With so many options on the market, choosing the right boiler for your home can seem daunting. However, it becomes much easier when you have an understanding of the main types of boilers available.
In this guide, we’ll explain the main types of boilers, dive into their benefits and drawbacks, and answer your FAQs so you can make an informed decision.
This post includes:
What are the different types of boilers?
What is a conventional boiler?
Book a boiler installation with JustFix
What are the different types of boilers?
Boilers are a central part of most heating systems. They heat water and supply it to your radiators, taps, and showers. While all boilers perform the same basic function, they come in different types, each suited for various needs.
In short, there are three main types of boilers you should be aware of: combi boilers, system boilers, and conventional boilers. Each type works differently, so it has its own pros and cons and is best suited to certain types of homes.
Now, let's take a closer look at what each type offers and how to determine the right one for your home.
What is a combi boiler?
A combi boiler, or combination boiler, provides both heating and hot water directly from the boiler. It doesn’t need a separate hot water cylinder or cold water storage tank, making it a space-saving option.
Combi boilers work by heating water on demand. When you turn on the tap or the heating, the boiler starts working instantly to provide hot water. This makes it an energy-efficient choice, as it doesn’t waste energy keeping a tank of water hot.
However, combi boilers may struggle to supply water to multiple outlets, like two showers simultaneously, and can be less effective in homes with lower water pressure.
What are the pros and cons of a combi boiler?
Pros:
- Space-saving: No need for separate tanks or cylinders
- Hot water on demand: They supply instant hot water whenever you need it
- Energy-efficient: They only heat the water you need, reducing energy bills
- Lower installation costs: Fewer components to install often mean lower installation expenses
Cons:
- Not ideal for large homes: If you have multiple bathrooms, a combi boiler might struggle to supply hot water to several outlets at the same time
- Water pressure dependent: They rely on good mains pressure, so they may not be suitable in areas with low water pressure
- No backup: If your boiler fails, you won’t have any hot water or heating
Is a combi boiler right for me?
Combi boilers are perfect for smaller homes or flats with limited space and one or two bathrooms. They’re also a good option if you want to reduce your energy bills, as they’re highly efficient. However, if you have a larger home with several outlets that are often used at the same time, a high hot water demand, or low pressure, you might need to consider other options.
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What is a system boiler?
A system boiler is similar to a combi boiler, but the key difference is that it requires a separate hot water cylinder to store the water.
However, unlike conventional boilers, a system boiler doesn’t need a cold water tank. This means it can still save some space while providing a steady hot water supply.
System boilers are a good choice for homes with higher hot water needs. The stored hot water means you can run multiple taps or showers simultaneously without losing pressure or temperature. Nonetheless, if you run out of stored hot water, reheating more may take a while.
What are the pros and cons of a system boiler?
Pros:
- Ideal for larger homes: They can supply hot water to several outlets at once
- Reasonably space efficient: They have no cold water tank, so they take up less space than a conventional boiler
Cons:
- Requires space for a hot water cylinder: Needs enough space for a separate cylinder, which is not always available in smaller homes/flats
- No instant hot water: If the stored water runs out, you’ll need to wait for it to reheat
- More expensive to install: Typically more complex, and hence more expensive, to install than combi boilers
Is a system boiler right for me?
System boilers are a great option for medium-to-large-sized homes, especially those with multiple bathrooms. They’re ideal if you regularly use hot water in different parts of your home simultaneously. However, if your home has limited space, you might want to consider a combi boiler instead.
What is a conventional boiler?
A conventional boiler, also known as a traditional or regular boiler, uses both a hot water cylinder and a cold water storage tank. It’s often found in older properties and can handle large volumes of hot water.
Conventional boilers are great for homes with old radiators or heating systems, as they are compatible with a wide range of plumbing. They can also provide hot water to multiple outlets at once, which is ideal for busy households.
What are the pros and cons of a conventional boiler?
Pros:
- Reliable for older systems/homes: They work well with traditional heating systems and radiators, meaning less maintenance costs
- High hot water output: They can handle large volumes of hot water, making them ideal for homes with several bathrooms and high water usage
- Back-up hot water: You’ll have a store of hot water even if the boiler is switched off, ideal for high-consumption households
- Can handle low water pressure: They don’t rely on mains for pressure, so low water pressure won’t be an issue
Cons:
- Less space efficient: They require both a cold water storage tank and a hot water cylinder, meaning they take up more space
- Longer heating time: They generally take longer to heat water compared to other types of boilers
- Less energy efficient: both combi and system boilers are more energy efficient, making conventional boilers the most expensive to run
Is a conventional boiler right for me?
Conventional boilers are best suited for large, older homes with traditional heating systems and multiple bathrooms. They’re also a good option if your property has low water pressure, as they don’t rely on the mains for pressure.
However, a combi or system boiler might be a better option if you want to save space or reduce energy bills.
Other types of boilers
Besides combi, system, and conventional boilers, there are a few other types of boilers that are less common. It’s helpful to be aware of these; they may even be a good fit for certain homes.
What is an electric boiler?
Electric boilers use electricity to heat water, making them ideal for homes without a gas supply. They are compact, quiet, and easy to install but can be costly to run, especially in larger properties with high hot water demands. They’re best suited for smaller homes or flats.
What is a biomass boiler?
Biomass boilers burn organic materials like wood pellets or logs to produce heat, offering a sustainable and renewable heating solution. However, you’ll need access to biomass fuel and sufficient space for the boiler and fuel storage. Initial costs are higher, but long-term savings can help offset this. If your primary concerns are environmental, this is the best option.
What is a back boiler?
Back boilers are fitted behind a fireplace or stove and can provide heat for radiators and hot water. While they save space and heat older homes effectively, they are less efficient and more difficult to maintain than modern boiler systems. They’re not commonly installed in new builds but may still be found in older properties.
What is an oil boiler?
Oil boilers use oil stored in a tank to generate heat, making them suitable for homes that aren’t connected to the gas network. They are highly efficient, but the oil tank takes up a lot of space. Plus, fluctuating oil prices can impact running costs. Oil boilers suit rural properties with no gas supply but won’t be a practical solution for most homes.
What is a condensing boiler?
A condensing boiler isn’t its own type of boiler, but a feature that can be found in combi, system, and conventional boilers. Condensing boilers are more energy-efficient because they capture heat that would otherwise escape and use it to preheat water.
Which type of boiler is best?
The best type of boiler for your home will depend on your property’s size, water pressure, and hot water needs. There are several less common types of boilers to consider, but chances are a combi, system, or conventional boiler will be the best fit for your property.
Here’s a quick recap of the three main types of boilers and what type of homes they’re best suited to:
- Combi boilers: Ideal for small-to-medium-sized homes with low to moderate hot water needs. They’re compact and energy-efficient, but they're not suitable for large households with high hot water consumption.
- System boilers: Best for medium to large homes with higher hot water demand. They provide consistent hot water but require space for a separate cylinder and may incur higher installation costs.
- Conventional boilers: Suitable for large or older properties with multiple bathrooms and traditional heating systems. They take up more space but can handle higher water consumption needs and work well even in areas with low water pressure.
Book a boiler installation with JustFix
Are you ready to switch to a new boiler? Or does your current boiler just need some TLC? Whatever the job, our Fixers are happy to help! From combi, system, and conventional boiler installation to boiler repairs and boiler servicing, trust JustFix to connect you with an accredited tradesperson.
With JustFix, it’s never been easier to find and book a local heating and gas engineer. Use our website or app to tell us about the job and where and when you want it carried out. Then, we’ll connect you with a qualified Gas Safe-registered engineer and provide you with a fixed price per hour at the point of booking.
Best of all, our work is guaranteed for 12 months, so you can relax knowing that whatever we fix stays fixed.
FAQs about types of boilers
What is the most common boiler in the UK?
The most common boiler type in the UK is the combi boiler. It is compact, energy-efficient, and cheap to run, effectively meeting the needs of most properties and individuals.
What type of boiler is the cheapest?
Combi boilers are generally the cheapest to run, especially in smaller homes, as they only heat water on demand. Their efficiency means less energy is wasted, reducing overall running costs.
It’s also worth considering installation costs: combi boilers are less complex and generally cost less to install than other types of boilers. Read our How Much Does a New Boiler Cost guide for further details.
Which is better, a combi or condensing boiler?
Condensing boilers are not a separate type of boiler but a feature found in some combi, system, and conventional boilers.
A condensing combi boiler is highly efficient and better at reducing energy bills than a regular combi boiler.
Are gas-fired boilers banned from 2025?
Gas-fired boilers are not banned from 2025 but are being phased out. To support the transition, the installation of gas and oil boilers will be banned in new-build homes starting in 2025. This does not affect existing homes, where gas boilers can still be installed and maintained.
How long should a boiler last?
A well-maintained and regularly serviced boiler should last for around 15 years. For an in-depth explanation, read our guide: How Long Should a Boiler Last?
