First Published: December 27, 2023. Updated: February 6, 2024
Best Oil Boilers 2024
It’s estimated that up to five million households across the UK aren’t connected to the mains gas grid. If you are one of them, oil is a fantastic alternative.
Whilst oil boilers are more expensive to buy than electric or LPG boilers, they tend to be cheaper to run. Like their gas equivalents, the choice of oil boilers is vast. Deciding on the best oil boiler for your needs can be challenging. This is where we can help.
We’ve worked hard for you and picked the best oil boilers in 2024. We enlisted the help of our heating engineers when compiling this list.
The following guide was written with our engineers and installers’ input. Combined, they have over 40 years of experience.
We’ve moved the recommendation to the top of the page to save you scrolling.
Model: LCB700 Blue Flame Combi Internal Boiler
Our recommendation for the best oil combi boiler for 2024 is the Navien LCB700 Blue Flame Combi Internal Boiler.
We have come to this conclusion based on the following:
- Efficiency: The Navien LCB700 provides excellent efficiency of 93%.
- Warranty: With a 10-year warranty, the Navien has the longest warranty period for an oil boiler.
- Technology: For superior efficiency, the Navien boiler uses different technology. This includes Blue-flame technology and a stainless steel heat exchanger. It also has self-learning hot water usage monitoring. Plus an integration with Navien Smart Plus room thermostats.
- Lighter: Making it easy to transport and install.
- Modulation: 1:10. The only oil boiler on the market to modulate.
Changes to recommendations: early in 2023, we recommended Grant boilers for oil installations. But in mid-2023, Grant stopped producing and selling ‘blue flame’ boilers. ‘Blue flame’ boilers are future-proof because they can burn bio-oils (once released). Because of this, we have adjusted our list to ensure the best value for money.
Getting Started With an Oil Boiler
If you don’t have a gas supply and prefer oil to LPG, you will need a tank to store the oil in bulk. This is normally located next to the property or garage. This will need filling at least once a year, but it depends on your oil tank size. The majority of oil boilers in the UK use kerosene oil.
Like gas and LPG, oil boilers come in three types: Combi boilers are an all-in-one unit providing heating and hot water without the need for a hot water cylinder; And system and regular boilers that do require additional tanks and cylinders, normally in the loft or airing cupboard.
When replacing an oil boiler, you are not required to replace your oil storage tank. But you may need to if the boiler and tank don’t pass building regulations.
We considered the following when recommending boiler brands and models: price, warranty, design, material quality, customer feedback, customer service, awards and accolades. As discussed in the introduction, we have also considered blue and yellow flame technology.
Boilerhut’s Recommended Oil Boilers
Navien is new to the UK market – having only been operating here since late 2014. They have been producing boilers in South Korea since 1978. In 1988, they became the first company in Asia to develop an efficient condensing boiler.
Today, they are the name behind the best-selling boiler in the US. They operate in 30 countries worldwide and have ambitious plans for growth in the UK market.
One major reason we recommend this Navien boiler is because it comes with a 10-year warranty. It’s is great for peace of mind. This covers the components and protects you against issues caused by manufacturing defects. To ensure this warranty remains valid, you must have the boiler serviced acording to Navien’s instructions.
Navien LCB700 Blue Flame Combi Internal Boiler
This boiler utilises blue flame technology. This assists it in achieving this high efficiency. It does this by enabling the boiler to emit low NOx emissions. A blue flame burns much hotter (1,500 to 1,700ºC / 2,600º F to 3,000º F) than yellow flame boilers, burning fuel more efficiently.
The presence of more oxygen in blue flame systems allows a higher heat output. Most oil boilers burn with a yellow flame, which is less efficient. In addition, blue flame boilers are bio-oil compatible. This means when bio-fuels become available the Naviens will be able to switch with minimal issues.
Stainless Steel Exchanger
All Navien oil boilers have stainless steel exchangers. We would always recommend stainless steel over aluminium (find out why here)
In addition to its efficiency, we recommend this Navien boiler because it comes with a 10-year warranty which is great for peace of mind. This warranty covers the boiler’s components and protects you against issues caused by manufacturing defects. However, to ensure this warranty remains valid, you must ensure that you have the boiler serviced annually by a Gas Safe registered engineer to the manufacturers guidelines.
Uses Smart Technology
These boilers will achieve an A+ efficiency rating when installed with a Navien Smart Plus room thermostat. The Smart Plus thermostat will enable you to control your heating and hot water from anywhere.
The Smart Plus thermostat will also enable you to check the status of your heating system. This includes seeing how much energy you’re using. It does this in several clever ways. The main one is using the intelligent weather forecast functionality. This allows your heating system to check the weather forecast using OpenWeatherMap. It can then adjust itself depending on the current outside temperature. This ensures you are only using energy when you need to.
The Smart Plus thermostat also allows geofencing technology. This will ensure your house is only being heated when needed. The system can detect registered app users close to or inside the home, turning it on or off to suit.
Lastly, the system monitors hot water usage and adapts it based on your typical routine.
Blue Flame Feature
Blue flame technology means that the fuel burns at between 1,500ºC to 1,700ºC (2,600º F to 3,000º F). The presence of more oxygen in blue flames contributes to their higher heat output. Some oil boilers burn with a yellow flame which is less efficient. In addition, blue flame boilers are bio-oil compatible, meaning when non-fossil fuels become available, the Navien’s will be able to switch over with minimal issues.
- A+ rated when installed with three Navien Smart Plus room thermostats
- Blue flame burner
- 1:10 modulation range
- Stainless steel heat exchanger
- Compatible with Navien’s Smart Plus thermostats for increased control and efficiency
- Built-in Intelligent Mode to monitor and adjust based on your typical usage
- Full text-driven control
- Self-diagnosis and error feedback provided by the display
- Built-in usage function to show how much fuel has been used
- 10-year warranty if installed by a Navien-approved installer
Grant Engineering has been designing and manufacturing oil boilers in the UK since 1978.
Grant is known for quality and reliability, offering an oil boiler range that is easy to install and maintain. This quality has been recognised by Which?, with the entire Grant oil boiler range being awarded a Which? Best Buy award from 2017 to 2021. The Energy Saving Trust has also recognised the efficiency of Grant oil boilers.
We no longer recommend the Grant boilers for oil installations. This is because they have stopped producing blue flame boilers. They aren’t compatible with bio oils, which should be released in the next few years. However, they are a great boiler brand.
Grant Vortex Pro Internal Combi Boiler
The Grant Vortex Pro oil boiler is known for its reliability and performance. It is available as a regular, combi and system boiler. It’s also available with options for internal and external installation.
The range has some of the highest efficiencies in the UK, achieving gross seasonal efficiencies of up to 93% (SAP 2009). This has been recognised with the range being endorsed by the Energy Savings Trust. But, when bio-oils become available in the next few years, Grant boilers won’t be compatible.
Contained in One Unit
As a combi boiler, one of the clearest benefits of the Grant Vortex Pro Internal Combi is the fact that everything is contained within one unit. With the water heater and the central heating boiler combined, no hot water cylinder is required with this boiler.
The Vortex Pro Internal Combi utilises Grant’s Vortex stainless steel heat exchanger. Unlike aluminium equivalents, this stainless steel heat exchanger is less resistant to corrosion. This increases the boiler’s efficiency as corroded heat exchangers will become less efficient over time.
- A-rated efficiency
- Endorsed by the Energy Savings Trust
- One of the most efficient oil boilers available in the UK
- Equipped with the award-winning Vortex stainless steel heat exchanger, ensuring efficiency
- Quiet operation – 50.6 dB
- 5-year warranty
Extended warranties with Grant Accredited Installers
Boilerhut works with Grant and is a G1-accredited installer. This means our installers are trained to meet the highest quality standards. By choosing Boilerhut to install your Grant boiler, you will also be eligible for Grant’s comprehensive 10-year guarantee.
Founded in 1962 as Worcester Engineering Co Ltd, the company was acquired by Robert Bosch GmbH in 1992 and became Worcester Bosch. Worcester Bosch offers an extensive range of boilers. They utilise a range of different fuels and is suitable for properties of all sizes.
Worcester Bosch Greenstar Heatslave II Internal Combi Boiler
The Worcester Bosch Greenstar Heatslave II is the UK’s most popular oil combi boiler and for this reason, has earned its place on this list. This boiler also comes recommended by Which?, having received their Best Buy award for oil boilers in September 2020.
Another oil boiler that is noted for its efficiency, whilst not quite as efficient as the other boilers recommended here, the Greenstar Heatslave II does have a respectable 94% efficiency rating and is A-rated as a result.
Designed to fit under a standard kitchen worktop, the Heatslave II can easily be installed in a kitchen alongside a washing machine or a dishwasher. Ensuring it doesn’t look out of place in your kitchen, the Heatslave II’s design features a drawer in which the controls are housed. This is also handy for families with small children, where the controls would otherwise be at the right height for little hands.
If you’re not keen on having the boiler on show, it can also be kept out of the way and housed in a kitchen cupboard – although it is a floor-standing unit so must be on the floor. Alternatively, it is suitable for installation in a utility room, airing cupboard or garage, should you have the space available.
For greater energy efficiency, the Heatslave II is also compatible with green energy sources such as solar panels.
Eco Hot Water Mode
Another feature of the Greenstar Heatslave II to aid efficiency is the Eco hot water mode. This is an optional feature that enables you to turn off the preheat option for water. Whilst this will take longer for hot water to be delivered, it will result in a marked difference when it comes to fuel usage.
The EasyControl smart thermostat can automatically turn the heating down if you’re not in the house. It can also detect when you’re returning home, turning the heating up to your desired temperature. The EasyControl smart thermostat enables you to view the performance of your Greenstar Heatslave II boiler and understand your gas consumption.
- Cross firing burner
- Concealed heating controls
- Compact design
- Designed to fit under a standard kitchen worktop
- Digital control offering precision heating and hot water control.
- Front access for routine servicing and providing flexibility in where the boiler can be installed
- Quiet operation – 56 dB
- Compatible with green energy sources
- Compatible with Worcester Bosch’s EasyControl smart thermostat
- 7-year warranty when installed by an accredited installer and using Worcester Bosch’s filters.
Should I buy a new oil boiler?
Boilers over 10-15 years old can be inefficient, operating at 50-70% efficiency. Upgrading to a modern condensing boiler, can give you efficiencies of up to 94% with oil. This could significantly reduce your heating bills and your carbon footprint.
Are oil boilers safe?
There is no more danger with oil than with gas. They’re both very safe. Often, oil boilers can be placed outside of the home, alleviating fears further. With proper upkeep, oil boilers are among the safest options for home heating.
What oil does my oil boiler use?
The most common oil used in home heating is kerosene. This is usually purchased in bulk through your local supplier. They will then deliver and transfer it to a tank on your property.
How do I maintain an oil boiler?
Like any boiler, we suggest getting an annual service through a manufacturer-authorised engineer. This will ensure proper servicing, and if the boiler is new, your warranty should be kept safe.