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Last updated: 7th May, 2024


Disadvantages of Oil Boilers: Exploring Key Concerns

Disadvantages of Oil Boilers: Exploring Key Concerns

Key takeaways

  • Oil boilers are a heating alternative for off-grid homes, but they come with several disadvantages.
  • Higher energy consumption and running costs are notable drawbacks for homeowners.
  • The need for a dedicated storage tank also poses challenges in terms of space and property requirements.

Oil boilers may be a popular choice for home heating, but they come with some significant disadvantages. Our guide explores the drawbacks of oil boilers, including high installation costs, environmental impact, and fluctuating fuel prices. We compare advice from reputable sources like TheGreenAge, Boiler Guide, and The Renewable Energy Hub to help you make an informed decision about your heating s

Oil boilers offer a heating solution to homeowners who do not have access to natural gas. Commonly used in off-grid locations, oil boilers are considered to be an alternative to traditional gas heating systems. 

While oil boilers provide warmth and hot water to those without access to gas, they come with a set of disadvantages that homeowners need to consider in order to make an informed decision.

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A significant drawback of oil boilers is the higher consumption of energy compared to their gas counterparts. 

This inherently results in higher running costs and increased carbon emissions, which contribute to the negative environmental impact. Moreover, oil-fired boilers tend to require a dedicated storage tank for the fuel, which takes up additional space on the property.

Understanding Oil Boilers:

Oil boilers are a popular choice for heating systems in homes located off the gas grid. These boilers use liquid oil as fuel, which is stored in a tank on the property and pumped to the boiler when needed. 

Modern condensing oil boilers are designed to be energy efficient and can provide considerable savings in heating costs when compared to older, non-condensing models.

One downside of oil boilers is the fluctuating cost of oil itself. As a commodity, its price is subject to international market forces and geopolitical events, which can cause significant fluctuations in the cost of fuel. 

This can lead to unpredictable heating costs for homeowners relying on oil-fired central heating systems.

Another drawback is that oil boilers require space for an outdoor storage tank. This can be an inconvenience for some homeowners, depending on the available space and the location of the property. It also necessitates regular deliveries of heating oil, which may pose logistical challenges in some cases.

While modern condensing oil boilers have made improvements in efficiency, they still contribute to carbon emissions. 

Since oil is a fossil fuel, burning it produces carbon dioxide (CO2), which impacts the environment and exacerbates climate change. This makes oil boilers less eco-friendly than renewable energy alternatives like solar, wind, or heat pumps.

Lastly, oil boilers can be prone to leakage and spills. If there's an issue with the storage tank or connecting pipes, spilled oil can lead to environmental hazards and potential penalties from regulatory agencies. This requires homeowners to be diligent in maintaining and monitoring their oil heating system.

In summary, while oil boilers are a viable heating option for properties off the gas grid, they come with several drawbacks. 

These include fluctuating fuel costs, the need for a storage tank, environmental concerns, and potential leakage risks. Homeowners should carefully consider these factors when deciding on an oil-fired central heating system.

Operational Efficiency

Oil boilers, while providing a viable heating solution for homes and businesses, do have certain efficiency drawbacks compared to other fuel options. Specifically, the efficiency of oil-fired boilers may be lower than that of natural gas or electric alternatives.

When considering boiler efficiency, there are two main factors to consider: the combustion efficiency and the system efficiency. Combustion efficiency refers to how effectively a boiler converts fuel into usable heat. System efficiency, on the other hand, takes into account how well the boiler distributes that heat throughout a building.

One key difference between heating oil and natural gas is energy density. Generally, heating oil has a higher energy density than natural gas, meaning it contains more energy per unit volume. Consequently, oil boilers require larger volumes of fuel to generate the same amount of heat as natural gas boilers.

Moreover, many oil-fired boilers contribute to a greater amount of heat loss than natural gas alternatives. This is partly due to the need for oil storage tanks, which can result in heat loss through the tank walls. Additionally, boilers using heating oil, gas oil, or red diesel may have less efficient burn patterns than natural gas boilers, resulting in incomplete fuel combustion and reduced overall efficiency.

The age of an oil boiler can also impact its operational efficiency. Older boilers are typically less efficient than newer models, leading to higher fuel consumption and energy costs. 

Upgrading to an A-rated oil boiler can help increase efficiency somewhat, but these ratings may not provide a complete picture of the boiler's real-world performance.

Ultimately, while oil-fired boilers can produce adequate heat for many homes and businesses, their efficiency may be less than optimal compared to natural gas or electric alternatives. Considering factors such as combustion efficiency, system efficiency, and the energy density of heating oil may be crucial in understanding and improving the overall operational efficiency of an oil boiler.


Energy Consumption

Oil boilers, while serving as a viable heating solution for off-grid homes, come with their own set of disadvantages, particularly in terms of energy consumption. As a fossil fuel, oil is less environmentally friendly than natural gas or electricity. 

In fact, oil boilers are responsible for producing approximately twice the amount of carbon dioxide compared to gas boilers. This not only contributes to increased energy consumption but also has a detrimental impact on the environment.

Regarding efficiency, modern oil boilers have significantly improved over the years. However, their flow rate typically remains lower than that of gas boilers. A lower flow rate suggests that oil boilers may take longer to heat a space, leading to more extended periods of burning oil, thereby consuming more energy and generating higher costs.

Affordability is another crucial aspect when discussing energy consumption. While oil can be a more efficient fuel source compared to electricity, it still suffers from fluctuations in market pricing. 

These price variations can affect the overall cost of heating a home with an oil boiler, making budgeting more challenging for households.

In terms of heating options, it is important to consider alternatives such as electric boilers, renewable energy sources like solar water heating, or biomass boilers. These sustainable options have their own sets of pros and cons, but they often provide greener solutions, reducing reliance on non-renewable fossil fuels.

In conclusion, while oil boilers remain an essential heating choice for many off-grid homes, they do come with certain disadvantages concerning energy consumption. Their environmental impact, lower flow rate, and fluctuating fuel costs are critical factors that cannot be overlooked. Therefore, when selecting a heating system, it is essential to weigh the pros and cons of oil boilers and consider alternative options such as electric boilers or renewable energy sources as viable, eco-friendly solutions.

Oil Boiler Costs

When considering an oil boiler, one of the primary concerns is the costs associated with the purchase and installation of the unit, as well as the ongoing expenses of fuel and maintenance. The price of oil can fluctuate significantly, which directly affects heating bills and may make budgeting difficult for homeowners.

Upfront costs for oil boilers can be relatively steep, with prices ranging between £2,500 - £4,500, depending on the job. This price includes both the cost of the boiler and the installation process. In addition, oil storage tanks need to be purchased, and these can range in size from 1,000 litres to 3,500 litres, costing between £500 - £2,000. Alternatively, it is possible to rent a tank from an oil fuel supplier, which might be a more cost-effective solution for some homeowners.

While oil boilers can be efficient and provide a great heating solution for off-grid homes, another financial aspect to consider is the running costs. As the price of oil is subject to market fluctuations, homeowners may find it difficult to accurately predict their heating bills. Consequently, budgeting for these potential price changes can be challenging.

Despite these drawbacks, homeowners can find affordable solutions by seeking free quotes from multiple service providers. Comparing three or more free quotes allows individuals to find the best deal and the most cost-effective option for their specific needs. Additionally, it's essential to explore various finance options and schemes that may be available to ease the burden of the initial investment and reduce monthly heating bills.

In summary, while oil boilers have their advantages, the costs associated with purchasing, installing, and maintaining the unit can be considerable. The fluctuating price of oil can make it difficult for homeowners to accurately budget for heating expenses. To make the most cost-effective decision, it is important to compare quotes, consider finance options, and be aware of potential market fluctuations when planning for long-term heating needs.

Negative Impact on Environment

Oil boilers, despite their efficiency and relative affordability, can have a negative impact on the environment. This is primarily due to their reliance on fossil fuels, which result in emissions of carbon dioxide, carbon monoxide, and other pollutants.

The burning of fossil fuels in oil boilers releases significant amounts of carbon dioxide into the atmosphere. As a well-known greenhouse gas, carbon dioxide contributes to climate change by trapping heat in the Earth's atmosphere. This causes global temperatures to rise, leading to more extreme and unpredictable weather patterns.

Apart from carbon dioxide emissions, oil boilers are known to release carbon monoxide, a poisonous gas that is dangerous to both humans and animals. When inhaled, carbon monoxide reduces the ability of blood to carry oxygen, resulting in potentially life-threatening symptoms such as dizziness, nausea, and vomiting. Furthermore, these emissions pose severe health risks if not adequately ventilated.

Oil leaks are another environmental concern with oil boilers. Inside properties, leaks might rapidly lead to fires. Meanwhile, leaks that occur outdoors could contaminate surrounding water, threatening local ecosystems by infiltrating nearby streams and rivers. This contributes to long-lasting damage and disruption to the balance of local habitats.

Coal-fired boilers, another fossil fuel-based heating system, are found to emit even larger amounts of pollutants. This highlights the need for alternative, renewable-based heating systems with lower ecological impacts. Nonetheless, oil boilers remain a significant source of pollution and present considerable challenges to efforts aiming for a greener and more sustainable way of life.

In conclusion, the use of oil boilers has a number of disadvantages, particularly concerning the environment. Emissions, leaks, and the reliance on fossil fuels contribute to negative impacts on both global climate change and local ecosystems. Promoting cleaner alternatives like renewable energy systems for heating purposes remains vital for ensuring a more environmentally friendly future.

Physical Challenges and Requirements

Oil boilers come with their own set of physical challenges and requirements. Although they can provide efficient heating for a home, it's essential to consider the limitations along with your specific needs.

Firstly, space can be a significant concern for oil boilers, as you will need sufficient room for the boiler itself, along with an oil storage tank. The size of your home may restrict the location and options for the boiler and tank installation. Tanks can range in size from 1,000 litres to 3,500 litres, which means they will require a considerable amount of space. Furthermore, an oil tank can cost between £500 - £2000, which is an additional expense you should take into account.

Another challenge is the noise produced by some oil boilers. Whilst manufacturers have made strides in reducing the sound levels, it's still something to consider if you are sensitive to noise or have the boiler placed close to living areas. The noise can be exacerbated if a poorly-maintained boiler or if it develops any mechanical issues over time.

Soot is another factor that needs to be considered. Oil boilers, albeit efficient, can produce soot as a by-product of combustion. This accumulation of soot can lead to internal components breaking down over time, as well as needing an annual service to make sure the system remains in good working order. To mitigate this issue, it's essential to ensure regular maintenance and cleaning; however, this may add to the overall running costs of the heating system.

In summary, when considering an oil boiler, it's crucial to weigh the physical challenges and requirements against the benefits provided by oil-fired heating. By carefully assessing your house size, available space, and personal preferences such as noise and maintenance, you can make an informed decision about whether an oil boiler is the right choice for your home.

Posed Risks

Oil boilers come with certain risks that can pose issues for homeowners. One such risk is the potential for leaks. Leaks can occur in various parts of the system, including the fuel lines, storage tanks, and boiler itself. When a leak happens, not only is it a waste of valuable resources, but it can also cause damage to the surrounding area and lead to the release of harmful emissions into the environment.

In addition to the risk of leaks, oil boilers can also be hazardous in terms of accidents. As oil is a highly flammable substance, any mishaps during the transportation, storage or delivery of oil could lead to dangerous situations. Moreover, incorrect installation or maintenance of the oil heating system may result in increased risk of fires or explosions.

Another posed risk comes from the inherent dependency on external factors regarding oil prices. Fluctuations of crude oil prices may directly impact the cost of heating for homeowners using oil boilers. Unstable political situations and changes in demand, particularly during the winter months, can lead to escalating costs, making it difficult for some households to afford the necessary fuel.

The space required for oil tank storage is also a notable risk for some homeowners. Oftentimes, properties with limited space may struggle to find a suitable location for the storage tank, which can be cumbersome and unattractive. This can result in added hassle and potential disputes with neighbours or local authorities due to planning regulations.

In conclusion, while oil boilers can provide efficient heating solutions for some households, it is essential to consider the posed risks, such as leaks, the potential for accidents, fluctuating oil prices, and issues relating to storage space. These concerns should be taken into account when deciding whether an oil boiler is the right choice for your home.

Maintenance and Servicing

When it comes to oil-fired boilers, regular servicing and maintenance are essential to ensure they remain efficient and reliable. An annual service by a qualified engineer, preferably a Gas Safe registered professional, can help to detect and fix any potential problems early on, and keep your system running smoothly.

One common issue faced by oil boilers is the risk of frozen water or air blocking the oil line, which can result in the boiler locking out. Regular checks, especially during the colder months, can help prevent this and ensure a consistent fuel supply to the boiler. Additionally, routine maintenance can reduce the likelihood of unexpected breakdowns and costly call-out fees.

In comparison to gas boiler systems, oil boilers may require more frequent servicing to ensure optimal performance. This is because oil-fired systems can be prone to soot and debris build-up, which can reduce their efficiency if not attended to. Engaging a trusted customer service team can provide you with the necessary support and guidance to manage your oil boiler's maintenance needs.

It's important to note that not all engineers are qualified to work on oil boilers, so it's crucial to select a technician with the relevant expertise. Gas Safe registered engineers are highly recommended, as they possess the skills and knowledge to carry out services and repairs for various types of boilers, including oil-fired systems.

In summary, the maintenance and servicing of oil boilers may require greater attention compared to their gas counterparts. Being proactive and engaging the services of a professional and qualified engineer can make all the difference in ensuring the longevity and efficiency of your oil boiler system.

Comparisons with Alternatives

Oil boilers are popular in off-grid homes, but there are alternative heating systems to consider, such as electric, gas, biomass, and heat pumps.

Electric boilers are advantageous as they are clean, quiet, and easy to install. They do not require a flue or fuel delivery system. However, they may result in higher electricity bills. When comparing electric and oil boilers, electric boilers are generally more expensive on a day-to-day basis, but are much more energy efficient (with an efficiency of 99%, compared to 93% for oil boilers). A hybrid system, combining electric heating with an additional heat source, could be another viable option.

Gas boilers are usually more efficient than their oil counterparts (up to 94% efficient). They have lower CO2 emissions, and gas is typically cheaper and more readily available. The downsides of gas boilers are that they require a flue and gas supply, which can be an issue in off-grid areas. Combi boilers combine both heating and hot water production into a single unit, making them a popular choice in modern homes. When comparing oil and gas boilers, it’s essential to consider the cost of installing a gas supply line if one does not already exist.


Heat pumps (air source or ground source) are eco-friendly alternatives that provide heating, ventilation, and air conditioning (HVAC) solutions. These systems transfer heat from the outside air or ground to heat the home. They are highly energy efficient, reducing CO2 emissions substantially. However, they may have higher initial costs and require sufficient outdoor space for installation.

Biomass boilers, burning sustainable wood pellets or logs, are a greener alternative to oil boilers. They can reduce your carbon footprint and offer a sustainable long-term heating solution. Nonetheless, the initial cost of installation is higher, and biomass systems require considerable storage space for the fuel. Additionally, they may not be suitable for urban settings due to regulations on smoke emissions.

To summarise, when considering a switch from oil boilers, one must compare the benefits and disadvantages of alternatives. Each system has its pros and cons, so it’s essential to identify the most suitable and efficient option for your specific circumstances and requirements.

Brands and Models

When discussing the disadvantages of oil boilers, it's essential to consider the various brands and models available on the market. Worcester Bosch, a renowned manufacturer, offers the Greenstar Heatslave II, a popular oil boiler in the UK. However, even the best oil boilers come with some drawbacks.

As a consumer, it's essential to research and compare different oil boiler models. Reviews play a crucial role in determining the quality and performance of a boiler. Worcester Bosch is known for its experience and expertise in the heating industry. However, oil boilers, in general, do have some cons that are worth considering.

One common issue with oil boilers is their higher initial and installation costs compared to gas boilers. Additionally, oil boilers require a storage tank for the fuel, which can take up valuable space on your property and contribute to environmental risks associated with potential leaks.

Another disadvantage of oil boilers is fluctuating fuel prices, which make it difficult to predict long-term heating costs. Heating oil prices can vary significantly over time, resulting in unpredictable expenses for homeowners.

Moreover, oil boilers generally have a lower energy efficiency compared to gas boilers, which can lead to higher running costs. This could potentially offset any savings gained from lower fuel prices in the long run. It's essential to weigh these factors when comparing oil boilers like the Worcester Bosch Greenstar Heatslave II against other options.

To make an informed decision, homeowners should compare at least three free quotes from different boiler providers. This will help them determine the best oil boiler for their needs, considering factors like cost, efficiency, and overall performance.

In summary, while reputable brands like Worcester Bosch provide reliable and high-quality oil boilers, it's crucial to consider the disadvantages of oil boilers before making a decision. By researching various brands and models, reading reviews, and comparing quotes, you can make a more educated and informed choice for your home.


Oil boilers come with several disadvantages that homeowners should take into consideration when making decisions about their home heating systems. One notable drawback is the fluctuation of oil prices. As domestic oil prices are linked to crude oil, factors such as demand, availability, and political situations can cause these prices to vary, particularly during winter when demand is high.

Another downside to oil boilers is the extra space they require, especially in the case of conventional models. These systems need room for both a hot water cylinder and a cold water tank, which can be inconvenient for homes with limited space. In contrast, combi boilers are a more compact option, offering heat and hot water in a single unit.

Despite these drawbacks, oil boilers do have some potential benefits, such as the prospect of utilising a renewable, low-carbon liquid fuel or bio-fuel in the future. Current oil heating systems would be compatible with this alternative fuel source, making the transition to a greener solution easier for homeowners. However, until such a fuel becomes widely available and affordable, the disadvantages of oil boilers remain significant factors for households to weigh.

In sum, it's important to carefully consider both the pros and cons of oil boilers before making a decision about your home's heating system. Though there are some potential benefits, it's essential to acknowledge the disadvantages, particularly the impact on the environment, fluctuating prices, and space requirements.

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Frequently Asked Questions

Are oil boilers being phased out?

Yes, oil boilers are being phased out in the UK. The government plans to phase-out high-carbon fossil fuel heating, including heating oil, in off-gas-grid homes during the 2020s. New homes cannot have oil heating after 2025. However, the government won't force homeowners to remove central heating systems that are in good working order.

Is it worth getting a new oil boiler?

While oil boilers are being phased out, if your existing oil boiler is nearing the end of its life, or if you live in a property with no access to the gas network, getting a new oil boiler might still be worth considering. You should also weigh the options of upgrading to a more environmentally-friendly and energy-efficient alternative, such as a biomass boiler or an air-source heat pump.

What is the cost of a new oil boiler?

The cost of a new oil boiler varies according to the size, manufacturer, and whether it's an internal or external model. Combi boilers start at £2,225, heat-only boilers from £1,200, and system boilers from £1,450.

Are oil boilers going to be banned?

The UK government plans to ban the installation of oil boilers in new homes after 2025. However, there is no planned outright ban on the existing oil boilers in homes with systems in good working order.

Is it worth replacing my oil boiler?

If your oil boiler is older than 15 years or experiencing frequent breakdowns, it might be worth considering a replacement. Upgrading to a modern, energy-efficient boiler could save you money on fuel bills and reduce your carbon footprint. However, be mindful of the impending phase-out of oil boilers and consider environmentally-friendly alternatives.

What should I replace my oil boiler with?

When replacing your oil boiler, consider low-carbon heating options, such as biomass boilers or air-source heat pumps. These alternatives can be more energy-efficient and environmentally-friendly, while still providing sufficient heating for your home.

Should I replace my 20-year-old oil boiler?

If you have a 20-year-old oil boiler, you should consider upgrading to a more energy-efficient and environmentally-friendly heating system. A modern, high-efficiency boiler or a low-carbon alternative, such as a biomass boiler or air-source heat pump, can potentially save you money on energy bills and reduce the carbon emissions associated with your home's heating.

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Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.