Head to head
Baxi 800 Combi 2 30kW vs Vaillant ecoTEC plus 835 35kW combi
The Vaillant ecoTEC plus 835 35kW combi puts out 12kW more to the radiators and runs 2.1 litres a minute more hot water.
Last reviewed 13 September 2026
Key differences
- Central heating output: the Vaillant ecoTEC plus 835 35kW combi puts out 12kW more to the radiators.
- Hot water flow rate: the Vaillant ecoTEC plus 835 35kW combi runs 2.1 litres a minute more hot water.
- Hot water output: the Vaillant ecoTEC plus 835 35kW combi has 5kW more hot water output.
- Seasonal efficiency: the Vaillant ecoTEC plus 835 35kW combi is 1 points more efficient.
Specifications side by side
| Baxi 800 Combi 2 30kW | Vaillant ecoTEC plus 835 35kW combi | |
|---|---|---|
| Hot water output | 30 kW | 35 kW |
| Central heating output | 21.2 kW | 32.8 kW |
| ErP class | A | A |
| Seasonal efficiency | 93% | 94% |
| Dimensions | 700 x 390 x 285 mm | 720 x 440 x 372 mm |
| Warranty | 10 years | 10 years with Vaillant Advance Boiler Protection Kit |
| Hot water flow rate | 12.2 litres per minute | 14.3 litres per minute |
Sources: Baxi 800 Combi 2 30kW, Vaillant ecoTEC plus 835 35kW 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...
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 ecoTEC plus 835 35kW combi if...
- you want one that puts out 12kW more to the radiators
- you want one that runs 2.1 litres a minute more hot water
- you want one that has 5kW more hot water output
- you want one that is 1 points more efficient
A gas combi boiler with 35 kW of hot water output, sized for a larger house with two bathrooms. It delivers about 14.3 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 10 years with Vaillant Advance Boiler Protection Kit. Seasonal efficiency is 94%.
Full ecoTEC plus 835 35kW combi specifications →Common questions
What is the difference between the Baxi 800 Combi 2 30kW and the Vaillant ecoTEC plus 835 35kW combi?
The Vaillant ecoTEC plus 835 35kW combi puts out 12kW more to the radiators and runs 2.1 litres a minute more hot water. The Baxi 800 Combi 2 30kW is a gas combi boiler, 30 kW hot water output; the Vaillant ecoTEC plus 835 35kW combi is a gas combi boiler, 35 kW hot water output.
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