The Best Boilers in 2023

✔ We’ve analysed 93 boilers to find the best ones for your home

✔ The Baxi 830 Combi picked up three of our awards

✔ But larger houses should look at getting the Ariston Alteas ONE Net

There’s never been a more important time to buy the right new boiler.

With energy prices staying high, making a good choice can save you hundreds of pounds per year on your bills.

Thankfully, we’ve got you covered. In this guide, we run through all the best boilers for your home, as decided by our tireless research team.

If you want to see how much a top-quality boiler would cost you, just fill in this form to receive free quotes from trusted installers.

The best boilers overall

Read our guide on how much a new boiler might cost you for all the information on boiler pricing you'll need.

Best combi boiler: Baxi 830 Combi

Baxi’s star boiler has won three of our nine awards, triumphing in the combi, three-bedroom house, and gas categories – and it’s easy to see why.

Firstly, its 89% water heating efficiency rating is the highest around.

That means there’s no machine on the market that’ll supply you with more hot water from the same amount of energy.

You’ll also receive a 10-year warranty if it’s installed by a Gas Safe-registered engineer – and at 48 decibels, its machinations are quieter than a moderate rainfall.

Get it fitted, then forget about it. Perfect.

This range also offers a variety of outputs, including a 36 kW model that’s able to serve a house with four or more bedrooms.

Best system boiler: Viessmann Vitodens 200-W

When it comes to gas boilers and system boilers, 94% efficiency is the best we can achieve at the moment – and the Vitodens 200-W hits it on the nose.

This rating will allow you to heat your home while paying less than you would with almost any other boiler.

It describes your boiler’s efficiency when it comes to circulating heat around your home, as opposed to water heating efficiency ratings, which measure combi boilers’ ability to heat water.

You also won’t find a quieter gas-powered system boiler, with Viessmann’s model hovering around the noise level of a hushed library.

The only major drawback is you’ll receive a warranty lasting just three years – or five, if you hire a Viessmann installer.

Best conventional boiler: Ideal Logic Max Heat

If you don’t fancy converting your conventional boiler – which is also known as a regular, heat-only, or open vent boiler – the Logic Max Heat is a fantastic upgrade.

It hits the industry-wide ceiling of 94% efficiency, and does so without fuss, weighing just 22.7 kg and producing just 47 decibels – a hum you’ll tune out after a couple of days.

This Ideal machine also comes in a range of output levels, so whether you live in a flat or three-bedroom house, you can get a version that’ll meet your needs.

And if anything does go wrong with the Logic Max Heat, you’ll have a 10-year warranty to fall back on, as long as you got a Gas Safe-registered engineer to install it.

Best boiler for flats: Worcester Bosch Greenstar Si Compact

Worcester Bosch took this award by giving consumers exactly what they need from a boiler: solid fundamentals and spectacular extras.

The Greenstar Si Compact is light and small enough to be hidden away – which is important in a flat – but its most impressive qualities relate to its performance.

A score of 86% for water heating efficiency and 94% on ErP (energy-related products) efficiency is unbeatable in this size category, and means you can look forward to lower bills and warm showers at the double.

The Baxi 224 Combi 2 has a better water heating energy efficiency rating than this model, and came close to taking the award, but was let down by its paltry two-year guarantee.

Baxi will only give you a lengthy warranty if you buy one of its large boilers, leaving anyone who lives in a flat to cross their fingers for the majority of their boiler’s lifespan.

In contrast, you can get a five-year warranty as standard with the Greenstar Si Compact, rising to 10 years if you get it installed by a Worcester Bosch engineer.

Best boiler for houses with 3 bedrooms: Baxi 830 Combi

Here it is again: the star boiler.

As mentioned above, it comes with a market-leading water heating efficiency score and an excellent ErP efficiency rating – plus a 10-year warranty if you get it installed by a Gas Safe-registered engineer.

But if you don’t already have a combi in your three-bedroom home, you may not want to go through the expensive process of converting it to a combi.

If you want to stick with a system boiler, we’d recommend you choose our best system boiler winner, the Viessmann Vitodens 200-W.

And if you feel the same way but have a conventional boiler, go for a Vaillant ecoTEC plus 430. It’s the best option for three-bedroom households.

Both machines have an ErP efficiency of 94%, so with either of them, you can rest safe in the knowledge that your boiler is keeping your bills as low as it can.

Best boiler for houses with 4+ bedrooms: Ariston Alteas ONE Net

When it comes to larger homes, the Ariston Alteas ONE Net can’t be beat.

This boiler has top-notch efficiency scores, enough power to comfortably heat a house with four or five bedrooms – and it’s light enough that your installer won’t throw their back out.

Plus it comes with a 12-year warranty – the longest offered by any of our winning boiler brands – and you don’t even have to use an Ariston installer to get this level of cover.

Worcester Bosch’s Greenstar 8000 Style Combi was extremely close to pipping the Alteas ONE Net to this award, but Ariston’s lengthy, no-strings warranty put it over the top.

Best electric boiler: EHC Mercury Combi Boiler

With electricity prices staying high, it’s important to pick the best electric boiler, to ensure your bills stay as low as possible.

Enter the Electric Heating Company’s Mercury Combi, which comes with an efficiency rating of 100%, can provide heat to a three-bedroom house, and does it all at the sound level of a whisper.

It’s also one of the smallest, lightest machines around right now, which means you can hide it away wherever you want.

You’ll also get a five-year warranty as standard, which is decent.

Best gas boiler: Baxi 830 Combi

The Baxi 830 wins its third award in style.

The best gas, combi, and three-bedroom house boiler has the highest water heating efficiency you’ll find, along with a world-class ErP efficiency rating and a relatively low weight.

The Baxi 800 range also goes as low as 25 kW – which would suit a large flat – and as high as 36 kW, which is perfect for a typical four-bedroom house.

And if you’ve read the whole article up to this point, you know this elite model comes with a 10-year warranty, if you have it installed by a Gas Safe-registered engineer.

Best oil boiler: Baxi 600 Combi LPG

Baxi’s 600 Combi LPG model has hands-down the best water heating efficiency in its category, as well as a superb ErP efficiency score.

This machine is also the quietest in its category, and weighs up to five times less than other models with similar power outputs.

It’s perfect for the average three-bedroom house, and the range caters to flat owners too.

Unfortunately, as Baxi offers less to smaller households, this model only comes with a seven-year warranty, not the 10-year guarantee you’d get with the Baxi 830 – but seven years is still pretty good.

If you’d rather get a conventional oil boiler than a combi, look instead to Grant’s Vortex Pro: External, which has a market-leading 94.56% ErP efficiency rating.

It emits 54 decibels, meaning it’s quieter than a typical dishwasher – and since it stays outside, you’ll probably rarely ever hear it.

Make sure you get an installer to do all the heavy lifting, though, because at 162 kg, this behemoth of a machine weighs as much as two average adults.

And if you’re after a system oil boiler, pick the Greenstar Danesmoor System Utility. Its ErP efficiency rating is 94%, and its 18/25 kW design means it can heat either a flat or a three-bedroom house.

Methodology

Our research team scoured the market to find boilers with as many top specs as possible in the following categories: power, range, water heating efficiency, ErP efficiency, decibel level, weight, and warranty.

With a focus on these all-important attributes, we found the 93 best boilers from 12 top brands.

We segmented these boilers into the different categories you’ve seen above, matched them up against each other, and found the best of the best – which we’ve presented here, to you.

The different types of boiler

• Combi
• System
• Conventional
• Oil
• Electric
• Biomass

At this point, you’ll probably be asking: which models are the best boilers? How much do they cost? And what size boiler do I need? But before we get to those important questions, we should take a look through all the types of boilers, so that you’re fully prepared.

You may have an image of a boiler in your head – a large box, usually rectangular or cylindrical, surrounded by pipes and hidden from sight. It’s not particularly spectacular, but within this unremarkable shape lies countless unique capabilities and possibilities.

Some are powered by fossil fuels – gas, oil, or Liquid Propane Gas (LPG) – while some run on wood pellets, or the trees you chopped down yourself today in the forest.

There are conventional boilers, which work best in large homes; the system boiler, their best-of-both-worlds cousin; and combi boilers, which can heat you up any time – though not always to the same standard.

All have their advantages and disadvantages; all cost a wide range of prices; all have their own efficiency ratings, abilities, and physical attributes. Let’s dig into their differences.

Combi boiler

These machines are geared for action. Combi boilers can provide unlimited hot water at a moment’s notice, because unlike conventional and system boilers, they don’t rely on a cold water tank or a hot water cylinder.

Instead, when you turn a tap, cold water rushes in from the mains to your combi boiler, where it goes through a heat exchanger and is quickly transformed into the hot shower of your dreams.

Central heating works the same way, with cold water from the mains being heated up and sent straight to your radiators whenever you need it.

Combi boilers don’t need to prepare or refuel before the big show – they’re ready to go when you need them. To quote the poet Shakira: whenever, wherever (as long as they’re connected to the right pipes).

✔ One advantage of combi boilers is that they only heat the water you use, so they generally cut your energy bills. Their compact nature also means they’re usually easier to install and take up less space, which is great for smaller homes.

They can also be powered by oil, gas, electricity, or LPG, allowing you to use a combi boiler even if you’re not connected to the gas grid.

✘ The main disadvantage of combi models is that water coming out of multiple places at once may reduce water pressure – so if someone’s trying to clean the dishes while you’re showering, that could cause problems.

Don’t worry, though – if you need to supply multiple bathrooms at once, there are combi boilers on the market which are up to the challenge.

Your water may take a little time to heat up, and if your mains pressure isn’t good, your shower’s water pressure won’t be either.

Combi boilers also don’t work well with solar panels – at least compared to the other main types of boilers – which reduces your ability to easily cut your carbon emissions.

Plus, if your combi boiler breaks down, you’ll have no built-in back-up and no reserves of hot water.

Conventional boiler

Also known as regular or heat-only boilers, conventional boilers take up the most space of any mainstream boiler – however, they can also get everyone in your home hot under the collar, all at once.

They can supply three or four bathrooms with no trouble and no reduction in water pressure, making them ideal for larger homes.

You’ll probably need to install two tanks in your loft: a cold water tank, which draws water from the mains and distributes it, and a feed and expansion tank, which keeps your water levels consistent.

The water is heated by your boiler whenever you choose (though doing it while everyone’s asleep seems wise), and stored in a hot water cylinder.

It can then fulfil your shower or heating needs whenever you choose – although it’s limited by how much water is in the cylinder.

✔ On the plus side, water pressure will stay the same no matter how many taps or showers are on, so you don’t need to get into arguments with anyone else in the house about who ruined whose shower.

Conventional boilers also combine well with solar panels, and you can fit the cylinder with an electrical immersion heater as a failsafe if the boiler breaks.

✘ The main negative is that with two tanks, a hot water cylinder, and a boiler, a conventional boiler takes up much more room, and is more difficult and costly to install than other heating systems.

You also need to decide how much hot water you want, and when – and you may be left with nose icicles or expensive bills if you get it wrong.

System boiler

Goldilocks would love a system boiler – after all, it’s the in-between. Depending on your perspective and needs, you may see it as being caught between worlds, or as a happy medium: not too combi, not too conventional – just right.

System boilers take their water supply directly from the mains, like a combi, then heat it up and store it in a hot water cylinder, like a conventional boiler.

This means there’s no need for an extra couple of tanks in your loft, which saves on space, but you’ll still have a higher capacity than combi owners.

If you need hot water for two bathrooms, rather than three or four, a system boiler may be the way to go.

✔ The best news when it comes to system boilers is that their water pressure is consistent (like conventional boilers), without you having to make the space in your home and bank account for two water tanks.

It’s also compatible with solar power, which is always a great option.

✘ The worst news is a repeat of the drawbacks of having a conventional boiler: a system boiler takes up more space than a combi, you have to heat the water up in advance, and the hot water can run out.

Condensing boilers

In 2007, the law was changed to require that all new boilers must be condensing.

The British government explained that it had taken this step because “around 16% of the carbon dioxide that the UK produces comes from the gas and oil boilers that we use to heat our homes.”

If a boiler is condensing, that means it has a Flue Gas Recovery System. Instead of releasing waste gases into the atmosphere, this ingenious piece of hardware captures them, so that it can generate as much heat as possible, using what would otherwise have been wasted.

Because of this, condensing boilers are more environmentally friendly, more energy efficient, and will save you money on your bills.

Don’t just take our word for it – according to Which, condensing boilers are typically at least 25% more efficient than non-condensing models.

Gas boilers

These boilers use a gas supply to heat water. This is either instantly sent to act as central heating or warm water, or stored in a hot water tank for later use. Gas boilers come in pretty much every mainstream variety, and are the most popular type of boiler.

They’re perfect if you’re part of the great majority of people who are connected to the gas grid – though if you’re not, they’re pretty much completely unworkable.

Gas boilers are set to be banned from newly built homes from 2023. Find out if you need to take action by checking out our guide to the UK gas boiler ban.

Oil boilers

As of 2015, an estimated 10% of households in the UK weren’t connected to the gas grid, according to government data. That’s about 2.7 million homes which have to rely on alternative sources, such as oil.

Oil is just another source of fuel, though in most cases, a very environmentally unfriendly one.

Oil boilers use the fuel to heat a container of water – either directly from your mains or in a storage tank – and that water is disseminated throughout your home for all your hygiene and heating needs.

Oil boilers are in the same ballpark as other models when it comes to efficiency, while oil is cheaper than most fuels. They’re still more expensive than gas boilers, though, which means you should probably use gas if you can.

They also release up to seven times as many milligrams of damaging nitrogen oxides into the atmosphere as gas boilers.

The other main drawback of using an oil boiler is that you’ll need a storage tank to hold all the oil, and regular deliveries to ensure that you never run out. Tanks generally hold between six and nine months’ worth of oil, so bear this in mind if you opt to use it.

If you overestimate the amount you’ll need, your energy bills will be unnecessarily expensive, while you may be stuck with a freezing home and no hot water if you don’t order enough. Oil isn’t easy to acquire at short notice, either.

Wood-burning boilers

If you don’t have a gas grid connection, or if you simply want to make your home more environmentally friendly and battle climate change, you can use firewood to heat your home and water.

This method works best if you have a ready supply of trees just waiting to be cut down and used for fuel.

However, even if you don’t live in a forest as a lumberjack, wood still has its advantages. As well as being potentially sustainable, it’s also affordable, and doesn’t have the same dramatic price fluctuations that fossil fuels sometimes suffer from.

If it was good enough for every single one of your ancestors up until a couple of centuries ago, it could work for you too.

Biomass boilers

Biomass boilers work in much the same way as any other, except they usually run off wood pellets or chips. They can sometimes automate the process, meaning you won’t have to throw some extra wood on every time you want to grab a quick shower.

You’ll need somewhere to store the fuel, as you would with a wood-burning boiler or oil boiler, and a biomass boiler is expensive – but you can get paid for using one.

Biomass boilers are one of the few energy sources which allow you to qualify for the government’s Domestic Renewable Heat Incentive, which pays homeowners potentially thousands of pounds for using renewable energy.

However, Dr Mathew Heal, who is the chair of atmospheric chemistry at Edinburgh University, told The Eco Experts that you shouldn’t go for a biomass boiler unless it’s your only good option.

“My personal view is that people should be very reticent about going out and buying biomass boilers, because the regulations aren’t that stringent. By using these boilers in a domestic setting, you are contributing to local air pollution,” he explained.

“If you don’t need it, I think you should be discouraged.”

He added that when it comes to air pollutants, “it doesn't matter what fuel you're using: all combustion has the potential to release NOx (nitrogen oxide) emissions. It all depends on the burning process.

“The trajectory we’re going on is that electricity is getting cleaner, so using electricity to heat your home has the potential to be much cleaner even than a biomass boiler.”

Electric boilers

Electric boilers represent another alternative if you’re one of the millions not connected to the gas grid.

You won’t need to arrange supplies of wood, oil or anything else – your new boiler will function like a combi gas boiler, except it’ll use your pre-existing electricity source to heat your water and home instead.

Because of this, electric boilers have the potential to be more environmentally friendly than other models. If your electricity already comes from renewable sources like solar or wind, you won’t be adding carbon emissions with your boiler.

Electricity can be a more expensive source of heat than gas, and electric boilers are of course susceptible to power cuts. However, they can also be more energy efficient, cheaper to install, and quieter than their rivals.

Free-standing boilers

Also known as floor-standing or floor-mounted boilers, free-standing boilers are larger machines that aren’t quite as friendly with gravity as their wall-mounted counterparts.

They can supply more hot water, but as a result of their build, they’re too heavy to be shut away in a small cabinet halfway up the wall, and will usually need a cupboard, kitchen cabinet, or small room to themselves.

This means there’s less flexibility in terms of where they can go – but usually, if your home is big enough to need a free-standing boiler, it’ll have enough space for one.

As well as generally having a larger water capacity than wall-mounted boilers, they also often possess a higher top temperature.

This can mean higher energy bills as they use more electricity, but if you need to supply hot water and heat to multiple bedrooms, bathrooms, and people, it might be worth it.

Wall-mounted boilers

Wall-mounted boilers are typically smaller, sleeker, and more modern.

Most new boilers come in this variety, partly because they’re easier to find space for, and partly because of the increasing need in the UK for small homes which don’t need (and can’t fit) free-standing boilers.

Of course, you’ll want the boiler that’s best for your specific needs – and if your home is a flat or a one-bedroom house, that probably means getting a wall-mounted boiler.

After all, you don’t need a free-standing behemoth extracting space and money from you for no good reason.

Summary

At this point, you’ll know which boiler is right for you.

All that’s left is to find out how much it’d cost you – and the best way to do that is to get multiple quotes from boiler installers.

Fortunately, we can help with that as well.

To receive free, bespoke quotes for a top-quality boiler from trusted installers, just fill in this form.