Boiler Pressure Too High
What happens when your boiler pressure goes too high, some possible causes and how to fix it.
18 May, 2021
Discover the best combi boilers on the market in 2021, prices, features and also what we don't like.
Are you looking to replace your combi boiler this year but don’t know which combi boiler to go for? Then you’ve come to the right place! We compare the likes of Worcester Bosch, Viessmann, Alpha combi boilers and many more to bring you the best combi boilers of 2021.
If you need to know the cost of a new boiler? Get a fixed price quote in as little as 30 seconds.
This guide will give you the Best Combi Boilers of 2021 and help you to evaluate which is right for you, we offer most of the boilers available in this guide. But first, let’s start out with what a combi boiler actually is.
There are dozens of different combi boiler types that each cover hundreds of thousands of models, and sometimes the small differences are the part that changes how well they suit your home.
These days, we are spending a lot more time at home with hot drinks and warm heating, so it might be time for an upgrade - here are some of the best combi boilers in 2021, as well as details on how you can choose the right option for you.
A combi or combination boiler combines a water heating system and central heating unit into a single body, acting as a unified way to handle heating and hot water without needing two separate boilers.
This means there is no need for a separate water tank system and therefore takes up less space in your home. A combi boiler is one of the most efficient types of combi boilers to install and tends to be much more reliable than normal combi boilers which is why we love them so much!
A combi boiler is the best option for almost all properties because it can be easily installed onto the water mains and offer instant control of heating in your home.
Whether your current combi boiler is on the blink or not, all combi boilers need to be replaced every 10 to 15 years. This means that even if you are not currently experiencing problems with your old combi boiler, but it has been in your home for more than a decade, it is time to consider what combi boiler can replace it.
According to the Energy Saving Trust, if your combi boiler is over fifteen years old and is a non-condensing boiler, it will be less efficient and may become faulty and even break down on a regular basis, as a result of corrosion on internal components from the thermal and mechanical stresses over years of constant use.
Not only is this an inconvenience for you, but it could also be costing you a lot more money to run an old inefficient boiler that frequently requires costly repairs, than it would to run a new A-Class efficiency rated combi boiler.
You can also have a read up on new boiler costs and how you could save money.
There are so many combi boiler brands and models to choose from, that deciding on which combi boiler is best for you, might seem impossible.
Boilers are also available at many different price points, which is another factor to consider when preparing to make a purchase.
That’s why we have researched and read plenty of reviews to compile our Top Best Combi Boilers of 2021, with reasons why we love them so much. Keep reading to find out our favourite!
While we have highlighted our top five combis for 2021, there may come a time when you need to shop for a unit on your own.
There are certain features you should look out for when shopping for combi boilers, including:
Combi boilers are given a grade based on how energy-efficient they are, with an A rating being the highest.
This is a good thing to consider because it will determine how expensive the boiler will be to run. A more energy-efficient boiler could potentially save you money over time.
The power outage of a combi boiler is listed as kW, and this determines the size of the boiler. Smaller homes tend to benefit from a boiler of between 25kW and 30kW, but this is something your gas engineer can help you with.
You will need a boiler that is large enough to handle your home heating.
The physical size of a combi boiler unit is important to consider too, as this will determine whether the unit can be installed into your home safely.
The average cost of getting a new combi boiler is between £1,500 and £3,000.
However the cost of a boiler can vary depending on the brand and the type.
When you get a new combi boiler, there are various costs involved that you need to consider along with the price of the unit itself.
Buying a boiler includes installation costs, labour costs, and potentially any additional parts as well as the price of the boiler itself.
For example, those in London will have to pay higher costs than those in the North even if they are getting the exact same boiler installed.
The type of home that you live in can also alter the cost of getting a new combi boiler, such as whether you live in a terraced or semi-detached property.
Boiler engineers will also need to consider how many bedrooms and bathrooms are in your home to gauge not only the kind of combi boiler you need but also the cost of installation.
This is it, the top 5 best combi boiler brands in the UK for in 2021:Start Your Quote
In fifth place comes Alpha, a well-established brand that has been one of the UK’s leading heating companies for over 50 years, giving them plenty of experience that combines traditional business values with a highly innovative approach to its operation.
Alpha ranks among the best combi boiler because they have amazing A-Class efficiency rated budget combi boilers that accommodate the needs of every property type and household size.
As part of the Immergas group which operates in 30 countries and has manufactured over 7 million boilers, Alpha benefits from some of the most advanced production facilities in the world.
This means you are guaranteed a high quality combi boiler, despite the low prices. They offer a range of boiler sizes from the compact E-Tec to the larger E-Tec Plus which deliver on every aspect.
Alpha Boilers are a budget option, but manage to balance price with some reliable design decisions to give you a cheap but fairly consistent boiler line.
The Italian design and surprisingly useful parts and labour warranties mean that each combi boiler is usually going to work just fine in the long-term.
A great set of sales and support staff also gives you an easy way to contact them if something goes wrong, and specific boilers have warranties of up to ten years, depending on the model you choose.
While Alpha Boilers may be relatively cheap, they are not poor-quality, so they can become a great mid-range choice when you do not want to go too high or low.
Other than that, there is not much else to say about Alpha Boilers, because they are a comfortable middle-of-the-road option that can fit into most homes and businesses without issue.
You are also covered for much longer than the price would suggest, so wear and tear are not as much of a setback.
|Alpha Model||Kilowatt (kW) Outputs|
The E-Tec is ideal for small and medium sized homes. The entire E-Tec range features brand new stainless steel heat exchangers, making them highly robust and they also have zinc plated expansion vessels to prevent corrosion.
Taking these extra steps to maximise the longevity of your boiler life is what makes this range stand out. The E-Tec also has a high-efficiency pump which helps to deliver an impressive 14.1 litres of hot water per minute and the single electrode drive charge is very easy to access, meaning your Alpha combi boiler will be easy to control and manage after installation.
Get your free fixed quote here.
Just some of the features of the E-Tec include:
The E-Tec Plus is similar to the E-Tec but is much larger and has a few extra benefits, such as a 10 year warranty, copper pipe tails with isolation valves, an integrated filling loop and a control panel and bottom cover.
This combi boiler is suitable for larger homes and offers a third higher output option than the E-Tec at 38kW
The best combi boilers from Alpha are the smallest. Its compact size and layout is an ideal solution for small to medium sized homes and has a stainless steel heat exchanger and many other amazing features such as:
The InTec combination boiler is different from the others due to its built-in GasSaver.
This combi boiler is perfect for anyone who is concerned about their impact on the environment as the InTec reduces gas usage by 35% compared to other gas combi boilers and has a low electrical consumption.
Some of the useful features of the InTec are:
In fourth place comes Ideal. This boiler brand is the best at small and affordable boilers such as the Logic range as well as flashier pricier models such as the Vogue range, catering for all their customers and their budgets.
Ideal Boilers has seen rapid growth over the last ten years, and offer a very simple warranty system that gives combi boilers either 2, 7, or 10-year warranties depending on which model you are buying.
In terms of quality, they sit around the same level as Worcester Bosch but with a slightly lower price, which can make them more budget-friendly if you are trying to save every penny you can.
Of course, this price depends on the installer, so the cost of getting a combi boiler form Ideal Boilers can vary by location.
When compared side by side, they are a good alternative to Worcester Bosch, and many of their ranges are similar enough to stand in for WB combi boilers if you need them.
A mid-range price and a compact design ensure that these combi boilers can be used in a wide variety of locations and situations, often knocking around 10% off the price when compared to more expensive brands.
However, this comes at the cost of not necessarily having the exact same features, so you may lose out on some unique benefits here and there.
Even still, Ideal combi boilers could end up offering you the best combi boiler depending on what you are looking for and how large your budget is.
They may be cheaper than other choices, but that does not make them worse or less reliable.
|Ideal Model||Kilowatt (kW) Outputs|
Although the Logic combi boilers aren't as flashy as the rest of Ideal’s range, they’re reliable, compact in size and easy to use, earning The Queens Award in 2013 as well as The Good Housekeeping Award in 2013 and 2017.
Ideal offers a standard 2 year warranty which can be extended to 5 years, though with only a 3% chance of The Logic's best combi boiler breaking down, it looks like you won’t even be needing it.
Here are some of the features of the Logic boiler:
This is Ideal’s best combi boiler for its features and attractive design, whilst remaining compact. It has a backlit 3.5” LCD full colour display and has multi-function buttons for ease of use, built using premium components.
Endorsed by the Energy Saving Trust, you can be sure that this combi boiler is better for the environment. This boiler comes with a standard 8 year warranty.
Ideal’s newest premium combi boiler has the same fantastic features and attractive appearance of the Vogue Gen2 with the addition of a high quality Ideal System Filter which boosts the warranty from 8 to 10 years.
Some of the other features include:
In third place is Vaillant, another Which? Best Buy Award winner. Vaillant is a premium contender and offers a 5 star boiler range for both small and large properties, though they do have premium prices which aren’t too friendly to your bank account.
However, they do come with a convenient app to control your heating anytime, anywhere and have a 5 year warranty which can be upgraded to 7 or 10 years.
Valliant is not mentioned quite as often as other top brands, but they operate at a similar level to Worcester Bosch, combining great quality with a variety of useful warranties and customer service options.
Warranties generally sit between 2-5 years in total, depending on the model, with a similar price range to other beloved brands.
One of the main benefits of Valliant is the variety on offer: the ecoTEC combi boiler line has become a favourite for people who want lower energy consumption without losing performance, and the warranty can be upped to ten years with a Valliant Advance Installer.
The improved efficiency can really help you save money, just like with Worcester Bosch combi boilers.
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.
|Ideal Model||Kilowatt (kW) Outputs|
|ecoTEC plus store||-||-||--||38|
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.
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.
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 combi boiler is appealing to large families with a high demand for hot water and comes with a 5 year warranty.
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.
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 every time. Worcester Bosch 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 with Worcester Bosch 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.
Getting Worcester Bosch combi boilers in 2021 can also be cheaper through third-party installers.
|Worcester Bosch Model||Kilowatt (kW) Outputs|
|Greenstar 8000 Style||30||35||40||45|
|Greenstar Si Compact||-||-||25||30|
The Greenstar i
is was Worcester Bosch’s most popular boiler that is ideal for small to medium sized homes and has simple and easy to use controls, this boiler has since been replaced by Worcester's new Greenstaf 4000 range. Here are some features of the Greenstar i:
This combi 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.
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.
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.
This combi boiler is an incredibly useful floor standing combi 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.
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 best 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 Model||Kilowatt (kW) Outputs|
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 combi 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:
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.
If you’re looking for a combi 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 combi 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 combi boiler.
Viessmann describes its Vitodens 111-W as rapid, reliable and compact- and that it is, its one of the best combi boilers that Viessmann offer. 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:
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 combi 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 combi boilers, then it is a good place to start looking.
Baxi is another high-quality option that fits somewhere between Worcester Bosch, 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 combi 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 and ranks them as one of the best combi boiler.
Potterton gets high ratings but is not known all that well, and their recent changes to their combi 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.
The problem with choosing the best combi 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.
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.
A bigger gas combi 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.
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 combi 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.
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