UK landlords searching for the best oil boilers need reliable, efficient condensing oil-fired heating systems for off-grid rental properties, delivering strong performance, long warranties, low maintenance, and improved EPC ratings while complying with current and future private rented sector regulations.
The 5 Best Oil Boilers: At a Glance
The top oil boilers for landlords in 2026 offer high condensing efficiency (90%+), extended warranties on heat exchangers, robust burners suited to kerosene, straightforward servicing by OFTEC-registered engineers, and proven reliability under high-demand tenancy conditions. These models suit rural or off-mains-gas rental homes of varying sizes.
| Model | Efficiency (SEDBUK/ErP) | Typical Unit Cost | Installed Cost (approx.) | Warranty (accredited install) | Trustpilot Rating | Key Landlord Benefit |
| Worcester Bosch Danesmoor | 93% | £1,800–£2,200 | £4,500–£6,000 | Up to 7 years | 4.6/5 | Largest UK oil service network |
| Grant Vortex Pro | 97% | £1,700–£2,100 | £4,300–£5,800 | Up to 10 years (heat exchanger) | 4.5/5 | Highest efficiency & low running costs |
| Firebird Envirogreen | 94% | £1,600–£1,950 | £4,200–£5,600 | Up to 10 years | 4.4/5 | Quiet operation & easy maintenance |
| Warmflow Agentis | 93% | £1,900–£2,300 | £4,600–£6,200 | Up to 10 years | 4.7/5 | Premium build & corrosion resistance |
| Mistral Hydroflow | 92% | £1,500–£1,850 | £4,000–£5,500 | Up to 5 years | 4.3/5 | Excellent value for larger rentals |
Notes: Prices are 2026 UK averages for 26-35kW oil boilers (suitable for 3-5 bedroom rentals). Installed costs include standard OFTEC installation, flue, and basic controls (oil tank & pipework extra if required). All are condensing oil boilers using kerosene.
If you’re a landlord with off-grid rental properties needing a reliable oil heating system, request a new boiler quote from Boilers 2 Go for expert advice, competitive pricing, and professional OFTEC installation.
1. Worcester Bosch Danesmoor
The Worcester Bosch Danesmoor consistently ranks among the best oil boilers for landlords due to its exceptional reliability and the largest network of OFTEC-trained engineers across the UK.
Specifications and Features
- Outputs: 18-32kW (wall-mounted or floor-standing options)
- Blue flame burner technology
- Compact design for utility rooms
- Compatible with smart controls
- Internal or external variants
Efficiency
93% ErP A-rated condensing performance for improved EPC scores.
Estimated Cost of the Boiler Unit
£1,800–£2,200.
Costs with Installation
£4,500–£6,000.
Running Costs
Competitive for oil with good modulation; typically £1,200–£1,800/year for a 3-bedroom rental.
Which? Trustpilot Ratings
4.6/5 Trustpilot; frequently Which? recommended for service and reliability.
2. Grant Vortex Pro
The Grant Vortex Pro leads the best oil boilers category for landlords seeking top-tier efficiency and one of the longest heat exchanger warranties available.
Specifications and Features
- Outputs: 21-36kW
- Internal/external models
- Riello burner
- Stainless steel heat exchanger
- Low NOx emissions
Efficiency
Up to 97% (best-in-class condensing).
Estimated Cost of the Boiler Unit
£1,700–£2,100.
Costs with Installation
£4,300–£5,800.
Running Costs
Lowest oil consumption among leading models.
Which? Trustpilot Ratings
4.5/5 Trustpilot; praised for efficiency.
3. Firebird Envirogreen
The Firebird Envirogreen performs strongly among the best oil boilers with quiet operation and straightforward servicing, ideal for occupied rental properties.
Specifications and Features
- Outputs: 20-35kW
- High-performance burner
- Compact casing
- Weather compensation ready
Efficiency
94% ErP A-rated.
Estimated Cost of the Boiler Unit
£1,600–£1,950.
Costs with Installation
£4,200–£5,600.
Running Costs
Efficient combustion keeps fuel use low.
Which? Trustpilot Ratings
4.4/5 Trustpilot.
4. Warmflow Agentis
The Warmflow Agentis stands out in the best oil boilers for its premium construction and long warranties, protecting landlords’ investments in rural rentals.
Specifications and Features
- Outputs: 15-44kW
- Stainless steel heat exchanger
- Low maintenance design
- Internal/external options
Efficiency
93% ErP A-rated.
Estimated Cost of the Boiler Unit
£1,900–£2,300.
Costs with Installation
£4,600–£6,200.
Running Costs
Durable components reduce long-term repairs.
Which? Trustpilot Ratings
4.7/5 Trustpilot.
5. Mistral Hydroflow
The Mistral Hydroflow delivers strong value among the best oil boilers, offering reliable performance at a competitive price for landlords managing multiple off-grid properties.
Specifications and Features
- Outputs: 26-35kW
- Robust burner
- Simple controls
- Good heat exchanger design
Efficiency
92% ErP A-rated.
Estimated Cost of the Boiler Unit
£1,500–£1,850.
Costs with Installation
£4,000–£5,500.
Running Costs
Affordable running costs for standard use.
Which? Trustpilot Ratings
4.3/5 Trustpilot.
How to choose the Best oil boilers
Choosing the best oil boilers for landlords rental properties involves balancing efficiency for EPC compliance, warranty length to minimise tenancy repair costs, OFTEC service network coverage, burner reliability, and overall cost of ownership in off-grid locations.
Choose the Worcester Bosch Danesmoor if you prioritise the strongest nationwide OFTEC support for multiple rural rentals.
Don’t choose Worcester Bosch if the absolute highest efficiency is more important than service availability.
Choose the Grant Vortex Pro if maximum condensing efficiency and low running costs are critical.
Don’t choose Grant if your local engineers have limited experience with the brand.
Choose the Firebird Envirogreen if quiet operation matters for tenant comfort in occupied properties.
Don’t choose Firebird if the longest heat exchanger warranty is your top priority.
Choose the Warmflow Agentis if premium build quality and long warranties are essential.
Don’t choose Warmflow if budget constraints require the lowest upfront price.
Choose the Mistral Hydroflow if you want reliable performance at the best value.
Don’t choose Mistral if you prefer the most established premium brands.
Looking for a New Boiler Quote?
Installing one of the best oil boilers ensures reliable heating, better EPC performance, fewer breakdowns, and improved tenant satisfaction in off-grid rental properties. Request a new boiler quote from Boilers 2 Go today for expert landlord advice, transparent pricing, and accredited OFTEC installation.
FAQs
How do oil boilers affect EPC ratings compared to gas boilers?
Oil boilers typically score lower on EPCs due to higher carbon intensity of kerosene, making it harder to achieve EPC C without excellent insulation and controls.
What are the legal requirements for oil tanks in rented properties?
Landlords must ensure oil tanks comply with current regulations including bunding, siting, and pollution prevention; annual checks and records are required.
Are there any government grants available for replacing oil boilers in 2026?
The Boiler Upgrade Scheme primarily supports heat pumps; grants for oil boiler replacements are limited, though energy efficiency improvements may qualify for landlord tax relief.
How often must landlords service oil boilers in rental properties?
Annual OFTEC-registered servicing is legally required for gas safety equivalent compliance, plus tank inspections to maintain warranties and tenant safety.
Can oil boilers be converted to low-carbon alternatives later?
Many modern oil boilers can be paired with hybrid systems or replaced with air source heat pumps; early planning for low-carbon readiness helps future compliance.
I’m Penny North, a home energy heating expert. My mission is to demystify new boilers and complex heating systems to help you achieve a warm, cosy home with lower energy bills and a smaller environmental footprint.