What are the best new boilers to buy in 2021? Re January 14, 2021

What are the best new boilers to buy in 2021?

engineer servicing a boiler

Last year, we brought you the best boilers of 2020 guide. We’re all hoping 2021 will be a better year, but to give yourself the best chance – if you need a new boiler in 2021, read our best boilers to buy in 2021 guide first and save yourself some heartache.

Nobody wants to spend their hard-earned cash on a boiler but it is an important appliance, some might say THE most important appliance in the house (we would say that). So when it comes to buying a new boiler, it’s important to make a smart choice based on your budget.

Replacing your old boiler can bring benefits like saving money on your heating bills, being better for the environment, increased efficiency, and less frequent boiler breakdowns.

It’s normal to not know much about boilers, why would you? They are boring and you only need to buy them every 10-15 years if you own a home. We know you don’t want to spend hours researching the best boiler for your home, finding out what kW output is, or learning what flow rate means and whether it matters.

So…We’ve created this guide to tell you the best budget and premium combi, system, and regular boilers to buy in 2021. Boiler best buys here we come.

First, let’s look at the different boiler types so you can identify whether you have a combi, system, or regular boiler, so you know what section to look at. We’ve covered this in a previous blog – ‘Boiler types explained’ if you want an in-depth explanation but we’ll briefly cover it in this article because we’re nothing if not helpful.

Have I got a combi boiler?

This is the most common boiler type. A combi or combination boiler is named for its ability to provide both heat and hot water for your home. They don’t have any water storage tanks as they are connected to the mains water supply coming into your home, which is heated directly by some kind of dark magic that takes place within the boiler.

Combi boilers are more economical as they only heat the water that you require. Many people that have older boilers (like a back boiler) switch over to a combi boiler when they purchase a new one.


  • No storage tanks in the loft or airing cupboard
  • Takes up less space
  • Economical
  • Cheaper to install than system and conventional boilers
  • Enjoy mains pressure showers without the need to install a shower pump


  • May not be able to produce enough hot water for multiple bathrooms in use at the same time.
  • Not all combi boilers are compatible with solar energy

Have I got a system boiler?

System boilers can be found in homes with multiple bathrooms that could potentially require hot water provided at the same time. Water is heated and stored in a separate water tank so it’s ready for use whenever it’s needed.


  • Ideal for homes with 2 or more bathrooms
  • Relatively easy to install
  • Doesn’t require a cold water tank
  • Compatible with solar thermal energy


  • Large storage tank required, not suitable for flats or smaller homes
  • Loss of heat from the hot water storage tank, no matter how well insulated
  • Hot water is limited to the capacity of the storage tank, once the hot water from the tank is used up you will have to wait for it to heat the water again. A combi boiler heats water straight from the mains so it will always be hot.

Have I got a regular boiler?

Regular boilers, also known as conventional, traditional, heat only, or open vent boilers, are the most difficult to install or replace. They are also the worst kind of boiler at picking a name for themselves.

A regular boiler includes both a hot and cold water storage tank, the boiler itself, and an expansion cistern located next to the cold water tank. This takes up quite a bit of space in a home and it’s usually preferable to switch to a combi so that these tanks can be removed.

They are also the least efficient boiler type and as they have more parts, there is more that could potentially go wrong.


  • Conventional boilers can supply hot water to two or more bathrooms at the same time and it won’t affect water pressure or heating.
  • An immersion heater can be fitted to the hot water tank to ensure you can still get hot water in the case of a boiler breakdown.
  • Conventional boilers are suitable for homes that suffer from low water pressure.
  • Compatible with solar energy sources in the same way as a system boiler.


  • Amount of space the boiler and tanks take up is impractical, particularly for smaller homes or flats.
  • Limited hot water up to the volume of your hot water storage tank.
  • Hot water tank loses heat, no matter how well insulated.
  • Difficult to install, only suitable as a replacement for another regular boiler system.

Hopefully, now you are able to identify which type of boiler you currently have and you can skip to the review section for the type of boiler you have.

Boiler kW Output

Knowing what boiler you have is half the battle, the other half is knowing what size boiler you need. This is usually expressed in kW output. A kilowatt is a unit that is used to measure how much energy is output by the boiler in the form of heat. As a general rule, the more heat and hot water you require for your home, the higher the kW boiler you will need.

At this point, you might be thinking ‘you lost me at kW output’, we get it, it’s boring and it’s stuff you don’t want to know but stuff you need to know. Or do you? This is the beauty of the WarmZilla website, we do all the hard work for you and calculate what size boiler you need by asking you a few simple questions about your home.

If you want to learn more about flow rates and kW output for your home, here is an article we wrote for Big Bathroom Shop about choosing the right size boiler for your home.

Ok, now we’ve done all the background work, we know what boiler type we have and we know about flow rate or we know that we can just take the WarmZilla survey and find out what size boiler we need. Now it’s time to take a look at the best boilers on the market for 2021.

We’ve broken the categories up into ‘best combi boilers in 2021’, ‘best system boilers in 2021’, and ‘best regular boilers in 2021’. Within each boiler type category, we will recommend the best budget boiler and best premium boiler.

This list was composed by a team of Gas Safe heating engineers with a combined experience of over 50 years in the industry, but it is a subjective view. In searching for the best boilers in all the land we considered all of the major boiler brands including Worcester Bosch, Vaillant, Ideal, Baxi, Vokera, Heatline, Potterton, Glow-Worm, Rinnai, Alpha, Ferroli and Viessman. There are a lot of boiler brands out there but we felt this list covers the major brands.

Best Combi Boilers in 2021

Best budget combi boiler 2021

There are always a lot of worthy competitors for the best budget boiler crown. There are a lot of boilers competing in the budget range that are reliable and very affordable.

Our winner in 2020 was the Vokera Excel, but this year it has been replaced by the Ideal Logic Combi for a few reasons. The Ideal Logic is a more reliable boiler than the Vokera with better aftercare, which, when you’re looking in the budget boiler range, is essential.

In addition, when purchasing from WarmZilla, the Ideal Logic comes with an impressive 8-year guarantee, whereas the Vokera comes with a 5-year guarantee.

On a like-for-like basis, the Vokera Excel 25kW is available from WarmZilla at £1,489 with the Ideal Logic 24kW boiler costing £1,569. Not a massive difference in price for the added peace of mind that comes with better aftercare and an additional 3 years cover.

As with all WarmZilla boiler installations, this includes Gas Safe installation, system filter, wireless controls, system cleanse, and inhibitor.

It’s always worth spending a bit more to get a premium boiler if you can afford it as you will get your money back over the course of the boiler’s lifespan, but if you need to make a budget choice then we highly recommend the Ideal Logic range.

It might be worth considering buying your boiler through one of our boiler finance plans and spread the cost monthly, our plans start from as little as £9.80 per month.

We’d like to give an honourable mention to the Worcester 2000 series, similar styling to the premium Worcester Life/Style boilers but with a much cheaper price tag. You would be getting Worcester’s famous aftercare and have a boiler from one of the most reliable brands out there.

When you look at some of the other boilers competing in this category like the Heatline or Alpha boilers you can see just how much of a bargain the Ideal Logic is. For a similar price you get a vastly superior boiler in terms of performance and reliability, with a longer guarantee and better aftercare.

Best premium combi boiler 2021

You’ll be delighted to hear that the winner for the ‘best premium boiler in 2021’ was unanimous and there was no arguing at all. Despite there being a few decent boiler brands at the higher end of the market the decision was an easy one.

For 2021 our best premium combi boiler is the Worcester Bosch Style 8000, retaining its crown from last year.

Whilst looks aren’t everything, this boiler is the best looking of the bunch, so if your boiler is in a visible area then this big iPad-looking boiler is the one for you. Described by Worcester as the ‘Beautiful Beast’ it certainly lives up to its name. It’s by far the best-looking boiler out there and it’s the most powerful wall-hung boiler on the market.

It has all the same great features as the Life range and it’s available in black or white. Engineers like it because it’s easy to fit, customers like it because it’s powerful and it looks good and we like it because of all the previous reasons and despite it being fairly early in its lifespan, it’s been a reliable boiler so far and Worcester boilers, in general, are the most reliable.

Additional benefits include:


  • Improved LCD display for ease of use
  • Easy integration with smart controls
  • Very quiet boiler
  • Award-winning customer service
  • Established brand leaders
  • 10-year guarantee (when purchased through WarmZilla)

Honourable mention goes to the Vaillant EcoTEC Plus combi boiler; a solid, reliable boiler without the flair of the Worcester Style boiler but a worthy runner up nonetheless. Vaillant have scooped the Which? Best Buy for 2021, always a good sign.

Best System Boilers in 2021

Best budget system boiler 2021

Taking the crown for the best system boiler in 2021 is the Ideal Logic Plus system boiler, retaining its crown from last year.

As with the Ideal Logic in the combi range, this boiler comes with an 8-year guarantee, giving you peace of mind for years to come. It’s also backed by the excellent customer service of Ideal, along with a 4.6 average review score on Trustpilot, it seems like Ideal customers are very happy with their boilers in general.

Whilst the Ideal Logic isn’t as energy efficient as the Worcester Bosch Greenstar (another great boiler in this category) it does come in about £100 cheaper. Some of the team argued that you would get that money back over the course of the boiler’s life in reduced heating bills and it would be better for the environment with the additional energy efficiency.

Additional benefits include:

  • Queen’s award for enterprise 
  • Built-in frost protection
  • Standard 2-year guarantee on parts and labour
  • SEDBUK A-rating
  • kW output boiler to suit every size home
  • Concealed pipe connections

There are also honourable mentions for Vaillant’s ecoTEC Plus & Vaillant ecoFIT Pure system boilers, and Viessmann Vitodens range in this category for good value system boilers that don’t break the bank.

Best premium system boiler 2021

We have a new winner for the best premium system boiler in 2021 and it’s the Worcester Bosch 8000 Style boiler. It replaces another strong Worcester system boiler – the Worcester Greenstar I system boiler.

It costs around £200 more than the Greenstar I system boiler (on a like-for-like kW boiler) but the Style offers more, well…style. It also has a 94% energy-efficiency rating compared to the Greenstar I’s 92% (still high) and it has a nicer LCD display but both boilers are highly recommended by WarmZilla.

When purchased through WarmZilla both A-rated boilers come with a 10-year guarantee, system filter, wireless controls, system cleanse, and inhibitor added to your system to help it stay rust-free.

In addition, you get all the usual benefits of buying from Worcester Bosch – reliability, performance, and service.

‘Reliability is the single most important consideration when buying a new boiler and Worcester Bosch has it in spades.’ Which? Best Boiler Brands Report 2019

Additional benefits include:

  • Available with a 10-year guarantee
  • Available in either black or white to suit your home
  • Ideal for larger homes with more than one bathroom
  • Easy-to-use full colour boiler display
  • One of Worcester Bosch’ quietest boilers to date

Best Regular Boilers in 2021

Best budget regular boiler 2021

As with all the budget categories, there are some great regular boilers available, all at similar cost and energy efficiency, so it was a tough one to call.

Our 2020 best budget regular boiler is the Ideal Logic+ Heat, giving the Ideal range a clean sweep of the budget range for combi, system, and regular boilers.

Regular boilers are also known as heat only, conventional, traditional, or open vent boilers – just to add some more jargon to a jargon-filled industry.

The Ideal Logic+ Heat boiler replaces last year’s winner – the Baxi 400 Heat boiler because of its increased energy-efficiency (94% on the Ideal vs the 89% on the Baxi), meaning it’s better for the environment and better on your bank balance as your heating bills will be lower.

In addition, the Ideal Logic+ Heat has built-in frost protection, a Quiet Mark Accreditation for quiet operation, and an endorsement from the energy-saving trust.

It also comes with an 8-year guarantee when purchased through WarmZilla, rather than the standard 5-year guarantee with the Baxi 400.

Additional benefits include:

  • Quiet Mark Accreditation
  • Queen’s Award 2013
  • Built-in frost protection
  • Energy Saving Trust endorsed
  • Manufactured in the U.K
  • Good Housekeeping Award 2013 & 2017
  • Compact cupboard fit
  • LPG conversion available

When compared to other boilers in this price range, such as the Alpha E-Tec range you start to see why we have picked the Ideal Logic+ as the winner. It is a vastly superior boiler with a much better reputation in terms of reliability and performance than the Alpha E-Tec range, with a reliable customer service team backing the product up.

Best premium regular boiler 2021

The best premium range regular boiler in 2021 will come as no surprise, it’s a brand that has dominated the market for years due to its reliability, economy, and output.

Our 2021 best premium regular boiler is the Worcester Bosch 8000 Life boiler. Giving Worcester Bosch a clean sweep on the premium models for combi, system, and regular boilers.

The Life replaces the Worcester Greenstar Ri, which took the crown last year. The Greenstar Ri is a great boiler, ticking all the boxes for a winner but the Worcester Bosch Life boiler just goes that one step further in terms of performance, looks, and efficiency.

It’s also one of the few A-rated energy-efficient conventional boilers on the market, saving you money on heating bills and saving the environment. There is no downside to this fantastic boiler and all of our engineers have no hesitation in recommending it as our number one heat-only boiler in 2021.

Additional benefits include:

  • Modern new design
  • Improved boiler display screen with easy to push control buttons
  • Ideal for larger homes with more than one bathroom
  • Excellent flow rates
  • Great value for money

An honourable mention goes to the Vaillant ecoTEC Plus regular boiler, a perfectly good option if you want to save a bit of money but ultimately not quite up to the spec offered by the Worcester Bosch Life model.


It’s always difficult to choose the winners in all these categories but we base our recommendations on technical specifications, reliability, parts availability, and aftercare. All of our premium selections in 2020 and 2021 have been Worcester Bosch. Like many others, Which? Included, we believe that Worcester Bosch is the most consistent premium boiler manufacturer on the market today when looking for central heating boiler best buys.

Viessmann produces good boilers, with the reliable efficient German craftsmanship you would expect, but occasionally there are issues getting parts and with Brexit and COVID added into the mix for 2021, we have opted for brands that have a base in the UK as they are less likely to face delivery issues.

Worcester Bosch has built up an enviable reputation for reliability and innovation across its product range and the introduction of the Life/Style range in 2019 has cemented its position as market leaders.

There is a very good reason why Which? Have voted Worcester Bosch – Best Buy for Boilers for the last 10 years running. But it’s not just the product that’s first class, they have excellent customer service and with a highly trained WAI (Worcester Accredited Installer) network across the U.K, they are quite responsive if you need to make use of your 10-year guarantee.

The budget market of boilers is a lot more competitive but given that it’s such a major investment we would advise paying a little bit more to have that reliable brand name and the benefits that go with it. If you pay using a WarmZilla boiler finance package the additional monthly expenditure is quite minimal and over the course of the boiler lifespan, you will earn your money back through added energy efficiency decreasing the price of your bills and the decreased likelihood of breakdowns and repair bills.

We hope our best boiler guide of 2021 has been of help in your quest for the perfect boiler, if you have any questions just use our live chat or email us at ask@warmzilla.co.uk, we’re always happy to help.

If you’d like to get an instant fixed price quote on a new boiler suitable for your home, then take our survey now, it only takes a couple of minutes and you’ll have an idea of how much a new boiler will cost you.

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