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Best Combi Boilers: What’s best to buy (and avoid) in 2020

What is the best combi boiler? It's the burning question on the UK's lips. Here, we'll tell you what to look for and what to avoid when buying a new combi boiler for your home in 2020.

You might not have even been aware of your boiler until it failed you. It was a seldom thought of white box in the corner of an equally seldom thought of cupboard in a lesser used room. Going about its job in peace with a resolute and unfailing work ethic despite knowing full well you not only don’t care for it but prefer to pretend it doesn’t exist like Quasimodo, isolated to his cathedral.

But your home is your boilers Esmeralda and he’ll do anything to protect it, eventually proving his worth to everyone and hailed a hero. Well. At least a new boiler will.

Everyone has a passing knowledge of cars – just enough to make an informed purchase. But, what makes a boiler the best? A brand name? Boiler size? Efficiency percentage? Awards?....Boiler awards exist?!

Our early spoiler has already let you in on our winner; Viessmann boilers. But there’s more to it than that, and much more boilers than that, including tough competition from the likes of Worcester Bosch, Vaillant, BAXI and more.

A loveable list to start, here are our top 5 best combi boiler brands in the UK right now, in 2020:

  • #1 Viessmann Combi Boilers
  • #2 Worcester Bosch Combi Boilers
  • #3 Vaillant Combi Boilers
  • #4 Ideal Combi Boilers
  • #5 BAXI Combi Boilers

#1 Viessmann Combi Boilers (Best boilers)

Viessmann are already an astronomical force in the European boiler market and also lead the way in commercial boiler installations. Now they’re here to bestow their majestic German engineering upon the UK domestic market providing your home with a new boiler so good, you can forget it about it for good this time.

Viessmann’s 2020 combi boiler range & overviews:

Viessmann Model Kilowatt (kW) outputs
Vitodens 050-W - 29kW 35kW
Vitodens 100-W 26kW 30kW 35kW
Vitodens 200-W - - 35kW
Vitodens 111-W 26kW - 35kW

Boiler not working? Fancy a Viessmann? Get your fixed price from £1,695, online. We can fit within as little as 24 hours.

Fixed Price Boiler Quote

Viessmann Vitodens 050-W Combi Boiler

Available in two kW outputs suitable for any home requiring a new combi boiler, the Viessmann Vitodens 050-W is the trusty work horse of the Viessmann family. It has a price to compete with boilers that don’t scratch the surface of its quality whilst maintaining high component standards – most importantly of all, a stainless steel heat exchanger (essentially a part in other boilers that’s likely to break and Superman would struggle to crack this one). Oh – and it has a Which? Best Buy award.

Like the Viessmann Vitodens 050-W? Get a fixed online price, including installation from £1,695.

Viessmann Vitodens 100-W Combi Boiler

Everything that makes its little brother Vitodens 050-W the super boiler it is and more. The Viessmann Vitodens 100-W should be any homeowners go-to combi boiler. A familiar endorsement from ‘Which?’ for its remarkably high end internal parts, a class A rating for efficiency, back-lit LCD display, low fan speed for quiet operation and low CO2 emissions to help ease your carbon footprint and conscience. This is Viessmann’s Lebron James.

Like the Viessmann Vitodens 100-W? Get a fixed online price

Viessmann Vitodens 200-W Combi Boiler

Meeting every demand a boiler buyer could possibly have of their combi boiler. The Vitodens 200-W is perfectly suited for the larger detached and semi-detached homes. It holds every feature and perk of Viessmann boilers before it whilst also boasting a colour touch screen display, smart thermostat compatibility and up to an incredible 98% efficiency rate.

Like the Viessmann Vitodens 200-W? Get a fixed online price

Viessmann Vitodens 111-W Combi Boiler

The only thing Viessmann can be accused of is a lack of imagination when it comes to naming their boilers, but their quality does all of the talking. The Vitodens 111-W is a monstrous storage combi – essentially rendering it a kind of beautiful Frankenstein boiler – half way between combi and regular boiler delivering a ludicrous 18litres of hot water per minute. Lucky enough to have that huge house you always wanted? Get luckier and get yourself the Vitodens 111-W.

Like the massive Viessmann Vitodens 111-W? Get a fixed online price

Typical Viessmann Combi boiler prices 2020 (ours are the best!):

Viessmann Model Our Price   
Vitodens 050-W 29kW £1,795
Vitodens 050-W 35kW £2,175
Vitodens 100-W 26kW £2,247
Vitodens 100-W 30kW £2,404

Vitodens 100-W 35kW £2,639
Vitodens 200-W 35kW £2,750
Vitodens 111-W 26kW £3,180
Vitodens 111-W 35kW £3,421

Please note: The above prices assume a straight forward swap of a new, replacement combi boiler. To get the best accurate price, click the get quotes button. Or, for a massive, in-depth article on prices, check out our new boiler costs article.

If time eluded you and you didn’t have time to read the life changing Viessmann overview above, then do read this brief conclusion.

Want to save money and energy on your heating bills? If so, you should consider installing one of the best smart thermostats.  

If Viessmann's really are the best combi boiler, why are they so cheap?

Heatable has a unique business model, allowing us to offer all our Viessmann’s with a 10-year warranty at mind bogglingly low prices.

But truthfully – Viessmann boiler prices will very shortly be on the rise and such bargains much harder to come by. Right now, Viessmann are priced so well to increase their exposure to Britain’s domestic boiler buyers but as their quality becomes more than just rumour – their prices will inevitably rise to reflect just how premium of a product they really are. The best combi boiler of 2020, may soon become the most expensive.

Viessmann boilers sponsor Huddersfield Football Club and since this engagement, the Huddersfield players have been so distracted by the beautiful heating machines in their homes, they’re practically guaranteed relegation from the Premier League this year – all without a care in the world. That’s the power of Viessmann.

*Post May 2019 update - Huddersfield were indeed, relegated. 

Viessmann boilers quality comes from within – literally. A boiler is the sum of all its parts and internal components make or break them.

Viessmann never compromise on the quality of their build - it’s a German thing. They only accept the best. Their boiler range is littered with endorsements from Which?, all so readily backing up their already unrivalled features and statistics.

Did we mention that Viessmann are the UK’s most reliable boiler? If nothing else swings it for you, that alone, should.

What's more, Viessmann boilers are the some of the best in class when it comes to efficiency too.

The Energy Saving Trust say:

If you replace your old boiler with an A-rated boiler and set of heating controls (you can even operate it remotely via an app on your phone) you could save about £340 and 1,500kg of carbon monoxide a year.

Convinced that the Viessmann combi range is the best for you? Get fixed online price today and get your installation as quickly as tomorrow.


#2 Worcester Combi Boilers (2nd Best boilers)

A prestigious name within the heating industry and probably the UK’s best, most sought after combi boiler, historically. One of three combi boilers with the Which? Best Buy award and you can’t go far wrong with a Worcester.

Worcester 2020 combi boiler range & overviews:

Worcester Model Kilowatt (kW) outputs
Greenstar i - - 25kW 30kW
Greenstar Si Compact - - 25kW 30kW
CDi Classic 29kW 34kW 38kW

CDi Compact - 28kW 32kW 36kW
CDi Highflow - - 44kW 55kW

Greenstar i Combi Boiler

The Greenstar 30i is Worcester’s best seller and over a million of them are in homes throughout the UK. If choosing between the two, then do consider opting for the Greenstar 30i over the Greenstar 25i as they are known to be much more reliable and often don't have too much disparity in price. If you do have a super small property though, then the 25i will be more than adequate and could secure you a hell of a Worcester bargain.

Greenstar Si Compact Combi Boiler

Very similar to its namesake, the Greenstar Si boasts almost identical statistics and features and again is suitable for small to medium homes with one bathroom but a smaller frame allows this model to nestle into a kitchen cupboard – it's probably the best option if you require your combi boiler to be out of sight.

CDi Classic Combi Boiler

A truly premium boiler from Worcester and their top of the line offering, in their opinion, it's probably the best combi boiler in their range. If you have your heart set on a Worcester then this is certainly one model to consider, although it may come with a more premium price tag.

CDi Compact Combi Boiler

Another range topper from Worcester Bosch boilers with more compact dimensions for homes short on space. The CDi compact is still complete with outstanding efficiency levels, a Which? Best Buy award and can still pack a punch for its size – comfortably powering homes with two bathrooms.

CDi Highflow Combi Boiler

A monstrous floor standing combi boiler with industry leading hot water flow rates. Perfect for large homes with multiple bathrooms that don’t want to make way for an additional water tank. It's the best combi boiler for massive homes, not many can match its credentials.


Worcester Bosch 8000 Style

Worcester's most powerful and connected wall hung boiler to date, capable of delivering up to 50kW's, and with optional smart technology that will top up the boiler for you when low pressure is detected. As its name suggests, it is also arguably the best looking boiler on the market and readily available in black - a boiler industry innovation on a par with the introduction of the iPod.

Worcester the way? Maybe, maybe not.

Worcester are without doubt a fine choice of boiler and in most cases, you should bag yourself a 10-year warranty (assuming you buy from a Worcester Approved Installer and not a rogue in an unmarked white van) giving you peace of mind no matter what.

If you’re hellbent on getting a Worcester and quality is your top priority, you may want to consider exploration beyond the Greenstar i range - where Worcester's real quality lies - the 8000 Style is a great place to start. However, unlike other manufactuers, irrespective of your chosen Worcester Bosch model - you can always bank on Worcester's outstanding aftercare which is without a doubt, industry leading.

If your Worcester Bosch boiler's losing pressure, get a fixed price replacement, online.

How much will a boiler installation cost? Check out our new boiler costs guide for the full rundown. 

#3 Vaillant Combi Boilers (3rd Best boilers)

Another proud owner of a Which? Best Buy award and huge player in the British boiler market. Vaillant are a time served and well respected boiler manufacturer and certainly amongst the premium contenders.

Vaillant combi boilers are made in the UK to impeccably high standards, they’re already in a staggering amount of UK homes, offer excellent warranties and are loved by boiler installers too.

Vaillants 2020 combi boiler range & overviews:

Vaillant Model Kilowatt (kW) outputs
ecoTEC exclusive - - 35kW 43kW
ecoTEC plus 25kW 32kW 35kW 38kW
ecoTEC plus store - - -

ecoTEC pro 24kW 28kW 30kW -
ecoFIT pure - 25kW 30kW 35kW

Vaillant ecoTEC exclusive Combi Boiler

Available in outputs at the higher end of the scale; 35kW and 43kW, the ecoTEC exclusive is a premium combi boiler for larger homes which boasts an impressive 17 litres of hot water per minute. Certainly impressive if you like lotsa' hot water.

Vaillant ecoTEC plus Combi Boiler

A broad range of kW outputs starting from 25kW makes Vaillant’s ecoTEC plus the combi allrounder for almost any small to medium homes. Excellent efficiency ratings, premium components and the addition of the Quiet Mark award for quiet operation makes this Vaillant’s flagship boiler.

Vaillant ecoTEC plus store Combi Boiler

A beast of a storage combi boiler that’s premium in every manor. A hot water delivery rate of up to 20 litres per minute that you would struggle to find elsewhere makes this an outstanding choice for larger homes if you don’t want to, or have the room to fit an additional water storage tank.

Vaillant ecoTEC pro Combi Boiler

The perfect combi boiler solution for small to medium homes with the kW model’s coming in three different outputs to suit all. A bright LCD display makes the ecoTEC pro super simple to use and it also comes with a Quiet Mark award so it’s not going to wake you up whilst warming your home in the morning.

Vaillant ecoFIT pure Combi Boiler

Another super-efficient combi boiler suitable for almost any sized home with the added bonus of being extra compact if you’re shy on cupboard space or a boy wizard lives under your stairs. It’s clever too – automatically reducing its energy usage to lower your bills.  

Premium Vaillant boiler, premium Vaillant price? Afraid so.

If you’re splashing out on a Vaillant then there is a very slim chance that your new boiler will disappoint but splashing out you will be.

Unfortunately, Vaillant’s price range does often make you feel like you've stood up too quickly so may well hold the more savvy shopper at bay.

They sit firmly behind Worcester and Viessmann in the boiler pecking order but are so often priced above and beyond them.

Recommended: Check out our top 10 list of the best boiler manufacturers for a complete rundown. 

It’s difficult to put our finger on why they’re priced so highly – perhaps five different combi boilers has spoilt their broth but whilst Vaillant have to make our best boiler list due to their undeniable quality, their pricing structure does make you wonder if boiling your kettle and washing in the sink is really that bad?

#4 Ideal Combi Boilers (4th Best)

Joyful wordplay aside, an Ideal combi boiler might just be the ideal boiler for your home.

Ideal boilers have been a mainstay in the British boiler market for what seems like an eternity. Picture a horse that relentlessly finishes in the top 6 at the Grand National but never quite get its nose in front – no cigar but you know that horse is from a damn good stable.

Ideal are all about inclusivity and range – their combi boilers range from budget to bedazzling and everything in between meaning they cater to the folks funding their new boiler installation with change found down the side of their couches and those looking for a boiler so sexy that dozens of perverts have been jailed for trying to hack its iCloud account (see; Ideal Vogue).

Ideal’s 2020 combi boiler range & overviews:

Ideal Model Kilowatt (kW) outputs
Logic 24kW 30kW 35kW
Vogue Gen2 26kW 32kW 40kW
Vogue Max 26kW 32kW 40kW

Ideal looking like an ideal choice? Get a fixed online price

Ideal Logic Combi Boiler

Ideal, Logic, Vogue. Ideal’s marketing team don’t like unnecessary syllables and love assigning words to their products that already hold positive connotations.

Fortunately, their technical team do tend to back this up.

The Logic combi is without a doubt a logical choice for any grudge purchase boiler installation. The odds of your boiler breakdown being expected and affordable? We’ve checked, it’s 3%. The Ideal Logic is a no thrills, solid boiler that’s popular for its price to quality ratio. Ideal offers a 2-year standard warranty providing you with required peace of mind – not bad for a dual award winner.

Ideal Logic combi's best boiler perks:

  • Made in the UK... so you know it's good
  • Compact in size (ideal for cupboards)
  • Roughly as difficult to program as peeling a banana
  • Won the Queens Award in 2013
  • Won Good Housekeeping Award 2013 & 2017
  • 2 year warranty as standard 

Want the best price on a new Combi Boiler? Get a fixed online price with installation within 24 hours.

Ideal Vogue Combi Boiler

Weary of churning out their regular award winning boilers, Ideal set out to make a boiler to break the mould.

The Ideal Vogue Gen2 is Ideal’s best, premium offering, also picking up numerous awards, it has been blessed with internal component upgrades, a back lit LCD colour display, a standard 10-year warranty, built in frost protection and an endorsement from the Energy Saving Trust for its outstanding efficiency and global warming protest organisational skills.

Ideal Vogue Max Combi Boiler

If it isn’t broken, don’t fix it. Ideal know that, it’s just plain logic. So their Vogue Max is just their regular Vogue but with an added Ideal approved water filter, magically increasing their already whopping 10-year warranty to an unprecedented and industry leading, 12-years. It's the best combi boiler in its class in terms of warranty length vs cost.

A note on the head turning, heart-breaking, bone chilling aesthetics of the Ideal Vogue:

This Adonis of a heating machine looks like a groomed wild boar, purring with unshakeable self-certainty but at the same time, exuding the divine grace of a gliding swan. Some of the UK’s oldest ducks cower in shame at the ease of which water rolls off this machines back.

Typical Ideal Combi Boiler prices (we offer the best online prices, period!):

Ideal Model Price (Guide)  
Logic Combi 24kW £1,650
Logic Combi 30kW £1,845
Logic Combi 35kW £2,245
Vogue Gen2 26kW £2,350

Vogue Gen2 32kW £2,550
Vogue Max 26kW £2,550
Vogue Max 32kW £2,690
Vogue Max 40kW £2,960

Please note: The above prices assume a straight forward swap of a new, replacement combi boiler. To get the best accurate price, click the get quotes button.

For the best budget combi boiler, as of 2020, we would recommend the Alpha E Tec, but for those looking for something a little more premium, then the Viessmann or Worsceter range is certainly worth looking into. These are some of the best boiler brands available, and that's why we fit them. You won’t find a better combi boiler in the Alpha boilers range in 2020.


#5 BAXI Combi Boilers (5th Best)

Nobody has ever been struck with such elation after being offered a BAXI boiler that they’ve moonwalked to work the next day and offered their colleagues a poorly baked lemon drizzle cake – but perhaps they should.

Baxi might not be considered amongst the premium boilers of the market but they certainly have some premium products backed up by award winning customer service and excellent warranties so if you’re looking for a bargain, you might just find it in a BAXI.

BAXI combi boiler range & overviews:

BAXI Model Kilowatt (kW) outputs
100 Combi 24kW 28kW - -
200 Combi  24kW 28kW - -
400 Combi 24kW 28kW -

600 Combi 24kW - 30kW 36kW
Duo-tec 24kW 28kW 33kW 40kW

EcoBlue Advance 24kW 28kW 33kW 40kW
EcoBlue + 24kW 28kW 33kW -
Platinum 24kW 28kW 33kW 40kW

We know what you’re thinking.

So many Baxi boilers and so little time and why do Baxi avoid prime numbers in the combi models like they know something we don’t?

Baxi have more combi boilers that we would care to run through but if you’re looking for top quality and aiming for that reassuring 10-year warranty mark, make sure you aim for the Baxi 600, the Baxi duo-tec, the Baxi EcoBlue range or the Baxi Platinum.

Consider avoiding the Baxi 100, 200 & 400 range if you’re looking for a premium standard and long warranty.

Which combi boiler is best for my home?

Batman would be pushing it if he wanted a combi boiler for Wayne Manor.

Fortunately though, modern combi boilers will be perfect for almost any home – from 1 bedroom flats to 6 bed detached houses.

But, if you've got a whopping great mansion with multiple bathrooms and shower units, we'd suggest you look for an alternative. For homes of that size, you'd be better looking at quotes for a new regular or system boiler. They store hot water in large tanks (separate from the boiler) and feed the water outlets at an even rate. If you had a combi boiler, and you tried to run 3+ baths at the same time, it'd likely trickle out rather than blast.

Here’s a quick glance at which combi boiler is best for your home in 2020:

Best combi boiler for a small flat/apartment

Best Boiler: Ideal Logic Combi
Best Boiler Size: 24kW

24 Kilowatts of pure Ideal, unadultered magic will heat your flat like a saucepan of milk gently brought to the boil. It’s also backed up by outstanding customer reviews and through Heatable, packs a whopping 5 year warranty.

Best combi boiler for a 2 bedroom house

Best Boiler: Ideal Logic Combi
Best Boiler Size: 28kW

A 28kW Ideal Logic with a 5-year warranty effortlessly glides into a 2 bedroom home like the elderly into a Morrisons Café. It’s the manufacturers best seller, isn’t at all bad to look at and remarkably simple to operate.

Best combi boiler for a 3 bedroom house

Best Boiler: Viessmann Vitodens 050-W
Best Boiler Size: 29kW

German design at it’s best. The Vitodens 050-W 29kW is perfect for three bedroom homes and not only more powerful than it’s competitors but officially more reliable too. Just make sure it’s the only bald white German you let into your home.

Read the Vitodens 050-W Review.

Best combi boiler for a 4 bedroom house

Best Boiler: Viessmann Vitodens 050-W
Best Boiler Size: 35kW

Eternal reliability, award winning and a 10-year parts and labour warranty – that’s basically like Helen Mirren personally looking after your homes heating requirements and keeping a close eye on your energy bills.

Best combi boiler for a 5+ bedroom house:

Best Boiler: Viessmann Vitodens 100-W
Best Boiler Size: 35kW

The only other building in the world that harbours more of these boilers than Viessmann’s actual factory is Buckingham Palace, Her Majesty has at least 1 per every member of staff and three for every dog. In all seriousness though, it is genuinely the boiler of choice for the palace and rightly so. It’s a peerless and powerful boiler built entirely from premium components.

Read the Vitodens 100-W Review.

Want to have your boiler moved to a different location? Check out "cost of moving boiler" guide.

Which combi boiler is best by size?

If you’re in the 99% of readers who have power-scrolled through this article picking up keywords like Good, Combi and Batman…

Then this lazy overview of best combi by size is the one for you.

Best small combi boilers:
#1: Viessmann Vitodens 100-W 26kW
#2: Baxi 600 – 24kW / 30kW

Best large combi boilers:
#1: Viessmann Vitodens 100-W 35kW
#2: Worcester CDi Classic 38kW

Best offensively large, powerful combi boilers:
#1: Worcester CDi Highflow 44kW / 55kW
 Viessmann 111-W 35kW

Want to know kW you need for your home? Check out our "what size boiler do I need" guide.

Who, What, Why, Where, When, Which?

Who are Which? anyway?

Which? are an independent consumer advise platform that offers UK homeowners and consumers impartial advice on an array of products and services. In all honesty, they border on patronising, but they are undeniably well informed and absolutely love question marks.

Some special products, of high birth and royal blood, even manage to secure themselves a prestigious nod from the mighty Which – the Which? Best Buy Award, with three lucky boilers earning that privilege; Viessmann, Worcester & Vaillant.

Those products will even be plastered with Which? Best Buy stickering like a teenager in a Spanish super club. Classic Which.

Getting yourself a bargain boiler is one thing. But getting yourself a well-priced Which? Best Buy boiler is like dropping the bandit.

Why a combi boiler, what makes them the best?

If you don’t already have a combi boiler, then you might feel left out and be wondering what all the fuss is about - like when other people talk about Snapchat or Making a Murderer – who wants to send even more photos?! And the American judicial system is none of your concern.

But we can reliably inform you that a combi boiler does indeed, live up to the hype.

They provide instant hot water for both your central heating and hot water demands. You might call them a com-bi. It loves both.

But it’s not just having the ease of instant hot water without having to give a giant metal tank one hours’ notice before you want a bath as though Robocop was your butler.

A combi boiler is also remarkably efficient at heating the water – up to 98% efficient. We had a mathematician check this number and it’s just 2% less than 100%! That makes it superior to immersion heaters

The efficiency offered by a combi isn’t just a lovely number though, it can make you some outrageous savings on your energy bills – savings you’ll actually notice in monetary value, not like the saving between Asda and Tesco on petrol.

They’re also much kinder on the environment so the birds outside your house choking on Monster Munch packaging have one less thing to worry about.

How to get the best deal on a combi boiler in 2020

Without boasting, buy from us.

We're an online, nationwide boiler installation business with 500+ 5 star reviews from a shed load of happy customers.

Because we're online, our overheads are low which means we pass those savings on to our customers, ensuring they're always getting the best deal on a new combi boiler. Plus, because of the volumes that we install, we're able to access exclusive warranty lengths from our partner manufacturers. For example, we can offer 10 years of protection on the Viessmann 050 range, whereas your traditional installer can only offer you 7. Boom.

Plus, all of our combi boiler installations come with upgraded wireless controls, an Adey Pro Filter and powerful chemical protection. We also offer the option of a powerflush for those wanting a more deep cleanse of their heating system. 

To get the best deal on a new combi boiler, answer some quick online questions and we'll give you an instant fixed price.

We also offer boilers on finance with pay monthly options and an incredible 2 years interest-free option on certain models. 


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[1] Price based on a like for like combi swap in a 2 bed, 1 bathroom terraced home with a standard flue

[*] Installation dates are subject to installer availability

[ยน] only available on combi boiler installations

Financial Support: If you are in receipt of certain benefits, you may be entitled to claim a free boiler grant.