Head to head
Glow-worm Energy Combi 25C 25kW vs Grant Aerona3 R32 17kW
The Glow-worm Energy Combi 25C 25kW is a gas combi boiler, 25.7 kw hot water output. The Grant Aerona3 R32 17kW is a r32 inverter driven air source heat pump, 17 kw heat output.
Last reviewed 13 September 2026
Specifications side by side
| Glow-worm Energy Combi 25C 25kW | Grant Aerona3 R32 17kW | |
|---|---|---|
| Dimensions | 700 x 390 x 280 mm | 1418 x 1024 x 403 mm (H x W x D) |
| Weight | 32 kg | 118 kg |
| Warranty | 7 years | 7 years when installed by a Grant G1 accredited installer |
| Hot water output | 25.7 kW | - |
| Central heating output | 18 kW | - |
| ErP class | A | - |
| Seasonal efficiency | 94% | - |
| Hot water flow rate | 10.4 litres per minute | - |
| Heat output | - | 17 kW |
| SCOP | - | 4.54 (35C flow), 3.57 (55C flow) |
| Refrigerant | - | R32 |
Sources: Glow-worm Energy Combi 25C 25kW, Grant Aerona3 R32 17kW. 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 Aerona3 R32 17kW if...
A 17kW 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 17kW specifications →Common questions
What is the difference between the Glow-worm Energy Combi 25C 25kW and the Grant Aerona3 R32 17kW?
The Glow-worm Energy Combi 25C 25kW is a gas combi boiler, 25.7 kW hot water output; the Grant Aerona3 R32 17kW is a r32 inverter driven air source heat pump, 17 kW heat output.
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