Head to head
Glow-worm Energy Combi 25C 25kW vs Worcester Bosch Greenstar 4000 30kW combi
The Worcester Bosch Greenstar 4000 30kW combi puts out 12kW more to the radiators and comes with 3 years more warranty.
Last reviewed 13 September 2026
Key differences
- Central heating output: the Worcester Bosch Greenstar 4000 30kW combi puts out 12kW more to the radiators.
- Warranty: the Worcester Bosch Greenstar 4000 30kW combi comes with 3 years more warranty.
- Hot water flow rate: the Worcester Bosch Greenstar 4000 30kW combi runs 1.9 litres a minute more hot water.
- Hot water output: the Worcester Bosch Greenstar 4000 30kW combi has 4kW more hot water output.
Specifications side by side
| Glow-worm Energy Combi 25C 25kW | Worcester Bosch Greenstar 4000 30kW combi | |
|---|---|---|
| Hot water output | 25.7 kW | 30 kW |
| Central heating output | 18 kW | 30 kW |
| ErP class | A | A |
| Seasonal efficiency | 94% | 94% |
| Dimensions | 700 x 390 x 280 mm | 710 x 400 x 310 mm |
| Weight | 32 kg | 32.3 kg |
| Warranty | 7 years | 10 years |
| Hot water flow rate | 10.4 litres per minute | 12.3 litres per minute |
Sources: Glow-worm Energy Combi 25C 25kW, 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 Energy Combi 25C 25kW if...
A gas combi boiler with 25.7 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: 7 years. Seasonal efficiency is 94%.
Full Energy Combi 25C 25kW specifications →Buy or hire the Greenstar 4000 30kW combi if...
- you want one that puts out 12kW more to the radiators
- you want one that comes with 3 years more warranty
- you want one that runs 1.9 litres a minute more hot water
- you want one that has 4kW more hot water output
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 Glow-worm Energy Combi 25C 25kW and the Worcester Bosch Greenstar 4000 30kW combi?
The Worcester Bosch Greenstar 4000 30kW combi puts out 12kW more to the radiators and comes with 3 years more warranty. The Glow-worm Energy Combi 25C 25kW is a gas combi boiler, 25.7 kW hot water output; the Worcester Bosch Greenstar 4000 30kW combi is a gas combi boiler, 30 kW hot water output.
GetBrent is an independent directory and is not a dealer for, nor affiliated with, either manufacturer. Model and brand names are the trademarks of their owners.