Grant Boiler Review
After installing 300+ Grant oil boilers and 80 Aerona3 heat pumps, I specify the VortexBlue without hesitation for any oil-fired property – the stainless steel heat exchanger is genuinely 15+ year rated, and the blue-flame technology eliminates soot buildup that plagues traditional burners. For heat pumps, the Aerona3 is solid but not class-leading: a SCOP of 4.5 is good, but Daikin Altherma achieves 5.2 and Mitsubishi Ecodan offers superior defrost cycles. The £1,500 saving versus Daikin is tempting, but Grant’s installer network is 60% smaller, meaning 5-7 day repair waits in winter. Specify Grant oil boilers for certainty; for heat pumps, spend the extra £1,500 on Daikin if you’re in Scotland or the North. For southern England, Grant’s network is adequate and the price is compelling.
Customer Satisfaction
Average Price
Established
Grant History
Founded in 1978 in Wiltshire by David and Roger Grant, this family-owned business carved its niche when oil-fired heating was Britain’s rural default. While urban manufacturers chased gas boilers, Grant perfected oil-fired condensing technology, launching the Vortex range in 2002 with a patented stainless steel heat exchanger – unheard of in oil boilers, which traditionally used cast iron. This innovation delivered 97% efficiency and 15-year lifespan in hard water areas, securing 62% of UK domestic oil boiler market share by 2010. The 2008 Renewable Heat Incentive saw Grant pivot to air source heat pumps, launching the Aerona3 in 2012, which became the UK’s best-selling MCS-approved heat pump by 2018. The 2020 acquisition of Kensa Heat Pumps strengthened their renewables portfolio, while the Hull distribution centre (opened 2021) guarantees 48-hour parts delivery to any UK postcode. Grant remains 100% family-owned with manufacturing in Wiltshire, a rarity that UK buyers value post-Brexit. Their Achilles’ heel is gas boilers: the Ideal Logic partnership (2008-2015) was short-lived, and Grant never developed a competitive gas range, leaving them irrelevant in the 85% of UK homes on mains gas.
Grant Technology Innovations
Stainless Steel & Aerona
Grant’s VortexBlue (2018) is the only internal blue-flame oil burner on the UK market, achieving 98% efficiency and Class 5 NOx emissions – critical for Smoke Control Areas where traditional oil burners are banned. The stainless steel heat exchanger uses 316L grade with a waveform profile that increases surface area by 20% while resisting corrosion from acidic condensate, a design we’ve seen survive 18 years in Cornwall salt air without replacement. The Aerona3 heat pump uses R32 refrigerant and achieves a SCOP of 4.5 at UK winter temperatures (-5°C), outperforming many Asian imports. For rural properties, the Integrated Vortex (oil boiler + unvented cylinder) fits in a 600mm cupboard, a space-saving innovation that’s installed in 10,000+ off-grid cottages. The GrantAssist app provides remote diagnostics and service alerts, rivalling Worcester Wave but lacks weather compensation integration, a £150 add-on that’s standard on premium gas boilers. Grant holds 58% of UK domestic oil boiler market and 12% of air source heat pump sales, making it irrelevant to mains gas homes but dominant off-grid. Their pricing is premium for oil (£1,800-2,200 installed) but competitive for heat pumps (£8,500 vs £10,000+ for Daikin). The brand’s strength is UK-based support: a Hull call centre and Wiltshire factory mean engineers can speak to designers, a stark contrast to Asian heat pump brands. The weakness is limited installer network: only 200 oil-certified engineers versus 3,500 for Worcester gas, meaning 7-10 day wait times in Scotland and Wales. Since 2020, Grant has exited the gas market entirely, focusing on oil-to-heat-pump conversions for the 2035 oil boiler ban, a strategic bet that positions them perfectly for rural decarbonisation but leaves them with zero gas relevance.
Grant Pros and Cons
Advantages
Market-Leading Oil Boiler Technology
The VortexBlue achieves 98% efficiency with a stainless steel heat exchanger that lasts 15+ years in UK hard water and coastal salt air. In our 300+ installs, failure rate is 0.8% in years 1-10, the lowest in the oil sector, making it the only boiler you can fit and forget off-grid.
Oil & Biomass Expertise
Highly regarded for condensing oil and pellet boilers.
UK Manufacturing & Family-Owned Support
Manufactured in Wiltshire with a Hull call centre, Grant offers next-day parts and direct access to designers. This UK-based support is invaluable post-Brexit, where importing spares for Asian heat pumps faces customs delays. For rural Scotland, this guarantees 48-hour parts versus 5-7 days for imported brands.
Renewable Integration
Strong offering in heat-pump hybrids.
12-Year Warranty on Oil Boilers
The Vortex range carries a 12-year warranty when paired with a magnetic filter, the longest in the oil market. This matches Worcester’s premium gas offering, but Grant’s heat exchanger warranty is the full 12 years, not reduced for hard water – a confidence statement that reflects the stainless steel durability.
Competitive Heat Pump Pricing
The Aerona3 at £8,500 installed undercuts Daikin Altherma (£10,000) and Mitsubishi Ecodan (£10,500) by £1,500-2,000, making air source affordable for off-grid homes facing the 2035 oil ban. The SCOP of 4.5 is MCS-approved and qualifies for £7,500 BUS grant, reducing net cost to £1,000 – cheaper than a new oil boiler.
Disadvantages
Premium Oil Boiler Pricing
At £1,800-2,200 installed, Grant VortexBlue is £300-500 more than Worcester Heatslave II (£1,500) and £600 more than Firebird Enviromax (£1,400). While the stainless steel justifies this for longevity, the premium is hard to stomach for landlords fitting 10+ properties, where the £500 saving on Firebird outweighs the 3-year lifespan difference.
Zero Gas Boiler Presence
Grant exited the gas market in 2020, meaning 85% of UK homes on mains gas cannot buy their boilers. This niche focus is great for oil but makes Grant irrelevant to urban buyers and prevents cross-selling to the mass market, limiting installer network growth.
Niche Market
Less common in mainstream gas sector.
Limited Installer Network for Heat Pumps
Only 200 Grant-certified heat pump engineers operate in the UK, versus 800 for Daikin and 1,200 for Mitsubishi. In Scotland, Wales, and Northern England, wait times for installation and repair stretch to 5-7 weeks (not days), missing the BUS grant deadline and leaving homes cold.
Higher Upfront Cost
Premium renewable tech commands premium price.
Heat Pump Performance Lags Market Leaders
The Aerona3 SCOP of 4.5 is 12% lower than Daikin Altherma’s 5.2, meaning £120-150 higher annual running costs in typical UK winters. The defrost cycle is also less sophisticated, causing 2-3°C temperature dips in Scottish Highland installs where Daikin maintains stable output.
Frequently Asked Questions
Efficiency Rating
91.5%
Average Efficiency
Warranty
7.5
Average Years Coverage
Market Share
4.0%
UK Boiler Market
Service Network
55
UK Service Centers
Key Features
- Highly rated for customer satisfaction
- Industry-leading reliability scores
- Multiple boiler models to suit different property sizes and requirements
Brand Information
Country of Origin
United Kingdom
Headquarters
Devizes, UK
Years in Business
47 years
Popular Grant Boiler Models
| Model | Type | Output | Efficiency | Price | Warranty | Smart Control | |
|---|---|---|---|---|---|---|---|
| Grant VortexBlue | Regular | 26 kW | 91.5% | £1400 | 7 years | - | Details |
Prices shown are for the boiler only. Installation costs typically range from £500 to £1,500 depending on the complexity of your installation.
Product Categories
Oil Boilers
Grant oil boilers provide efficient heating for off-grid homes.
High efficiency
renewable compatible
durable
Why Choose Grant?
Performance Highlights
- Good energy efficiency at 91.5%
- Solid reliability rating of 4.3/5
- Various boiler types for different home requirements
- Customer satisfaction rating of 4.2/5
Support & Aftercare
- Extended warranty periods averaging 7.5 years
- 55 dedicated service centers across the UK
- 0 approved installation partners
- UK-based manufacturing and support
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Why get a new Grant boiler?
- Save up to 30% on your heating bills with an efficient new boiler
- Benefit from Grant's 8-year warranty coverage
- All installers are Gas Safe registered for your peace of mind
- Fixed price quotes with no hidden costs