Head to head
NIBE S2125 Model 8 vs Viessmann Vitocal 150-A13
The NIBE S2125 Model 8 is a air/water heat pump, up to 5.4 kw heat output. The Viessmann Vitocal 150-A13 is a r290 air source heat pump, 8.1 kw heat output.
Last reviewed 13 September 2026
Specifications side by side
| NIBE S2125 Model 8 | Viessmann Vitocal 150-A13 | |
|---|---|---|
| Heat output | 5.33 kW (average climate), 5.4 kW (cold climate) | 8.1 kW at A7/W35 |
| Sound power | 49 dB(A) at nominal rating (EN12102) | 51 dB(A) assessed total at A7/W55 |
| Dimensions | 1070 x 1130 x 820 mm (H x W x D) | 920 x 450 x 360 mm (H x W x D) (indoor unit); 841 x 1144 x 600 mm (H x W x D, single fan) (outdoor unit) |
| Weight | 150 kg | 162 kg (single fan) (outdoor unit) |
| Max flow temperature | up to 75C | 70C down to -10C outdoor |
| SCOP | 5.0 at 35C, 3.7 at 55C (average climate); 4.1 at 35C, 3.2 at 55C (cold climate) | - |
| COP | - | 4.7-5.0 at A7/W35 |
| Refrigerant | - | R290 (propane), GWP 0.02 |
Sources: NIBE S2125 Model 8, Viessmann Vitocal 150-A13. 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 Vitocal 150-A13 if...
A Vitocal 150-A monobloc-style split heat pump using the natural refrigerant R290, rated at 8.1kW and reaching a 70C flow for boiler-replacement work. Viessmann-trained installers can extend the standard warranty on registration.
Full Vitocal 150-A13 specifications →Common questions
What is the difference between the NIBE S2125 Model 8 and the Viessmann Vitocal 150-A13?
The NIBE S2125 Model 8 is a air/water heat pump, up to 5.4 kW heat output; the Viessmann Vitocal 150-A13 is a r290 air source heat pump, 8.1 kW heat output.
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