The Ultimate Guide To Gas Boiler Types: Choosing The Best One For Your Home
A boiler is an essential feature of any home. That said, it can be challenging to make the right purchase decision, especially as the typical boiler has a lifespan of around 10-15 years, meaning a boiler isn’t something most homeowners buy too often.
If you are about to call time on your current boiler, making a good decision is important. That’s because your choice of boiler will have an impact on the thermal comfort of the property and even the cost of your energy bills.
To help you decide, the WhatPrice team have put together the following post on the different boiler types.
We’ve covered the most common types of boiler including combi, system and regular boilers. Plus, we’ll also highlight some of the alternative boiler options to consider such as electric, hydrogen-ready and biomass boilers. If you are interested in oil boilers, please visit; Guide to Oil Boiler Costs, Installation & Savings.
Introduction to boiler types
We all have boilers in our homes. But what exactly do they do?
Every boiler works slightly differently. However, the general idea is that boilers work by transferring heat to water. This heated water is then pumped around your home to supply your taps and radiators with hot water.
Lots of boiler types exist, and while it can be confusing to understand which option is right for your home, the large variety available is actually to cater to different property types and overall usage needs.
Don’t worry if you are unsure! When you partner with a trusted heating engineer, they can provide you with tailored advice based on what your home would benefit from.
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The three main types of boilers
A good place to start is with the boiler types you are likely most familiar with, including if you are buying a boiler for the first time having only rented up to now. Likewise, if you have just moved from one property to another and are considering your options.
Combi boilers (combination boilers)
Combi boilers provide heating and hot water on demand. So, when a call for heating is made, the boiler will start working to heat the water so that it can be circulated around your home.
How combi boilers work is that a single unit provides the hot water and central heating capabilities, rather than requiring a separate hot water cylinder or cold water storage tank like a system or regular boiler. As a result, combi boilers are less expensive to install and preferred for smaller properties with modest usage needs, where there also isn’t room for additional water tanks.
Advantages
Combi boilers are typically the easiest types of boiler to install, especially when performing a like-for-like swap. They also don’t take up too much room in your home, with most combi boilers able to fit in a small cupboard.
Considerations
For larger homes, combi boilers cannot always meet high demand, including where multiple bathrooms are used at the same time. If the boiler fails, there is no backup supply.
Is a combi boiler right for you?
You have a small to medium size home and do not need to run multiple showers or taps at once. Also, if your water pressure is generally adequate to enable a good supply throughout your home. Likewise, you don’t want separate storage tanks taking up space in a loft or bedroom. Read more in our what is a combi boiler page.
System boilers
System boilers have separate cylinders for storing water, meaning they are able to provide a constant supply of hot water. This makes system boilers a great choice for larger homes or even commercial properties which require a large volume of hot water.
How system boilers work is that they take water directly from the mains. They will only send hot water to taps and radiators when needed.
Advantages
Ideal when the usage demands are beyond the capabilities of a combi boiler. Can be compatible with solar hot water systems.
Considerations
You will need the space to accommodate the hot water cylinder.
Who should choose a system boiler?
Anyone with a larger home, including with multiple bathrooms. Also, where you want to be able to maintain a good water pressure from the taps.
Regular (conventional/heat-only) boilers
Regular boilers (also known as conventional or heat-only boilers) are more of a traditional boiler type. They usually require two tanks. Typically, one tank is stored in the loft and the other in an airing cupboard.
How regular boilers work is that they send heated water to your hot water cylinder, so that the cylinder is ready to distribute hot water to the taps in your home. Providing there is sufficient hot water in the cylinder, you can run multiple hot taps at the same time. This often makes regular boilers a great fit for larger families, or properties with multiple bathrooms.
To avoid having to wait for hot water, you can use programmable controls to arrange for the water to be heated in advance. You can also install an immersion heater as backup, including in the event your boiler breaks down.
Advantages
Great choice for larger properties with high demand and low water pressure.
Considerations
Regular boilers need two separate tanks meaning they aren’t a good fit for smaller homes which lack the necessary space.
When to choose a regular boiler
If you have a large home with multiple bathrooms and require the boiler to meet high usage demands. The presence of two tanks makes regular boilers better equipped to cope with high demand homes. Also, when it’s not feasible to upgrade to a more modern system, including one which doesn’t need any tanks (i.e. a combi boiler). Read more in our what is a regular boiler page.
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Alternative & specialised boiler types
Modern technology has resulted in the development of alternative boiler types. With the exception of some boiler types, this usually means moving away from traditional gas fired combi, regular or system boilers.
Condensing boilers vs non-condensing boilers
The main differences between condensing boilers and non-condensing boilers are based on their heat recovery and overall efficiency.
While both boiler types burn gas, condensing boilers recover heat from flue gases, recycling it back into the system. In contrast, non-condensing boilers release that heat directly outside which results in lower energy efficiency.
Electric boilers: Pros & cons
Electric boilers offer an alternative fuel source to gas or oil, plus the other alternative fuels that exist (i.e. biomass or hydrogen).
If your home is powered by renewable energy sources, then an electric boiler can drastically cut the carbon emissions of your home. There is also no need for gas pipes, a flue or external ventilation with an electric boiler. As well as being safer than a gas boiler, electric boilers are often far quieter, not to mention compact.
However, since electricity is more expensive than gas, electric boilers can be more costly to run. Also, if the electricity cuts out for any reason, the boiler won’t work until the electricity supply is restored.
For larger homes, an electric boiler may not be able to meet demand. Some users have found gas boilers to deliver hot water far faster than electric boilers.
Biomass boilers: Are they worth it?
If you are looking to take your property off gas completely, then biomass boilers offer a sustainable and highly reliable energy source. That said, biomass boilers do have a higher upfront cost to consider, meaning it may take longer to recoup the money you will spend compared with a gas boiler. But, if you can take a long term view of the decision, biomass boilers are a worthy investment.
Hydrogen-ready boilers: The future of heating?
If you’re looking to buy a new boiler soon, choosing a hydrogen-ready boiler may prove to be a smart move.
While gas and electric boilers remain the standard options, hydrogen is being introduced to offer a greener alternative. Hydrogen boilers would work much the same as gas boilers apart from running on 100% hydrogen.
The UK government is set to phase out gas boilers by 2035. Hydrogen remains the current frontrunner to replace gas alongside the introduction of heat pumps.
As for whether hydrogen-ready boilers will truly be the future of heating, the answer is fairly probable but isn’t fully conclusive at this stage. At WhatPrice, we’ll be keeping a close eye out on any developments in this space.
Comparing boiler types: Which one is best for you?
Unlike other things you might buy for your home, purchasing a boiler needs to consider specific things about your property and overall usage requirements.
We’ve compiled some of the most important information in a table below to help you compare the different boiler types.
Combi vs system vs regular boiler
| Feature | Combi boiler | System boiler | Regular boiler |
|---|---|---|---|
| Best for | Small to medium homes with 1 bathroom | Medium to large homes with more than 1 bathroom | Large homes with high demand |
| How is hot water provided? | On demand | Stored in a hot water cylinder | Stored in a hot water cylinder |
| Simultaneous hot water use? | Yes, if the mains pressure is compatible | Yes | Yes |
| Space requirements | Minimal | Requires a hot water cylinder | Requires both a hot water cylinder and a tank in the loft |
| Water pressure requirements | Needs good water pressure | Needs good water pressure | Low water pressure compatible |
| Efficiency | Excellent efficiency | Good efficiency for larger homes | Can be less efficient due to heat loss in tanks |
| Installation complexity | Typically very straightforward | Moderate | Most complex |
Best boilers for small homes & apartments
Combi boilers offer the most compact boilers of any boiler type, making them ideal for small homes or apartments. It is usually possible to install combi boilers in a cupboard, so long as there is enough room to allow for ventilation and maintenance access. Best of all, as combi boilers get their water directly from the mains, there’s no need to install a hot water tank which can also work to free up space in smaller properties.
Best boilers for large homes & families
If your property has multiple bathrooms, a combi boiler may not be powerful enough to meet demand. Instead, a system or regular boiler will be better equipped to deal with multiple showers or taps needing hot water at the same time.
💡Top tip: We recommend Alpha, Ideal Heating, Vaillant, Worcester Bosch and Viessmann when in search of the best boiler brands across all boiler types.
Most energy-efficient boiler options
We’ve scoured review platforms to find the regular, system and combi boilers that have been voted as the most energy efficient.
For combi boilers, these include the Viessmann Vitodens 100-W, Worcester Bosch Greenstar 8000 Style and the Vaillant ecoTEC plus – both the Viessmann & Vaillant made it into our top 10 best combi boilers.
The most energy efficient regular boilers include the Worcester Bosch Greenstar 8000 Life, Baxi 600 Heat and the Ariston Clas ONE R.
Some of the top options for efficient system boilers include the Viessmann Vitodens 200-W, Ideal Logic Max and the Vokèra Unica Max S.
Gas boiler costs, installation & maintenance
| Boiler Type | Approximate cost of boiler | Approximate cost of installation | Approximate total cost |
|---|---|---|---|
| Combi (28kW) for small to medium homes | £650-£950 | £1,200 | £1,850-£2,150 |
| Combi (33kW) for small to medium homes | £750-£1,000 | £1,200 | £1,950-£2,200 |
| Combi (38kW) for small to medium homes | £850-£1,100 | £1,200 | £2,050-£2,300 |
| System (20-35kW) for small to medium homes | £950-£1,100 | £1,700 | £2,650-£2,800 |
| Regular (15-25kW) for small to medium homes | £750-£1,100 | £1,700 | £2,450-£2,800 |
In the above table, we’ve listed the typical prices for regular, system and combi boilers for small to medium homes. As well as the cost of the boiler itself, we have also checked out boiler installation prices across the UK.
Psst: Have you just purchased a new boiler? Tell us how much you paid to keep our prices updated!
How much do different boilers cost?
You should expect to pay anywhere from £650 to £1,100 on average for a new boiler. With installation included, the total cost is usually around £2,000 to £3,000 for small to medium sized homes. For larger homes you can expect this to go up to £4,000.
The price variation covers the different types and sizes (kW) of boilers that are available.
To break this down further, we found the average price submitted to WhatPrice for a combi boiler installation cost £2,811.
Regular or Conventional boilers have a slightly higher average price of £2,851.
System boilers cost to install is around £2,948.
Installation considerations for each boiler type
Combi boilers: Installing a combi boiler is often more straightforward than other boiler types. A major advantage is that they don’t need separate water tanks, which can free up space in your home. Various compact combi boilers also exist, which is ideal if your property is on the smaller size. That said, combi boilers do require adequate water pressure along with the installation of an external flue exhaust to work.
Regular boilers: A regular boiler is one of those types of boiler that needs lots of space. Specifically, a cold water tank in the loft and a hot water cylinder in an airing cupboard. In some cases, the pipework or insulation may also require an upgrade to be able to install a regular boiler. An external flue is also required.
System boilers: The installation of a system boiler can be longer and more complicated than other boiler types. While there’s no need for a hot water tank, a hot water cylinder is still required. As with combi and regular boilers, system boilers also need an external flue.
Boiler Installation Cost Calculator
Based on actual quotes provided to WhatPrice by homeowners like you, our boiler installation cost calculator will give you an instant estimate of how much you can expect to pay for a new boiler and installation.
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Boiler maintenance: How to extend lifespan
Similar to how an MOT puts a car through its paces to check its roadworthiness, your annual boiler service is the best way to help ensure your boiler continues to work optimally.
During a boiler service, the engineer will run through a vast checklist of performance criteria. If necessary, replacement parts can be ordered which can help prevent costly, not to mention frustrating boiler breakdowns.
Opening up the boiler also gives your engineer an opportunity to remove any grease or grime that has built up within the system.
As a homeowner, you should also keep an eye out for the overall performance of your boiler. If you suddenly notice problems like a lack of hot water or strange noises, it’s time to arrange a repair.
Other top tips include bleeding your radiators to remove airlocks, keeping an eye on the boiler pressure and insulating any pipework. These tips all work to avoid stressing the boiler, while also helping to avoid related issues such as frozen or burst pipes.
Government grants & financial support for boilers
If you meet certain criteria based on your income or personal circumstances, you may be able to claim financial relief to help you with the cost of a new boiler.
Most of the schemes currently available are for the cost of a new heat pump rather than a boiler.
However, the boiler-specific schemes to look out for include:
Boiler Upgrade Scheme: This is a government scheme that will give you up to
£5,000 towards a biomass boiler. Your property must meet a number of criteria to qualify, including not being on the gas grid.
The Energy Company Obligation (ECO) scheme: ECO is another government scheme and is now in its fourth phase (ECO4). The eligibility criteria for ECO4 is determined by Ofgem and is aimed at the most low income and vulnerable households. ECO4 provides financial help for making energy efficiency improvements to properties. The repair or replacement of boilers is covered under the section of ECO4 known as The Affordable Warmth Obligation. ECO4 will run until 31 March 2026.
Finally, if you live in specific parts of the UK you may qualify for additional boiler grants. These include the Warmer Homes Scheme (Scotland) and Nest (Wales).
Finding a reliable boiler installer
Comparing the different boiler types is only part of the process of getting a new boiler. That’s because you also need to carefully choose who will install your boiler.
It is a legal requirement that the engineer is on the Gas Safe Register. If you head over to the Gas Safe Register website, you can enter your postcode to see engineers who are registered near you. Alternatively, you can also enter to check the registration status of a company or individual.
Opting for a plumber who has professional accreditations can offer further peace of mind. Some accreditations to look out for include:
- Chartered Institute of Plumbing and Heating Engineering
- ISO 9001, ISO 14001 and ISO 45001
- SSIP (Safety Schemes in Procurement)
- The Nationally Accredited Certification Scheme for Individual Gas Fitting Operatives (ACS)
- Trading Standards Approved (Buy with confidence)
- WaterSafe
- Which? Trusted Trader
Also, depending on the brand of boiler you are looking to install, it can be possible to find gas and heating engineers who are accredited with the brand, i.e. Worcester Bosch or Vaillant. This means the engineer has been individually trained and approved to install the boiler by the manufacturer.
Taking the time to do your research can help ensure the installation process is stress-free.
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FAQs
Still have questions about the best boiler type for your property? We’ve answered some of the most popular queries below.
For more help or advice, check out our boiler cost guides to find pricing information for all the major boiler types and brands.
What is the most energy efficient boiler type?
It is widely considered that combi boilers are the most energy efficient boilers available. This is especially the case if replacing your boiler with a modern combi boiler, since newer boilers must meet strict standards for energy efficiency.
What size boiler do I need for my home?
The perfect boiler size (also known as the kW output) is different for every home. It considers the simple formula of the number of radiators, bathrooms and bedrooms your property has. The larger the total number, the more powerful the boiler will need to be to meet demand.
Before you get a new boiler installed, your plumber should assess your property to determine the most suitable boiler size for your property.
How long does a boiler last?
The average lifespan of a boiler is between 10 and 15 years. Though, it is not unheard of for a boiler to last a few years longer than this before it needs replacing.
As you might expect, how long a boiler lasts will ultimately depend on the make and model of the boiler, the quality of the installation and whether the boiler has been serviced regularly.
If you are currently considering purchasing a new boiler, buying a model with a longer warranty is one of the best ways to be financially covered in the event of a boiler breakdown. In other words, to avoid having to buy a new boiler too soon after the last one was installed.
What are the signs that I need a new boiler?
As a homeowner, you will typically know when it’s time for a new boiler based on when your existing boiler was installed. Or, if you’ve only recently moved into your property, you can also check the paperwork your boiler should have been supplied with to find out the age of your boiler.
Also, if you get your boiler serviced regularly, you will be advised by your engineer if the boiler is reaching the end of its life.
Outside of these scenarios, some top signs to look out for that could mean your boiler needs replacing include:
- Parts for your boiler model are now too expensive or no longer available
- Frequent boiler breakdowns
- Poor performance (i.e. difficulty getting hot water or a long time for the radiators to heat up)
- The boiler has become noisy
- Unusual smells
- Yellow flame
- Reduced pressure
How long does it take to install a new boiler?
For a like-for-like boiler replacement (i.e. replacing an old combi boiler with a new combi boiler in the same location), the installation can take 4-6 hours.
Where there is a need to relocate the boiler, the job can take anywhere from 1-3 days. This extra time can be needed for tasks like rerouting pipework or installing new radiators.
More complex boiler installations can take anywhere up to 4 days. Often, this is when you are changing the type of boiler you have. Although rare, it could also be the case that a boiler is being installed in the property for the first time (i.e. if renovating a historic property). If so, all of the pipework would need to be installed from scratch.
In general, be wary of anyone promising a ‘quick boiler installation’, unless the installation is a straightforward switch. That’s because installers should always prioritise being methodical to ensure the new boiler is safe and that all components have been installed correctly.
Do I need new radiators when replacing my boiler?
Potentially, you may need to replace your radiators when you get a new boiler. This is most likely if the boiler you choose isn’t compatible with your existing radiators, or if your radiators are more than 15 years old and deemed inefficient.
While replacing your radiators at the same time as your boiler might seem like an expensive hassle, it can actually save you money in the long run. That’s because newer radiators will have better energy efficiency. Also, if your radiators are currently installed in the wrong location (i.e. not on the coldest walls of your property), re-routing and replacing them can make an incredible difference to the thermal comfort of your home.
How often should I service my boiler?
Most boiler manufacturers require your boiler to be serviced at least once every 12 months for the boiler to remain under warranty. Even if you have an older boiler that is no longer covered, keeping to this timescale will help ensure your boiler is safe to use. Regular servicing is also crucial to identify potential maintenance issues at the earliest opportunity, which can help avoid more costly problems from occurring.
It’s also important to note that if your boiler is showing signs it is dangerous or faulty, then you should schedule a repair without delay, even if its annual service is not yet due.
Is it better to repair or replace an old boiler?
The choice of repairing vs replacing a boiler should consider several aspects.
In most cases, it is usually better to replace an old boiler, especially if it is no longer meeting demand, isn’t energy efficient or has become unreliable. Replacing an old boiler will prevent you from experiencing a complete boiler breakdown.
However, if the boiler is still under warranty, then repairing it is often the most sensible, not to mention cheaper way to go. The only exception would be if an engineer overruled this decision, including on the grounds of safety or efficiency.
