Grant Aerona3 R32 Review
Grant isn't a name that comes up first when people start researching heat pumps. But if you're in Ireland, the west of England, or anywhere with a strong traditional plumbing and heating culture, your plumber almost certainly knows them. That familiarity counts for more than it gets credit for.
Who Grant are
Grant Engineering is an Irish company that's been making heating products since 1979. They built their UK and Irish reputation on oil boilers, specifically the Vortex range, which is still one of the most-installed oil boilers on the island of Ireland. The Aerona3 is their air source heat pump, and it carries the same design philosophy: build it robust, support it properly, make sure the people who fit it can actually get it working.
That heritage matters in markets where oil boilers are being replaced. An installer who's been fitting Grant boilers for 20 years and now also does Grant heat pumps is a meaningfully better prospect than someone who only learned heat pumps last year.
The specs
| Spec | Detail |
|---|---|
| Refrigerant | R32 (Aerona 290 R290 also available) |
| COP (A7/W35) | Up to 5.28 (10kW model) |
| Noise level | 49.8–54.2 dB(A) sound pressure at 1m |
| Capacities | 6–17kW |
| Installed price | £8,000–£12,000 |
| Warranty | 5yr standard / 7yr with G1 Installer registration |
Where it performs well
The Aerona3 has a strong reputation for cold-weather performance and robustness. The build quality is solid. Grant designs products knowing they'll be serviced by plumbers and heating engineers who need to get inside them and understand what they're looking at. The construction reflects that: accessible, logical, well-made.
The 6–17kW range is wide and useful. The 17kW upper limit is one of the highest on this list, which makes it suitable for larger detached homes, farmhouses, or properties with higher heat loss: the kind of property common in rural Ireland and western UK where Grant has its strongest installed base.
The 7-year warranty with registration matches the base Vaillant warranty and is better than the 5-year standard most competitors offer. It shows Grant is confident in the product.
The honest downsides
Noise varies by model: the 13kW is actually quite quiet at 49.8 dB(A) sound pressure at 1m, while the 6kW is louder at 54.2 dB(A). Sound power levels range from 60.8–65.2 dB(A) across the range. It's not the quietest on this list, but it's not as loud as earlier models were. If siting the outdoor unit close to a neighbour's property line, check the specific model's noise figures carefully.
The COP of up to 5.28 (10kW model) and SCOP of up to 5.40 (13kW model) actually puts the Aerona3 among the most efficient heat pumps on this list, matching or exceeding the Vaillant and Daikin on paper. This often surprises people who assume Grant is a mid-range option. The efficiency numbers are genuinely competitive at the top end.
Grant's profile is lower outside its core markets. If you're in the south-east of England or Scotland, you may find fewer Grant-trained installers than you would for Mitsubishi or Vaillant.
Grant has also launched the Aerona 290, a fifth-generation range using R290 refrigerant (4, 6.5, 9, 12, and 15.5kW). SCOP up to 5.08 at 35°C and much lower noise levels (48–54 dB(A) sound power). If you're buying new, the R290 range is the future-proof choice.
Who should buy this
- Anyone in Ireland where Grant's installer network is strongest and their brand trust is highest.
- Anyone in western UK: particularly those replacing a Grant oil boiler, where your existing installer may already be familiar with the product.
- Larger properties that need a unit at the upper end of the capacity range.
- Anyone who values a traditional heating brand with genuine UK and Irish manufacturing heritage.
Who should look elsewhere
- If noise is a concern for your siting, the Vaillant or Samsung are quieter options.
- If you're outside Grant's core installer network geography, the Mitsubishi's broader UK coverage is more practical.
- If you want R290 from Vaillant or Daikin instead, those options exist too. Check the Aerona 290's specs first, as the efficiency is genuinely competitive.
The Grant Aerona3 is a solid, well-built mid-ranger from a company that knows heating. It won't win spec-sheet comparisons against the Vaillant. But in the right location, with the right installer, it's an excellent choice. For the full brand comparison, see our best heat pumps UK guide, and check our heat pump costs guide for what you'll pay after the £7,500 BUS grant.