types of boiler

If you are looking for a new boiler for your home and feel slightly confused about the different models that are on the market, don’t worry; we have you covered. There are three main types of boilers out there, which are differently designed to accommodate smaller spaces. 

These are known as combi boilers, system boilers and conventional boilers. Newer models also tend to be more energy efficient, which helps households save money on energy and heating bills. In this post, we will take a look at the different types of boilers available to you and how to weigh up the pros and cons of each to ensure that you select the right boiler model for you.

What is a Boiler and Why Does Its Type Matter?

A boiler is effectively the device in your home that ensures the property gets hot water. Most boilers are also responsible for the central heating of the property. That is why so many boilers have a gas connection, too. 

The different boiler models and designs also vary according to energy efficiency levels, and the selection of them is usually dependent on the size of the property, the age of the property, the number of people living in the home and the overall demands on the boiler. 

Boiler Basics

So, what exactly does a boiler do? The key function of a boiler is to create hot water to feed the rest of the house. If a home uses a heating system that includes radiators, then a boiler will also provide the heat for these systems. In environments where the weather gets cold in the winter, boilers that power central heating systems are incredibly necessary. 

Importance of Choosing the Right Type

Different types of boilers operate on different specifications. These usually pertain to aspects like cost efficiency and their energy-saving status. The boiler you choose, therefore, depends on the types of long-term benefits you want to take advantage of. 

As a rule of thumb, more modern boiler models are more energy efficient, which is why they are ideal for modern homes that need to be more sustainable. Older homes tend to have models that use a lot of energy to power up. 

It’s, therefore, important to understand what the different types of boilers are so that you don’t end up overspending on bills once they are installed.

Common Types of Boilers

On the domestic market, there are several types of boilers you can choose from. They vary in function and the space they take up in your home. Let’s take a closer look at the different types of boilers available on the market and the benefits you can look forward to when you choose each one. 

Combi Boilers

Combination boilers are great for smaller homes as they offer the most compact option. They are ideal for the likes of apartments and small houses as they heat the home’s hot water system and heating system all from one unit. 

They are also the more energy-efficient option as they heat the water supply on demand, straight from the mains, meaning that excessive energy is not wasted on heating. They are also quite small, only requiring a square metre on a wall to hang. Therefore, they can be easily fitted into a cupboard or storage unit. The pros and cons of combi boilers are as follows. 


  • Compact and able to fit into smaller spaces
  • Easy to service or repair
  • Provide hot water instantly 
  • Highly energy efficient


  • Pressure depends on the supply for the mains, so they are prone to pressure issues.
  • Pressure drops when water is used in more than one room of the house at the same time. 

System Boilers

System boilers tend to take up more space as they require a hot water cylinder, similar to conventional boilers. They do not, however, require a cold water tank. They are also more compact than conventional boilers, as many of the components required for operation are installed within the boiler system. These include parts like valves and pumps. 

They are usually installed in larger homes as they are more suitable for keeping up with the heating demand for households with more people. The hot-water cylinder heats the entire contents and then distributes the heated water to where it is needed. 


  • Easy to install as there are not many components. 
  • Space efficiency. 
  • There is less chance of leaks or freezing over in the winter months. 


  • The pressure depends on the mains; therefore, a poor flow rate will mean you suffer from low pressure. 
  • Slightly more space taken up than a combi boiler. 

Conventional Boilers

Conventional boilers are another form of boiler that requires a separate water tank. Hot water is heated in a storage tank before being released to where the hot water is needed, such as to your radiators or hot water taps when opened. The other name for a conventional boiler is a heat-only boiler. 

There are two main tanks with conventional boilers, one that is to draw the water supply from the mains and another one that is to store hot water before it is distributed to the rest of the property. 


  • No problems with hot water supplied to more than one source
  • Conventional boilers are easily powered by solar – saving you money
  • Optional backups with immersion heaters provide hot water even during a breakdown. 
  • They are cost-effective to replace


  • You need to wait for the cylinder to heat up before you get hot water. 
  • Not optimal for energy efficiency
  • Take up the most space out of all the boiler types

Condensing Boilers

Condensing boilers are the ideal option for homes that want to enhance their efficiency as they work on a system that recycles heat, typically lost in conventional systems. Condensing boilers reuse the heat that is released and filter it back into the system so that the heat can be reused, thereby reducing the amount of energy it takes to heat water for the rest of the home. 


  • More energy efficient
  • Cost savings on bills 
  • Increased safety for your home 


  • They take longer to install as they are slightly more complex systems
  • More expensive to maintain than other boiler types
  • They contain corrosive parts which can be easily damaged 

Electric Boilers

Electric boilers are becoming increasingly popular, especially in modern homes. Not all homes are fitted with gas fixtures. Therefore, the electric alternatives are perfect for these types of properties. In some cases, electric boilers can also be a safer alternative to other gas-powered boilers. 


  • Additional safety for your home
  • Compatible with renewable energy sources
  • Do not require as many services
  • Usually quite compact to save space


  • Possibly higher electricity bills unless connected to a renewable energy source
  • Varying temperature and pressure when multiple taps are turned on

Factors to Consider When Choosing a Boiler

When deciding on the type of boiler to choose for your home, there are several factors you will have to take into consideration. Let’s take a closer look at these below. 

Size of Your Home

The size of your home will have a profound impact on the type of boiler you choose. You will need to ensure that the boiler has the capacity and pressure specs to sustain your home. If you choose a boiler that is too weak or cannot supply hot water to every room in the house, it is a great inconvenience. 

Energy Efficiency

Most boilers will have different energy ratings. Ratings closer to “A” are usually the cheapest to run and the most energy-efficient. If you have a home that is geared towards sustainability, then you will need to choose a boiler that is more energy efficient. 


Before you decide on the type of boiler you go for, you will need to establish a budget, as boilers vary in price depending on their types. You will also need to budget for the amount of money you’re willing to spend on energy bills throughout the year. 

How Long Does A Boiler Last

Installation Considerations

Before you select a boiler and have it installed, you also need to ensure that your home meets the minimum installation requirements for that type of boiler. The two factors you will have to consider most are the following. 

Space Requirements

Types of boilers vary according to size and space efficiency. Before installing a boiler, you need to ensure that the space you have allocated to it is sufficient. Conventional boilers and other types of boilers with a water storage tank are usually the ones that take up the most space. However, other types of boilers, like combi boilers, are more appropriate for smaller homes. 

Time for Installation

A boiler’s installation time depends on the system’s complexity that needs to be installed. If you go for boilers with more moving parts and complex systems, you will have to allow for more time for the installation. You should also be aware that the more components of the overall heating system that needs to be installed, the longer the process will take. 

Frequently Asked Questions

What is the most energy-efficient type of boiler?

The most efficient type of boiler is a condensing boiler, given the fact that it reuses the heat released in the form of gas to heat water. It, therefore, emits far fewer emissions and will cost less to run as more heat is generated using less energy. If you are after an energy-efficient boiler, a condensing or gas-condensing boiler is certainly the way to go. 

How often should I replace my boiler?

A boiler typically has a lifespan of around 20 years. However, if they are well-maintained and have regular services in line with their warranty requirements, they can last a bit longer. Most boiler types require owners to have annual services from gas-safe certified engineers conducted to ensure their boilers are functioning optimally and safely. 

Can I install a boiler myself?

Under no circumstances should you or anyone other than a gas-safe certified engineer install a boiler for you. These systems often have multiple fixtures and must be connected to pipework, such as the water mains or gas inlets. For this reason, trained professionals like our team at SD Plumbing and Heating should be the ones who install your boiler. 


There are several different types of boilers on the market today, which vary in specs, size, and efficiency. The type of boiler you choose to go for depends on what the demands of your property and household are. It also depends on how efficient you want your property to be. 

If you need help choosing a boiler, consider speaking to a professional to help you. The team at SD Plumbing and Heating are always on hand to help you out with any boiler queries you may have.