Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The B1HA 26, 94 and B1HA 35, 125 are the two heating-only models of the B1HA generation and share the 79.4 lb (36 kg) cabinet, 95.0% AFUE, 1.02 USG water content and 45 psig rating. The 35, 125 fires to 125 MBH natural gas against 94 MBH, with a 101 MBH Net AHRI rating against 76.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Viessmann Vitodens 100-W B1HA 26, 94 | Viessmann Vitodens 100-W B1HA 35, 125 |
|---|---|---|
| CSA input, minimum (natural gas) | 21 MBH | 21 MBH |
| CSA input, maximum (natural gas) | 94 MBH | 125 MBH |
| CSA input (liquid propane) | 31-94 MBH | 31-125 MBH |
| CSA output / DOE heating capacity (natural gas) | 20-87 MBH | 20-116 MBH |
| Net AHRI rating | 76 MBH | 101 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| Weight | 79.4 lb | 79.4 lb |
| Maximum operating pressure | 45 psig | 45 psig |
Both boilers are wall-hung condensing models with a 21 MBH (6.2 kW) natural gas minimum input, 20 MBH output floor and a 31 MBH propane minimum. They share the 400 x 400 x 768 mm cabinet, 79.4 lb (36 kg) weight, 88.2 lb shipping weight and 45 psig maximum operating pressure.
Maximum input separates them: 94 MBH (27.5 kW) natural gas on the 26, 94 against 125 MBH (36.6 kW) on the 35, 125, with propane ranges of 31-94 and 31-125 MBH. Outputs top at 87 and 116 MBH, and Net AHRI ratings read 76 and 101 MBH at the same 95.0% AFUE.
Neither model produces domestic hot water; both pair with an indirect tank, and the B1KA 35, 125 combi covers on-demand DHW in the same generation. The heat-loss calculation decides the ceiling, and both models are documented in the B1HA/B1KA technical data manual (doc 5784 566 - 12).
Viessmann
The Vitodens 100-W B1HA 26, 94 is the smaller heating-only model of the B1HA/B1KA generation: 21 to 94 MBH natural gas input at 95.0% AFUE in a 79.4 lb (36 kg) wall-hung boiler.
The Vitodens 100-W B1HA 35, 125 is the larger heating-only model of the B1HA generation: 21 to 125 MBH natural gas input at 95.0% AFUE in the 79.4 lb (36 kg) cabinet.
Yes. Both weigh 79.4 lb (36 kg) and measure 400 x 400 x 768 mm (15¾ x 15¾ x 30¼ in) with 1.02 USG of boiler water.
No — both are heating-only and use an indirect tank. The B1KA 35, 125 is the combi model of the same generation.
21-94 MBH natural gas on the 26, 94 and 21-125 MBH on the 35, 125, with propane minimums of 31 MBH on both.
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.