The best oil boilers in 2020

worcester greenstar danesmoor oil boiler
Credit: Worcester Bosch

Did you know there are over two million UK homes that aren’t connected to the gas mains?

If this is you, you’ll know you have to heat your home using something other than a gas boiler.

An oil boiler is often the best way to do this as you can fit an oil tank on your property and then run your central heating using this fuel. 

Although they may be pricey to install, oil burning boilers can be a much cheaper heating solution than using electricityrunning costs are around 20% more than gas.

In this review of the best oil burners in 2020, we’ll look at:

  • what an oil boiler is
  • how much it costs to run an oil boiler
  • how much you can save annually with an energy efficient oil boiler
  • what the 3 types of oil boiler are
  • what size of oil boiler you will need for your property
  • the HomeSage boiler ranking system and how it works
  • the 10 cheapest oil combi boilers
  • the top 5 oil combi boilers as ranked by HomeSage
  • the 10 cheapest oil system boilers
  • the top 5 oil system boilers as ranked by HomeSage
  • the 10 cheapest oil regular boilers
  • the top 5 oil regular boilers as ranked by HomeSage
  • how much it costs to install an oil boiler and how long it takes
  • whether an oil boiler can run on diesel
  • whether it’s safe to install an oil boiler in your loft or attic

In this article, we’ve scored each of the top ten oil combi, system, and regular boilers according to our unique ranking system and given you the top 10 budget oil boilers for each of the three forms of boiler.

We’re HomeSage – we’ve partnered with a network of reliable, trusted and established Gas Safe boiler installers up and down the UK in order to save you hundreds of pounds on your oil boiler installation. 

Simply fill in a form on this page with your information.

Once we have your details, we get in touch with three or four local and trusted boiler installation companies. The one offering the most competitive price will contact you directly to arrange an appointment, during which they’ll give you their competitive quote.

This service is 100% free for you and with no obligation, whatever you choose to do.

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What is an oil boiler?

An oil boiler is a boiler which, as you know, uses oil as its source of fuel as opposed to gas or electricity.

Oil boilers both heat your home and provide you with hot water.

The main difference between gas and oil boilers is the way they store fuel.

As a gas boiler is connected to the gas mains, it doesn’t need to store fuel as it’s delivered on demand by your supplier.

In contrast, an oil boiler must have a storage tank in order to be able to fuel your heating system. 

In the UK, all oil boilers are legally required to have a SEDBUK rating of at least 86%.

This was developed by the UK Government to ensure that all boiler manufacturers provide customers with a fair and efficient product compared to other boilers available. 

The SEDBUK rating refers to the overall efficiency of the boiler in a typical domestic set up.

It takes into account the average climate, control, and pattern of usage and the rating is stated from ‘A’ to ‘G’. The most energy-efficient oil-fired boilers are between 89% and 93% efficient. 

The cost of running an oil boiler

The exact cost of running an oil boiler depends on the output of the boiler and how much you use it.

On average, a standard UK home spends about £700 per year on heating and hot water with an oil boiler. For the same amount of heat but using a gas-fuelled boiler, it would be £150 cheaper at £550.

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How much will an A-rated boiler save you every year?

The higher the efficiency grading on your boiler, the cheaper it costs to run.

Here, we have provided the average cost of heating different sized UK homes with boilers of varying efficiency.

Below are statistics, representing typical annual savings from upgrading to an A-rated boiler, adapted from figures released by the Energy Saving Trust:

Your current boilerIts energy efficiencyFlatMid-terrace propertyDetached bungalowDetached two-story homeSemi-detached two story home
GUp to 70%£95£165£150£295£190
F70%-74%£65£115£100£205£135
E74%-78%£55£95£85£170£110
D78% to 82%£55£85£75£150£100

Although investing in a new boiler is an expensive upfront cost, the money you save annually by choosing a more efficient system will likely save you more than the cost of the installation of your new boiler in the long run.

This is because your energy bill will be considerably lower.

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What are the three types of oil boiler?

As with gas boilers, there are three choices to consider.

Combi oil boilers

An oil combi boiler is a smaller unit which heats water directly from the mains water source as it passes through the system.

This means you can have hot water instantly as soon as you turn the heating or hot tap on.

The downside of this is that you often lose water pressure if two people or more are using the hot water at one time.

System oil boiler

An oil system boiler is a larger system which requires more space as it stores the hot water you need in a tank.

The boiler heats up the water inside the cylinder where it is stored until you need it.

This means you never suffer from loss of pressure even with high demand however, once the hot water in the tank is used, you have to wait until it heats up again.

Regular oil boiler

An oil regular boiler, often referred to as conventional boiler, requires more space still.

It has two storage tanks, a cold water storage tank usually found in the loft and a separate hot water cylinder where the heated water is stored before use.

As with system boilers, you need to wait for the water to heat up again once it’s been used but they handle high demands of hot water well in larger properties. 

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Which type of oil boiler is best?

Oil combi boilers are the smallest in size of the types of oil boilers and they are usually wall-hung units.

Often, they can be hidden away discreetly behind a cupboard door and are great for smaller properties lacking in space.

They are the most energy efficient type of boiler due to their ability to make excellent use of all the energy the system provides.

Oil system boilers require a little more space – often people house them in their airing cupboards.

They are floor-standing units and generally not as energy efficient as combi boilers but they work well in areas of low water pressure.

Oil regular boilers are the largest of the boiler options as they need two separate water tanks.

One is for cold water and it is usually installed in the loft and the other is for storing the heated water.

This type of boiler is not as energy efficient as combi boilers so your annual heating costs will be higher albeit marginally so.

Flow rate

The flow rate of a boiler refers to how much water can be piped through per minute.

Flow rates only apply to combi-boilers as the water is taken directly from the mains supply.

As the hot water is stored in both system boils and regular boilers, you don’t need to worry about the flow rate.

As long as there is hot water in the tank, it will pump it through at a high pressure. 

For combi boilers, the higher the flow rate, the more water you can get through your taps but it depends on the capacity of the mains supply in your area.

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What size of oil boiler is right for your home?

You need to consider the output of your oil burner to make sure it will fit your property needs.

Boiler output refers to how much energy your boiler uses when it’s working and it tells you how much it will cost to run it.

If you have a boiler with an output of up to 28kW and the price of a unit of gas is 4p, each hour the boiler is switched on will cost you 28 x 4p – which equals £1.12.

The more hot water you need for heating and washing, the higher the output of your oil boiler needs to be too. 

Below, we have illustrated what output rate will likely be recommended by an installer for your property size.

Property typeRadiatorsBedroomsBathroomsBoiler type recommendationBoiler size recommendation
Apartment/small mid-terraced/small bungalow101 or 21Oil combi24kW-27kW
Semi-detached house/medium mid-terrace/medium bungalow153 or 41-2Oil combi28-34kW
Large semi-detached/detached house204 or more2 or moreOil combi or conventional oil boiler34-42kW
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The HomeSage boiler ranking system

We have developed our own unique boiler ranking system to make sure you are as informed as possible for your new boiler purchase.

The HomeSage system takes a variety of features and factors into consideration in order to give a fair run down of the available boilers on the market.

Our scores take into consideration the following factors:

  • the type of fuel the boiler uses (as gas is the cheapest option by far, each gas boiler gets a maximum score for this automatically – oil boilers are slightly penalised by this system but not greatly),
  • the length of the guarantee,
  • the energy efficiency rating, and
  • the amount of genuine customer reviews and average company rating from Trustpilot

Oil boilers generally score a little lower than gas boilers because they cost more to run and they also tend to have shorter warranties.

Both of these factors are reflected in our ranking scores.

Condenser oil boiler prices

With no extra water storage tank to consider and no waiting time for hot water, condenser oil combi boilers are an ideal choice for many households.

They are energy efficient, space saving, and cheaper to install and run.

Currently there are 94 oil combi boilers on the market in the UK and the average price is £2,543.

On a budget? The ten cheapest oil combi boilers

For those on a tight budget, we have compiled a list of the ten cheapest oil combi boilers available.

They are ranked in order of price. 

As you can see, the total average score for these boilers is good but it could be better – gas fuelled combi boilers rated around 20% higher in total on average after considering efficiency, price and fuel factors.

Make and Model NameEfficiency RatingParts and Labour Wty (months)Output in kWFlow RatePrice fromTOTAL
Firebird Enviroblue Combi-Pac 20kw Boiler93.00%242012£1,27571.77%
Warmflow Utility UC70HEE 21kw Boiler89.10%602118£1,32075.14%
Warmflow Utility UC90HEE 26kw Boiler89.10%602624£1,37075.02%
Firebird Enviroblue HEC26 26kw Boiler93.00%242616£1,47071.29%
Grant VortexBlue 26kw Boiler91.70%242617£1,47073.21%
Firebird Enviromax HEC20 20kw Boiler90.70%242016£1,54071.12%
Firebird Enviroblue Combi-Pac 26kw Boiler93.00%242616£1,57071.05%
Firebird Enviromax HEC26 26kw Boiler90.70%242616£1,62070.92%
Firebird Enviromax Combi-Pac 20kw Boiler91.10%242015£1,76570.57%
Mistral Standard C1 20kw Boiler87.00%242013£1,76560.00%
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The HomeSage top-rated 5 oil combi boilers

If you have an unlimited budget for your boiler, you could consider one from the list below.

These boilers have been ranked according to the HomeSage scoring system to give you a clear oversight of their benefits and features. 

All 5 of these boilers have a high efficiency rating and a moderate to high overall score.  

Make and Model NameEfficiency RatingParts and Labour Wty (months)Output in kWFlow RatePrice fromTOTAL
Worcester Bosch Greenstar Heatslave II 12/18 Boiler90.00%241815£2,41080.33%
Worcester Bosch Greenstar Heatslave II 25/32 Boiler90.00%243222£2,71579.58%
Warmflow Utility UC70HEE 21kw Boiler89.10%602118£1,32075.14%
Warmflow Utility UC90HEE 26kw Boiler89.10%602624£1,37075.02%
Warmflow Utility UC120HEE 33kw Boiler89.10%603324£1,95073.60%
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Oil system boiler prices

For constantly high water pressure you may wish to consider an oil system boiler.

These boilers don’t require extra storage space in your attic and they provide a high level of hot water until they require refilling and heating. 

The average price for a condenser oil system boiler in the UK is £1,823 and there are currently 49 available on the market. 

On a budget? The ten cheapest oil system boilers

Budget boiler shoppers can consult this list for the top ten cheapest oil system boilers as of June 2020.

The total scores for these boilers are moderate to low, although many do have high efficiency ratings at grade ‘A’ or ‘B’.

Here, we have ranked them in order of the average price of the boiler.

Make and Model NameEfficiency RatingParts and Labour Wty (months)Output in kWPrice fromTOTAL
Warmflow Utility US70HE 21 Boilers90.70%6021£1,15075.57%
Grant Vortex Eco Utility 21 Boiler92.70%2421£1,28573.67%
Mistral Sealed S1 20 Boiler87.00%2420£1,29561.16%
Grant VortexBlue Kitchen/Utility 21 Boiler90.80%2421£1,31073.60%
Mistral Sealed S2 26 Boiler87.00%2426£1,35061.02%
Warmflow Kabin Pak KS70HE 21 Boiler90.70%2421£1,39072.48%
Firebird Envirolite 20 Boiler93.00%2420£1,39571.48%
Grant Vortex Eco Wall Hung 16 Boiler90.10%2416£1,44573.27%
Mistral Outdoor Sealed OD SS1 20 Boiler87.00%2420£1,47060.73%
Mistral Sealed S3 35 Boiler87.00%2435£1,47060.73%
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The HomeSage top-rated 5 oil system boilers

If price is no object for your boiler, the top 5 scoring condenser system boilers are listed below. 

The Worcester Bosch Greenstar Danesmoor wiped out the competition and the various models available dominated our results.

This range are market leading oil system boilers and the company even has the Royal Warrant seal of approval from Her Majesty The Queen.

They feature a 5-year guarantee as standard, they can be used with Greenskies solar panels for a minimal environmental footprint, and they are easy to program and use. 

The highest finishing non-Worcester Bosch boiler in our results was a Warmflow boiler that ranked at 7th place with a total average score of 75.57%.

Make and Model NameEfficiency RatingParts and Labour Wty (months)Output in kWPrice fromTOTAL
Worcester Bosch Greenstar Danesmoor Utility 12/18 Boiler90.00%2418£1,70582.06%
Worcester Bosch Greenstar Danesmoor Utility 18/25 Boiler90.00%2425£1,78581.86%
Worcester Bosch Greenstar Danesmoor 12/18 Boiler90.00%2418£2,10081.09%
Worcester Bosch Greenstar Danesmoor Utility 25/32 Boiler91.00%2432£2,15580.95%
Worcester Bosch Greenstar Danesmoor 25/32 Boiler91.00%2432£2,60579.85%
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Oil regular boiler prices

The average price of an oil regular boiler in the UK is £1,787 and there are 144 regular oil boilers on the market as of June 2020.

Oil regular boilers provide a high amount of hot water on demand and they can be cheap to run however they require more space than combi or system boilers.

Regular boilers can be beneficial for large properties with big hot water requirements but there is a waiting time for the water to heat up.

On a budget? The ten cheapest oil regular boilers

Here we have compiled a list of the ten cheapest oil regular boilers on the market in the UK.

We’ve ranked them from cheapest to more expensive so, if you’re on a budget, you can quickly see your financial options.

The average price of the boiler is written in the table and, as you can see, the total scores that consider elements such as the price and the length of warranty are moderate at around 60-70%. 

Make and Model NameEfficiency RatingParts and Labour Wty (months)Output in kWPrice fromTOTAL
Warmflow Boilerhouse B70HE 21 Boiler90.70%8421£1,02577.54%
Mistral Boiler House Classic BH1 20 Boiler87.00%2420£1,05561.75%
Mistral Kitchen Utility Classic KUT1 20 Boiler87.00%2420£1,05561.75%
Firebird Enviromax Popular Boilerhouse 18 Boiler92.00%2418£1,06072.30%
Firebird Envirolite Utility 20 Boiler93.00%2420£1,10072.20%
Mistral Boiler House Classic BH2 26 Boiler87.00%2426£1,11561.60%
Mistral Kitchen Utility Classic KUT2 26 Boiler87.00%2426£1,11561.60%
Warmflow Utility HE U70HE 21 Boiler90.70%8421£1,15077.23%
Mistral Boiler House Classic CBH1 20 Boiler92.00%2420£1,16064.00%
Firebird Envirolite Boilerhouse 20 Boiler93.00%2420£1,16572.04%
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The HomeSage top-rated 5 oil regular boilers

The top 5 rated oil regular boilers according to our HomeSage scoring method are below.

These boilers are worth considering if you have no financial restrictions and want the best for your property.

Much like the oil system boilers, our top 5 was taken over by the Worcester Bosch Greenstar Danesmoor range.

They feature concealed boiler controls, a wide range of heating outputs, and they are compatible with Greenstar hot water cylinders. 

Worcester Bosch took up the first 12 places on our oil regular boiler scoreboard, and the highest finishing non-Worcester Bosch model was a Baxi boiler that had a total score of 77.54%.

Make and Model NameEfficiency RatingParts and Labour Wty (months)Output in kWPrice fromTOTAL
Worcester Bosch Greenstar Danesmoor 12/18 Boiler90.00%2418£1,400.0082.81%
Worcester Bosch Greenstar Danesmoor Utility 12/18 Boiler90.00%2418£1,415.0082.77%
Worcester Bosch Greenstar Danesmoor Utility 18/25 Boiler90.00%2425£1,520.0082.51%
Worcester Bosch Greenstar Danesmoor 18/25 Boiler90.00%2425£1,665.0082.16%
Worcester Bosch Greenstar Danesmoor 18/25 Boiler90.00%2425£1,840.0081.73%
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How much do oil boilers cost to install and how long does it take?

Oil burners are considerably more expensive to purchase and install than other options like gas combi boilers or storage boilers.

On average, you can expect to pay between £4,000 and £5,000 for both the boiler and installation depending on how much work needs to be done to prepare your property. 

Installing an oil boiler can take anything between 1 and 3 days.

It depends how much work needs to be completed before installing the boiler and, if your property needs some considerable adjustments, it may take longer.

It’s best to ask your boiler installation company for their estimate before you commence work.

Can my oil boiler run on diesel fuel?

System and regular boilers can be converted to diesel providing they are installed outside and they have a high-level flue.

This is because burning diesel with a low-level flue isn’t permitted in the UK.

Combi boilers cannot be converted to diesel as it is not recommended for running indoor heating systems.

Most oil-fuelled boilers run on kerosene which is another form of oil.

Kerosene is the only fuel oil suitable for use with an indoor oil-fired boiler because it burns cleanly, economically, and it produces a high level of heat.

As diesel and gas oil are more expensive than kerosene, this would only make economic sense where the fuel is bought in bulk, such as in the agricultural sector. 

To convert your boiler to run on diesel, you should hire an OFTEC qualified technician. 

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Can I put an oil boiler in my attic/loft?

The main consideration for installing your boiler is the temperature of the environment.

An attic or loft can be considerably colder in winter and hotter in summer and this can affect how efficiently your boiler works. 

Because of the change in temperatures in a loft, you will need to ensure your boiler has adequate frost protection and pipe insulation.

It if is wall-hung, it must be installed on a wall that can support the full weight of the boiler.

Installing a boiler in a loft can save space in your home but there needs to be ample room around it for any engineer to be able to access and maintain your system.

You should also consider how easy it is to get up in the loft in the first place and whether the space has a light source.

Systems such as regular boilers will require loft space for their water tank but combi boilers and system boilers are more versatile in their installation options. 

Save up to 54% on the installation of your new oil boiler

You can save up to 54% of the cost of the supply and the installation of your new oil boiler simply by leaving your details with us through a form anywhere on this page. 

Once we have your details, we can pass them on to three or four local, trusted oil boiler installation companies.

We only contact Gas Safe engineers so you can be sure you are in trusted hands.

The cheapest of them will contact you with a competitive quote and it’s up to you if you want to go ahead.

Our service is 100% free, it’s no obligation and could save you hundreds of pounds. 

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Andy

Andy is one of the HomeSage founders and an occasional content contributor. His love for boilers is only just outweighed by his love for football.