Head to head
Vaillant ecoFIT pure 825 25kW combi vs Worcester Bosch Greenstar 5800i AW 7kW
The Vaillant ecoFIT pure 825 25kW combi is a gas combi boiler, 25.2 kw hot water output. The Worcester Bosch Greenstar 5800i AW 7kW is a r290 monobloc air source heat pump, 7.97 kw heat output.
Last reviewed 13 September 2026
Specifications side by side
| Vaillant ecoFIT pure 825 25kW combi | Worcester Bosch Greenstar 5800i AW 7kW | |
|---|---|---|
| Dimensions | 700 x 390 x 295 mm | 800 x 1100 x 540 mm (H x W x D) |
| Weight | 32 kg | 143 kg |
| Hot water output | 25.2 kW | - |
| Central heating output | 19.1 kW | - |
| ErP class | A | - |
| Seasonal efficiency | 94% | - |
| Warranty | 10 years when installed by Vaillant Advance installer | - |
| Hot water flow rate | 10.4 litres per minute | - |
| Heat output | - | 7.97 kW at 7/35C |
| SCOP | - | 4.54 (MCS, 35C flow) |
| Refrigerant | - | R290 (propane) |
| Sound pressure | - | 42 dB(A) |
| Max flow temperature | - | 75C |
Sources: Vaillant ecoFIT pure 825 25kW combi, Worcester Bosch Greenstar 5800i AW 7kW. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the ecoFIT pure 825 25kW combi if...
A gas combi boiler with 25.2 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: 10 years when installed by Vaillant Advance installer. Seasonal efficiency is 94%.
Full ecoFIT pure 825 25kW combi specifications →Buy or hire the Greenstar 5800i AW 7kW if...
The larger 5800i AW unit, for a slightly bigger house than the 5kW model while sharing the same cabinet size and 42 dB(A) sound rating. Its R290 refrigerant and 75C flow temperature suit a radiator-based retrofit.
Full Greenstar 5800i AW 7kW specifications →Common questions
What is the difference between the Vaillant ecoFIT pure 825 25kW combi and the Worcester Bosch Greenstar 5800i AW 7kW?
The Vaillant ecoFIT pure 825 25kW combi is a gas combi boiler, 25.2 kW hot water output; the Worcester Bosch Greenstar 5800i AW 7kW is a r290 monobloc air source heat pump, 7.97 kW heat output.
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