Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
Buderus SB745WS 1300 and Buderus SB745WS 1550 are two condensing boilers from the Bosch Thermotechnology Buderus SB745WS line. The Buderus SB745WS 1300 is documented at 4,692 MBH rated input, natural gas and 4,364 MBH gross output, while the Buderus SB745WS 1550 is documented at 5,443 MBH rated input, natural gas and 5,029 MBH gross output. Buderus SB745WS 1550 lists 751 MBH more rated input, natural gas than Buderus SB745WS 1300 (5,443 MBH against 4,692 MBH). Buderus SB745WS 1550 lists 420 kg more shipping weight than Buderus SB745WS 1300 (3,100 kg against 2,680 kg).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Buderus SB745WS 1300 | Buderus SB745WS 1550 |
|---|---|---|
| Weight of boiler | 2,680 kg | 3,100 kg |
| Fuels | Natural gas or #2 oil | Natural gas or #2 oil |
| Rated input, natural gas | 4,692 MBH | 5,443 MBH |
| Rated input, #2 oil | 33.5 GPH | 38.8 GPH |
| Gross output | 4,364 MBH | 5,029 MBH |
| Maximum working pressure | 80 psi | 80 psi |
| Maximum admissible temperature | 230 °F | 230 °F |
| Maximum working temperature | 210 °F | 210 °F |
| Water capacity | 482.1 US gal | 501.9 US gal |
| Heat exchanger surface area | 604.93 sq ft | 670.37 sq ft |
Published ratings: the Buderus SB745WS 1300 is rated 4,692 MBH rated input, natural gas and 4,364 MBH gross output; the Buderus SB745WS 1550 is rated 5,443 MBH rated input, natural gas and 5,029 MBH gross output. Buderus SB745WS 1550 lists 751 MBH more rated input, natural gas than Buderus SB745WS 1300 (5,443 MBH against 4,692 MBH).
Buderus SB745WS 1550 lists 420 kg more shipping weight than Buderus SB745WS 1300 (3,100 kg against 2,680 kg). The water capacity differs: the Buderus SB745WS 1300 lists 482.1 US gal, while the Buderus SB745WS 1550 lists 501.9 US gal. The heat exchanger surface area differs: the Buderus SB745WS 1300 lists 604.93 sq ft, while the Buderus SB745WS 1550 lists 670.37 sq ft.
Both records print the same fuel (Natural gas or #2 oil), maximum working pressure (80 psi), maximum admissible temperature (230 °F) and maximum working temperature (210 °F), per the cited sources.
Bosch Thermotechnology
The Buderus SB745WS 1300 is a discontinued commercial stainless steel condensing boiler block rated 4,692 MBH natural-gas input (33.5 GPH oil) with 4,364 MBH gross output and 482.1 US gal water capacity.
Bosch Thermotechnology
The Buderus SB745WS 1550 is a discontinued commercial stainless steel condensing boiler block rated 5,443 MBH natural-gas input (38.8 GPH oil) with 5,029 MBH gross output and 501.9 US gal water capacity.
The Buderus SB745WS 1550 lists 5,443 MBH, against 4,692 MBH on the Buderus SB745WS 1300, per the cited documentation.
The Buderus SB745WS 1550 lists 5,029 MBH, against 4,364 MBH on the Buderus SB745WS 1300.
It ships at 3,100 kg against 2,680 kg for the Buderus SB745WS 1300, per the cited sources.
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.