Head to head
Worcester Bosch Greenstar 4000 25kW combi vs Worcester Bosch Greenstar 4000 30kW combi
The Worcester Bosch Greenstar 4000 30kW combi has 5kW more hot water output and puts out 5kW more to the radiators.
Last reviewed 13 September 2026
Key differences
- Hot water output: the Worcester Bosch Greenstar 4000 30kW combi has 5kW more hot water output.
- Central heating output: the Worcester Bosch Greenstar 4000 30kW combi puts out 5kW more to the radiators.
- Hot water flow rate: the Worcester Bosch Greenstar 4000 30kW combi runs 1.8 litres a minute more hot water.
Specifications side by side
| Worcester Bosch Greenstar 4000 25kW combi | Worcester Bosch Greenstar 4000 30kW combi | |
|---|---|---|
| Hot water output | 25 kW | 30 kW |
| Central heating output | 25 kW | 30 kW |
| ErP class | A | A |
| Seasonal efficiency | 94% | 94% |
| Dimensions | 710 x 400 x 310 mm | 710 x 400 x 310 mm |
| Weight | 32.0 kg | 32.3 kg |
| Warranty | 10 years | 10 years |
| Hot water flow rate | 10.5 litres per minute | 12.3 litres per minute |
Sources: Worcester Bosch Greenstar 4000 25kW combi, Worcester Bosch Greenstar 4000 30kW combi. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the Greenstar 4000 25kW combi if...
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 →Buy or hire the Greenstar 4000 30kW combi if...
- you want one that has 5kW more hot water output
- you want one that puts out 5kW more to the radiators
- you want one that runs 1.8 litres a minute more hot water
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 12.3 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 30kW combi specifications →Common questions
What is the difference between the Worcester Bosch Greenstar 4000 25kW combi and the Worcester Bosch Greenstar 4000 30kW combi?
The Worcester Bosch Greenstar 4000 30kW combi has 5kW more hot water output and puts out 5kW more to the radiators. The Worcester Bosch Greenstar 4000 25kW combi is a gas combi boiler, 25 kW hot water output; the Worcester Bosch Greenstar 4000 30kW combi is a gas combi boiler, 30 kW hot water output.
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