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The Ultimate Guide to Oil Boiler Installation with All Heat UK

The Ultimate Guide To Oil Boiler Installation

The Ultimate Guide to Boiler Installation discusses everything you need to know about getting a new oil boiler installed or replaced. If you have any questions about your oil fired boiler or central heating system, do not hesitate to contact us.

An Introduction to Oil Boiler Installation

Most homes in the UK are linked to the mains gas supply. Gas fuel is the most popular way to heat homes and water. However, there are over 4 million homes in the UK who are not connected to the gas mains for several reasons. Hence, these homes must get their heat and hot water in other ways.

Oil boilers are less common than gas boilers, but they are a good alternative to the mains gas network and come with many benefits. In many ways there are very similar to gas boilers, except you can keep an oil boiler outside if you wish. And, just like gas boilers, you can get a new installation the very next day and have heating and hot water in your home without delay.

Table of Contents:

  1. Introduction
  2. What Are The Different Types Of Oil Boiler?
  3. How Do Oil Boilers Work?
  4. Benefits of an Oil Boiler
  5. What Do Oil Boilers Need?
  6. Brands Of Oil Boiler
  7. How Much Is A New Oil Boiler Installation?
  8. How Much Does Oil Cost?
  9. How Much Oil Do I Need?
  10. What To Expect With A New Oil Boiler Installation
  11. What Happens After My New Boiler Installation
  12. Who Can Install My New Oil Boiler?
  13. Oil Fired Combi Boiler Prices
  14. Oil Boiler Pros and Cons
  15. How Do I Get Oil For My Boiler?
  16. Replacing an Oil Boiler
  17. Why Choose An Oil Boiler
  18. Oil Boiler Regulations
  19. Renewable Energy and Oil Boilers
  20. Conclusion

different types of oil boilers - all heat uk

What Are The Different Types Of Oil Boiler

The different types of oil boiler include combi, system and heat only.

  • Combi Oil Boilers provide hot water and heating from a single unit, which usually stands on the floor.
  • Heat Only Oil Boilers are available as open vented systems, which require tanks in the loft and as sealed system models, which work with a hot water cylinder.
  • System Oil Boilers also work with a hot water cylinder. The main difference is that they can only work on s sealed system. In other words, the expansion vessel and circulating pump components are within the boiler.
  • External oil boilers are fitted with a weather resistant case. Most oil boilers are floor standing, with a few wall hung models. So keeping your oil boiler outside may be beneficial to you.

Whichever boiler type you choose, you will need a storage tank outside to store your oil in. Also, it’s up to you to make sure there is enough oil in the tank.

how do oil boilers work - all heat uk

How Do Oil Boilers Work?

Oil boilers burn the oil to heat up the water in your system and pump the hot water around all of the radiators. Combi oil boilers can heat drinkable water via a heat exchanger. Whereas System and Heat only boilers work with a hot water cylinder.

Oil boilers must have an energy rating of at least 86% or A+. A condensing oil fired boiler will usually have an efficiency of 90% or higher. The main difference between a gas and oil boiler is the way the appliances store their fuel. A gas boiler doesn’t need to store gas because it’s connected to the mains, which means there is a constant supply of fuel. But, an oil boiler requires a tank to store the oil until you need it.

The oil tank must be on your property and follow certain oil boiler installation regulations, which we will cover in this article later on.

Internal Vs External Boiler

Oil boilers can go inside or outside. The best space depends on existing pipework, electric points and where there is enough room. If you choose outside, they will need a hard standing and minimum clearance area.

Furthermore, it’s important to consider where the flue will go. Oil boilers can give off large plumes of moisture which need to be directed away from windows, footpaths and driveways.

Benefits Of An Oil Boiler

  • Energy Efficient: Condensing oil boilers have a very high energy efficiency. They use the waste heat which is generated by the combustion of the oil. As such, these boilers use less energy and the emissions are considerably lower compared to normal oil heaters.
  • Low Running Costs: Furthermore, oil is an energy efficient fuel and oil boilers can cost less than electric boilers to run. Therefore, it’s a good alternative to gas and to heating your home as running costs are low. Condensing boilers operating with oil can reduce heating costs by up to 15 %.
  • Renewable heating: It’s worth considering an oil boiler as they can work alongside a renewable heating system such as solar thermal panels or a heat pump.
  • Versatility: Oil boilers can flue through chimney breasts and run over long distances. You can choose to have them inside or outside. Thus making them a versatile option.

what do oil boilers need - all heat uk

What Do Oil Boilers Need?

Oil Storage Tank

A tank to store the oil is an essential part of an oil boiler installation. Your oil will be delivered to your home. As the owner of an oil storage tank, it’s your responsibility to make sure that the oil is safe and isn’t going to leak out and affect the environment.

Modern oil tanks are usually made of plastic and are relatively easy to maintain. You will need to refuel the tank when necessary to ensure you don’t run out at any point. Some people only need to refuel once a year, however, for larger homes with more radiators, you might need to refill it more.

Hot Water Storage Tank

An oil boiler also needs a hot water storage tank, which stores hot water for later consumption. The average oil tank in size ranges from 1000 litres (220 gallons) and 1360 litres (300 gallons). The tanks can be made from steel, fibreglass or a combination of the two.


In a similar way to a gas heating system, your home should have at least one thermostat to tell you the room temperature, weather compensation or smart controls.


There are two types of heating oil, gas oil and kerosene. The most common oil fired boilers run on Kerosene. It’s a clean oil and leave minimal deposits when it comes to smoke or soot. Gas oil is a heavier oil generally used in old agricultural or commercial boilers.

As oil needs to be stored in a tank, it’s recommended that you buy it in bulk, which means you can save money on it. Some people may think that heating oil is expensive. However, the prices of heating oil are competitive which keeps prices as low as possible. Average oil prices are currently at a lower level than in recent years.


Oil boilers can be fitted with open flues. A balanced flues is far more efficient and versatile. A flue is a pipe or duct designed to connect heating appliances to fresh air and allow combustion gases to be released safely.

oil fired boiler brands - all heat uk

Brands of Oil Boiler

At All Heat UK, engineers work with a variety of boiler brands that you can choose from. So, there are many options available, as there are with gas boilers. In the same way, you can choose the one that suits your home and your budget.


Navien is a global leader in condensing technology, meaning they are more efficient than conventional boilers. So every one of their models has a good energy rating and certificate. Navien boilers are compact and affordable. The products are eco friendly.


The Grant company is based in England and specifically design and manufacture oil fired boilers. Grant are committed to helping homeowners to lower their carbon footprint and heat their homes more efficiently. They are developing innovative technology to help customers incorporate renewable energy sources such as solar or biomass in their oil heating system.

Worcester Bosch

Meanwhile, Worcester Bosch manufacture a wide range of boilers including gas and LPG as well as oil. Also based in England, Worcester Bosch was established in 1962 and is a well known brand in the UK offering excellent warranties.


Vaillant is one of Europe’s most well known heating brands. It’s a family business, founded over 140 years ago. The company manufacturers all types of boiler including oil boilers.


Vokera operates in the UK and Northern Ireland and provides domestic gas and oil boilers. Their products can be cheaper than a Worcester Bosch for example, but the warranty is usually lower.

how much does an oil boiler cost - all heat uk

How Much Is A New Oil Boiler Installation?

For many homeowners who don’t know much about heating, it may just come down to price when choosing a new boiler. So, if you are going for the cheapest option, you may choose a model from the Vokera brand which could be up to £300 cheaper than an oil boiler installation with Worcester Bosch.

However, you may also wish to consider your boiler warranty or energy rating. For example, some boiler brand installations come with a 10 year warranty. Hence, giving you peace of mind that if anything does go wrong with your boiler, you are covered by the warranty. Although, a word of caution here, you do need to get a regular boiler service in order to keep your warranty valid.

Other boiler brands come with a 2-5 year warranty, and overall this is likely to be a cheaper option.

As with any large purchase such as a new boiler, you may also want to look at reviews of particular brands. This will help you to make an overall decision.

Things To Consider

Labour costs

The cost of hiring a heating engineer to install your new oil boiler can range from £800 to £1500. Often, it is cheaper to use a local heating engineer than one from a big national company. But you will want to get different quotes to make a considered decision.

Inside or Outside (Location)

There are different prices if your oil boiler is internal or external. Costs can include the price of the boiler, standard flue, power flush, standard control and running a new condense pipe. It may even include any associated building works. Depending on the boiler size and quality, a new internal combi boiler is around £3,500-£4,500. Prices increase by around £300-£400 for an external model.

How Much Does Oil Cost?

According to the Energy Saving Trust, the average price of oil in England and Wales is 4.81 p/kWh. It’s measured by comparing the cost per kilowatt hour. This makes oil more affordable than wood pellets and cheaper than electricity. Natural gas is still the cheapest way to heat your home. However, this doesn’t include renewable energy sources, such as solar, which are ‘free’ ways of generating energy.

There’s no set price for heating oil. The amount you pay will depend a range of factors. For example, premium kerosene is more expensive than the standard version. The price of heating also fluctuates. So when you buy your fuel will have an effect on how much it costs. In general, you can expect to pay anything between 45 and 55 pence per litre if you’re buying heating oil for domestic use.

You may need to refuel your oil tank once a year, or more often, depending on the size of your home and your energy usage.

How Much Oil Do I Need?

Generally speaking, the average home in the UK that uses an oil boiler to heat the property is thought to use around 17,000 kWh on heating. Most oil boiler systems use kerosene. One litre of kerosene equals around 19 kWh. Therefore in one year, you might use approximately 1,700 litres of oil to heat your home and provide hot water.

Although, you don’t have your heating on every single day. Hence, most of the oil will be used in autumn and winter and much less in spring and summer.

As another very rough guide, a medium sized boiler might use around 3.5 litres of oil per hour when on full, whereas a large appliance might burn around 4 litres per hour.

However, this is when the boilers are working flat out. When the water in your heating system is already hot and your boiler is maintaining this level of warmth, it will burn less oil. Another factor to consider is the size of your home and how well insulated it is. This will affect how much oil your boiler burns.

Therefore, with this level of variation, 1,000 litres of fuel is enough to stay cosy throughout the year for some households. Whereas for others, this may not be enough to get them through the winter.

Furthermore, heating oil should last for a long time. Generally speaking, if you store it correctly, it should remain in good use for up to 18 months or more. But, there are some factors which can degrade the fuel early. Such as a corroded tank or if it’s contaminated with dirt or water because it isn’t sealed properly.

Using contaminated fuel is bad for your boiler, so it’s worth asking an expert if you’re not sure whether your heating oil has gone bad.

what to expect with a new oil boiler installation - all heat uk

What to Expect With a New Oil Boiler Installation

Making a decision on your new boiler can be rather complicated. However, once you have made your mind up, you will need to find an engineer to install it. With this in mind, the costs of installation will depend on several factors. Such as who you choose to work with, the warranty that comes with the boiler and any additional building or pipe work if needed.

Can I Move My Old Oil Boiler

Firstly, if your old boiler is inside and you want to move it outside, you can. There are external oil boilers available on the market which come as complete, ready to go units. Also, they have all weather casing to protect them outside. However, your engineer will need to drill a new hole for an external boiler. Any existing holes left by the pipework are filled in.

Oil Line and Fire Valve

Next, your engineer will install a new oil line which has safety features to protect you and your household. It is a legal requirement for all oil boilers to have an oil line fire valve. This safety feature is triggered if there is a really high temperature, for example, from a fire. The valve then cuts off the oil supply to the boiler immediately. Thus, the fuel is cut off which eliminates the risk of fire reaching your oil storage tank.

What Is A System Flush

Then, the next step is to carry out a complete system flush. This cleans the pipes from debris and sludge that builds up. Thus, the new boiler is able to function properly from the very beginning as all the old dirt or corrosion flushes away. Moreover, it will give you the best efficiency from your new system.

Installing a Flue Kit

As we have previously spoken about the location of the flue, you will be aware that there are legal requirements on where to place it. The flue is designed to direct any moisture away from your home. Legally, it must be at a suitable height and position. Your engineer will take this into consideration and you may need a new approved flue kit.

The Condensate Pipe

So, as well as the oil line, it’s also necessary to fit a condensate pipe. It’s a plastic pipe which connects to your nearest drain. The pipe must be a specific diameter for internal fittings and a wider diameter for external fittings. There will be an air gap of around 10mm. Don’t worry about this, it’s normal. The air gap is there to stop external boiler condensate pipes from freezing.

what happens after my oil boiler installation - all heat uk

What Happens After My New Boiler Installation?

Choosing Your Controls

Essentially, when choosing your new boiler, you can opt for the standard manufacturer controls or smart technology. By using smart technology, you can adjust your heating through a device or your phone. There are different options of smart controls available. Whichever you choose, your engineer will be more than happy to talk it through with you so you are absolutely confident in operating your new boiler.

Register Your Boiler

With this in mind, you must make sure you register your new boiler. Ultimately, this is important because if you don’t register it, then your guarantee won’t be in place if you need it in the future. Your engineer will be able to upload the details and will know what to do. However, it’s up to you to make sure this happens as part of the process.

Register Your Installation

Furthermore, you need a building control notice whenever a new boiler is installed. This confirms that your boiler is fitted in accordance with all OFTEC regulations. You should keep the original document in a safe place.

Book A Boiler Service

Now it’s time to book an annual service for your boiler. There are many advantages to this. Notably, the main one is that it keeps your warranty valid. This may be even more important if you have bought a new boiler with a 10 year warranty. If you don’t look after your boiler with an annual service, it can affect your warranty.

Furthermore, an annual service will pick up on any minor problems or repairs before they turn into bigger emergencies. Hence, you can gain peace of mind knowing that your boiler is safe and working properly.

Who Can Install My Oil Boiler


OFTEC stands for the Oil Firing Technical Association. It’s the oil equivalent of the Gas Safe Register. OFTEC recognises installers who are approved to install oil, solid fuel and renewable heating equipment.

But in contrast with gas installations, homeowners are not legally required to get an OFTEC registered engineer. However, there are many advantages of doing so.

Firstly, OFTEC installers are able to self certify that their work meets Building Regulations. Moreover, they can also carry out certain work without a building control notice. Therefore, homeowners don’t have to spend time or money getting the work checked by the local authority.

Additionally, any homeowner who uses OFTEC will receive an official certificate to confirm that the work done meets the official industry standards. This certificate is important and may be required by a solicitor if you are selling your home. Ultimately, it’s usually simpler and easier to work with an OFTEC registered installer.

With this in mind, If you choose an engineer who is not registered, they must notify the local authority’s building control department before carrying out any work. Furthermore, the installation will then need to be certified by a competent person to ensure it meets building regulations.

Remember to shop around here and collect a few quotes from different companies. That way you can compare the prices of a few installers and choose which one is best for you.

Oil Boiler Certificate

If you’re selling your home, the solicitors may wish to see your boiler certificate. If you’re not sure where it is, there are a couple of options you can try. Look in the manufacturer’s guidebook to the boiler. In the back, there is a benchmark book. The contact details of the engineer who installed your boiler should be there. You can call them to see if you can get a copy.

Or, find a local engineer to come out and provide a compliance form. They will have to carry out a service on the boiler and risk assessment for the tank.

Oil Fired Combi Boiler Prices

Depending on the boiler size and quality, the cost of a new oil boiler installation, including labour costs could be anywhere between £3,400-£4,500 for an internal combi boiler. Then, for an internal heat only boiler, it’s between £2,500 and £3,800. An external boiler will be slightly more.

When considering the brands, there are many options available. For example, the Worcester Bosch Greenstar Heatslave II is one of the most popular oil combi boilers. It holds a ‘Which’ Best Buy award and is an A rated boiler. This model has excellent reviews and the cost is around £2,500 before installation.

Or the Grant VortexBlue internal oil boiler comes with a state of the art blue flame and a 2 year warranty. It’s a free standing boiler with an efficiency rating of 91.7%. The typical cost before installation is around £1,500.

Meanwhile, the Navien LCB 700 Blue flame oil boiler has an efficiency rating of 93% and comes with a standard warranty of 10 years. It’s a floor standing internal oil boiler.

Mistral is another name for oil boiler brands. The Mistral Combi Standard CC2 internal oil boiler has an efficiency rating of 92% and a 2 year warranty. Therefore it costs just below £2,000 before installation.

Oil Boiler Pros and Cons

There are pros and cons to installing an oil boiler. However, if you are not connected to the mains gas supply, an oil boiler may be your best option and they do have benefits.


  • Your oil boiler can be internal or external
  • Oil is cheaper than other alternative fuel sources on the market such as biomass and electric.
  • By having an external oil boiler, you can free up space in your home.
  • Oil is an excellent heating solution if you live off the mains gas supply.
  • Having an external boiler reduces the risk of carbon monoxide poisoning.
  • Also, if there is a leak and your oil boiler is outside, it won’t cause any damage to your property.
  • Once your oil is delivered, you don’t have to depend on anything else for your heating. You don’t need electricity or connection to a gas line. It’s a good choice for a back-up system.


  • You will need a storage tank for the fuel as well as a boiler.
  • Oil boiler installation is more expensive than gas boiler installation.
  • Also, burning oil produces twice as much carbon as gas.
  • Gas is a cheaper fuel than oil. The cost of oil fluctuates depending on demand.
  • Your fuel supply needs to be physically delivered, so there is the chance of delays or human error.
  • With an external boiler, there is a greater potential of damage that comes with exposure. Cold, frost and rain can cause components to rust or malfunction.

how do i get oil for my boiler - all heat uk

How Do I Get Oil For My Boiler?

Your oil fuel will be delivered to you by a driver from your local oil company. Oil tanks have a vent and fill pipe that goes from your tank inside your home to the outside of your home.

If you run out of oil, your boiler will stop working. There’s a safety system in place in every furnace that disables the burner when there’s no flame. So, you don’t need to worry about any safety issues if you run out of fuel.

Most fuel oil tanks have a float-style gauge. This will give you a general indication of how full the fuel tank is. Check the gauge to see if it you need to order more oil. If there’s enough oil in there and your heating is not working, there is another issue with your system.

You can order your fuel online, some companies have predetermined delivery routes so you can see exactly who will be near your home on which days. You may even be able to get fuel delivered on the same day.

Obviously it’s best not to let your oil tank run empty. Your heating system may be affected by the sludge at the bottom of the oil tank which in turn, could clog the oil filter. If this happens, you may need an expensive emergency service to get your heating back up and running again.

Replacing an Oil Boiler

By maintaining your oil boiler and getting a regular service, it could last for up to 15 years. Although, it is worth considering replacing it after about 8-10 years. This is because when boilers get older, they show signs of wearing down and you may be calling out an engineer more often. The more you need to call your heating engineer, the more expensive it may get.

Therefore, replacing your boiler may be a cheaper option in the long run than getting your current one continually repaired.

You will be able to tell if your boiler needs replacing by looking out for a number of signs including:

  • Home is taking longer to heat up
  • Boiler or radiators are noisy
  • Your boiler leaks
  • Replacement parts are getting harder to find
  • The blue flame is now yellow
  • There are odd smells
  • It breaks down frequently

If you do need to replace your oil boiler, modern condensing boilers are now much more efficient than non condensing ones. With a new boiler, you will waste less fuel. On average, a new condensing boiler will be around 10-15% more efficient.

However, it’s worth doing some research on getting the right boiler for you. Just because it’s cheaper to run, it doesn’t mean that fitting a new boiler will be cheaper overall. For example, if you use around £1500 of oil per year and save 10% on your fuel bill, you will save £150 a year. Essentially, that’s a good saving. But, buying a new oil boiler and installation can cost between £2,500- £4,000.

Furthermore, it’s worth considering when you are going to replace your old boiler. Preferably before it breaks down completely. If you know that your boiler is getting old, and parts are getting more difficult to replace, it’s worth thinking about a new boiler in advance of an emergency.

why choose an oil boiler - all heat uk

Why Choose An Oil Boiler

Nowadays, oil boiler designs are just as good as combi boilers, so they can provide hot water when necessary. Furthermore, oil boilers can achieve at least 95% efficiency when turning fuel into heat, that’s a higher energy density than natural gas. Additionally, you have the freedom to change suppliers whenever you want with an oil boiler. There are no contracts. You don’t have the same freedom with a gas or electricity supplier.

Also, as you adapt to using an oil boiler, you can start to buy oil in bulk, if you have a large enough storage tank. Because the price of oil fluctuates depending on demand, you can choose to buy it when it’s cheaper.

Oil Boiler Regulations

Owning an oil boiler comes with regulations to keep you and your home safe. Firstly, it is against the law to cause pollution. Therefore you are legally responsible for maintaining your oil tank.

With this in mind, be aware that you could face a hefty fine or even prosecution if you fail to prevent an oil leak from your tank. You will also have to pay for the cost of the environmental clean up. Ultimately, oil spillages can cause significant damage to the environment and cleaning up is expensive.

New Oil Tanks

New domestic oil tanks must meet the minimum standards set by building control regulations. These include how near the tank is to the building and boundaries and the type of tank. Additionally, it includes who can certify the installation and the size of the oil supply pipe.

Existing Oil Tanks

There are no mandatory requirements for upgrading a non compliant oil tank because it is deemed unsafe. This is not the same for gas appliances, which you must upgrade legally if they are unsafe.
However, it is illegal to cause pollution. Therefore it’s necessary to get Oil Spill insurance. Notably, most policies require an annual inspection by an OFTEC engineer.

Regulatory Responsibilities

When you are getting a new boiler installation or a service, your engineer will carry out an inspection of the oil tank as well. Then, you will then be told about any defects and non compliances. Furthermore, the engineer will make recommendations for you to improve the tank.

Generally speaking, problems can include leaks from a deteriorating tank or oil line which can lead to an environmental clean up. Other issues include water problems in the tank. If you get water in the oil, it can transfer dirt from the tank into the boiler affecting your whole system.

Comparatively, unlike Gas safety regulations, you are not at risk of the heating being cut off due to having a defective oil storage tank. However, your OFTEC engineer may refuse to change the boiler without changing the tank. Although this is up to the engineer’s discretion.

Environmental Responsibilities

You have a duty to the environment if you store heating oil. Make sure you check your home insurance. Oil tanks and spills should be covered by this. With this in mind, most home insurers cover loss of metered oil due to theft or accident. They do not cover general wear and tear or gradual leaks due to poor maintenance. It’s your responsibility to keep the tank in good repair and declare any problems as soon as you see them. There is an option to take out a wider cover, such as a specialist oil spill policy. Notably, if an engineer advises you to replace your tank because your boiler is at risk of damage, it’s worth taking their advice. The cost of preventative work now will likely be much less than the costs of any damage caused to the environment in an emergency.

Renewable Energy and Oil Boilers

In general, you can also have flexibility with your oil boiler and heating if you use renewable energy heaters. Renewable energy technology includes solar heating and ground source heat pumps which are both compatible with oil boilers. Moreover, by supplementing your oil boiler with renewable energy heaters, you can bring your monthly fuel bills down even more.

Solar Heating

Solar heating panels can fit into the roof to capture the maximum energy from the sun. The thermal gain from the solar panels heats the water which is then transferred to a connecting technology system, such as a thermal store. These hot water stores allow several heat sources to be connected on one system such as an oil boiler with renewables. The hot water store keeps the water up to temperature for when you need water. Therefore you can utilise green energy alongside your oil boiler. Reducing both your carbon footprint and energy bills.

The modern design of solar panels means that they can look aesthetically pleasing to your home. Generally speaking, they are easy to install and can produce up to 70% of the energy your hot water boiler needs.

Ground Source Heat Pumps

A ground source heat pump is another good option for oil boilers. Underground temperatures sit at around 10 degrees plus. Ultimately, they are always able to take this heat in to be used for central heating. The water and antifreeze solutions contained in the heat pump are then circulated around the heat exchanger. This heat is then transferred into the home for use with a central heating system.

Conclusion: The Ultimate Guide To Oil Boiler Installation

As you can see, oil boilers are a good option to heat your home and water if you are not connected to the mains gas supply.

At All Heat UK, you can choose from a variety of boiler brands for your oil boiler installation, including; Navien, Grant, Worcester Bosch and Vaillant. So there are several options and you can choose the one that suits your home and your budget. The team at All Heat UK are more than happy to give you friendly and expert advice.

You can even get your new oil boiler the very next day and have heating and hot water for your home in no time.

The Ultimate Guide To Oil Boiler Installation should have covered all the questions you may have had, but if not: You can contact us on 0800 054 1116 or use our boiler installation quote tool to get a price for your new boiler in no time at all.

Looking for Gas instead? Read our Essential Guide to Gas Boiler Installation.