Head to head
NIBE S2125 Model 12 vs Worcester Bosch Greenstar 5800i AW 5kW
The NIBE S2125 Model 12 is a air/water heat pump, up to 8.4 kw heat output. The Worcester Bosch Greenstar 5800i AW 5kW is a r290 monobloc air source heat pump, 6.80 kw heat output.
Last reviewed 13 September 2026
Specifications side by side
| NIBE S2125 Model 12 | Worcester Bosch Greenstar 5800i AW 5kW | |
|---|---|---|
| Heat output | 6.80-7.60 kW (average climate), 8.4 kW (cold climate) | 6.80 kW at 7/35C |
| SCOP | 5.0 at 35C, 3.8 at 55C (average climate); 4.2 at 35C, 3.4 at 55C (cold climate) | 4.53 (MCS, 35C flow) |
| Dimensions | 1070 x 1130 x 820 mm (H x W x D) | 800 x 1100 x 540 mm (H x W x D) |
| Weight | 160 kg | 143 kg |
| Max flow temperature | up to 75C | 75C |
| Sound power | 49 dB(A) at nominal rating (EN12102) | - |
| Refrigerant | - | R290 (propane) |
| Sound pressure | - | 42 dB(A) |
Sources: NIBE S2125 Model 12, Worcester Bosch Greenstar 5800i AW 5kW. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the S2125 Model 12 if...
The larger NIBE S2125, sized for a medium house and rated to hold output down to -25C outdoor temperature. It shares its cabinet size with the smaller model but weighs 10 kg more for the larger compressor.
Full S2125 Model 12 specifications →Buy or hire the Greenstar 5800i AW 5kW if...
Worcester Bosch's entry-size 5800i AW, using the natural refrigerant R290 and reaching a 75C flow temperature for existing radiator systems. It is marketed as one of the quieter units in this size at 42 dB(A) sound pressure.
Full Greenstar 5800i AW 5kW specifications →Common questions
What is the difference between the NIBE S2125 Model 12 and the Worcester Bosch Greenstar 5800i AW 5kW?
The NIBE S2125 Model 12 is a air/water heat pump, up to 8.4 kW heat output; the Worcester Bosch Greenstar 5800i AW 5kW is a r290 monobloc air source heat pump, 6.80 kW heat output.
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