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Last updated: 8th May, 2024


Are Old Boilers Expensive to Run?

Are Old Boilers Expensive to Run?

Key takeaways

  • Old boilers generally have poor efficiency, resulting in higher running costs and increased energy bills.
  • Regular maintenance and servicing of old boilers can further add to their overall expense.
  • Replacing an old boiler with a new, more efficient model may offer long-term financial and environmental benefits.

Old boilers can be expensive to run, as they are often less efficient and more prone to breakdowns than newer models. Our guide explores the costs and efficiency of old boilers, including how to evaluate the efficiency of your current boiler and the potential cost savings of upgrading to a newer model.

The issue of whether old boilers are expensive to run is a topic that has sparked debate among homeowners and experts alike. 

As energy prices continue to rise, the efficiency and cost-effectiveness of heating systems have become increasingly important. 

With many homes still relying on old boilers for their heating needs, it is essential to understand the implications of using such devices, both from a financial and environmental standpoint.

Old boilers often exhibit poor efficiency and performance, leading to higher running costs and a negative impact on energy bills. 

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Additionally, regular maintenance and servicing can add to the financial burden of keeping an old boiler in operation. While investing in a new, more efficient boiler may require a significant upfront cost, the long-term savings and potential environmental benefits may outweigh this initial expense.

Understanding Old Boilers-

Old Boilers can be less efficient than newer models, which can lead to higher energy bills for homeowners. There are several factors that contribute to the decreased efficiency of older boilers such as outdated technology, wear and tear, and lack of regular maintenance.

One aspect that affects the performance of an old boiler is its flue system. The flue is responsible for venting waste gases produced during the combustion process. Over time, the flue might suffer from corrosion or damage, which could result in heat loss and reduced efficiency.

Furthermore, moving parts in old boilers can also pose a problem. These boilers typically contain more mechanical components than modern ones. As these parts wear out, the boiler's performance might decline, leading to an increase in energy consumption and maintenance costs.

Maintenance is another crucial factor in the performance of an old boiler. Regular servicing can help to identify and resolve issues that may affect efficiency. However, as older boilers have more complex systems and parts that are harder to source, maintenance can be more expensive and time-consuming.

In summary, old boilers can be more expensive to run due to factors such as outdated technology, wear and tear, and increased maintenance costs. Homeowners with older boilers might want to consider upgrading to a more energy-efficient model, as this could result in significant savings on energy bills and reduce the environmental impact of their heating system.

The Expensive Running Costs of Old Boilers:

Old boilers can be quite expensive to run, primarily due to their inefficiencies. Compared to newer models, older boilers tend to consume more fuel. As a result, this leads to higher gas boiler running costs for homeowners.

It is undeniable that fuel prices have a significant impact on the cost of running old boilers. In the past, the cost of gas was relatively lower, making gas boilers a popular choice among homeowners. However, with the increasing prices of natural gas, it has become apparent that old gas boilers can be uneconomical in the long run.

When observing electric boilers, the costs of running them in the UK can range from £500 to £1,500 per year on average. While electric boilers are energy-efficient, they generally have higher running costs due to the higher price of electricity compared to gas. For instance, a gas unit typically costs less than an electricity unit, making electric boilers somewhat less appealing from a cost perspective.

Moreover, old boilers can be harder and more expensive to maintain. Regular servicing and possible repairs add to the operational costs. In one example, an old boiler may cost £225 more in gas and £105 more annually for a maintenance contract, amounting to £120 per year in higher running costs compared to a new boiler.

To sum it up, the running costs of old boilers can indeed be expensive, attributable mainly to their inefficiencies, high fuel consumption, and maintenance expenses. Both gas and electric boilers may contribute to higher bills for homeowners. Therefore, upgrading to a more efficient boiler can provide significant long-term savings while also minimising the impact on the environment.

Poor Efficiency and Performance-

Older boilers can often be quite inefficient, causing homeowners to spend more on their heating bills than necessary. The efficiency of a boiler decreases as it ages, and over time this can lead to an appreciable increase in costs. For instance, boilers that are 25 years or older generally have an efficiency rating between 60% and 70%, which means that a significant percentage of the energy used is wasted.

The performance of these ageing boilers also tends to be less consistent, causing erratic heating throughout the home. On the other hand, modern boilers are required to have an A-rating for efficiency, ensuring that they operate at a significantly higher level. These newer models have the advantage of an Energy-related Products (ERP) rating visible on the unit or its packaging. The higher the ERP rating, the more energy efficient the boiler will be, leading to reduced energy bills.

In addition to the financial implications, an inefficient boiler can also have a negative impact on the environment. The lower the boiler efficiency, the more energy the unit requires to heat a home, resulting in increased carbon emissions. By upgrading to a more efficient heating system with a higher ERP rating, homeowners can contribute to a reduced carbon footprint whilst also saving money.

When assessing the efficiency of a boiler, there are several factors to consider aside from its age. The type of heating system, as well as the proper maintenance and appropriate insulation, plays a significant role in the overall performance of your boiler. It is essential for homeowners to ensure their heating system is checked and serviced regularly, as this will help to maintain the boiler's efficiency over time.

In conclusion, older boilers not only have a higher tendency to be inefficient but also underperform in terms of heating consistency and energy consumption. Considering the financial and environmental implications, upgrading to a modern, high-efficiency boiler with a good ERP rating should be a priority for homeowners seeking to improve their heating systems.

Negative Impact on Energy Bills

When it comes to old boilers, one of the main drawbacks is their negative impact on energy bills. Numerous factors contribute to this issue, including the boiler's age, efficiency, and overall functionality.

In many cases, old boilers tend to be less efficient than their modern counterparts. A 10- to 15-year-old boiler may only reach 60% efficiency, ultimately overpaying for the energy it consumes. With heating and hot water accounting for more than half of a household's energy bills, an inefficient old boiler can significantly contribute to increased expenses.

Moreover, a common issue with older boilers is their size, often much larger than necessary. This disproportion not only adds to the consumption of energy but also exacerbates the problem of high energy bills. As energy prices continue to rise, this inefficiency becomes an even more pressing concern.

Fortunately, there are steps that can help mitigate the negative impact of an old boiler on energy expenditure. For example, lowering the flow temperature on your boiler might save up to 8% on heating expenses. 

This translates to a reduction of around £200 at the current electricity and gas prices. Additionally, small improvements in heating efficiency can lead to substantial monetary savings over time.

In conclusion, the age, efficiency and size of older boilers can indeed contribute to higher energy & heating bills, making them expensive to run. An upgrade to a more energy-efficient boiler may represent a wise investment, but costs of purchasing and installing a new boiler must also be considered. Nonetheless, even with old boilers, it's possible to implement measures such as reducing the flow temperature to alleviate their impact on energy bills.

Maintenance and Servicing

When it comes to old boilers, maintenance and servicing play a crucial role in their efficiency and overall running costs. Maintenance costs can vary depending on the age, make, and model of the boiler. Regular servicing by a qualified heating engineer can help to prolong the lifespan of the boiler and ensure its safe operation.

One of the significant advantages of servicing your boiler is to detect any potential issues early on, preventing major breakdowns or costly repairs down the line. An annual service typically includes a thorough inspection of the boiler components, cleaning of the burner and heat exchanger, and checking the safety controls, among other tasks.

In a 2023 boiler customer survey, it was found that the average repair cost people had paid was £196. A boiler cover package typically costs £200 to £300 a year, which should include an annual service and cover repair costs. People paid an average of £270 a year for a boiler cover package.

It is essential to hire a reputable and qualified heating company, who’s engineers are Gas Safe registered to carry out the servicing. 

In summary, proper maintenance and servicing can help to keep old boilers running efficiently, reducing overall costs and potential breakdowns. Regular inspections and the use of a qualified heating engineer are crucial to ensure safe and effective operation. Utilising platforms such as Which? Trusted Traders can aid in finding trustworthy professionals to perform these vital services.

Negative Environmental Impact

It is apparent that old boilers can have a significant negative impact on the environment. As the core component for providing heat within homes, their role in contributing to carbon emissions and climate change cannot be overlooked.

Firstly, older boilers tend to be less energy-efficient, meaning more fuel is required to produce the same amount of heat. This results in higher carbon emissions and an increased carbon footprint for households relying on outdated systems. Furthermore, these boilers often use fossil fuels, such as natural gas, which inevitably produces greenhouse gases.

In addition, excessive cycling often plagues older boilers; they heat up too fast, run for short durations and turn off as they become too hot. This rapid cycling causes larger quantities of fuel to be consumed, exacerbating the release of harmful gases into the atmosphere.

Another crucial aspect is that older boilers typically lack modern technologies, such as condensing systems, which recover and utilise waste heat. This leads to a vast amount of wasted energy and inefficiencies that harm the environment.

In light of these issues, it is evident that the transition to more environmentally friendly alternatives, such as heat pumps or biomass boilers, gains more and more importance. As the UK government seeks to reduce carbon emissions and combat climate change, efforts to phase out outdated boilers are paramount.

In conclusion, while old boilers might seem economical in the short term, their negative environmental impact makes them unsustainable choices in the long run. The switch to modern, eco-friendly solutions is necessary to mitigate their detrimental effects on the climate and improve energy efficiency for a greener future.

Benefits of New Gas Boilers

Modern gas boilers present a myriad of advantages over their older counterparts. First and foremost, they excel in energy conservation. Today's boilers are meticulously crafted to maximise fuel efficiency, leading to appreciable savings for homeowners. Switching from an outdated boiler to a contemporary model can substantially reduce annual heating costs.

Furthermore, embracing a high-efficiency boiler has clear environmental upsides. Old boilers, given their diminished efficiency, tend to release more carbon dioxide and harmful greenhouse gases. By updating to a newer model, homeowners actively reduce their ecological impact, taking a step toward a sustainable future.

Beyond the tangible financial and environmental benefits, today's gas boilers are infused with innovative technologies that amplify comfort and user experience. Many of the latest units come with intuitive thermostats, ambient sensors, and thermostatic radiator controls, enabling homeowners to fine-tune temperature levels and ensure uniform warmth throughout their dwellings.

Lastly, transitioning to a contemporary gas boiler enhances the safety metrics of your heating system. As older models age, they can showcase operational challenges or potential leakages, heightening risks like carbon monoxide incidents. Investing in a new boiler aligns with the latest safety standards, offering residents increased peace of mind.

New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Boiler costs can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat.

Boiler Cost Guide Prices

Installation Type

Price (inc VAT)


Combi to combi swap


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System to combi conversion


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New boiler install


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Back boiler to a combi


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System to system


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Some location factors that can influence the price of your new boiler

You will be given a specific quote from the boiler installation company based on:

The type of home you have (i.e. terraced, semi-detached, etc.)

  • How many bedrooms you have

  • How many bathrooms you have

  • Your postcode and specific location

Ground source heat pumps utilise the earth's natural heat, absorbing it from the ground. Although they require a larger initial investment, they are highly efficient and can lead to substantial energy savings over time. The cost of installing a ground source heat pump can range from £10,000 to £18,000.

Air source heat pumps extract heat from the air outside and can be less expensive to install compared to ground source heat pumps. However, their efficiency can be influenced by external temperatures. The installation cost for an air source heat pump typically ranges between £4,000 and £12,000.

Solar panels, on the other hand, harness energy from the sun to heat a home's water system. The installation cost of solar thermal panels is estimated to be between £3,000 to £5,000. While solar panels don't directly contribute to heating the home, they can complement traditional boilers and offer energy savings.

Upgrading an old boiler to a modern, high-efficiency combi boiler can significantly reduce heating bills. In fact, a new boiler could save over £800 per year on energy costs. Despite the initial outlay, the long-term savings and eco-friendly benefits make it a worthwhile investment for many homeowners.

In conclusion, various eco-friendly alternatives and energy-efficient boilers are available in the market, varying in costs and installation expenses. Prioritising long-term savings, environmental responsibility, and individual preferences can guide homeowners in choosing the most suitable option for their home.

Wrap Up: Ensuring Your Boiler is Economical

To optimise the economical performance of your boiler, several measures can be implemented, ultimately leading to energy savings and reduced heating bills. Firstly, consider updating your boiler if it's over 10 years old. Older boilers tend to be less efficient, which can significantly increase your energy expenses. By replacing it with a more modern, energy-efficient variation, you can save money in the long run.

Another effective strategy is to install appropriate heating controls. By using programmable thermostats and more advanced features such as zonal heating, you can ensure that the heat is distributed more effectively in your home. Moreover, adopting these technologies enables you to maintain a comfortable temperature while minimising energy usage.

The Energy Saving Trust offers valuable guidance on how to make boilers more efficient, thus allowing homeowners to reduce both their fuel bills and carbon footprint. Some suggestions include maintaining your heating system and keeping radiators balanced to guarantee optimal performance.

In addition, consider incorporating energy-saving habits into your schedule. This may involve turning off heating in unused rooms or lowering the thermostat by a few degrees during the colder months. Small changes like these can have a considerable impact on your overall energy consumption and costs.

To wrap up, ensuring your boiler is economical ultimately boils down to a combination of upgrades, maintenance, and prudent energy use. By following these steps, you can achieve both cost and environmental benefits that contribute to a more sustainable lifestyle.

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Frequently Asked Questions

Is it worth replacing a 20 year old boiler?

Considering an upgrade from a 20-year-old boiler is an astute home improvement choice, especially if symptoms like dwindling efficiency or regular interruptions surface. Modern boiler technologies consistently deliver efficiencies upwards of 90%, a stark contrast to older versions. Transitioning to an advanced boiler model optimizes energy efficiency, a key metric for both cost-saving and environmental sustainability on search engines.

Should I replace a 25 year old boiler?

With the average prime boiler lifecycle spanning 10 to 15 years, pondering a replacement for a quarter-century-old unit is a strategic step forward. Aging boilers, over time, can compromise on both efficiency and safety. Embracing a new-age boiler not only amplifies home heating efficiency but also ensures reliable warmth, a crucial factor for online searchers prioritizing comfort and safety.

Are old boilers worth anything?

While traditional boilers may command some resale value rooted in their metal components, this is frequently overshadowed by the overheads of sustaining an aging system. A holistic view reveals that channeling funds into a technologically-advanced boiler promises optimal efficiency, a prime keyword for homeowners searching for sustainable heating solutions.

Should I replace my 17 year old boiler?

Seventeen years in service suggests a boiler is inching towards its operational sunset. Encountering consistent operational hiccups, escalating maintenance, or a discernible dip in efficiency necessitates considering a timely upgrade. With the advent of modern boilers championing energy thriftiness, a switch can be a lucrative choice, especially for searchers keen on smart energy solutions.

Can a boiler last 40 years?

Some resilient boilers might march on for an impressive four decades, but they often lag in the efficiency race against their contemporary peers. Generally, boilers flaunt their best performance within a 10 to 15-year window. Venturing beyond can lead to diminished efficiency and amplified repair needs, an insight valuable for online users evaluating long-term heating strategies.

Are older boilers more expensive to run?

Absolutely, the longevity of a boiler inversely affects its operational efficiency, culminating in heightened energy expenditures. The evolution in boiler technology has heralded models with stellar efficiencies, often touching or surpassing the 90% mark. For online users eyeing energy frugality, pivoting from an archaic boiler to its modern counterpart can drastically slash energy bills and concurrently bolster environmental mindfulness.

How efficient will a 30 year old boiler be?

A boiler with three decades of service might significantly trail in efficiency compared to its modern counterparts. The passage of time typically erodes boiler prowess, augmenting both utility bills and carbon footprints. On the flip side, today's boilers, armed with advanced tech, often showcase efficiency levels near or above 90%. An upgrade is a tangible step towards fiscal prudence and green living, a combination that resonates with eco-conscious searchers.

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