Head to head
Glow-worm Energy Combi 25C 25kW vs Worcester Bosch Greenstar 4000 25kW combi
The Worcester Bosch Greenstar 4000 25kW combi comes with 3 years more warranty and puts out 7kW more to the radiators. The Glow-worm Energy Combi 25C 25kW has 1kW more hot water output.
Last reviewed 13 September 2026
Key differences
- Warranty: the Worcester Bosch Greenstar 4000 25kW combi comes with 3 years more warranty.
- Central heating output: the Worcester Bosch Greenstar 4000 25kW combi puts out 7kW more to the radiators.
- Hot water output: the Glow-worm Energy Combi 25C 25kW has 1kW more hot water output.
- Hot water flow rate: the Worcester Bosch Greenstar 4000 25kW combi runs 0.1 litres a minute more hot water.
Specifications side by side
| Glow-worm Energy Combi 25C 25kW | Worcester Bosch Greenstar 4000 25kW combi | |
|---|---|---|
| Hot water output | 25.7 kW | 25 kW |
| Central heating output | 18 kW | 25 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 | 32.0 kg |
| Warranty | 7 years | 10 years |
| Hot water flow rate | 10.4 litres per minute | 10.5 litres per minute |
Sources: Glow-worm Energy Combi 25C 25kW, 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 Energy Combi 25C 25kW if...
- you want one that has 1kW more hot water output
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 25kW combi if...
- you want one that comes with 3 years more warranty
- you want one that puts out 7kW more to the radiators
- you want one that runs 0.1 litres a minute more hot water
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 Glow-worm Energy Combi 25C 25kW and the Worcester Bosch Greenstar 4000 25kW combi?
The Worcester Bosch Greenstar 4000 25kW combi comes with 3 years more warranty and puts out 7kW more to the radiators. The Glow-worm Energy Combi 25C 25kW has 1kW more hot water output. The Glow-worm Energy Combi 25C 25kW is a gas combi boiler, 25.7 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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