) | 95 % | 95% for all models per the Canadian product page. |
| Venting and air | ||
| Maximum vent run | 198 ft | Vent lengths up to 198 ft per the Canadian product page. |
| Physical and connections | ||
| Weight | 269 lb | 122 kg |
| Width | 26 in | 660 mm |
| Depth | 27 in | 684 mm |
| Height | 61.5 in | 1562 mm with the control interface closed; 67 in (1707 mm) with it open |
| Operating limits and other | ||
| Turndown ratio | 5:1 | Per the Canadian product page. |
| Maximum altitude | 10,000 ft | High-altitude operation up to 10,000 ft (3,000 m) per the Canadian product page; the page prints no derating note. |
| Fuel type | Natural gas (NG) or liquid propane gas (LPG) | As printed on the Canadian product page. |
Manuals
Alerts documented for this model
Frequently asked questions
What is the CU3A-94's firing range?
From a 19,000 BTU (5.6 kW) minimum input up to 94,000 BTU (27.5 kW) maximum, per the Canadian product page — the smallest of the four CU3A models.
How efficient is the CU3A-94?
95% AFUE on all CU3A models per the Canadian product page. The vertical stainless steel Inox-Crossal heat exchanger is described on the page as achieving efficiencies of up to 98%.
Is the CU3A-94 a combi boiler?
No combi configuration is listed on the Canadian page. The CU3A is a floor-standing space-heating boiler, so domestic hot water is handled by separate equipment such as a DHW tank.
Questions about the Viessmann Vitocrossal 300 CU3A-94?
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
Sources and verification
- Viessmann Canada — Vitocrossal 300 CU3A product page · accessed September 8, 2026
- Service Instructions — Vitocrossal 300 CU3A, Canadian models 26, 35, 45, 57, 94, 125, 160, 199, doc 5673 649 - 20 · 5673 649 - 20 · accessed September 8, 2026
Facts checked September 8, 2026. Last updated September 8, 2026. Technical reviewer: not yet assigned.