Viessmann · Vitogas 100 (GS1 / GS10)
Viessmann Vitogas 100 GS1-48
The Vitogas 100 GS1-48 is the second-largest GS1 boiler: 190 MBH input (56 kW), 161 MBH output and 85.5% AFUE on a six-section chassis.
Key figures
- Max input
- —
- Max CSA output
- —
- AFUE
- 85.5 %
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Viessmann Vitogas 100 GS1-48 in practice
The GS1-48 fires at 190 MBH (56 kW) input with 161 MBH (47 kW) output and a 140 MBH (41 kW) Net I=B=R rating at 85.5% AFUE. It carries six cast-iron sections and seven burners in a 864 x 930 mm (34 x 36½ in) cabinet, weighing 481 lb (218 kg) with 4.7 USG of boiler water.
The larger width reflects the added sections; height stays 845 mm and the maximum operating pressure 60 psig. The GS1 line is documented in Viessmann Canada's historic manuals, including the technical data manual (doc 5167 462 v1.5) and installation instructions.
Best suited to
- Existing GS1-48 installations needing printed ratings
- Larger residential loads between 165 and 240 MBH
- Comparing six-section GS1 builds
Applicability and support
- Model number
- GS1-48
- 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 (natural gas) | 190 MBH | 56 kW, per the technical data manual |
| Output | ||
| CSA output / DOE heating capacity | 161 MBH | 47 kW |
| Net I=B=R rating | 140 MBH | 41 kW; based on piping and pick-up allowance of 1.15. |
| Efficiency | ||
| Efficiency (AFUE) | 85.5 % | With intermittent pilot electronic ignition and vent damper. |
| Venting and air | ||
| Vent pipe collar | Per model | 5 to 7 in. outside diameter per the technical data manual. |
| Physical and connections | ||
| Weight (boiler with insulation, burner and control) | 481 lb | 218 kg |
| Overall length | 864 mm | Printed as 34 in; heights 33¼ in (845 mm) with control in operating position. |
| Overall width | 930 mm | Printed as 36½ in |
| Overall height (operation) | 845 mm | 33¼ in; 955 mm with control in operation position, 1180 mm for servicing. |
| Operating limits and other | ||
| Fuel | Natural gas or propane | 5 in. w.c. minimum NG supply pressure; 11 in. w.c. for propane. |
| Cast iron sections | 6 | 7 burners. |
| Boiler water content | 4.7 USG | |
| Maximum operating pressure | 60 psig | |
| Boiler supply / return | 1½ in. male thread | Gas supply ½ in. NPT. |
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 GS1-48 rated at?
190 MBH (56 kW) input, 161 MBH (47 kW) output, a 140 MBH (41 kW) Net I=B=R rating and 85.5% AFUE.
How wide is the GS1-48?
930 mm (36½ in) overall with 864 mm (34 in) length and 845 mm (33¼ in) height, at 481 lb (218 kg).
Can the GS1-48 serve light-commercial loads?
The GS1 range is documented as Viessmann's residential fully assembled boiler; larger commercial needs in this family were served by the GS10 series (300-380 MBH). Sizing always follows the load calculation.
Questions about the Viessmann Vitogas 100 GS1-48?
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
- Viessmann Vitogas 100 GS1-48 vs GS1-60Comparison
- Viessmann Vitogas 100 GS1-22Same series
- Viessmann Vitogas 100 GS1-29Same series
- Viessmann Vitogas 100 GS1-35Same series
- Viessmann Vitogas 100 GS1-42Same series
- Viessmann Vitogas 100 GS1-60Same series
- Viessmann Vitogas 100 GS10-72Same series
- Viessmann Vitogas 100 GS10-84Same series
- Viessmann Vitogas 100 GS10-96Same series
- Vitogas 100 (GS1 / GS10) series hub
- Buying guide
Sources and verification
- Technical Data Manual — Vitogas 100 GS1 Series, doc 5167 462 v1.5 · 5167 462 v1.5 · 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.