Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The WB1B 26 and WB1B 35 are the two second-generation Vitodens 100-W boilers and share the 78 lb (34.1 kg) cabinet, 0.87 USG water content, 45 psig rating, 94.0% AFUE and a 37 MBH NG/LPG minimum input. The WB1B 35 fires to 118 MBH against 91 MBH, with a 94 MBH Net I=B=R rating against 72.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Viessmann Vitodens 100-W WB1B 26 | Viessmann Vitodens 100-W WB1B 35 |
|---|---|---|
| CSA input, minimum (NG/LPG) | 37 MBH | 37 MBH |
| CSA input, maximum (NG/LPG) | 91 MBH | 118 MBH |
| CSA output / DOE heating capacity | 34-83 MBH | 34-108 MBH |
| Net I=B=R rating | 72 MBH | 94 MBH |
| Efficiency (AFUE) | 94 % | 94 % |
| Weight | 78 lb | 78 lb |
| Boiler water content | 0.87 USG | 0.87 USG |
| Maximum operating pressure | 45 psig | 45 psig |
Both boilers are wall-hung condensing models with combined natural gas and LPG ratings, a 37 MBH (10.8 kW) minimum input, a 34 MBH output floor and 94.0% AFUE. They share the 400 x 360 x 725 mm (15¾ x 14⅛ x 28½ in) cabinet, 78 lb (34.1 kg) weight, 95 lb shipping weight, 0.87 USG water content and 45 psig maximum operating pressure.
Maximum input separates them: 91 MBH (26.7 kW) on the WB1B 26 against 118 MBH (34.6 kW) on the WB1B 35, with outputs of 34-83 and 34-108 MBH and Net I=B=R ratings of 72 and 94 MBH.
Both are heating-only boilers; Viessmann Canada's historic manuals also list a WB1B CombiPLUS version with on-demand DHW. The WB1B generation sits between the earlier WB1A and the later B1HA/B1KA series.
Viessmann
The Vitodens 100-W WB1B 26 is the smaller WB1B boiler: 37 to 91 MBH NG/LPG input at 94.0% AFUE in a 78 lb (34.1 kg) wall-hung cabinet.
Viessmann
The Vitodens 100-W WB1B 35 is the larger WB1B boiler: 37 to 118 MBH NG/LPG input at 94.0% AFUE in the same 78 lb (34.1 kg) cabinet.
Yes. Both weigh 78 lb (34.1 kg) and measure 400 x 360 x 725 mm with 0.87 USG of boiler water.
37-91 MBH (10.8-26.7 kW) on the WB1B 26 and 37-118 MBH (10.8-34.6 kW) on the WB1B 35, on natural gas or liquid propane.
Yes — a WB1B CombiPLUS version is documented in Viessmann Canada's historic manuals with its own technical data manual and instructions.
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.