Top 5 Best Combi Boilers 2021

Finally, great customer service is always useful, and Valliant is keen to offer it. If something goes wrong and you need help fixing a problem or identifying a failure, then it is not hard to get in contact with them, meaning that you will always have a way to contact the company and won't have to hunt down an obscure email address or phone number.

Vaillant Boiler Range

ecoTEC exclusive

This combi boiler is great for larger homes with its higher outputs. It has the potential to generate an impressive 17.8 litres of hot water per minute and is eco-friendly and 85% recyclable. Like all of the Vaillant products, the ecoTEC exclusive has been Quiet Mark approved, meaning it is one of the quietest products on the market.

ecoTEC plus

This is the all rounder of Vaillant’s combi boilers with the broadest range of kW outputs. It has precision heating to reduce fuel bills, delivers hot water within 5 seconds and has a 5 year standard warranty.

ecoTEC plus store

This boiler is a powerful solution for larger homes with its high performance control, efficiency and an integrated hot water storage device at the back of the boiler. Providing up to 20 litres of hot water per minute and hot water within 5 seconds, this boiler is appealing to large families with a high demand for hot water and comes with a 5 year warranty.

Vaillant ecoFIT pure

The ecoFIT pure is another of Valliant’s highly efficient, smart control and high performance combi boilers but much more compact to fit in a kitchen cupboard in a smaller home. This boiler comes with a less impressive 2 year warranty, but there is the option to increase this to 7 or 10 years for an extra cost.

#2 Worcester Bosch Combi Boilers

In second place come the Worcester Bosch boilers, the pioneers of combi boilers. In 2019, they secured a Which? Best Buy award for the 10th year and their bestseller, the Greenstar i can be found in over a million UK homes.

If you ask most people what the best combi boiler is, the Worcester Bosch group will come up very often. The brand covers quite a range of boiler types and features, which means that they are suited to plenty of different situations.

However, they are also consistent in terms of quality, so there is not any risk of a certain model being extremely poor or unreliable.

One of the biggest draws is their warranty offers. Depending on the exact boiler model you choose and the features included in the design, you can have a warranty of anywhere between five and ten years.

This means that you are covered in case something goes wrong, even if the fault only becomes obvious nine years after installation.

Even better, installing more Worcester Bosch products can extend this warranty: adding their filter system to one of their boilers can add another year to your overall warranty time, which means that you get even more protection if you gradually upgrade your new combi boiler during the existing warranty period.

Higher quality often comes with higher prices, and Worcester Bosch used to be a major example. Over time, though, some of their models have become much more affordable, and there are monthly payment options for people who can’t afford an up-front cost.

Worcester Bosch Boiler Range

Greenstar i

The Greenstar i is Worcester Bosch’s most popular boiler that is ideal for small to medium sized homes and has simple and easy to use controls. Here are some features of the Greenstar i:

• Condensate discharge resilient to freezing up to -15?
• Wide choice of controls
• Low energy pump reduces electrical usage
• Hot water instantly heated from cold mains
• Achieves A-Rated efficiency
• Fills a kitchen sink in 45 seconds

Greenstar Si Compact

This boiler has pretty much all the same features as the Greenstar i but is much more compact to enable it to fit in a kitchen cupboard. It also has extra features such as frost protection and can also fill a kitchen sink in 45 seconds.

CDi Classic

This is one of the more expensive combi boilers available, but does guarantee reliability, fuel efficiency and a user-friendly interface. Available in four heating outputs, this boiler is suitable for many property types and sizes. Its modulating pump and intelligent controls also allow a 30% electrical energy reduction. It also comes with a 5 year warranty for peace of mind.

CDi Compact

This boiler is like the classic except much smaller to enable it to fit in a kitchen cupboard, making it more ideal for smaller homes. It comes with frost protection, a user-friendly display and simple boiler controls to ensure you can manage your comfort and costs.

CDi Highflow

This boiler is an incredibly useful floor standing boiler for large homes with lots of bathrooms. It provides high hot water flow rates over 90 litres draw-off. It has a wide choice of simple to use controls and a temperature display, however, with having such a large unit, a large space such as underneath a kitchen counter is required.

#1 Viessmann Combi Boilers

In first place comes Viessmann. Viessmann surpasses all other best combi boiler brands in the market with their advanced German engineering and efficient heating systems that are a great value for money.

This isn't to say we don't think the other boilers listed in this article are not some of the best combi boilers on the market, the Viessmann is just the cream of the crop!

Their prices are currently so low as they are still attempting to increase their exposure in Britain, so now really is the time to buy yours before the prices rise! Get your fixed quote here.

One of their key selling points is the longer lifespan, something that makes their combi boilers last much longer than a lot of competing products. Because of this, they will often appear near the top of any combi boiler list.

Efficiency can mean a lot when it comes to heating, which often makes Viessman a good choice for keeping costs low in the long-run.

Even in designs that have a lower maximum heat output, the improved efficiency can save plenty of money and make better use of the power you are already consuming.

All of their models come with ten-year warranties when bought through iHeat, and there are simple finance options available for their more expensive offerings

Even better, most are designed to be silent or near-silent when in use, which can make all the difference in a crowded home where the boiler can’t easily be tucked away.

In general, Viessman is a great choice for a smaller building, especially if you do not have as much room to store it.

The higher efficiency removes a lot of the hassle from setting the combi boiler up and also means that there is more power packed into a single body.

You can fit a lot of them into existing cupboards or small alcoves, and the long-lasting design prevents them from breaking down easily.

Viessmann Boiler Range

Vitodens 050-W

The Vitodens 050-W 29kW in particular is the most reliable and has the highest quality with its stainless steel heat exchanger (which makes it extra robust), exceptionally quiet operation and an impressive water flow rate of 12 litres/min.

With compact dimensions and low weight, the Vitodens 050-W will integrate into any home without compromising on quality. Winner of the 2019 Which? Best Buy award, this boiler is Class-A rated for its energy efficiency and is easy to control with an LCD display.

Here are just some of the amazing featured this boiler has to offer:

• 10 Year Warranty when installed with iHeat
• Integral instantaneous water heater
• High efficiency of up to 97%
• Low CO2 emissions for reduced environmental impact
• Digital user interface

Vitodens 100-W

This combi boiler has all the great features of the 050-W as well as extra features such as the extra 26kW output option and the user friendly backlit LCD Touchscreen for easy operation. This boiler was endorsed by Which? and up to 94% of the fuel used is converted into heat, making it more environmentally friendly and Boiler Plus ready.

Vitodens 200-W

If you’re looking for a boiler for a larger home, this is the boiler for you. It has greater efficiency and lower emissions, with up to 98% of the fuel used converted into heat. Despite having to operate on a larger scale, this boiler remains compact and quiet thanks to its low speed fan.

Viessmann have made this boiler incredibly easy to operate by incorporating a 7” colour touchscreen with an integrated WiFi interface for internet connection. It also has a new environmentally responsible MatriX-Plus burner which automatically adapts to the properties of different gas types to keep costs down and reduce the environmental impact of the boiler.

With its 10-Year Warranty you can be sure you’ll have a long lasting and reliable boiler.

Vitodens 111-W

Viessmann describes its Vitodens 111-W as rapid, reliable and compact- and that it is. This combi boiler is perfect for large families who have a high demand for hot water. With this high performance wall mounted storage boiler, you can be sure there will be no more arguments in the morning about ‘who is using all the hot water?!’.

With the capacity to fill a bath in just 8 minutes, this combi boiler will never fail to provide the means for a relaxing soak. Here are some of the features that are bound to impress even those with minimal boiler interest:

• 10 Year Warranty
• Cylinder loading system (CLS) and integrated stainless steel storage tank
• User friendly control via backlit LCD touchscreen
• High hot water capability of >18 litres per minute
• Large range of outputs available
• Optional wireless remote available

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Mains Gas

LPG

Other boiler brands to mention

• Glow worm
• Baxi
• Potterton

Glow Worm Boilers

Glow Worm are the exact opposite of the previous two choices: they might be somewhat simple, but they are also incredibly cheap, often appearing in rental properties and budget renovation projects.

Lower reliability can make them a risk in some cases, but they also come with warranties between two to five years, and installation is extremely straightforward.

This gives you a very unique option for situations where a full boiler may not actually be needed, especially if you are actively planning to replace it with another boiler in the next few years.

This niche is hard to fill with larger and more expensive options, making Glow Worm useful in the short-term.

The very low cost can also make them a suitable choice in the long-term as long as you can keep replacing or repairing them.

For example, if you are saving up money for a full house renovation and do not want to spend thousands on a top-tier boiler, one or two Glow Worm models can do the same job until you are ready to renovate the entire building.

This does not make Glow Worm a bad choice, it just means that they are suited to particular situations. If you need cheap, straightforward and functional boilers, then it is a good place to start looking.

Baxi

Baxi is another high-quality option that fits somewhere between Worcester, Valiant, and Ideal Boilers.

Their boiler range includes combi boilers as well as other varieties, and all of them are relatively easy to install, coming in at a slightly lower price that makes them more affordable in the long-term.

Baxi boilers are designed primarily for homes that do not demand a lot of hot water all at once, meaning that they may not be as effective if you have two bathrooms or multiple hot taps that you are using at the same time.

However, they are very small and can easily be installed almost anywhere in the average home, which makes them a perfect choice if you are looking for a compact solution.

They also come with a variety of efficiency improvements and other benefits, which can lead to them becoming very useful if you are looking to keep your cost down and your heating functioning well.

This combination of compact construction and reduced costs make them a great middle-ground option for most homeowners.

Potterton

Potterton gets high ratings but is not known all that well, and their recent changes to their boiler models have given them two distinct types of boiler.

Older Potterton models are very durable, whereas newer ones are cheaper but lose some of their durability in the process.

Even so, engineers often install them purely because of their excellent support, which makes it much easier to resolve faults or report issues that might be covered under warranties.

They are also the cheapest of the top-tier boiler brands featured on this list, which can make them much more accessible without sacrificing too much in terms of quality.

While Potterton may not be mentioned very often, that does not make them a bad choice, and there are many people who still swear by using them over and over again.

They fill a niche for people who do not have a high budget but still want something more than cheaper options.

Which do I choose?

The problem with choosing the best boilers is that every homeowner can want different things.

Combi boilers are meant to heat water and provide heating, so it is obvious that they will need to do those basic things, but other features can really vary depending on what you are looking for.

For example, some people are desperate for high-efficiency models that cost less to run, especially if they are already on a tight budget and do not want high heating bills that can eat into their savings.

Other people have more than enough money to cover the bills and want higher heating speeds or temperatures instead.

On top of that, there are some people who just want the lowest install price and do not care about the actual effectiveness of the boiler, especially in rental properties or homes that they are renovating. In many cases, a cheap boiler can be good holdover until you are ready to replace it with something more expensive.

Price of a new boiler

If the price is all you care about, then the best combi boilers are the ones that do not cost much to install and cost even less to run.

A cheap but inefficient boiler will add up over time, so something that is efficient and low-priced can be the best choice in terms of affordability.

If you can get the boiler on a finance plan rather than with an upfront payment, this becomes even better.

Remember that installation fees are sometimes a thing, so you’ll want to keep that in mind if you are not going to install the combi-boiler yourself.

The more complex the process, the more it can cost, especially if you need new pipes and systems to be installed so that the boiler can connect properly.

Size of the boiler

A bigger boiler can often be more powerful, but it also takes up more room and will generally make more noise.

If a boiler is too bulky, then you will need space to keep it somewhere, and that can often mean that you will have to do more work opening up space in a wall or building something to cover it.

On the other hand, a compact boiler can easily be fitted into existing spaces with minimal effort, and usually sounds quieter.

On the other hand, this might also reduce the power it uses and the level of heating that it can offer: improving efficiency but reducing overall strength.

Neither is necessarily better than the other, it just comes down to personal preference and the number of items in your home that will need hot water or higher water pressure to operate.

Quality of the boiler

Many of the best combi's will be the ones built to a high standard of quality. There are rarely any times where a low-quality boiler is better unless it is far cheaper, and in most cases, a single high-quality boiler can cost less than having to replace a low-quality option multiple times.

If you have the option, always go for the better-quality models if they are available, and be sure to look up any common issues with the boiler before you decide to purchase it.

Warranties can matter a lot, too, since they will sometimes make up for a drop in quality by allowing you to get a replacement or repair job done.

Now you know our best combi boilers of 2021, for more information on which combi boiler may be best for you, feel free to give us a call on 0333 305 6880 or use our bespoke boiler quote service which will automatically recommend the best combi boiler for you and your household.