Head to head
NIBE S2125 Model 8 vs Worcester Bosch Greenstar 4000 30kW combi
The NIBE S2125 Model 8 is a air/water heat pump, up to 5.4 kw heat output. The Worcester Bosch Greenstar 4000 30kW combi is a gas combi boiler, 30 kw hot water output.
Last reviewed 13 September 2026
Specifications side by side
| NIBE S2125 Model 8 | Worcester Bosch Greenstar 4000 30kW combi | |
|---|---|---|
| Dimensions | 1070 x 1130 x 820 mm (H x W x D) | 710 x 400 x 310 mm |
| Weight | 150 kg | 32.3 kg |
| Heat output | 5.33 kW (average climate), 5.4 kW (cold climate) | - |
| SCOP | 5.0 at 35C, 3.7 at 55C (average climate); 4.1 at 35C, 3.2 at 55C (cold climate) | - |
| Sound power | 49 dB(A) at nominal rating (EN12102) | - |
| Max flow temperature | up to 75C | - |
| Hot water output | - | 30 kW |
| Central heating output | - | 30 kW |
| ErP class | - | A |
| Seasonal efficiency | - | 94% |
| Warranty | - | 10 years |
| Hot water flow rate | - | 12.3 litres per minute |
Sources: NIBE S2125 Model 8, 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 S2125 Model 8 if...
A smaller NIBE S2125 rated to keep working in cold climates, reaching up to 65C flow even at -25C outdoors. It suits a smaller house where cold-weather reliability matters more than raw output.
Full S2125 Model 8 specifications →Buy or hire the Greenstar 4000 30kW combi if...
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 NIBE S2125 Model 8 and the Worcester Bosch Greenstar 4000 30kW combi?
The NIBE S2125 Model 8 is a air/water heat pump, up to 5.4 kW heat output; the Worcester Bosch Greenstar 4000 30kW combi is a gas combi boiler, 30 kW hot water output.
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