Head to head
Grant Aerona3 R32 17kW vs Viessmann Vitodens 100-W 35kW combi
The Grant Aerona3 R32 17kW comes with 2 years more warranty.
Last reviewed 13 September 2026
Key differences
- Warranty: the Grant Aerona3 R32 17kW comes with 2 years more warranty.
Specifications side by side
| Grant Aerona3 R32 17kW | Viessmann Vitodens 100-W 35kW combi | |
|---|---|---|
| Dimensions | 1418 x 1024 x 403 mm (H x W x D) | 700 x 400 x 360 mm |
| Weight | 118 kg | 35 kg |
| Warranty | 7 years when installed by a Grant G1 accredited installer | 5 years |
| Heat output | 17 kW | - |
| SCOP | 4.54 (35C flow), 3.57 (55C flow) | - |
| Refrigerant | R32 | - |
| Hot water output | - | 34.9 kW |
| Central heating output | - | 32 kW |
| ErP class | - | A |
| Seasonal efficiency | - | 98% |
| Hot water flow rate | - | 17 litres per minute |
Sources: Grant Aerona3 R32 17kW, Viessmann Vitodens 100-W 35kW combi. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the Aerona3 R32 17kW if...
- you want one that comes with 2 years more warranty
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 →Buy or hire the Vitodens 100-W 35kW combi if...
A gas combi boiler with 34.9 kW of hot water output, sized for a larger house with two bathrooms. It delivers about 17 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 5 years. Seasonal efficiency is 98%.
Full Vitodens 100-W 35kW combi specifications →Common questions
What is the difference between the Grant Aerona3 R32 17kW and the Viessmann Vitodens 100-W 35kW combi?
The Grant Aerona3 R32 17kW comes with 2 years more warranty. The Grant Aerona3 R32 17kW is a r32 inverter driven air source heat pump, 17 kW heat output; the Viessmann Vitodens 100-W 35kW combi is a gas combi boiler, 34.9 kW hot water output.
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