HUGE boiler savings!

Compare obligation-free quotes now!

  • All boiler models quoted
  • Trusted local boiler engineers
  • Latest May deals

New & Replacement

Save on new boiler installs!

  • Upgrades and new installs
  • Expert advice included
Get Free Quotes

Repairs & Servicing

Boiler maintenance for less!

  • Emergency repair work
  • Annual service savings
Get Free Quotes

Oil Boiler Replacement Costs & Quotes - 2024 Guide

2024 oil boiler costs guide

If you are not connected to the main gas network, oil boilers tend to be the best solution for your hot water and central heating needs.

Despite gas being a popular fuel in the UK, it cannot be ignored that around 4 million people here can’t access the gas grid meaning that they have to rely on other types of fuels. In this regard, oil is, in most cases, the ultimate alternative fuel. The good thing with oil boilers is that they are very cost-effective and do not compromise energy efficiency in any way. Despite oil boilers being cheaper than electricity and LPG boilers, they work similarly, only that the fuels need to be managed differently.

Not so many manufacturers produce oil boilers, but they are still available in a wide variety of sizes and types. The three main categories of oil boilers are combi, regular and system boilers.

Free Boiler Quotes? Apply online now!

How does an oil-fired boiler operate?

The working principle of oil boilers is very similar to that of gas boilers, only that they use oil to heat water instead of gas. The heated water is sent to your central radiators and any hot water tap in your home.

For oil boilers to operate, they must be connected to a separate external tank that will store the oil. Since these tanks only hold a limited amount of oil, you need to monitor your oil usage so that you know when to order for a refill.

The working process

  • The boiler unit is supplied with hot water from a cold storage tank if you have a conventional boiler, or the mains if you have a combi or system boiler.
  • Oil is fired in the combustion chamber and the heat produced is passed to the cold water through a heat exchanger.
  • The hot water is sent to radiators, showers and taps all over the house to provide both heating and hot water.

Main types of oil boilers

To make the right decision on the brand, you will get and the kind of installer you will hire, you should understand the main categories of boilers available.

There are three main types of boiler systems in the UK- combi, system and regular boilers. Note that these boiler types apply to all three fuels (gas, oil and LPG).

Regular boiler

Regular boilers, also known as conventional boilers, take cold water from a cold water tank, heats it and sends it to a separate hot water tank for storage. Just like a system boiler, you will have to wait for them to refill for you to use the hot water when the cylinders empty.

System boiler

Just like a combi boiler, a system boiler gets water from the mains but sends it to a different unit (hot water tank) for storage. The storage tank will provide the hot water on demand, but when the cylinders empty, you may have to wait until they refill to use the hot water.

Combi boiler

A combi (combination boiler) provides both heating and hot water in a single unit. A combi boiler will take cold water directly from the main and heat it on demand. The result of this is the provision of much hot water to the central heating and the taps.

Remember that the type of boiler you need depends on the size of your home and the amount of water you need. We’ve partnered with a great team of highly experienced installers who will advise you on the most suitable boiler for your home.

What size of oil boiler is suitable for your home or workplace?

Oil boiler size, also known as the output rating, is a measure of the maximum power (in KW) that the unit produces. A unit with a higher output rating delivers more in terms of central heating and hot water.

Regular and system boilers only have central heating output ratings. Combi boilers have both the central heating and domestic hot water output ratings since they deliver water directly to the central heating radiators and the access taps.

The size or output rating of the oil boiler you require mainly depends on your home's size. You can simply estimate the oil boiler output rating you need by determining the number of bathrooms and radiators installed in your home. Note that if your boiler is too powerful, it may make you incur cost on fuel that you will not need. On the other hand, if the oil boiler is not powerful enough, it will not sufficiently serve the heating needs of your home.

Oil boiler costs

The price of an oil boiler unit will be anything between £1,500 and £3,500. The exact price will be affected by factors such as boiler type and size. If you want to estimate what the entire project will cost, then you have to factor in the installation cost, which will be around £1,200 to £2,000. If you satisfy certain qualifications, you can get a government grant under the Energy Company Obligation; ECO. The grant may be in form of a free oil boiler or an amount of money to fund the replacement.

In this region, not many manufacturers produce oil boilers and therefore, you may have a few options to choose from. Even with this, there is a decent number of oil boilers and you should not lack one that fulfills all your heating needs.

Model kW ErP Warranty Price
Firebird Enviromax Blue Supreme 20kW Utility 20
A Heat
5 £2916.61
Warmflow Agentis 21-27kW External 26
A Heat
2 £1842.72

Oil boiler installation costs

The costs you will incur installing an oil boiler in your home are determined by various factors. These factors include the size of the boiler unit and storage tank, the complexity of the installation, and where most of the boiler system's components will be installed (internal or external). The installer’s charges also affect the total costs incurred during installation.

Considering all these factors, you should expect to pay around £600 to £2,200 for installation (including labor cost) of a new oil boiler in your home. The total figure will definitely be higher and you should expect to pay around £2,700 to £4,700 for the entire project.

To get the best deal, you should compare quotes from several highly qualified specialists. You are not limited to hiring either a local or national company as long as they are offering a budget-friendly quote. Complete our online form today and get up to 4 quotes from reliable oil boiler installers from your locality.

Running costs

Generally speaking, an oil boiler is more expensive to run than a gas boiler but more cost-effective than running an electric or LPG boiler. As a guide, a unit of heating oil (1KW) will cost around 6p. The cost of heating a 3 bedroom house will stretch to around £1,100. These figures will vary from one home to another as heating needs are never the same, even for two similar houses. The running cost will also change as the fuel prices rise and fall and depending on the working efficiency of the boiler you have installed.

The storage and delivery process of heating oil

There must be a tank outside in all oil boiler installations to serve as storage for the boiler’s firing oil. You have many options for oil storage tank sizes, but generally, homeowners go for tanks that will hold oil enough to fuel heating in their home for around 6-9 months. The advantage of having a large tank is that you can order the oil in bulk when the prices are favorable.

For domestic heating purposes, there are two main oils that you can acquire- kerosene or gas oil (also known as red diesel). The kind of oil you go for is determined by the type of boiler you have. Still, some boilers work with both and hence this is a factor you need to consider when acquiring the unit. Kerosene is better in terms of operating efficiency and therefore, homeowners with the boiler type that can work with either fuel prefer it.

Oil is delivered to your home by a tanker, so the tank needs to be installed somewhere where it can be easily accessed. If you have restricted access, though, there are some suppliers with small trucks that can effortlessly do the delivery. The oil is transferred from the tank into your storage tank using a pumping mechanism. If you choose a reliable supplier, they can deliver the oil even when you are not home. You just have to make sure that they are not restricted to access your tank by the person in charge of securing your home.

No one likes to incur high costs when there are cheaper alternatives with similar results. Yes, you need to have highly efficient fueling oil, but at the same time, you should also compare a few quotes to know what deal is most affordable for you. You can get the quotes directly from local and national suppliers as well websites such as BoilerJuice offering prices and quotes comparisons and pick the one that offers the best value for your money.

Another smart idea to lower the cost is asking suppliers if they can beat a quote you have received from another supplier. This way, you stand a chance of getting a cheaper supply and thus saving your money.

Internal vs. external oil boilers

As a homeowner, you always have two options when installing oil boilers. You can either choose to have an internal or external boiler. The working principle of these two ‘types’ of boilers is the same and both require an oil tank installed outside your home. The only difference is that an external installation has most of the boiler’s components moved outdoors.

Due to this reason, external boilers are more suitable for people looking to have more free space in their homes. External oil boilers are also safer as they reduce the risk of having the notorious gas carbon monoxide in your home. What’s more, they are quiet and will barely disturb your peace.

Considering that outdoor environment elements are harsher than what indoor spaces offer, external boilers’ efficiency may reduce on long exposure. The British weather is especially harsh on external boilers and will cause problems such as rusting or freezing during winter. To respond to these weather-related risk factors, many external oil boilers’ manufacturers use sturdy materials and designs aimed at increasing weatherproofing. This, of course, attracts additional costs when acquiring the unit and during installation.

In case you don’t like the aesthetic an external boiler brings to your home, you can have the oil tank installed underground. If you choose to follow this path, be prepared to incur more, especially for the installation works.

Oil boiler efficiency explained

Modern oil boilers are highly efficient and they will operate at an efficiency level of 90% or higher. This means that if you, for example, spend £1 on your home heating, only 10p will be ‘wasted’. If you compare this with traditional oil boilers that waste 30 to 40p for every £1 spent (70% efficiency), modern oil boilers make a lot of financial sense for homeowners. It is needless to say that modern oil boilers' high efficiency will help cut the money you spend on energy bills.

Pros and cons of oil boilers

As mentioned above, oil boilers are suitable for homeowners not connected to the mains gas. Even with this, they come with their own share of merits and downsides that any homeowner should understand before making a purchasing decision. Let’s discuss the pros and cons of oil boilers so that you will be able to gauge if they are worth the shot or not.


  • Relatively cheaper than electric and LPG boilers - This is one of the merits that will make a lot of sense to homeowners. Running modern oil boilers is generally less expensive compared to running electric and LPG boilers. The result of reduced running cost by oil boilers has a long-term effect of giving better value for your money.
  • They are very efficient - A nicely designed oil boiler model should clock efficiency levels of 90% and above. This is a decent efficiency level considering that oil boilers are not pricey. To increase their working efficiency, oil boilers recycle waste flue gases.
  • Saves space - As seen above, oil boilers can be installed outdoors, meaning that they must not take up the limited space you have indoors.
  • Compatible with modern technologies - Oil boilers can be coupled with renewable energy technologies such as solar thermal heating, further increasing their working efficiency and reducing energy bills.


  • The oil storage tank can be unattractive - Even when installed outside, the oil storage tank can negatively affect your home's aesthetic elements.
  • A given tank will only hold a specific amount of oil - If you are not strategic when installing your oil storage tank, you may end up having one that does not serve your heating needs effectively. This is because storage tanks come with an oil amount threshold that they can hold. This means that you have to plan ahead so that you do not get short of fueling oil before your next delivery.
  • The boiler and the storage tank require frequent servicing - To ensure that your system is running optimally, efficiently and safely, you need to service it annually. The annual maintenance practices will lead to additional costs.
  • Unpredictable oil prices - Like gas, oil prices are highly unpredictable and can be subject to hikes any time. If this is the only choice you have for your heating needs, you will have to incur the costs even when they are high.
  • Lower water flow rate - Water heated by an oil boiler has lower pressure and therefore flows slower than water produced by a gas boiler. The implication of this is a great temperature drop in the heated water before you practically use it.
Free Boiler Quotes? Apply online now!

News Discover the latest boiler offers this May, get some free quotes!