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Last updated: 11th February, 2024


6 Combi Boilers Which Could Save You Hundreds of Pounds in Bills

6 Combi Boilers Which Could Save You Hundreds of Pounds in Bills

Key takeaways

  • Combi boilers are an efficient and space-saving choice for heating and hot water.
  • Choosing the right model can lead to long-term savings for homeowners.
  • New technology in combi boilers offers improved energy efficiency.

Combi boilers are celebrated for their energy efficiency and compact size, a departure from traditional systems. Their efficiency ratings often surpass the 90% mark, making them significantly more efficient than conventional boilers, which may only use 55% of energy for heating.

Combining cost-effectiveness with high energy efficiency, combi boilers have become a go-to choice for homeowners looking to cut down their heating bills. These boilers not only supply hot water and central heating in one compact system without the need for a separate cylinder or loft space, but the latest models are designed to minimise energy waste. As energy prices fluctuate, it's more crucial than ever to make smart choices in home heating solutions.

The selection of the right combi boiler could mean the difference between a ballooning energy bill and substantial savings over time. Advancements in boiler technology have led to a new generation of combi boilers that can provide significant savings without compromising on performance or comfort. Homeowners can now choose from high-efficiency models that suit a range of budgets and house sizes, all while being straightforward to install and maintain.

Understanding Combi Boilers

Combi boilers, a consolidation of efficiency and convenience, offer homeowners a modern solution to meet their central heating and hot water needs.

Benefits of Combi Boilers

Combi boilers are celebrated for their energy efficiency and compact size, a departure from traditional systems. Their efficiency ratings often surpass the 90% mark, making them significantly more efficient than conventional boilers, which may only use 55% of energy for heating. Homeowners might see considerable reductions in energy bills, potentially saving substantial amounts annually:

How Combi Boilers Work

The mechanics of combi boilers rest on their ability to provide hot water on demand without the need for a separate storage tank. They heat water directly from the mains when a tap is turned on, ensuring immediate hot water delivery. This process negates the energy loss associated with heating and storing water in a tank, aligning with the principles of condensing boilers that recycle heat from exhaust gases.

  • Direct Mains Connection: Instant hot water without a cylinder.

  • Immediate Response: Water is heated as it is needed.

Combi Boilers vs Conventional Boilers

Comparing combi to conventional boilers underscores the former's space-saving design; they do away with the need for a hot water tank, often freeing up considerable space. However, combi boilers might face limitations in providing hot water to multiple outlets simultaneously, contrasting with conventional systems that store pre-heated water.

  • Space-Saving: Combi boilers require less room due to the absence of a tank.

  • Hot Water Supply: Conventional boilers can supply several outlets at once, but combi boilers might struggle with multiple simultaneous demands.

Selecting the Right Combi Boiler

Selecting an appropriate combi boiler is a pragmatic decision influenced by distinct factors, from the size of the household to the boiler's energy efficiency ratings.

Factors to Consider

When choosing the combi boiler that best suits one's needs, several criteria emerge as pivotal. Brand reputation and the associated reliability of the boiler should guide the decision. Leading brands such as Worcester Bosch and Viessmann have established themselves at the forefront due to their consistent delivery of A-rated, high-efficiency boilers that promise both enhanced performance and cost savings.

The lifespan of boilers and their warranties are also indicators of quality. A longer warranty often reflects the manufacturer's confidence in the boiler's durability. Power output, measured in kilowatts (kW), requires careful matching to the household's demand to ensure optimal functioning without excessive energy consumption.




Reputation for reliability and performance

Energy Efficiency

A-rated models preferred for savings and environmental impact

Lifespan & Warranty

Longer warranties indicative of higher quality and durability

Power Output

Tailored to household size to balance efficiency and performance

Assessment of Home Requirements

A meticulous assessment of one's home will illuminate the power output necessary for a new combi boiler. Smaller homes typically require less powerful boilers, ranging from 24 to 27 kW, while larger homes with multiple bathrooms might necessitate a boiler with 28 to 34 kW or more. It's essential to consider both the number of bathrooms and the overall demands for hot water and heating when making this determination.

Energy Efficiency Ratings

Boilers with an A-rating are exemplary for their lower carbon footprint and reduced energy costs. Potent amongst the league of best combi boilers are the Worcester Bosch 4000 and the Viessmann Vitodens 050-w, both heralded for their efficient use of energy. Analysing a boiler's Sedbuk rating, which measures annual efficiency, can further aid in discerning the most frugal models.

The calibration of these integral features will lead to an informed choice, ensuring the combi boiler selected is not only adept in its functionality but also an ally in energy conservation.

Cost Implications

Investing in a combi boiler offers the potential for significant savings on energy bills, but it's important to consider both the immediate costs and the long-term financial implications.

Boiler Price Range

Combi boilers come in various models and brands, each with a distinct price range. Purchasers can expect to find combi boilers priced from roughly £500 to £3,000. The variety in prices can be attributed to differences such as the size of the boiler, the brand reputation, and the specific features that each model offers. For instance:

  • Glow-worm: £560 to £1,360

  • Ideal: £600 to £1,000

  • Vaillant: £610 to £1,200

  • Worcester: £730 to £2,500

Installation and Maintenance Costs

Installation costs for a new combi boiler are an additional expense to consider. Typically, the cost to install a boiler will be around £600 but can rise to £1,800 if there's a need to relocate the boiler to a different area within the home. During the ongoing cost of living crisis, where every expense is scrutinised, it's prudent to also factor in potential maintenance costs over the boiler's lifespan. Regular maintenance helps prevent breakdowns and ensures the boiler operates at peak efficiency.

Long-Term Savings

While the initial outlay for a new combi boiler might seem steep, the potential for long-term savings on energy bills is noteworthy. The highly efficient nature of modern combi boilers can lead to a reduction in energy consumption, adhering to the energy price cap and buffering against fluctuations in energy prices. This is because they provide hot water on demand without the need for a separate hot water cylinder or cold water tank, thereby saving space and energy.

To illustrate, a well-maintained, energy-efficient combi boiler replacing an older, less efficient system could yield annual energy bill savings. However, exact savings will vary based on individual energy use and the efficiency of the old boiler compared to the new unit.

6 Combi Boilers that can save you money

Investing in an energy-efficient combi boiler can lead to substantial savings on energy bills. The following models are renowned for their efficiency and could reduce your costs by hundreds of pounds.

Viessmann Vitodens 100-W

The Viessmann Vitodens 100-W is known for its reliable performance and efficient operation. Sporting a high energy efficiency rating, it can convert up to 94% of fuel into heat. Customers report appreciating its quiet operation and user-friendly controls.

Worcester Bosch Greenstar 4000

With an impressive reputation, the Worcester Bosch Greenstar 4000 strikes an ideal balance between performance and cost-effectiveness. It boasts an A-rated energy efficiency and is popular among homes for its compact size. Additionally, reviews highlight the boiler's consistency in providing hot water without lag.

Vaillant EcoFit Pure

The Vaillant EcoFit Pure excels in quiet operation and compact design, making it suitable for small spaces. Its features include high modulating ratios that adjust the burner power to what you need, minimising waste and fuel consumption.

Ideal Logic² Plus

The Ideal Logic² Plus is favoured for its value for money and ease of installation. Its energy-efficient technology aims to reduce household energy bills and emissions, meeting expectations for cost-savings in the long term.

Alpha E-tec Plus

Finally, the Alpha E-tec Plus emerges as a strong contender in the market, with high energy efficiency and a stainless-steel heat exchanger that increases longevity. Reviews consistently point to the E-tec Plus as a reliable boiler offering long-term savings.

Baxi 800

Baxi 800 Series is renowned for its exceptional efficiency, achieving up to 93% fuel to heat conversion with an A-rated energy efficiency score. It is praised for its easy installation, compact design, and the assurance of a 10-year warranty, making it a reliable and cost-effective choice for homeowners.

Advancements in Boiler Technology

Recent years have seen remarkable strides in boiler engineering, particularly with combi boilers, which stand at the forefront of energy efficiency and smart home compatibility.

Smart Home Integration

Smart controls are reshaping the landscape of home heating systems. These sophisticated devices allow users to precisely manage their heating from anywhere, using a smartphone or other connected devices. The integration of these controls in modern condensing combi boilers ensures not only convenience but also enhances the ability to maintain optimal energy usage—contributing to a significant reduction in household energy bills.

The synergy between smart controls and energy-efficient boilers is noteworthy. For instance, some condensing technology incorporated in current combi boilers may adapt their output to real-time demands thanks to smart thermostats. This not only optimises comfort but also ensures that the boiler operates at peak efficiency, leading to a leaner energy consumption profile.

Additionally, many modern boilers are now compatible with smart home ecosystems, seamlessly integrating with other smart home devices for a unified home management experience. This advancement speaks to the industry's commitment to user-centred and environmentally conscious heating solutions, where convenience and sustainability go hand in hand.

Combi Boiler Alternatives; System & Heat-Only Boilers

When homeowners consider heating solutions, combi boilers often come to mind due to their compact size and efficiency. However, alternatives such as system and heat-only boilers can be more appropriate for certain homes due to their distinct operating methods.

System Boilers

A system boiler directly heats the central heating system and stores hot water in a cylinder. Crucially,

  • They're ideal for homes with higher hot water demand.

  • Hot water is readily available from multiple taps simultaneously.

  • Unlike combi boilers, they don't provide instant hot water, but they can supply hot water to several bathrooms at once, which is beneficial for larger households.



Better for multiple bathrooms

Requires space for a cylinder

Consistent water pressure

Not instant hot water

Can run off mains pressure

Higher initial installation cost

Heat-Only Boilers

Also known as conventional boilers, these are the oldest type of boiler system:

  • These boilers require a cold water tank in the loft and a hot water cylinder.

  • They're compatible with older central heating systems, which may not be able to cope with the high pressure of combi or system boilers.

  • Suitable for properties where a combi boiler isn’t robust enough to meet hot water demands.



Good for low pressure areas

Takes up the most space

Compatible with old pipework

Less efficient than combi

Ideal for high usage

Requires a cold water tank

Both system and heat-only boilers offer a reliable alternative to combi boilers, especially in homes where water demand is high or multiple outlets are used concurrently. These systems can offer savings by efficiently managing hot water and heating in larger properties.

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.

Effectively, new boiler cost 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 (guide only).

Installation Type

Price (inc VAT)

Combi to combi swap


Get a quote

System to combi conversion


Get a quote

New boiler install


Get a quote

Back boiler to a combi


Get a quote

System to system


Get a quote

Frequently Asked Questions

Are combi boilers cheaper to run?

Yes, combi boilers tend to be cheaper to run compared to traditional systems because they only heat water when it's needed, which reduces wasted energy.

Is it worth converting to a combi boiler?

For many, converting to a combi boiler is worth the investment, as it offers significant space savings and typically delivers improved energy efficiency, which can translate into lower heating bills.

Is it still worth getting a combi boiler?

Even with advancements in technology, getting a combi boiler remains a valuable choice for most households looking for a cost-effective heating system that also provides instant hot water without the need for a separate tank.

What should I set my combi boiler at to save money?

To save money, set your combi boiler's thermostat to around 19°C – 21°C. However, exact temperatures can vary based on individual household preferences and the specific efficiency of the boiler model.

How much will a new combi boiler save me?

A new combi boiler can save you up to £630 annually on your energy bills, depending on your current system's efficiency and the specific model you choose as a replacement.

Should I replace my 20 year old boiler?

Replacing a 20-year-old boiler can be beneficial, as modern combi boilers are generally significantly more efficient, which can lead to reduced energy usage and considerable cost savings over time.

Does a combi boiler save money?

Combi boilers typically save money by providing higher energy efficiency and reducing heat loss, as they heat water directly from the mains on demand and therefore don't require a hot water storage cylinder.

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.