Head to head
Baxi 800 Combi 2 36kW vs Vaillant ecoFIT pure 835 35kW combi
The Baxi 800 Combi 2 36kW runs 0.9 litres a minute more hot water and has 1kW more hot water output. The Vaillant ecoFIT pure 835 35kW combi puts out 0kW more to the radiators and is 1 points more efficient.
Last reviewed 13 September 2026
Key differences
- Hot water flow rate: the Baxi 800 Combi 2 36kW runs 0.9 litres a minute more hot water.
- Hot water output: the Baxi 800 Combi 2 36kW has 1kW more hot water output.
- Central heating output: the Vaillant ecoFIT pure 835 35kW combi puts out 0kW more to the radiators.
- Seasonal efficiency: the Vaillant ecoFIT pure 835 35kW combi is 1 points more efficient.
Specifications side by side
| Baxi 800 Combi 2 36kW | Vaillant ecoFIT pure 835 35kW combi | |
|---|---|---|
| Hot water output | 36 kW | 35 kW |
| Central heating output | 26.4 kW | 26.7 kW |
| ErP class | A | A |
| Seasonal efficiency | 93% | 94% |
| Dimensions | 700 x 390 x 285 mm | 700 x 390 x 295 mm |
| Weight | 29.5 kg | 33 kg |
| Warranty | 10 years | 10 years when installed by Vaillant Advance installer |
| Hot water flow rate | 15 litres per minute | 14.1 litres per minute |
Sources: Baxi 800 Combi 2 36kW, Vaillant ecoFIT pure 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 36kW if...
- you want one that runs 0.9 litres a minute more hot water
- you want one that has 1kW more hot water output
A gas combi boiler with 36 kW of hot water output, sized for a larger house with two bathrooms. It delivers about 15 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 36kW specifications →Buy or hire the ecoFIT pure 835 35kW combi if...
- you want one that puts out 0kW more to the radiators
- 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 14.1 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 835 35kW combi specifications →Common questions
What is the difference between the Baxi 800 Combi 2 36kW and the Vaillant ecoFIT pure 835 35kW combi?
The Baxi 800 Combi 2 36kW runs 0.9 litres a minute more hot water and has 1kW more hot water output. The Vaillant ecoFIT pure 835 35kW combi puts out 0kW more to the radiators and is 1 points more efficient. The Baxi 800 Combi 2 36kW is a gas combi boiler, 36 kW hot water output; the Vaillant ecoFIT pure 835 35kW combi is a gas combi boiler, 35 kW hot water output.
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