Head to head
Vaillant ecoFIT pure 825 25kW combi vs Viessmann Vitodens 050-W 35kW combi
The Vaillant ecoFIT pure 825 25kW combi comes with 7 years more warranty. The Viessmann Vitodens 050-W 35kW combi puts out 13kW more to the radiators and has 9kW more hot water output.
Last reviewed 13 September 2026
Key differences
- Warranty: the Vaillant ecoFIT pure 825 25kW combi comes with 7 years more warranty.
- Central heating output: the Viessmann Vitodens 050-W 35kW combi puts out 13kW more to the radiators.
- Hot water output: the Viessmann Vitodens 050-W 35kW combi has 9kW more hot water output.
- Hot water flow rate: the Viessmann Vitodens 050-W 35kW combi runs 3.7 litres a minute more hot water.
- Seasonal efficiency: the Vaillant ecoFIT pure 825 25kW combi is 1 points more efficient.
Specifications side by side
| Vaillant ecoFIT pure 825 25kW combi | Viessmann Vitodens 050-W 35kW combi | |
|---|---|---|
| Hot water output | 25.2 kW | 34.2 kW |
| Central heating output | 19.1 kW | 32 kW |
| ErP class | A | A |
| Seasonal efficiency | 94% | 93% |
| Dimensions | 700 x 390 x 295 mm | 700 x 400 x 300 mm |
| Warranty | 10 years when installed by Vaillant Advance installer | 3 years |
| Hot water flow rate | 10.4 litres per minute | 14.1 litres per minute |
| Weight | 32 kg | - |
Sources: Vaillant ecoFIT pure 825 25kW combi, Viessmann Vitodens 050-W 35kW combi. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the ecoFIT pure 825 25kW combi if...
- you want one that comes with 7 years more warranty
- you want one that is 1 points more efficient
A gas combi boiler with 25.2 kW of hot water output, sized for a flat or small house with one bathroom. It delivers about 10.4 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 10 years when installed by Vaillant Advance installer. Seasonal efficiency is 94%.
Full ecoFIT pure 825 25kW combi specifications →Buy or hire the Vitodens 050-W 35kW combi if...
- you want one that puts out 13kW more to the radiators
- you want one that has 9kW more hot water output
- you want one that runs 3.7 litres a minute more hot water
A gas combi boiler with 34.2 kW of hot water output, sized for a larger house with two bathrooms. It delivers about 14.1 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 3 years. Seasonal efficiency is 93%.
Full Vitodens 050-W 35kW combi specifications →Common questions
What is the difference between the Vaillant ecoFIT pure 825 25kW combi and the Viessmann Vitodens 050-W 35kW combi?
The Vaillant ecoFIT pure 825 25kW combi comes with 7 years more warranty. The Viessmann Vitodens 050-W 35kW combi puts out 13kW more to the radiators and has 9kW more hot water output. The Vaillant ecoFIT pure 825 25kW combi is a gas combi boiler, 25.2 kW hot water output; the Viessmann Vitodens 050-W 35kW combi is a gas combi boiler, 34.2 kW hot water output.
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