Head to head
Vaillant ecoTEC Pro 24kW combi vs Worcester Bosch Greenstar 4000 25kW combi
The Worcester Bosch Greenstar 4000 25kW combi comes with 8 years more warranty and runs 0.9 litres a minute more hot water.
Last reviewed 13 September 2026
Key differences
- Warranty: the Worcester Bosch Greenstar 4000 25kW combi comes with 8 years more warranty.
- Hot water flow rate: the Worcester Bosch Greenstar 4000 25kW combi runs 0.9 litres a minute more hot water.
- Hot water output: the Worcester Bosch Greenstar 4000 25kW combi has 2kW more hot water output.
- Seasonal efficiency: the Worcester Bosch Greenstar 4000 25kW combi is 1 points more efficient.
- Central heating output: the Worcester Bosch Greenstar 4000 25kW combi puts out 0kW more to the radiators.
Specifications side by side
| Vaillant ecoTEC Pro 24kW combi | Worcester Bosch Greenstar 4000 25kW combi | |
|---|---|---|
| Hot water output | 23.4 kW | 25 kW |
| Central heating output | 24.8 kW | 25 kW |
| ErP class | A | A |
| Seasonal efficiency | 93% | 94% |
| Dimensions | 720 x 440 x 338 mm | 710 x 400 x 310 mm |
| Weight | 38 kg | 32.0 kg |
| Warranty | 2 years standard, 7 years with Vaillant Advance registration | 10 years |
| Hot water flow rate | 9.6 litres per minute | 10.5 litres per minute |
Sources: Vaillant ecoTEC Pro 24kW combi, Worcester Bosch Greenstar 4000 25kW combi. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the ecoTEC Pro 24kW combi if...
A gas combi boiler with 23.4 kW of hot water output, sized for a flat or small house with one bathroom. It delivers about 9.6 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 2 years standard, 7 years with Vaillant Advance registration. Seasonal efficiency is 93%.
Full ecoTEC Pro 24kW combi specifications →Buy or hire the Greenstar 4000 25kW combi if...
- you want one that comes with 8 years more warranty
- you want one that runs 0.9 litres a minute more hot water
- you want one that has 2kW more hot water output
- you want one that is 1 points more efficient
- you want one that puts out 0kW more to the radiators
A gas combi boiler with 25 kW of hot water output, sized for a flat or small house with one bathroom. It delivers about 10.5 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 10 years. Seasonal efficiency is 94%.
Full Greenstar 4000 25kW combi specifications →Common questions
What is the difference between the Vaillant ecoTEC Pro 24kW combi and the Worcester Bosch Greenstar 4000 25kW combi?
The Worcester Bosch Greenstar 4000 25kW combi comes with 8 years more warranty and runs 0.9 litres a minute more hot water. The Vaillant ecoTEC Pro 24kW combi is a gas combi boiler, 23.4 kW hot water output; the Worcester Bosch Greenstar 4000 25kW combi is a gas combi boiler, 25 kW hot water output.
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