Head to head
Grant Aerona3 R32 6kW vs NIBE S2125 Model 12
The Grant Aerona3 R32 6kW is a r32 inverter driven air source heat pump, 6 kw heat output. The NIBE S2125 Model 12 is a air/water heat pump, up to 8.4 kw heat output.
Last reviewed 13 September 2026
Specifications side by side
| Grant Aerona3 R32 6kW | NIBE S2125 Model 12 | |
|---|---|---|
| Heat output | 6 kW | 6.80-7.60 kW (average climate), 8.4 kW (cold climate) |
| SCOP | 4.61 (35C flow), 3.29 (55C flow) | 5.0 at 35C, 3.8 at 55C (average climate); 4.2 at 35C, 3.4 at 55C (cold climate) |
| Dimensions | 675 x 898 x 379.4 mm (H x W x D) | 1070 x 1130 x 820 mm (H x W x D) |
| Weight | 51 kg | 160 kg |
| Refrigerant | R32 | - |
| Warranty | 7 years when installed by a Grant G1 accredited installer | - |
| Sound power | - | 49 dB(A) at nominal rating (EN12102) |
| Max flow temperature | - | up to 75C |
Sources: Grant Aerona3 R32 6kW, NIBE S2125 Model 12. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the Aerona3 R32 6kW if...
A 6kW R32 inverter driven heat pump from Grant's Aerona3 range, a common choice for off-gas-grid homes that previously ran an oil boiler. It carries a 7 year warranty through Grant's G1 installer scheme, one of the longer standard terms in this category.
Full Aerona3 R32 6kW specifications →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 →Common questions
What is the difference between the Grant Aerona3 R32 6kW and the NIBE S2125 Model 12?
The Grant Aerona3 R32 6kW is a r32 inverter driven air source heat pump, 6 kW heat output; the NIBE S2125 Model 12 is a air/water heat pump, up to 8.4 kW heat output.
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