Viessmann · Vitogas 100 (GS1 / GS10)
Viessmann Vitogas 100 GS10-72
The Vitogas 100 GS10-72 is the smallest commercial GS10 boiler: 300 MBH full-load input (88 kW), 257 MBH output and 85.6% combustion efficiency, two-stage fired at 70% partial load.
Key figures
- Max input
- —
- Max CSA output
- —
- AFUE
- —
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Viessmann Vitogas 100 GS10-72 in practice
The GS10-72 is a two-stage commercial cast-iron boiler rated 300 MBH (88 kW) full-load input, 210 MBH (62 kW) at 70% partial load, and 257 MBH (75 kW) full-load output with a 224 MBH (66 kW) Net I=B=R rating. Combustion efficiency prints at 85.6%.
It is built from seven cast-iron sections with six burner tubes, holding 9.9 USG of boiler water at 60 psig maximum operating pressure. The boiler shell ships as an assembled block at 714 lb (324 kg); the complete boiler with insulation, burner, control, fittings and draft hood weighs 927 lb (420 kg).
Best suited to
- Existing GS10-72 installations needing printed ratings
- Commercial loads from 300 MBH with two-stage firing
- Documentation for the entry GS10 size
Applicability and support
- Model number
- GS10-72
- Canadian availability
- historical
- Production status
- discontinued
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Not verified
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by Viessmann. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| CSA input, full load | 300 MBH | 88 kW, per the technical data manual |
| CSA input, partial load (70%) | 210 MBH | 62 kW |
| Output | ||
| CSA output, full load | 257 MBH | 75 kW |
| CSA output, partial load (70%) | 180 MBH | 53 kW |
| Net I=B=R rating | 224 MBH | 66 kW; based on piping and pick-up allowance of 1.15. |
| Efficiency | ||
| Combustion efficiency | 85.6 % | Printed for all three GS10 sizes. |
| Venting and air | ||
| Vent pipe collar | 8 in | Nominal diameter per the technical data manual. |
| Physical and connections | ||
| Weight, boiler shell (as delivered incl. burner) | 714 lb | 324 kg |
| Overall weight (with insulation, burner, control, fittings and draft hood) | 927 lb | 420 kg |
| Overall length | 1,007 mm | Boiler shell as delivered is 912 mm (36 in). |
| Overall width | 1,010 mm | |
| Overall height | 1,088 mm | 43 in; 1227 mm (48 in) with a Vitotronic control. |
| Operating limits and other | ||
| Fuel | Natural gas or propane | 7 in. w.c. minimum NG supply pressure; 11 in. w.c. for propane. |
| Cast iron sections | 7 | 6 burner tubes. |
| Boiler water content | 9.9 USG | |
| Maximum operating pressure | 60 psig | 4 bar. |
| Boiler supply / return | 2 in. NPTM | Safety supply 1½ in.; gas supply ¾ in. NPTM. |
Manuals
- Technical Data Manual — Vitogas 100 GS1 Series, doc 5167 462 v1.55167 462 v1.5 · 2011-02
- Installation Instructions — Vitogas 100 GS1, rev 1.31.3 · 2011-02
- Technical Data Manual — Vitogas 100 GS10 Series, doc 5167 466 v1.35167 466 v1.3 · 2011-02
- Service Instructions — Vitogas 100 GS10, rev 1.11.1 · 2007-11
Alerts documented for this model
None documented yet.
Frequently asked questions
What is the GS10-72 rated at?
300 MBH (88 kW) full-load input, 210 MBH at 70% partial load, 257 MBH (75 kW) full-load output, a 224 MBH Net I=B=R rating and 85.6% combustion efficiency.
Is the GS10-72 a two-stage boiler?
Yes. The Vitogas 100 GS10 series is documented as a natural gas/propane-fired two-stage boiler, with partial-load values based on 70% of rated full-load input.
What vent collar does the GS10-72 use?
A nominal 8 in. vent pipe collar, with approximately 100 CFM of combustion and dilution air per the technical data manual.
Questions about the Viessmann Vitogas 100 GS10-72?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Compare and explore
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- Vitogas 100 (GS1 / GS10) series hub
- Buying guide
Sources and verification
- Technical Data Manual — Vitogas 100 GS10 Series, doc 5167 466 v1.3 · 5167 466 v1.3 · accessed September 9, 2026
- Viessmann Canada — Historic manuals · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.