Head to head
Glow-worm Energy Combi 30C 30kW vs Vaillant ecoFIT pure 835 35kW combi
The Vaillant ecoFIT pure 835 35kW combi comes with 3 years more warranty and has 4kW more hot water output.
Last reviewed 13 September 2026
Key differences
- Warranty: the Vaillant ecoFIT pure 835 35kW combi comes with 3 years more warranty.
- Hot water output: the Vaillant ecoFIT pure 835 35kW combi has 4kW more hot water output.
- Hot water flow rate: the Vaillant ecoFIT pure 835 35kW combi runs 1.6 litres a minute more hot water.
- Central heating output: the Vaillant ecoFIT pure 835 35kW combi puts out 2kW more to the radiators.
Specifications side by side
| Glow-worm Energy Combi 30C 30kW | Vaillant ecoFIT pure 835 35kW combi | |
|---|---|---|
| Hot water output | 30.6 kW | 35 kW |
| Central heating output | 25 kW | 26.7 kW |
| ErP class | A | A |
| Seasonal efficiency | 94% | 94% |
| Dimensions | 700 x 390 x 280 mm | 700 x 390 x 295 mm |
| Weight | 33 kg | 33 kg |
| Warranty | 7 years | 10 years when installed by Vaillant Advance installer |
| Hot water flow rate | 12.5 litres per minute | 14.1 litres per minute |
Sources: Glow-worm Energy Combi 30C 30kW, 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 Energy Combi 30C 30kW if...
A gas combi boiler with 30.6 kW of hot water output, sized for a three-bed house with one or two bathrooms. It delivers about 12.5 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 30C 30kW specifications →Buy or hire the ecoFIT pure 835 35kW combi if...
- you want one that comes with 3 years more warranty
- you want one that has 4kW more hot water output
- you want one that runs 1.6 litres a minute more hot water
- you want one that puts out 2kW more to the radiators
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 Glow-worm Energy Combi 30C 30kW and the Vaillant ecoFIT pure 835 35kW combi?
The Vaillant ecoFIT pure 835 35kW combi comes with 3 years more warranty and has 4kW more hot water output. The Glow-worm Energy Combi 30C 30kW is a gas combi boiler, 30.6 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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