Oil boilers use oil to heat water and are a popular choice among homeowners who are not on the main gas network.
Around 4 million households in the UK are without mains gas and have to rely on an alternative fuel to heat their homes, with oil being the most popular choice. The majority of homeowners living off-grid opt for oil-fired boilers because these systems are cost-effective and highly energy efficient. Although there is only a handful of brands that manufacture oil boilers, they are still available in various sizes and types including combi, system and regular (conventional) models.
How Do Oil-Fired Boilers Work?
Oil-fired boilers work in a very similar way to gas-powered boilers but they use oil to heat your water instead of gas, making them ideal for properties off the mains gas grid. The water that is heated by the oil is sent to the taps and radiators around your home when needed. So, the major difference between oil and gas boilers is the fuel that is used to heat your water.
You also need to be aware that all oil boilers connect to a separate external tank, which is used to hold the oil supply until it is required. The tank will only be able to store a limited amount of oil, so regular oil deliveries are necessary. This means you’ll need to monitor how much oil you’re using and place your oil orders in advance to avoid running out.
Oil Boiler Prices
Oil boilers can cost anything from £1,500 to over £3,500, depending on the type and size. You also need to factor in the cost of installation, which typically ranges between £1,200 and £2,000. If you’re on certain qualifying benefits, you may be eligible for an oil boiler grant under the government Energy Company Obligation (ECO) Scheme. Under this scheme, eligible UK residents can receive a free oil boiler or some money towards a replacement.
Not all boiler manufacturers produce oil boilers so there are fewer models to choose from but there are still plenty of oil-fired solutions nonetheless. The table below enables you to compare a selection of oil-fired boilers and their prices, which include VAT and exclude the cost of installation.
| Manufacturer | Model | Dimensions | Output & Flow Rate | Efficiency | Typical Price |
|---|---|---|---|---|---|
| Worcester Bosch | Greenstar Danesmoor 25 Regular | H – 855 mm W – 370 mm D – 600 mm | 25kW N/A | A | £1,570.80 |
| Grant | Vortex Blue Kitchen Utility 21 Regular | H – 860 mm W – 470 mm D – 600 mm | 21kW N/A | A | £1,800.32 |
| Worcester Bosch | Greenstar Danesmoor 18 System | H – 855 mm W – 370 mm D – 600 mm | 18kW | A | £1,801.89 |
| Grant | Vortex Blue Kitchen Utility 21 Internal System | H – 860 mm W – 470 mm D – 600 mm | 21kW | A | £2,019.18 |
| Worcester Bosch | Greenstar Heatslave II 18 Combi | H – 855 mm W – 520 mm D – 600 mm | 18kW 15 l/min | A | £2,256.00 |
| Worcester Bosch | Greenstar Utility 70 Regular | H – 1012 mm W – 520 mm D – 815 mm | 70kW | A | £2,268.00 |
| Firebird | Enviromax 26 External Oil Combi | H – 945 mm W – 720 mm D – 625 mm | 26kW 21 l/min | A | £2,520.14 |
| Grant | Vortex Blue 21 Internal Oil Combi | H – 860 mm W – 610 mm D – 600 mm | 21kW 15 l/min | A | £2,537.98 |
| Mistral | CKUT2 Condensing Kitchen Utility Regular | H – 865 mm W – 410 mm D – 600 mm | 26kW N/A | A | £2,571.20 |
| Worcester Bosch | Greenstar Danesmoor System External 25 | H – 950 mm W – 565 mm D – 780 mm | 25kW N/A | A | £2,616.00 |
| Mistral | CS3 Condensing Internal System | H – 865 mm W – 410 mm D – 600 mm | 35kW N/A | A | £3,560.00 |
Please note: As oil boilers are available in a range of types and sizes (heat outputs), we strongly recommend you always ask a qualified heating engineer to help you determine the right boiler for your home and needs.
Oil Boiler Running Costs
An oil boiler is usually more expensive to run than a gas boiler, but it’s cheaper than an LPG or electric boiler. Just one unit of heating oil is around 6p/kW, and the average cost of oil heating for a typical 3-bedroom property is £1,100. Of course, these prices won’t be accurate for every home. The running costs will depend on certain factors, such as boiler efficiency and the changes in fuel prices throughout the year.
How is Heating Oil Stored and Delivered?
Heating oil must be stored in a separate tank, which is installed outside. There are various tank sizes available, but most people have a tank that can hold enough oil to fuel their home for between 6 and 9 months. By having a fairly large tank, you can order your oil in bulk when you think you’re getting a reasonable price for it. You can actually purchase two types of oil for domestic heating, which are kerosene and gas oil (red diesel). The type of oil you’ll need will depend on the type of boiler you own, but there are some oil-fired boilers that take both. As kerosene is the most efficient, most people with a boiler that can take either fuel use this type.
The oil is delivered in a tanker, so there needs to be sufficient access to your home and storage tank. Some suppliers have baby or 4 wheeled tankers so that they can deliver oil to properties with restricted access. When the tanker arrives at your location, it will pump the oil into your storage tank (located outside). Most suppliers will even deliver your oil when you’re not at home, provided they are given easy access to your storage tank.
TOP TIP: It’s always a good idea to compare quotes so that you can find the cheapest price on your heating oil. In addition to getting quotes directly from local and national suppliers, use comparison sites (such as BoilerJuice) to discover the best price. You can also try to haggle for a lower price and ask suppliers if they’ll beat another quote that you have received in order to save money on your heating oil.
Advantages and Disadvantages of Oil Boilers
Oil boilers are popular among homeowners that don’t have mains gas because they have many good points, but it’s important to know that oil-fired systems also have downsides. With this in mind, let’s take a look at both the advantages and disadvantages to help you decide whether or not you should get an oil boiler installed in your home.
The Advantages
Highly efficient: Oil boilers are generally very efficient, with many modern models achieving efficiency ratings of 90% or above. They also recycle waste flue gases to further increase efficiency.
Cheaper than LPG and electric boilers: Modern oil-fired boilers are much cheaper to run than LPG and electric boilers, giving you a better return on your money.
Compatible with renewable technologies: Oil-fired boilers can be used with renewable technologies (such as solar thermal heating), which can help to cut your heating bills.
Space saving: Some oil boilers can be installed outdoors, meaning you can make the most of your existing indoor space.
The Disadvantages
Rises in oil prices: Like gas, oil prices are volatile. This means there may be times when you’ll have no other choice than to buy heating oil when prices are high.
Unsightly oil storage tank: Even though your oil storage tank will be located outside, it can still be a bit of an eyesore.
Both the boiler and oil storage tank need an annual service: Yes, the boiler and storage tank need servicing annually to ensure your system runs safely and efficiently.
The tank holds a limited amount of oil: The amount of oil the storage tank can hold will depend on the size of tank you choose. As mentioned above, you need to plan ahead to avoid running out of oil before your next delivery.
Lower hot water flow rate: The hot water flow rate of an oil boiler is typically lower than the flow rate of a gas boiler, so you’re likely to experience more drops in water temperature when using an oil-fired system.