Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
Stepping from the B2HB 35, 125 to the B2HB 45, 160 crosses the B2HB chassis boundary: weight nearly doubles from 110 to 210 lb, water content rises from 1.02 to 3.85 USG, the pressure rating moves from 45 to 60 psig, the minimum fire jumps from 19 to 32 MBH, and the 45, 160 gains the right to be common-vented with same-size Vitodens 200-W boilers.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Viessmann Vitodens 200-W B2HB 35, 125 | Viessmann Vitodens 200-W B2HB 45, 160 |
|---|---|---|
| CSA input, minimum (natural gas) | 19 MBH | 32 MBH |
| CSA input, maximum (natural gas) | 125 MBH | 160 MBH |
| CSA input (liquid propane) | 31-125 MBH | 60-160 MBH |
| CSA output / DOE heating capacity (natural gas) | 18-117 MBH | 30-149 MBH |
| Net AHRI rating | 102 MBH | 127 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| Weight | 110 lb | 210 lb |
| Boiler water content | 1.02 USG | 3.85 USG |
| Maximum operating pressure | 45 psig | 60 psig |
| Width | 17.75 in | 19 in |
| Depth | 15.7 in | 21 in |
| Height | 41 in | 43.5 in |
The B2HB 35, 125 closes the compact group at 19-125 MBH natural gas input in a 110 lb (50 kg) cabinet with 1.02 USG of water and a 45 psig rating. The B2HB 45, 160 opens the large group at 32-160 MBH (9-47 kW) natural gas — with a higher 60-160 MBH propane range — in a 210 lb (95 kg) chassis with 3.85 USG and 60 psig.
Output rises from 18-117 MBH to 30-149 MBH and the Net AHRI rating from 102 to 127 MBH at the same 95.0% AFUE. Cabinet dimensions grow from 17¾ x 15.7 x 41 in (450 x 400 x 1040 mm) to 19 x 21 x 43½ in (480 x 530 x 1105 mm), changing the mounting wall, handling and doorways.
The most consequential difference is venting: the 35, 125 must not be common-vented with any other appliance, while the 45, 160 can be common-vented with other Vitodens 200-W boilers of the same size and series. The minimum fire also rises from 19 to 32 MBH, so low-load homes keep more modulation headroom on the smaller model.
The Vitodens 200-W B2HB 35, 125 is the largest model of the B2HB compact chassis: 19 to 125 MBH natural gas input (31 to 125 MBH propane) at 95.0% AFUE with a 102 MBH Net AHRI rating.
The Vitodens 200-W B2HB 45, 160 opens the B2HB large chassis: 32 to 160 MBH natural gas input (60 to 160 MBH propane) at 95.0% AFUE in a 210 lb (95 kg) wall-hung boiler with a 60 psig rating.
210 lb (95 kg) against 110 lb (50 kg), per the technical data manual, with water content rising from 1.02 to 3.85 USG and the rating from 45 to 60 psig.
The B2HB 45, 160 — but only with other Vitodens 200-W boilers of the same size and series. The B2HB 35, 125 and all smaller B2HB models must not be common-vented with any other appliance.
Yes. The 35, 125 fires down to 19 MBH natural gas; the 45, 160 only to 32 MBH, so a low-load home keeps more modulation range on the smaller chassis.
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.