Head to head
Glow-worm Energy Combi 25C 25kW vs NIBE S2125 Model 12
The Glow-worm Energy Combi 25C 25kW is a gas combi boiler, 25.7 kw hot water 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
| Glow-worm Energy Combi 25C 25kW | NIBE S2125 Model 12 | |
|---|---|---|
| Dimensions | 700 x 390 x 280 mm | 1070 x 1130 x 820 mm (H x W x D) |
| Weight | 32 kg | 160 kg |
| Hot water output | 25.7 kW | - |
| Central heating output | 18 kW | - |
| ErP class | A | - |
| Seasonal efficiency | 94% | - |
| Warranty | 7 years | - |
| Hot water flow rate | 10.4 litres per minute | - |
| Heat output | - | 6.80-7.60 kW (average climate), 8.4 kW (cold climate) |
| SCOP | - | 5.0 at 35C, 3.8 at 55C (average climate); 4.2 at 35C, 3.4 at 55C (cold climate) |
| Sound power | - | 49 dB(A) at nominal rating (EN12102) |
| Max flow temperature | - | up to 75C |
Sources: Glow-worm Energy Combi 25C 25kW, NIBE S2125 Model 12. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the Energy Combi 25C 25kW if...
A gas combi boiler with 25.7 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: 7 years. Seasonal efficiency is 94%.
Full Energy Combi 25C 25kW 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 Glow-worm Energy Combi 25C 25kW and the NIBE S2125 Model 12?
The Glow-worm Energy Combi 25C 25kW is a gas combi boiler, 25.7 kW hot water output; the NIBE S2125 Model 12 is a air/water heat pump, up to 8.4 kW heat output.
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