The Best Boilers in 2021

The top 15 gas boilers in the UK, right now in 2021

The average price of a new boiler in the UK is £1,049, with installation charges of between £500 and £1,000 on top.

So, for around £2,049 all in, it’s fair to say that replacing your boiler is a significant investment not only in the warmth and comfort of your home or apartment, but also in its future value when the time comes to take it to market.

For this article we have examined, in depth, 445 different gas boilers from dozens of Britain’s leading manufacturers.

The price of a supply-only new boiler ranges from around £435 for a Vokera Evolve S 18kW Boiler system boiler right up to around £4,450 for a super-powered Ideal EvoMax 150kW Boiler Regular, best for the very largest homes and commercial premises.

But how do you choose which is the best boiler for you?

We’ve scored each of the 445 gas boilers on the market in the UK right now and, in this piece, we’ll be sharing the best boilers from 15 different manufacturers as measured by our exclusive best boiler evaluation system.

We’re HomeSage – we work with a network of trusted, established Gas Safe boiler installers up and down the UK.

By filling in the form anywhere on page, you can save up to 54% on the total cost of the supply and installation of your new boiler. 

How? When you send us your details, we’ll forward them to local boiler installation companies who can give you the best boiler quotes around.

Nothing brings down the price you pay like competition so, by sending us your details, you could save hundreds of pounds on your new boiler.

What’s more, our service is 100% free and you have no obligation to accept any quote our installers give you!

In this article, we look at:

• The three different types of boilers on the market.
• Boiler specifications – how to choose the best boiler for your home.
• The exclusive HomeSage best boiler rating system and how it works.
• The top 15 best boilers of all types in the UK at the moment (using gas as fuel).
• How to save up to 54% on the cost of the installation of your new best boiler.

What are the three main types of boiler?

There are a few different types of boiler available in the UK but the main three offered by Gas Safe engineers are the:

• combi boiler,
• standard boiler, and
• system boiler.

Other types of boiler still exist within older British homes.

However, if you are seeking to replace a very old boiler, the strong likelihood is that your installer will recommend one of the three types above.

What is a combi boiler?

Traditionally, most boilers had one or more storage tanks in which they either held water which was heated or was to be heated later.

Combi boilers were originally introduced by manufacturers to offer homeowners the same level of warmth and hot water without needing as much space within a home – remember that the UK has some of the smallest homes in the Western World.

With a combi boiler, the hot water needed both for your radiators and for your taps is provided on demand.

Water from the mains passes through a combi boiler and the technology within the boiler instantly heats up the cold water it has drawn and it then distributes that hot water around your home.

The biggest drawback for combi boilers is, however, that they have a maximum capacity in volume for heating water.

This means that, if someone wants to use the shower while another person wants to use a hot water tap at the same time, the amount of water reaching each point falls meaning a drop in water pressure. 

In addition, depending on the boiler’s capacity, the water the person in the shower is cleansing themselves with may suddenly become a lot colder.

If you’re interested, we have more information in our post specifically about combi boilers.

What is a standard boiler?

A standard boiler, sometimes called a traditional boiler, regular boilers, heat-only boiler, or open-vent boiler, needs a lot of space – space for a water tank (you’d normally find one in a loft or attic) and a storage cylinder (you’ll normally find them in a large utility room or an airing cupboard).

The water is kept hot within the storage cylinder and it’s then provided by the cylinder on demand to any radiators, showers, or hot water taps around your home when needed.

Unlike with a combi boiler, the water pressure you experience when you require hot water from one or more points at the same time doesn’t drop.

However, once the hot water in the storage cylinder has run out, it then refills and it can take a while to heat up.

What is a system boiler?

A system boiler shares many of the same characteristics as a standard boiler, however they’re really only the best boilers for very large domestic properties. 

Unlike a standard boiler, they don’t however require a water tank for the loft; however, like a standard boiler you can run out of hot water, meaning that you’ll have to wait for the storage cylinder to heat up new water it has drawn from the mains.

With both standard boilers and system boilers, the maximum amount of hot water is governed by the size of the cylinder.

All standard and system boilers now come with set timers which instruct the system to produce more hot water at the times when you think your household will need it.

If you like you can read more about system boilers on our blog post here.

By the numbers – choosing the best boiler

There are five main considerations to take into account when selecting a boiler.

We would always advise that your final choice of boiler is made following consultation with a boiler engineer – because of their experience, they will better understand the capacity your household needs.

They can then recommend which boilers are capable of satisfying your demand for hot water and heating based on your family’s demands.

The output of your boiler

The output is how much energy your boiler uses when it’s switched on.

This, of course, has an impact on running costs and, to work out just how much a boiler will add to your energy bill, you multiply the output by the price of a unit of gas.

Let’s try an example. For smaller properties like an apartment or a mid-terraced house, you will need a boiler with an output of up to 27kW.

If the price of a unit of gas is 4p, each hour the boiler is switched on will cost you 27 (the number of kilowatts) multiplied by 4p – this equals £1.08.

For medium sized properties with 3 or 4 bedrooms and up to 15 radiators, your installer will likely recommend a 28-34kW boiler.

If you live in a smaller or medium sized property, your installer is likely to recommend a combi boiler as the best boiler for your home.

For larger properties with 4 or more bedrooms and 20-or-so radiators, you should have a 34-42kW output boiler installed.

Depending on the configuration of and the size of your property, your installer is likely to recommend a regular or combi boiler.

Your boiler’s energy efficiency

The energy efficiency of your boiler refers to the amount of energy it uses to carry out its core functions of heating your home and providing hot water to your taps.

The more energy efficient your boiler, the more you save money on the gas you use to power it.

For example, according to the Energy Saving Trust, you will save up to £305 a year on your gas bills if you change your current G-rated boiler for an A-rated boiler if you live in a detached home.

Where your boiler is situated

Boilers can be internal (situated within your home) or external (situated outside your home but within the boundaries of your property). For this article, we have only reviewed internal boilers.

Boilers vary in size – some can be stored within the cover of a kitchen or bathroom cabinet while others will be too large for this and they will probably require your installer to fit it in a utility room instead.

The manufacturer’s warranty

You should get at least 10 years’ full use from any new boiler you install as a minimum.

Boiler technology improves year on year and, in 10 years’ time, the cost of any new boiler you install should then save you more over the 10 years of its life through reduced energy usage bills.

The manufacturers and the models we examined for this article offer between 2 and 12 year warranties.

Please remember that, as soon as your new boiler has been installed, you should register the installation with the manufacturer themselves otherwise you may only receive a 12 month warranty.

You may also need to have your unit inspected once a year by a registered installer to maintain the warranty.

The flow rate (combi boilers only)

The flow rate is closely linked with the output rate and it describes how much water can be heated every minute by your boiler. The higher than flow rate, the more hot water it can distribute to your radiators and hot taps.

How HomeSage rates boilers

We consider a range of factors in our comprehensive rating system to find the best boilers, and the scores we provide are given as percentages. 

Of course, we factor in both the price and the length of warranty offered on your new boiler. However, we also consider:

• the type of fuel used (gas is the cheapest option by far for most homeowners so each gas boiler on our list gets the maximum score),

• the energy efficiency ratings, and

• users’ opinions of each manufacturer as reflected by the number of reviews and the average score on TrustPilot.

The best boilers in 2021: the top 15 gas boilers by manufacturer in the UK today

With all that in mind, welcome to our list of the top 15 best boilers in the UK today.

Prices of the boilers on our list range from just £515 for the RavenheatWH80 25 boiler for larger homes. 

Better still, most of them cost around the same or less than the average gas boiler price of £1,049 so, budget dependent, you can afford to invest in the best boiler for your home without breaking the bank.

1. Baxi Platinum 24 Combi Boiler (92.69%)

Finishing in top place, our choice for the best boiler in 2021 is the Baxi Platinum 24 boiler, rating 92.69% on the HomeSage test.

It’s a compact wall-mounted combi boiler available in white with snug dimensions of 450mm width, 780mm height, and 345mm in depth.

Price-wise, it comes in way under the average, it’s an economical 24kW unit, and new owners benefit from a 10 year guarantee.

2. Worcester Bosch 2000 25kW Combi Boiler (91.89%)

In second place comes the Worcester Bosch 2000 25kW boiler.

Cheaper than the first-placed Baxi, it narrowly misses out on top spot because of the shorter warranty, less voluminous flow rate, and the extra kW it takes to do the same job.

It measures 400mm across by 724mm down and it is 300mm in depth so it’s quite a bit smaller than its winning rival meaning a tighter, snugger fit within a kitchen or bathroom cabinet.

3. Vaillant ecoTEC exclusive Green iQ 627 Boiler (88.85%)

The top system boiler on the list is the Vaillant ecoTEC exclusive Green iQ 627 Boiler.

Coming in at 27kW output, this third-best boiler will cost more to run than other system boilers suitable for small houses however whatever energy it needs it uses efficiently as it has been awarded an A-grade in this important category.

The price is around the average you’d expect to pay for a boiler in a smaller home and we like the fact it’s guaranteed for 8 years following purchase.

4. Glow-worm Ultimate3 30kW Boiler (85.82%)

Popular brand Glow-worm finishes as fourth-best boiler with what we believe is the best one across their range – the Glow-worm Ultimate3 30 boiler.

Unlike the top three finishes, the Ultimate3 30 boiler is intended for use in medium sized houses and its requirement of just 30kW to operate means that the boiler’s running costs might be lower than you anticipated.

At between £690 and £720, it’s a bargain in terms of its pricing and the 10 year warranty on the appliance gives a strong indication into Glow-worm’s confidence in the boiler’s longevity.

5. Ideal Vogue GEN2 S15 Boiler (86.42%)

Next up is the Ideal Vogue GEN2 S15 627 system boiler.

We love the ten year warranty and we love the customer feedback.

Coming in at a very compact 445mm by 740mm by 330mm, this boiler, designed for a very small property, will provide heat and hot water to your home for a very long time. Best of all, it’s backed by a 10 year warranty.

6. Vokera Evolve S 18kW Boiler (83.89%)

Lesser-known Vokera finishes sixth with the Vokera Evolve S 18.

Designed for very small houses and apartments with an output of just 18kW (very cheap to run), this is the cheapest combi boiler in the UK at the moment with prices varying from £435 to £450 supply-only.

The eight-year guarantee offers peace of mind that you should get years of trouble-free use from your new boiler.

7. Intergas Compact HRE OV 18kW Boiler (83.32%)

In seventh place is the Intergas Compact HRE OV 18 system boiler which, like the Vokera in 5^th place, is designed for very small properties.

It’s more than 50% more expensive than the Vokera and it’s less efficient.

What pushed it way up the rankings in our eyes was its very compact size (just 450mm by 590 mm by 240mm) and the great reviews customers have posted online about the company and its products.

8. ATAG IR24 24kW Boiler (83.18%)

The eighth-best boiler is the ATAG IR24 24 system boiler.

A significant investment at around £1,950 and with a ten year guarantee, the IR24 24kW boiler is the best offering in the ATAG range. Why does it score so highly? 

The ATAG brand is highly respected among both customers and installers and, if budget is not a consideration, we’d be very tempted to recommend this to clients.

9. Ariston Clas Net One 24kW Boiler (81.02%)

Scoring just higher than 81% is the Ariston Clas Net One 24kW regular boiler.

A compact 400mm by 745 mm x 385mm, it’s an A-rated and highly energy efficient boiler big enough to heat medium sized properties but only needing 24kW to do so.

In fact, it’s the specification of the unit which makes it a contender and it has managed to score 80%+ despite Ariston’s lower average score from users who have reviewed it online.

10. Biasi Inovia ErP 35kW Boiler (80.75%)

Lesser-known Biasi sneaks into the top 10 with what we believe is their best boiler across their entire range, the Biasi Inovia ErP 35kW boiler.

Designed for larger properties, this 35kW boiler is just 700mm high by 400 wide by 290mm deep meaning that it will fit well into most covering kitchen or bathroom cabinets.

Pricewise, at around £700, it comes in way below the average for a boiler with this power although we do wish that customers were offered more than a 5 year warranty.

That said, online feedback from customers is very complimentary about the company.

10. Ferroli Modena 25s HE Boiler (80.50%)

Next up is the A-graded Ferroli Modena 25s HE regular boiler, designed for smaller properties.

A very credible choice as a low-cost option for homeowners working to a budget, its 25kW output should keep electricity bills down.

We’re slightly concerned about the reviews online about the company as we are about a 5-year warranty – if the company could sort either of those two factors out, their top model would rank even higher on this chart of manufacturers’ top models.

12. Ravenheat WH80 25kW Boiler (79.88%)

Ravenheat comes in twelfth place for its Ravenheat WH80 25kW combi boiler.

Another budget option again with a 5 year warranty, it’s managed to grab an A-grade for its efficiency rating – this is a real achievement for the company considering that the unit itself barely costs more than £500 – about half the average.

User reviews online about the company are few and far between and their average customer score is not one of the highest among boiler manufacturers.

It’s a compact unit coming in at 700mm high, 400mm wide and 300mm deep.

13. Potterton Titanium 28kW Boiler (79.80%)

In 13th is the Potterton Titanium 28 combi boiler for medium-sized properties.

Its flow rate is one of its stand-out features – you should be able to run two taps at the same time and not notice a drop in either water pressure or the heat provided.

At £830 or thereabout, the unit is much cheaper than the average priced new gas boiler and we like its 7-year warranty.

We’re not so keen on the lack of customer feedback and the unit is quite big at 450mm by 780mm by 345mm.

14. Viessmann WB1B Vitodens 100-W 13 Boiler (79.61%)

The Viessmann WB1B Vitodens 100-W 13 regular combi boiler finishes in 14th place.

15. Keston S30 30kW Boiler (74.87%)

The Keston S30 30 system boiler scrapes into our top 15 boilers with 74.87% – that’s still an impressive feat though!

It’s a compact system boiler measuring just 395mm by 700mm by 378mm.

It narrowly misses out an A-grade efficiency rating, but its score on this table is depressed by the fact that there are better deals out there and the very low scores the company has received from its customers on TrustPilot, surprising given that it’s part of the Ideal group.

Save up to 54% on the price of your new boiler installation

To save up to 54% on the installed price of a boiler from the above list, feel free to fill in the form dotted throughout this page.

We’ll then send your details to multiple local trusted Gas Safe engineers.

You’ll get a call back with a quote and they’ll talk through with you which is the best boiler to provide your home and your family with the hot water and heat you need, exactly when you need it!

There is no obligation on you to accept any of the quotes provided to you by our partner installers.

Our service is free of charge whether or not you choose to go ahead with a local firm whose services we recommend to you.