Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Gen 2 SSB800 and SSB1000 are the same 31.5 x 35.4 x 70.9 in cabinet and 96.8% AHRI thermal-efficiency platform with 80 psi MAWP and 2" NPT gas. The SSB800 fires 79,800 to 798,000 BTU/hr with 97.6% combustion efficiency and a 743 lb dry weight; the SSB1000 raises the ceiling to 1,024,000 BTU/hr with 991,000 BTU/hr gross output at 787 lb dry.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Buderus SSB800 (Gen 2) | Buderus SSB1000 (Gen 2) |
|---|---|---|
| Input, maximum | 798 MBH | 1,024 MBH |
| Input, minimum | 79.8 MBH | 100 MBH |
| Turndown | 10:1 | 10:1 |
| Combustion efficiency (AHRI) | 97.6 % | 95.4 % |
| Thermal efficiency (AHRI) | 96.8 % | 96.8 % |
| Gross output (AHRI) | 772 MBH | 991 MBH |
| Net rating (AHRI) | 671.3 MBH | 861.7 MBH |
| Water volume | 13 gal | 16 gal |
| Weight, dry | 743 lb | 787 lb |
| Gas connection | 2" NPT | 2" NPT |
| Water connections | 3" | 3" |
| Dimensions (L × W × H) | 31.5 × 35.4 × 70.9 in (800 × 900 × 1800 mm) | 31.5 × 35.4 × 70.9 in (800 × 900 × 1800 mm) |
Both are single-module ASME Section IV condensing boilers in the same 31.5 x 35.4 x 70.9 in (800 x 900 x 1800 mm) cabinet with dual 441 stainless steel heat exchangers, 3" system supply and return, 6" vent/air connections and a 10:1 turndown. The SSB800 carries 54 sq ft of heat-exchanger surface; the SSB1000 carries 86 sq ft.
The performance rows from the 08.2025 submittal sheet separate them: SSB800 max input 798,000 BTU/hr, gross output 772,000, net rating 671,300, combustion efficiency 97.6%; SSB1000 max input 1,024,000, gross output 991,000, net rating 861,700, combustion efficiency 95.4%. Both print the same 96.8% AHRI thermal efficiency.
Weights and water volumes grow with the rating: 743 lb dry / 13.0 gal on the SSB800 against 787 lb / 16.0 gal on the SSB1000. Both draw 15.1 FLA and share the same gas pressure ranges (NG 3.5-20 in. W.C., LP 8-20 in. W.C.). Size from the building's heat loss plus any cascade redundancy plan.
Bosch Thermotechnology
The Buderus SSB800 (Gen 2) is a commercial condensing boiler module rated 798 MBH maximum input (79.8 MBH minimum) with 96.8% AHRI thermal efficiency, 772 MBH gross output and 743 lb dry weight.
Bosch Thermotechnology
The Buderus SSB1000 (Gen 2) is a commercial condensing boiler module rated 1,024 MBH maximum input (100 MBH minimum) with 96.8% AHRI thermal efficiency, 991 MBH gross output and 787 lb dry weight.
The submittal sheet prints 96.8% AHRI thermal efficiency for both; the SSB800 alone prints 97.6% combustion efficiency against the SSB1000's 95.4%.
Yes: 2" NPT gas, 3" system supply and return, 6" vent and air intake on both. The larger SSB1000TL is the one that moves to a 3" flanged gas connection and 5" water connections.
219,000 BTU/hr of gross output: 991,000 against 772,000 BTU/hr, with the net AHRI rating rising from 671,300 to 861,700 BTU/hr.
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.