The Best Condensing Boilers In 2021
Are you considering changing your existing condensing boiler to a new one?
There’s a huge choice of options available for you on the market so we’ve compiled this article to help narrow down your choice.
In this review of the best condensing boilers in 2021, we look at:
- what a condensing boiler is
- how much money a condensing boiler can save you annually
- what the three main types of condensing boilers are
- what size of condensing boiler is right for your home
- the 10 cheapest condensing combi boilers
- the top 5 condensing combi boilers according to HomeSage’s exclusive grading system
- the 10 cheapest condensing system boilers
- the top 5 condensing system boilers according to HomeSage’s exclusive grading system
- the top 10 cheapest condensing regular boilers
- the top 5 condensing regular boilers according to HomeSage’s exclusive grading system
- how much condenser boilers cost to install
- how long it takes to install a condenser boiler
We’re HomeSage – we’re connected to a network of reliable, trusted, and established Gas boiler installers up and down the UK.
We want to help you save money on your next condensing boiler installation and, if you fill in the form anywhere on this page, the evidence from feedback of users of our service suggests that you could save hundreds of pounds.
Simply fill in a form with your information and leave the rest to us.
We get in touch with 3 or 4 local and reputable boiler installation companies who’ll want to offer you their most competitive quote.
The one who can give you best value will contact you directly.
They’ll make an appointment to see you, during which they price up how much your condensing boiler installation is going to cost.
Our service is 100% free and no obligation. You don’t have to accept any of the quotes you’ve been given.
What is a condensing boiler?
Most new boilers on the market today are condensing boilers.
What is a condensing boiler?
When a boiler is heating up your water, you inevitably lose some energy in the form of gases escaping up the flue pipe.
Condensing boilers capture these gases and cool them down – often condensing them, hence the name.
They use this energy to continue to heat your water so you benefit from an efficient system which costs you less to run.
Condensing boilers have large heat exchangers allowing you to make these savings.
It means that most of the gas produced from heating the water is returned to your central heating system, resulting in a smaller amount of lost energy.
Older boilers lose energy when they’re heating up the water.
This energy still costs you money but you don’t receive any extra heat for your home from it.
Essentially, condensing boilers are more energy efficient because they make best use of the energy they produce as a system.
How much will an A-rated boiler save you every year?
There’s no doubt that an ‘A’ rated boiler will bring down the cost of your annual heating bill.
In the table below you can see just how much money you could save.
The monetary figures are your potential annual savings from upgrading to an A-rated boiler – they are different depending on the size of your property.
| Your current boiler | Its energy efficiency | Flat | Mid-terrace property | Detached one-story | Detached two-story | Semi-detached two story |
| G | Less than 70% | £90-£95 | £160-£175 | £145-£155 | £285-£305 | £185-£200 |
| F | 70% to 74% | £60-£65 | £115-£120 | £100-£105 | £200-£210 | £130-£140 |
| E | 74% to 78% | £50-£55 | £90-£105 | £80-£90 | £160-£180 | £105-£120 |
| D | 78-82% | £35-£55 | £70-£105 | £60-£90 | £120-£180 | £80-£120 |
Although replacing your boiler can cost a considerable amount of money upfront, a new boiler with greater energy efficiency should pay for itself over a few years through a lower annual gas bill.
If you are on a very tight budget, there are grants available for those living on low-income through the Energy Companies Obligation (ECO) scheme.
This may apply if you have an old boiler with a low efficiency grading and funding may be available to replace your boiler with a more efficient model for free or for a subsidised price.
What are the three types of condensing boiler?
Condensing combi boiler
This heats water directly from the mains supply so there is no water storage tank needed.
Once you turn the heating or hot tap on, the water passes through the boiler and it’s heated up as it goes so you always have access to hot water without any waiting time.
Condensing regular boiler
A condensing regular boiler requires a cold-water storage tank in your loft that feeds the hot water cylinder.
The water is heated up in the cylinder meaning you have a large amount of hot water ready to use that won’t drop in pressure even during high demand.
Once this water is used, you need to wait for it to heat up again. These boilers are large in size and tend to take up a fair amount of space.
Condensing system boiler
Similar to a regular boiler, but doesn’t require the cold-water storage tank.
Instead, it is a singular floor-standing unit which both heats and stores the water.
System boilers are able to cope with high hot-water demands without losing pressure but, as with the regular boiler, they need time to heat up the water once the tank has been emptied.
Combi boilers are much smaller than regular or system boilers.
They can be wall-hung units and can often fit within a kitchen cabinet so taking up very little space.
They range slightly in size depending on the features and output of the boiler but they are the most compact boilers available.
The energy efficiency ratings of most combi boilers are either ‘A’ or ‘B’ so they are highly efficient in using energy to heat your home.
Combi boilers are affected by water pressure and flow rate.
This is because the water is passing through the system and being heated as it goes.
The flow rate of a combi boiler depends on the specification of the boiler and your mains water supply pressure.
Smaller flow rates allow for less hot water and you can lose pressure if you turn on more than one hot tap, for example.
Flow rates don’t apply to system or regular boilers because they already have the hot water stored in their tanks.
This means that, no matter how many people are using hot water at one time, they can provide it without any loss of pressure until they run out of the stored hot water.
What size of condensing boiler is right for your home?
Boiler output is measured in kilowatts (kW).
The output rating tells you how much power the boiler has and how much it will cost you to heat your home.
It’s an important factor to consider because you need to balance the output of your boiler with the size and requirements of your property in order to make sure you’re only paying what you need to be paying.
To work out how much running your boiler will cost, you take the output rate and multiply it by the price of a unit of gas.
For example, if your boiler has an output of 35kW and a unit of gas is 4p, the equation is 35 x 4p which equals £1.40.
Here is a guide to give you an idea of what boiler size you will need for your property.
An installer will usually recommend a gas combi boiler as they are the cheapest to run:
| Property Type | Bathrooms | Bedrooms | Radiators | Boiler type recommendation | Boiler size recommendation |
| Apartment/small bungalow/small mid-terraced | 1 | 1 or 2 | 10 | Combi | 24kW-27kW |
| Semi-detached house/medium bungalow/medium mid-terraced | 1 or 2 | 3 or 4 | 15 | Combi | 28-34kW |
| Large semi-detached/detached house | 2 or more | 4 or more | 20 | Combi or Conventional | 34-42kW |
The HomeSage condenser boiler ranking system
There are hundreds of condenser boilers on the market today and they all have their own benefits and features.
Here at HomeSage, we have developed our own original online scoring system to help you make the best choice for your home size and budget.
We have split our grading system into combi, system, and regular boilers and we have then ranked boilers according to their efficiency, price, fuel type, and warranty options.
We have also ranked our top 10 cheapest boilers for customers on a budget.
Condenser combi boiler prices
Condenser combi boilers are generally the most effective boilers available.
Due to their ability to maximise on the energy they use, they cost far less to run than regular or system boilers.
Combi boilers are cheaper to install as you don’t need to plumb extra pipe work to a storage tank in your loft.
They can be installed in a small space in your kitchen or utility room and they often come with various flue pipe and accessory options to make installation and maintenance easy and quick.
There are 205 on the market in the UK as of 2021 and the average price is £1,098.
On a budget? The ten cheapest condenser combi boilers
Here, we have listed the top ten budget boilers available.
The prices shown below relate to the average price of the boiler and they are ranked according to price.
| Make and Model Name | Efficiency Rating | Parts and Labour Wty (month) | Output in kW | Flow Rate | Price from | TOTAL |
| Vokera Easi-Heat Plus 25Ci Boiler | 93.00% | 60 | 25 | 10.2 | £440 | 82.21% |
| Vokera Easi-Heat Plus 29Ci Boiler | 93.00% | 60 | 29 | 11.9 | £465 | 82.15% |
| Glow-worm betacom4 24 gas boiler | 89.20% | 60 | 24 | 10 | £515 | 82.08% |
| Ravenheat WH80 25 Boiler | 90.30% | 60 | 25 | 10.2 | £515 | 79.88% |
| Ravenheat WH90 30 Boiler | 90.30% | 60 | 25 | 12 | £515 | 79.88% |
| Biasi Riva Plus ErP 24 Boiler | 88.00% | 24 | 24 | 11.6 | £515 | 76.15% |
| Biasi Riva Plus ErP 28 Boiler | 88.00% | 24 | 28 | 13.6 | £515 | 76.15% |
| Ravenheat CS80 25 Boiler | 90.30% | 24 | 25 | 11.9 | £535 | 77.34% |
| Vokera Compact 25A Boiler | 89.10% | 24 | 25 | 10.2 | £535 | 76.97% |
| Ravenheat CSI 120 25 Boiler | 92.00% | 36 | 25 | 13.2 | £540 | 78.16% |
The HomeSage top-rated 5 condenser combi boilers
If price is no object, the top 5 scoring condenser combi boilers are as follows.
Baxi boilers lead the way with consistently high efficiency ratings, warranty options, and value for money.
The highest-finishing non-Baxi boiler was a Worcester Bosch boiler in 8th place with a score of 91.89%.
| Make and Model Name | Efficiency Rating | Parts and Labour Wty (month) | Output in kW | Flow Rate | Price from | TOTAL |
| Baxi Platinum 24 Boiler | 89.00% | 120 | 24 | 9.8 | £870 | 92.69% |
| Baxi EcoBlue Advance 24 Boiler | 89.10% | 120 | 24 | 9.8 | £945 | 92.51% |
| Baxi 636 Boiler | 89.00% | 84 | 36 | 15 | £975 | 92.43% |
| Baxi Platinum 28 Boiler | 89.00% | 120 | 28 | 11.5 | £1,005 | 92.36% |
| Baxi EcoBlue Advance 28 Boiler | 89.10% | 120 | 28 | 11.5 | £1,080 | 92.18% |
Condenser system boiler prices
Condenser system boilers allow readily available hot water without the need for a cold water tank.
The flow rate of condenser boilers is always high as long as you have hot water stored and you don’t lose pressure even if more than one person is using hot water at the same time.
There are currently 135 condenser system boilers on the market and the average price is £961.
On a budget? The ten cheapest condenser system boilers
Our table shows you the ten cheapest condenser system boilers in the UK market.
We have ranked them according to price so you can pick a suitable boiler for your budget.
As you can see, the total average score for these system boilers is around 10% lower than that of the combi boilers above.
| Make and Model Name | Efficiency Rating | Parts and Labour Wty (months) | Output in kW | Price from | TOTAL |
| Vokera Evolve S 18 Boiler | 94.00% | 84 | 18 | £435 | 83.89% |
| Vokera Easi-Heat Plus 24S Boiler | 93.00% | 60 | 24 | £490 | 82.08% |
| Vokera Evolve S 24 Boiler | 94.00% | 84 | 24 | £500 | 83.73% |
| Vokera Easi-Heat Plus 30S Boiler | 93.00% | 60 | 30 | £515 | 82.02% |
| Biasi Riva Plus ErP 28 Boiler | 88.10% | 24 | 28 | £515 | 76.16% |
| Biasi Riva Plus ErP 24 Boiler | 88.00% | 60 | 24 | £520 | 78.64% |
| Vokera Mynute i20 Boiler | 89.50% | 60 | 20 | £540 | 79.45% |
| Biasi Advance Plus ErP 16 Boiler | 88.70% | 60 | 16 | £560 | 78.55% |
| Ravenheat WH 4-24 26 Boiler | 90.30% | 60 | 26 | £565 | 79.76% |
| Vokera Vision20s Boiler | 90.00% | 60 | 20 | £565 | 79.39% |
The HomeSage top-rated 5 condenser system boilers
For those with no upper limit to their boiler budget, below are the top 5 scoring system boilers.
The total average scores for these boilers come in highly – above 90%.
The Greenstar range dominates the results and it is Worcester Bosch’s most popular boiler due to their lengthy warranty (10 years), easy to navigate controls, and low energy electrical pump – this reduces your electricity usage.
The Greenstar range also features a large Condensesure-style siphon built into the boiler itself which eliminates any frost risk giving you extra peace of mind in colder seasons.
The highest-finishing non-Worcester Bosch boiler was a Baxi boiler with a score of 90.55% coming in at 12th place.
| Make and Model Name | Efficiency Rating | Parts and Labour Wty (months) | Output in kW | Price from | TOTAL |
| Worcester Bosch Greenstar 9i Boiler | 93.00% | 60 | 9.2 | £880 | 91.59% |
| Worcester Bosch Greenstar 12i Boiler | 94.00% | 60 | 12.2 | £890 | 91.57% |
| Worcester Bosch Greenstar 15i Boiler | 94.00% | 60 | 15.3 | £950 | 91.42% |
| Worcester Bosch Greenstar 18i Boiler | 94.00% | 60 | 18.4 | £1,005 | 91.29% |
| Worcester Bosch Greenstar 21i Boiler | 94.00% | 60 | 21.6 | £1,015 | 91.26% |
Condenser regular boiler prices
Condensing regular boilers provide high volumes of hot water to multiple bathrooms at one time so they’re great for larger properties with big families.
They are also known as traditional, conventional, or heat-only boilers and they require a cold water storage tank in the loft.
The main advantage of regular boilers is their ability to provide high pressure hot water when required although, once the hot water has gone, you need to wait for it to heat up again.
There are currently 104 condenser regular boilers on the market and the average price is £1,118.
On a budget? The ten cheapest condenser regular boilers
If you’re on a budget, we’ve compiled a list of the ten cheapest regular boilers available in 2021.
We have ranked them according to price so you can see what you can get for your money at a glance.
The total average score for these condenser regular boilers are generally much lower than combi boilers and slightly lower than system boilers.
| Make and Model Name | Efficiency Rating | Parts and Labour Wty (months) | Output in kW | Price from | TOTAL |
| Vokera Mynute 20VHE Open Vent Boiler | 88.80% | 24 | 20 | £460 | 77.15% |
| Vokera Mynute 15VHE Open Vent Boiler | 89.30% | 24 | 15 | £520 | 77.00% |
| Baxi 424 Heat 24 Boiler | 89.10% | 60 | 24 | £650 | 89.07% |
| Potterton Promax SL Heat 12 Boiler | 91.10% | 12 | 12 | £660 | 75.20% |
| Glow-worm Easicom3 25 Boiler | 94.00% | 36 | 25 | £670 | 82.54% |
| Baxi 212 Heat 12 Boiler | 89.20% | 36 | 12 | £680 | 87.33% |
| Baxi 412 Heat 12 Boiler | 89.20% | 60 | 12 | £680 | 88.99% |
| Baxi 415 Heat 15 Boiler | 89.20% | 60 | 15 | £680 | 88.99% |
| Potterton Titanium 12 Boiler | 93.00% | 84 | 12 | £685 | 77.64% |
| Glow-worm Energy 12 Boiler | 89.30% | 84 | 12 | £700 | 83.29% |
The HomeSage top-rated 5 condenser regular boilers
For customers wishing to invest in a more premium product with no budget restrictions, here is our HomeSage list of top 5 condenser regular boilers.
The Greenstar range has clearly dominated the results due to its high energy efficiency rating and exceptional value for money.
The highest finishing non-Worcester Bosch boiler was a Baxi regular boiler that charted at 13th place.
The average score of that boiler was 88.99% and was also the 8th cheapest condenser regular boiler in the UK according to our results, too.
| Make and Model Name | Efficiency Rating | Parts and Labour Wty (months) | Output in kW | Price from | TOTAL |
| Worcester Bosch Greenstar 12Ri Boiler | 92.00% | 60 | 12 | £800 | 91.79% |
| Worcester Bosch Greenstar 15Ri Boiler | 92.00% | 60 | 15 | £825 | 91.72% |
| Worcester Bosch Greenstar 18Ri Boiler | 92.00% | 60 | 18 | £880 | 91.59% |
| Worcester Bosch Greenstar 24Ri Boiler | 92.00% | 60 | 24 | £935 | 91.45% |
| Worcester Bosch Greenstar 21Ri Boiler | 92.00% | 60 | 21 | £975 | 91.36% |
How much do boilers cost to install and how long does it take?
The cost of installing a new boiler varies hugely on how much work is required, the parts needed and their availability, where your property is, and who you choose to employ for the job.
According to Which?, quotes for installing a new boiler can vary by up to £3,200 so it’s worth your while to do your research.
The cost of the new boiler itself depends on the model you opt for, the size of the output, and if you decide to extend the standard warranty.
Depending on the complexity of the job, installing your new boiler can take between 1 and 3 days.
You should also account for any preliminary visits by the boiler installer to check out your property and survey what needs to be done to prepare your system.
Some companies offer initial consultations via video call but the traditional method requires an engineer coming to your property to assess how many rooms, bathrooms, and radiators you have as well as asking you about your usual hot water usage.
Still have questions about how long it takes to install a boiler? Why not read our post specifically about the topic!
Save up to 54% on your new condensing boiler
You can save up to 54% of the cost of the supply and the installation of your new condensing boiler simply by leaving your details with us on the form at the top of the page.
Our service is 100% free of charge and no obligation.
We pass your details on to three or four local and trusted Gas Safe registered engineers who will then get in touch with you directly and offer you a free, competitive quote.
You could save hundreds of pounds on the cost of your new boiler installation and the option of quotes to suit your budget and calendar.
