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A top-rated combination boiler or combi boiler is a compact boiler unit that can heat hot water and central heating. It does not require additional components such as hot water storage cylinders to work, making it space-saving and, therefore, a popular choice among homeowners in the UK. It is the country’s most commonly installed boiler type under the government ECO4 scheme.

Combi boilers are easy to install and can be hidden in a kitchen cupboard or boiler cabinet. These features enable you to merge a combi boiler with your home’s style. On top of that, they are also very convenient. Combi boilers provide a fast supply of instant hot water since they take water directly from the mains and heat it as required. In this article, we will look closer at the 10 must-have features of combi boilers.

Are you interested in a combi boiler? At Grant Boilers, we can help you find the one that best meets your needs. Thanks to our team of heating experts, we will save you hours of research time and effort. 

Let’s Explore the Top Features of The Combi Boiler

We think the critical factors in determining a top-rated combination boiler’s quality are:

  • Energy efficiency
  • Performance and reliability
  • Features, including safety concerns
  • Durability and build quality
  • Installation process
  • Manufacturer 
  • Cost
  • Warranty
  • Customer support
  • Aesthetic appeal

Energy efficiency

A high-efficiency combi boiler operates more economically, consuming less fuel to provide the same heat and hot water level, directly lowering energy bills. These savings can be substantial over the boiler’s lifespan. Energy-efficient boilers also produce fewer carbon emissions. By using the fuel they consume better, energy-efficient boilers have a reduced environmental footprint, which is increasingly important given global efforts to combat climate change.

Performance and reliability

When discussing a combi boiler’s performance, we refer to its ability to generate heat and hot water efficiently and consistently. A high-performing boiler can quickly heat your home to your desired temperature and provide a steady hot water supply. This becomes particularly critical during winter months when heating demands are high.

Reliability refers to the boiler’s ability to perform its functions consistently over a prolonged period without breaking down. An unreliable boiler can cause significant inconveniences, potentially leaving you without heat or hot water access. In addition to the discomfort, this could also suffer emergency repair or replacement costs.

Our experts thoroughly check the reliability and performance of the combi boilers we review.

Features, including safety concerns

Our experts analyse every combi boiler for its features, focusing on its safety considerations. 

Features such as programmable thermostats, user-friendly interfaces, and compatibility with smart home systems can enhance the boiler’s usability. Programmable thermostats, for example, enable you to set the temperature for different times of the day, allowing optimal comfort and efficiency. A user-friendly interface makes it easier to operate the boiler and adjust settings, while smart home compatibility provides for remote control and heating system monitoring.

Some boilers also offer features for specific needs, such as frost protection for areas with cold temperatures or compatibility with solar panels for households aiming for renewable energy use. These features help customise the user experience, catering to specific household requirements.

In addition, safety concerns are equally, if not more significant. Combi boilers have various safety features to prevent gas leaks, overheating, or excessive pressure build-up, which can pose substantial risks. Many models include the ability to detect potential gas leaks. The system will shut down automatically if a leak is detected to prevent accidents. These safety measures protect the households and the heating system’s efficiency.

Durability and build quality

A top-rated Combination Boiler with a durable design and high build quality will likely have a longer lifespan. This means you won’t need to replace the boiler as often, but the unit will maintain optimal functionality over a more extended period, providing consistent heat and hot water supply without frequent breakdowns. Longevity in a boiler’s performance gives households a sense of security and reliability.

A high build quality indicates that the boiler’s components are more solid and resistant to wear and tear. This reduces the chance of mechanical or electrical failures, than can result in costly repairs or replacements. Additionally, a well-built boiler is more likely to operate efficiently, leading to energy savings in the long run.

Also, it’s important to note that poorly constructed boilers could pose risks, including gas leaks or failures in safety systems. A high-quality build ensures these systems function as intended, protecting your home and family from potential dangers.

Installation process

Some combi boilers are easier and quicker to install than others, which can result in lower labor and installation costs. They also minimise the disruption to your household routine, which can be crucial for many homeowners.

The installation process can also impact the performance and efficiency of the boiler. If a boiler requires a complex installation, there’s a higher risk of an incorrect fitting, which could compromise its operation, efficiency, and even safety. Boilers that are easier to install correctly are more likely to operate as intended and deliver optimal performance.

We research the entire installation process of every combi boiler we review.


The Top-rated Combination Boiler manufacturer is essential when reviewing and evaluating an appliance. Its reputation and track record can provide insights into the expected quality and reliability of the boiler. Manufacturers with a strong reputation in the market typically have rigid quality control processes, leading to products that deliver consistent performance and have fewer issues.

Committing to research and development can influence the technological advancement and efficiency of the boiler. Manufacturers investing heavily in this sector are often at the forefront of introducing modern features and improving energy efficiency.


When considering the cost, the upfront cost of the high-efficiency Combi Boiler and the long-term operational expenses are essential. A cheaper boiler might seem attractive initially, but if it’s less efficient and costs more, the overall cost over the boiler’s lifespan could be higher. This is why it’s crucial to consider the boiler’s energy efficiency and potential maintenance costs as part of the total cost.

In addition, the cost can also reflect the quality and features of the boiler. Higher-priced boilers often incorporate advanced features, higher efficiency ratings, and better build quality. They also come with better after-sales service or more extended warranties, which can provide more value over time.


High-efficiency Combi Boilers are complex appliances with multiple components that can malfunction. A warranty protects the buyer against these unforeseen issues, ensuring the manufacturer or supplier will repair or replace the faulty parts without additional cost.

Without a warranty, the homeowner could be responsible for the total cost of any repairs, which can be significant. Furthermore, a warranty should cover these expenses and save the owner considerable sums over time, making it an essential factor in the overall cost of owning and maintaining a combi boiler.

Our experts study and analyse every aspect of each warranty.

Customer support

Even if you are familiar with combi boilers, there may still be moments when you need assistance understanding their functioning, troubleshooting problems, or performing essential maintenance. Good customer support can provide accurate guidance, saving time and stress. 

A strong customer support team reflects the manufacturer’s commitment, demonstrating confidence in the reliability and quality of its boilers. This usually means it stands by its product and is willing to help if something goes wrong. Support is also critical in the context of warranty claims. If a boiler comes with a warranty, the company should provide seamless claims handling service to give you the peace of mind that you are covered.

Aesthetic appeal

Unlike other heating systems, Combi boilers are often installed in visible areas of the home, such as the kitchen, hall, or rooms. Given this, a boiler with an aesthetically pleasing design can easily blend into your home interior instead of being unattractive or invasive.

Moreover, aesthetic appeal is not just about how a combi boiler looks but also about how it’s designed for ease of use. A boiler with a user-friendly design, marked dials, an intuitive display, or easy maintenance access, for example, makes it easier for you to operate and maintain it, which adds to the overall positive experience of using the product.


Overall, top-rated combination boilers are a good option for homeowners in the UK. This is due to their ability to provide hot water on demand and their economic nature, as you only pay for what you use. Their small size makes them easy to install, and their systems are highly efficient, meeting all your heating and hot water needs. This blog overviews the top features of a combi boiler.

Further, if you’re looking to buy a new boiler or replace an old one but don’t know who to contact, look no further! At Grant Boilers, we can help you get the right boiler for your home. 



The timeframe can vary depending on the workload of your chosen installer and the availability of boilers. However, once your application is approved, you can expect the installation in a few days.

Anyone who has a boiler installed before 2005 or has an inefficient boiler can qualify for a boiler grant in the UK. To meet the requirements, you must be a homeowner or private tenant of the home in the UK.

The ECO4 Scheme is a government-funded program that provides grants and funding to homeowners in Scotland, who want to install energy-saving measures in their homes. The aim of the Eco4 scheme is to help people reduce their energy consumption and save money on their energy bills.

Yes, it’s quite easy. You should regularly check that the evaporator and air intake grill are clear of leaves and other particles.

To be eligible for a first time central heating grant, you must not have prior central heating installed in your homes. Also your home’s EPC rating should be lower than D.