Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The discontinued SB625WS 160 and 640 are stainless steel condensing boiler blocks at 80 psi maximum working pressure and 210 °F maximum working temperature. The 160 takes 563 MBH natural-gas input (4.0 GPH oil) for 532 MBH gross output and 85.3 gal water; the 640 takes 2,200 MBH (15.7 GPH) for 2,081 MBH gross output and 203.4 gal water.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Buderus SB625WS 160 | Buderus SB625WS 640 |
|---|---|---|
| Rated input, natural gas | 563 MBH | 2,200 MBH |
| Rated input, #2 oil | 4 GPH | 15.7 GPH |
| Gross output | 532 MBH | 2,081 MBH |
| Water capacity | 85.3 US gal | 203.4 US gal |
| Weight of boiler | 575 kg | 1,345 kg |
| Heat exchanger surface area | 65.65 sq ft | 310 sq ft |
Both sizes share the SB Series design: a stainless steel condensing boiler with a lightly pressurized combustion chamber and turbulators in the tube bundle, sold with a field-supplied burner from Bosch's UL-listed burner sheet, at 80 psi MAWP, 230 °F maximum admissible temperature and 210 °F maximum working temperature.
Ratings scale: natural-gas input 563 to 2,200 MBH, oil input 4.0 to 15.7 GPH, gross output 532 to 2,081 MBH, water capacity 85.3 to 203.4 US gal and heat-exchanger surface 65.65 to 310.0 sq ft. The manual's boiler weights use the kg row (575 to 1,345 kg) because its printed lb row is mis-converted in the source PDF.
Both are discontinued: the SB625WS has its own page under Bosch's US 'Discontinued Boilers' section with installation/operating manuals and the UL-listed burner sheet. The later SSB family (series-bosch-ssb) is the current commercial condensing line.
Bosch Thermotechnology
The Buderus SB625WS 160 is a discontinued commercial stainless steel condensing boiler block rated 563 MBH natural-gas input (4 GPH oil) with 532 MBH gross output and 85.3 US gal water capacity.
Bosch Thermotechnology
The Buderus SB625WS 640 is a discontinued commercial stainless steel condensing boiler block rated 2,200 MBH natural-gas input (15.7 GPH oil) with 2,081 MBH gross output and 203.4 US gal water capacity.
Only burners included in the UL listing: the recommended-burners submittal sheet groups approved Riello gas and dual-fuel models by size; any other burner requires a UL field evaluation before commissioning.
203.4 US gallons (770 l), against 85.3 US gal (323 l) on the 160, per the installation manual technical table.
Yes - it is a stainless steel condensing boiler with a lightly pressurized combustion chamber and turbulators, with category IV venting covered in the installation manual.
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.