Best Conventional Boiler Brands 2023 Re February 6, 2023

Best Conventional Boiler Brands 2023

Kitchen with boiler in it

If you’re losing sleep over which conventional boiler brand you should choose this year, we’re here to help you rest easy! Even if you’re not boiler-savvy (yes, this is a thing – some people are!), by the end of this guide you will know the top 5 conventional boiler brands and which one truly is the best.

Here, we’ll look at the top 5 best conventional boiler brands on the market, comparing them on their reliability, efficiency, overall performance, and everything you need to know to become a boiler expert! But first, you may want to check what type of boiler you have, so take a look at our boiler types guide.

If you’re curious to know which conventional boiler model is best, check out our blog on that subject.

What is a conventional boiler?

Conventional boilers, also known as regular, 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 – so it can be confusing to know what to look out for!

Conventional boilers require a cold water tank in the attic, in addition to a hot water storage cylinder, usually in an airing cupboard. Due to the space these tanks take up, the combi boiler has become the preferred choice of boiler type in the UK.

If your home is short of space, or you would like to convert your loft space, then having a conventional boiler would be less desirable than a combi boiler. Combi boilers work by heating water directly from the mains water supply, so they also supply the central heating and hot water from one compact unit.

If you have a high hot water demand in your home and you would like to be able to supply hot water to two bathrooms at the same time then this is where you might prefer a regular boiler. As the water is preheated and stored in a tank, there is plenty of hot water to use and there is no loss of pressure. However, when the stored water is used up, you’ll have to wait hours for the tank to be refilled with hot water or risk having a tepid bath! 

Unlike a combi boiler which heats water on demand, a conventional boiler stores the hot water it produces. While this hot water is stored there is inevitably some heat loss that occurs, making regular boilers less energy-efficient. This could be tough on your wallet!

Most homes in the UK choose to have a combi boiler fitted, and you can choose to convert your regular boiler to a combi boiler when you complete the WarmZilla online survey to get your boiler quote if you decide it’s the right option for you. It only takes a few minutes and you’ll be given a selection of boilers to suit your home.

So how does a conventional boiler work?

Conventional boilers work slightly differently from a combination boiler. Rather than heating water directly from the mains water feed as is the case with combi boilers, a conventional boiler will have a large cold water storage tank (usually in the attic or loft) where it will receive water from the mains supply.

The cold water feeds down from the attic or loft into the boiler where it is heated by the boiler’s heat exchanger and then pumped to a hot water cylinder, where it is stored ready for use.

A conventional boiler is similar to a system boiler in that they both heat and store hot water in a cylinder ready for use. However, a system boiler doesn’t have a cold water tank in the loft, it heats water directly from the mains as a combination boiler does.

If you aren’t sure what type of boiler you have, have a look at our blog on boiler types. This is useful if you are planning to replace your regular boiler.

Things to consider before buying a conventional boiler

Saying “I do” to the right boiler is a huge decision – although it might not be the most exciting one! 

There are so many conventional boiler brands out there, which makes the process more difficult. Worry not, we’ve got you covered. Here is our checklist of things to consider before making the big decision:

  • Brand reputation – this is what customers say about the brand. To find out more about your chosen brand, check out their TrustPilot reviews, Which? score or even Twitter – or just simply scroll down this blog!
  • Warranty – indicates the manufacturer’s confidence and trust in their boilers, at the end of the day a long warranty gives you the peace of mind you need when you’re making a huge purchase like investing in a new boiler. But don’t confuse a warranty with a guarantee, have a look at our blog here. WarmZilla offers a range of cover between 5 – 12 years depending on the boiler manufacturer and the boiler model. When WarmZilla fit a new boiler, we will register your guarantee or warranty with the boiler manufacturer on your behalf. That’s another thing you don’t have to worry about when you buy your boiler from WarmZilla.
  • Size – The size of the boiler indicates how powerful it can be. Choosing the right size kW boiler will ensure that your home is warm enough and you always have enough hot water when you need it. To find out what size kW boiler you need to heat your home, take a look at our guide. 
  • Energy efficiency rating – it’s a great way to lower your heating bills and ensure you’re doing your bit for the environment. If you want to maximise your boiler’s energy, read our blog here. 
  • Awards and accolades – Check out the BRIT Awards of the heating industry, also known as the “Which? Best Buy Awards”. This award recognises businesses that have achieved positive change and deliver excellent products and services.
  • Price – although the price could be an indicator of which boiler is best for you, it’s not always the case, that’s why it’s always important to do your research before buying a boiler.

Conventional boiler pros and cons

  • Excellent for homes with low water pressure. 
  • Conventional boilers are so powerful, they can supply hot water to more than two bathrooms at the same time without affecting the water pressure or heating.
  • You will have hot water even if the boiler breaks down, thanks to the immersion heater which can be fitted to the hot water tank.
  • Compatible with older central heating systems.
  • Compatible with solar energy sources – aah sunny days. ☀️
  • Take up valuable Christmas tree storage space in your attic!
  • Limited hot water up to the volume of your hot water storage tank.
  • A hot water tank loses heat, no matter how well insulated.
  • Difficult to install, only suitable as a replacement for another regular boiler system.

The best conventional boiler brands

We’re looking at the top five best conventional boiler brands on the market, so you don’t have to.

We will review your chosen brands side by side, and discuss the overall brand scores from the Which? Best Boiler Brand Survey in 2021. This survey rates the boilers on reliability, efficiency, and overall performance. We also get to see what engineers think about these boiler brands. Things are about to get heated!

1# Worcester Bosch

Worcester Bosch is the “Apple of the heating industry”. They are known for their reliable boilers, outstanding build quality, sleek designs and long warranties. 

Worcester Bosch has won the Which? Best Buy Award for their range of boilers for the last ten years. This prestigious award is judged on reliability, build quality, recommendation, and customer score.

To rewind, Worcester Bosch was formed in 1962 in Worcester. The company started off as a small engineering works before growing into the biggest boiler manufacturer in the UK. 

Later on, it was acquired by Robert Bosch Holdings in 1992 to form the Worcester Bosch Group. For a full timeline of Worcester Bosch history, visit their history page. 

If you’re curious to know what customers and heating engineers said about Worcester Bosch in the Which? Best Boiler brand 2021 survey, check out the reviews: 

Once again, Worcester Bosch didn’t fail to win Which? over. Here’s their verdict: As you can see from the results, Worcester Bosch was awarded a huge 5 stars for their customer scores and reliability, which supports the claim that Worcester Bosch is indeed one of the best boiler brands on the market. Not only do their boilers offer a high-efficiency rating of 94%, but all their boilers also come with a ten-year standard warranty – (hopefully you won’t need it!)

“Worcester Bosch is one of only two gas boiler brands to earn our Best Buy recommendation, thanks, in large part, to high owner satisfaction and recommendation. Its boilers can be on the expensive side, but build quality is good and heating engineers praised the brand in general. The design of Worcester Bosch boilers can make them a bit difficult to repair, but you’re less likely to need a repair as Worcester Bosch boilers are very reliable.”

When you look at their warranty length below, you’ll know that this brand is built to last – maybe as long as your classic indestructible Nokia phone!

Worcester Bosch boiler modelkWEfficiency

Manufacturer’s warranty

Average Price*(boiler only)

Greenstar Ri Regular Gas Boiler1215182192%8 years£830 – £948
Greenstar Ri High kW Regular Boiler24273092%8 years£948 – £1,210

CDi Floor-Standing Regular Gas Boiler

30kW42kW92%7 years£1,700 – £2,185
Greenstar 8000 Life Regular Gas Boiler30kW35kW40kW45kW50kW94%10 -12 years£1,304 – £2,285

Worcester Bosch Key facts

  • Manufacturer’s warranty period – Up to 12 years, pretty legendary! 
  • Which? Best Buys – For 10 years running! 
  • Price range (without installation) – between £830  – £2,285
  • Efficiency – 92%+
Worcester Bosch Greenstar CDi Classic Installer On Phone Garage

Worcester Bosch Trustpilot reviews

Worcester Bosch prides itself on its superb customer aftercare. It is something that you can clearly see throughout their excellent Trustpilot reviews and that’s what earned them their 4.6 stars. If you’re not sold yet, read what their customers said about them:

“Brilliant installer, cleaned up as he went along, nothing was too much trouble. Had the boiler nearly a year now, it’s fantastic, so easy to use, house warmer 100% happy.” 

“Boiler has operated with no issues since installer. The equipment has now been in and operating for over 10 months.” 

For any Worcester Bosch conventional boiler, get an instant quote now.

2# Viessmann

Viessmann, the European heating giant, is one of the boiler market’s leading names. 
The brand is known for its reliability, high efficiency, exceptional performance and high-tech design. They offer reliable boilers that represent German engineering at its finest!
Viessmann’s roots go back even further than Worcester’s, starting in 1928, where Johann Viessmann was asked by a local gardener to build a boiler for his greenhouse. Johann, then a locksmith, thought ‘why not’ (they didn’t have Playstations or Facebook/Meta to pass the time back then!)
Viessmann innovated on the iron boilers around at the time and built his using steel which heated up faster and used less fuel. Nice work Johann! Soon, all the gardeners in the village wanted one, and Johann got his model patented and set to work.  
Since January 2018, the company is led by Martin Viessmann (Chairman of the Executive Board), Maximilian Viessmann (Co-CEO and part-time Bond villain), and Joachim Janssen (Co-CEO). Making Viessmann a family-owned business for four generations, quite a rare thing.
You can find out more about the Viessmann company and the rich history of over 100 years in business yourself, as that could be a blog on its own!

Viessmann not only impressed their customers and heating engineers, but they’ve also managed to become Which?’s “Best Buy” this year.

Here’s what Which? said about it:

“With a high proportion of satisfied owners and being well-liked by heating engineers, Viessmann boilers are a great Best Buy. These boilers are reliable, and a number of heating engineers in our survey mentioned good build quality. The only minor drawback is that sourcing replacement parts can be a little slow.”

Viessmann Which? Best Boiler Brand Survey Results:

Viessmann boilers bagged an overall score of 81% and a couple of 5-star ratings for their reliability and customer score, revealing that Viessmann boilers are excellent boilers that are loved by their customers. 

Here’s an overview of the Viessmann Vitodens 100-W regular gas boiler range:

Viessmann boiler modelkWEfficiency

Manufacturer’s warranty

Average Price*(boiler only)

Vitodens 100-W Regular Gas Boiler13kW16kW19kW26kW35kW94%5 years£924 – £1,418

To view all Viessmann boilers prices – including combi, system and regular boilers, have a look at our guide.

Viessmann Key facts

  • Manufacturer warranty period – Up to 5 years
  • Which? Best Buys – Viessmann conventional boilers are highly recommended by Which?. In fact, they are “Which? Best Buy” this year. 
  • Price range (without installation) – between £924 and £1,418
  • Efficiency – 94%+ this allows you to save hundreds of pounds a year on your heating bill.

Viessmann Trustpilot reviews

Although Viessmann UK only has 2.5k reviews, over 89% of those are above average on Trustpilot.

Here are what customers have to say about Viessmann boilers:

“Excellent product and does what it says on the tin.”

“Yes great boilers! In fact my second one now in another property, installed by a viessmann installer it comes with a 10-year warranty plus parts, just make sure it is serviced once a year by viessmann, I also have weather compensate which balances the outside temp with the inside temp to give a more comfortable heating experience and it also saves me money on my heating bill per year.”

“Brilliant product easy to use fantastic 10/10.”

Don’t forget to get an online boiler quote from WarmZilla today. It only takes two minutes, you don’t need to have any technical knowledge, and it’s all done online. It’s that simple!

3# Baxi

Baxi is the third-best conventional boiler brand, according to Which? reviews. 

Founder Richard Baxendale opened the doors to his new company in 1866. By 1955, Baxi became a household name for heating. Bermuda, Baxi’s most famous gas-fired boiler was launched in 1966, the same year in which Baxi celebrated 100 years in business. For more information on Baxi’s history, you can click here. 

In the Which? Best Boiler Brand Survey in 2021, Baxi boilers were awarded an overall brand score of 76%.

Baxi Which? Best Boiler Brand Survey Results:

Put simply, Baxi conventional boilers are great boilers with excellent reliability and ease of service.

Here is what Which? had to say about Baxi boilers: 

“Baxi is one of only three brands to earn five stars for ease of servicing. Parts availability is good and reliability is excellent. Baxi narrowly misses out on our Best Buy recommendation: engineers aren’t quite as emphatic about build quality and the brand achieves a slightly lower customer score than the very best gas boiler brands in our survey.”

Here you will see our side-by-side comparison: 

Baxi boiler modelkWEfficiency

Manufacturer’s warranty

Average Price*(boiler only)

800 Regular Gas Boiler16kW25kW30kW


10 years

£990 – £1,175
600 Regular Gas Boiler13kW16kW19kW25kW30kW


7 years

£830 – £970
400 Regular Gas Boiler12kW15kW18kW24kW30kW


5 years

£790 – £977
200 Regular Gas Boiler12kW15kW18kW24kW30kW


3 years

£636 – £750

Baxi Key facts

  • Manufacturer warranty period – Up to 10 years
  • Which? Best Buys – not yet.
  • Price range (without installation) – affordable boilers starting from £636 – £1,175
  • Efficiency – 93%+ (which means for every £1 you spend on energy to heat your home, 7p of that £1 is being wasted).

Baxi conventional boilers are one of the cheaper conventional boilers on the market with a high-efficiency rating of 93%, therefore, they are the perfect choice for those looking for a reliable boiler on a budget.

Baxi Trustpilot reviews

The average rating of Baxi’s reviews is 4.5, which is as good as Viessmann, however, they have over 35k reviews – impressive! 
Over 86% of Baxi’s reviews are above average, showing that these are again, another great boiler brand. Baxi has won many awards including Gas Industry Award in 2017, for both customer service and energy efficiency.

Here are some customer reviews:

“EXCELLENCE. The work required should have been reasonably easy. However it wasn’t so easy as he had to do a considerable amount of extra work. Due to his vast knowledge he brought along other components which may be needed. Just as well as they were needed. Not a moan or complaint about the extra work required. A true professional and pleasant engineer. Would recommend he gets the recognition he deserves…”

“Arrived promptly, Polite, helpful and above all understanding of our needs with regarding COVID distancing.
More than happy for the same ending ever to return time and time again
On another note, I much prefer the level of service from BAXI than any other provider we have used… far superior.”

“On time, identified the problem quickly and fixed it. Showed me what he was doing. Friendly and efficient.”

Unfortunately, WarmZilla don’t sell Baxi boilers currently, however, if you like the look of a Baxi boiler, you can use our Boiler Comparison tool which allows you to compare up to three boiler models or brands at a time. We’re all about helping you to find the perfect new boiler for your home!

4# Vaillant

Vaillant was formed way back in 1874 by Johann Vaillant in Remscheid, Germany. Johann Vaillant, the tenth child in his family, founded his own workshop as a copper beater and pump maker.

Many inventions have been credited to Vaillant over the years including modern-day central heating in 1924. Previously each room was heated individually by stoves or fireplaces until Vaillant introduced the central heating boiler that could heat multiple radiators simultaneously – revolutionising home heating.

The Vaillant boiler range has been given a Which? Best Buy award. They have also been awarded a Quiet Mark Accreditation, from the Noise Abatement Society for their quiet running boilers.
For a full timeline of the Vaillant, company history click here.

Now, let’s get into the juicy bit. Let’s see what customers really think about Vaillant boilers.
Vaillant boilers were awarded the best overall score in the Which? Best Boiler Brand survey 2021.

Vaillant Which? Best Boiler brand 2021 survey results:

We can see from the survey results that Vaillant are consistent in all categories with nothing below 4 stars, conveying that they are a great boiler brand with efficient and reliable boilers which their customers love.Vaillant have smashed it out of the park when it comes to their overall brand score for the Which? Best Buy Survey in 2021.

Here is what Which? has to say about Vaillant: 

“Vaillant boilers were a Best Buy in 2020 and are highly regarded by heating engineers who say they’re good quality and easy to work on and source parts for. However, they’re not entirely without problems and Vaillant’s lower customer score this year means it’s no longer a Best Buy.”

Vaillant boiler modelkWEfficiency

Manufacturer’s warranty

Average Price*(boiler only)

EcoTEC Plus Regular Gas Boiler12kW15kW18kW24kW30kW35kW94%5 years£720 – £1,520
EcoFIT Pure Regular Gas Boiler12kW15kW18kW25kW30kW35kW94%2 years£730 – £1,440

Vaillant Key facts

  • Manufacturer warranty period – Up to 5 years
  • Which? Best Buys – Yes. In 2020, Vaillant boilers were a Best Buy. 
  • Price range (without installation) – between £720 – £1,520
  • Efficiency 94%+ (which means for every £1 you spend on energy to heat your home, only 6p of that £1 is being wasted).

To see all the benefits for yourself, have a look at our boiler comparison tool which allows you to compare your current boiler against two other boiler models to see which is best for your home.

Vaillant Trustpilot reviews

Vaillant has a rating of 4.6 out of 5 stars on Trustpilot from over 15k reviews. With over 90% of Vaillant’s reviews being above average, customers can be confident that they are dealing with a reliable and efficient boiler brand that cares about its customers.

Here are some Trustpilot reviews to support this statement:

“Good boiler, no complaints. It does what it’s supposed to do. Really like the smart feature with the added Drayton wiser thermostat which I can operate from my phone.”

“New boiler installed to a very high standard, set up and commissioned. Delivers a consistent controlled temperature range around the house. Replaced an old and fatigued boiler, but very impressed with the performance so far.”

“I’m really pleased with my new Vaillant, it’s very quiet and easy to use. Would highly recommend.”

Vaillant’s reviews not only show how satisfied customers are with their boilers but also with their customer service. 

In general, Vaillant boilers have warranties of 2-5 years depending on the model and whether certain terms are met, which is great. 

Don’t forget to get a boiler quote in minutes, just click here.

5# Ideal

Ideal boilers were founded in 1905, giving them over 100 years of experience in delivering boilers to homes throughout the UK.

Ideal is one of the pioneers in bringing high-efficiency boilers to market and they continue to bring reliable, efficient boilers to market to this day. 

One of the first modern-day boilers was brought to market by Ideal in 1920 and is known as the Cookanheat. The Cookanheat was a freestanding stove that combined an open fire, central heating boiler, cooking oven, and hot cupboard.

Ideal boilers have come a long way from the days of Cookanheat, offering a range of boilers that offer high efficiency at a very reasonable price. For more information on Ideal’s brand history, click here. 

Which? Best Boiler Brand Survey in 2021, gathered insights about the Ideal system boiler and here are the results: 

To top it up, this is what Which? Said about the ideal conventional boiler: 

“The feedback from heating engineers about Ideal boilers is generally positive. They’re keenly priced and viewed as suiting landlords and those on a budget, but there can be problems with lower-quality parts. Few Ideal boiler owners in our survey have experienced any issues though, and Ideal sits in the top half of the boiler brands we’ve reviewed.”

To dive deeper into the range of ideal conventional boilers, we’ve put together this side by side comparison table:

Ideal boiler modelkWEfficiency

Manufacturer’s warranty

Average Price*(boiler only)

Mexico HE MEX Regular Gas Boiler15kW18kW24kW30kW36kW88%-89%2 years£1,229 – £ £2,090
Logic Plus Heat Regular Gas Boiler12kW15kW18kW24kW30kW93%7 years£870 – £1,101
Logic Max Heat Regular Gas Boiler12kW15kW18kW24kW30kW93%-94%10 years£950 – £1200
Logic Heat Regular Gas Boiler12kW, 15kW, 18kW, 24kW, 30kW93%2 years£779.18 – £1,002.37

Ideal Key facts

  • Manufacturer’s warranty period – Up to 10 years
  • Which? Best Buys – Not yet! But watch the space. 
  • Price range (without installation) – between £870 – £2,090
  • Efficiency – 88%+

Ideal Mexico HE MEX and Ideal logic heat regular gas boiler range both come with a standard 2-year warranty from the manufacturer, which is significantly lower than other boiler brand warranties. However, when purchasing an Ideal boiler with WarmZilla, you will receive an 8-year warranty. 

The prices shown in the comparison tables are taken from an online heating supplier and do not include installation or labour costs. 

This is probably a great time to mention that all WarmZilla boiler prices include Gas Safe installation as standard. It also comes with a system filter, system cleanses, inhibitor, smart thermostat, up to 12 years guarantee, any flues or extension kits you may need; plus, if your condensate or gas pipes require upgrading – that’s included in your fixed price regular boiler quote too!

Ideal boiler in kitchen

Ideal Trustpilot reviews

Let’s have a look at the Ideal’s Trustpilot score here: 

93% of Ideal’s Trustpilot reviews are above average, 87% of these being excellent reviews. 

Here are a couple of customer reviews:

“Nice to deal with a professional, sorting out the boiler and leaving it running as it should, highly recommended company .”

“I was extremely pleased with the service this time as the engineer was very good and took his time to do a good job. Thank you so much.”

From looking at Ideal’s Trustpilot reviews, the majority discusses the installation process and the company’s superb customer service or aftercare. 

WarmZilla offers the best boiler prices on the market, guaranteed! Or we’ll give you £50 off your order. So get a boiler quote for an Ideal conventional boiler here.

*Average boiler prices were taken from an online heating supplier 
** Prices correct at time of blog publication (3.11.21)
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