Head to head
Baxi 800 Combi 2 30kW vs Viessmann Vitodens 100-W 30kW combi
The Baxi 800 Combi 2 30kW comes with 5 years more warranty. The Viessmann Vitodens 100-W 30kW combi runs 3.4 litres a minute more hot water and puts out 4kW more to the radiators.
Last reviewed 13 September 2026
Key differences
- Warranty: the Baxi 800 Combi 2 30kW comes with 5 years more warranty.
- Hot water flow rate: the Viessmann Vitodens 100-W 30kW combi runs 3.4 litres a minute more hot water.
- Central heating output: the Viessmann Vitodens 100-W 30kW combi puts out 4kW more to the radiators.
- Hot water output: the Viessmann Vitodens 100-W 30kW combi has 2kW more hot water output.
- Seasonal efficiency: the Viessmann Vitodens 100-W 30kW combi is 5 points more efficient.
Specifications side by side
| Baxi 800 Combi 2 30kW | Viessmann Vitodens 100-W 30kW combi | |
|---|---|---|
| Hot water output | 30 kW | 31.7 kW |
| Central heating output | 21.2 kW | 25 kW |
| ErP class | A | A |
| Seasonal efficiency | 93% | 98% |
| Dimensions | 700 x 390 x 285 mm | 700 x 400 x 360 mm |
| Warranty | 10 years | 5 years |
| Hot water flow rate | 12.2 litres per minute | 15.6 litres per minute |
| Weight | - | 35-38 kg |
Sources: Baxi 800 Combi 2 30kW, Viessmann Vitodens 100-W 30kW combi. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the 800 Combi 2 30kW if...
- you want one that comes with 5 years more warranty
A gas combi boiler with 30 kW of hot water output, sized for a three-bed house with one or two bathrooms. It delivers about 12.2 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 10 years. Seasonal efficiency is 93%.
Full 800 Combi 2 30kW specifications →Buy or hire the Vitodens 100-W 30kW combi if...
- you want one that runs 3.4 litres a minute more hot water
- you want one that puts out 4kW more to the radiators
- you want one that has 2kW more hot water output
- you want one that is 5 points more efficient
A gas combi boiler with 31.7 kW of hot water output, sized for a three-bed house with one or two bathrooms. It delivers about 15.6 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 5 years. Seasonal efficiency is 98%.
Full Vitodens 100-W 30kW combi specifications →Common questions
What is the difference between the Baxi 800 Combi 2 30kW and the Viessmann Vitodens 100-W 30kW combi?
The Baxi 800 Combi 2 30kW comes with 5 years more warranty. The Viessmann Vitodens 100-W 30kW combi runs 3.4 litres a minute more hot water and puts out 4kW more to the radiators. The Baxi 800 Combi 2 30kW is a gas combi boiler, 30 kW hot water output; the Viessmann Vitodens 100-W 30kW combi is a gas combi boiler, 31.7 kW hot water output.
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