The Best Gas Boilers In 2020

best gas boilers in 2020

Gas boilers are an excellent choice for many properties in the UK as long as they are connected to the mains grid

There are many options of gas boilers available for homeowners to choose from and it can be difficult to work out what style will suit you best

We believe that investing in a new gas boiler should be an easy and smooth process where you have access to all necessary information in order to make a sound decision. 

We’ve created this guide to help you understand your gas boiler options so you can make a wise investment on your next home heating solution. 

In this article on the best gas boilers of 2020, we examine:

  • what a gas boiler actually is
  • how much a gas boiler costs to run
  • the three main types of gas boiler
  • what size of gas boiler is right for your home
  • how we rank over 700 different types of quality for value for money so you don’t have to
  • the best 5 gas combi boilers for a smaller property
  • the best 5 gas combi boilers for a medium-sized property
  • the best 5 gas combi boilers for a large property
  • the top 10 gas regular and system boilers for larger properties
  • how much has combi boilers cost to install
  • how much will an A-rated efficient boiler save you on your gas bills
  • how to save up to 54% on the installed price of your new gas boiler

We’re HomeSage – and we are connected to a network of trusted UK Gas Safe boiler engineers and installers. By using us, you can save you hundreds of pounds on your gas boiler installation. 

If you would like to receive 3 or 4 quotes from companies in your local area, simply fill in our form and we will do the rest.

We contact friendly, experienced, and reliable engineers who then get in touch with you directly with a competitive quote, giving you different options and further understanding of what your installation will need.

Our service is 100% free and no obligation whatever you decide to do so you really have nothing to lose

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What is a gas boiler?

A gas boiler is a heating system that is fuelled by gas usually drawn from the mains grid. 

Gas boilers can be either combi boilers, system boilers or regular boilers – the most popular and energy efficient boiler you can choose will normally be a gas combi boiler

All boilers are given a SEDBUK rating which scores their energy efficiency levels on a scale of ‘A’ to ‘G’ depending on how much power is used to provide you with hot water and heating. 

Much like other modern appliances that have energy ratings, SEDBUK is calculated by a combination of boiler type, fuel method, the UK climate and approximate usage so it is a comprehensive rating of how the boiler will operate in your property. 

The higher the rating, the more energy efficient the gas boiler will be and the cheaper it will cost for you to run. 

How much does a gas boiler cost to run?

Generally speaking, gas boilers are the cheapest way to fuel a boiler as gas costs less per unit than electricity, oil or LPG. 

You can work out how much your gas boiler will cost to run using the output level of the boiler.

For example, if the output is 24kW, to calculate the cost you simply multiply 24 by the price of a unit of gas (4p).

The sum would be 24 x 0.04, so you can see the cost to run that boiler for an hour would be 96p.

It’s important to bear in mind that modern boilers often turn on and off to regulate the heating in a house therefore costing you less.

The three main types of gas boiler

Gas combi boilers draw water directly from the water mains so you have a constant supply available to heat as it passes through the system.

They use an internal heat exchanger which instantly heats up the water as soon as you need it – for example, when you turn a hot water tap on.

They are usually fairly small, wall-hung units and don’t require any additional water storage tanks. 

Gas regular boilers require two units, one cool water storage tank in the loft and the boiler itself which is often in an airing cupboard.

Regular boilers store hot water so it is there when you need it with no loss of water pressure however once the water is used you need to wait for more to be heated.

Gas system boilers are similar to regular boilers in that they store the water within their internal tanks

The main difference is that they don’t use a cool water storage tank so are slightly less cumbersome in their installation requirements. 

Both regular and system boilers are usually floor standing units which take up more room than a standard combi boiler. 

Combi boilers always have a flow rate as a specification which applies to the number of litres of hot water it can produce in one minute

Flow rates don’t apply to regular or system boilers because the water is coming straight from the internal tank. 

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What size of gas boiler is right for your home?

A boiler’s output refers to the power it uses to perform its core functions and is used to work out how much it will cost to run.

You need to make sure you choose a boiler with the correct output for the size of your property, otherwise you may miss out on energy saving costs. 

Depending on the number of radiators, bedrooms and bathrooms you have, this will affect the choice of output you need. 

Here, we have created a table to give you an indication of what an engineer might recommend for your property:

Property TypeRadiatorsBedroomsBathroomsBoiler type and output recommendation
Apartment, Small mid-terrace, small bungalow101 or 21Gas combi with 24kW-27kW output
Semi-detached house, Medium mid-terrace, Medium bungalow153 or 41-2Gas combi with 28kW-34kW output
Substantial semi-detached, Detached house204 or more2+Gas combi, regular, or system boiler with 34-42kW

The HomeSage boiler ranking system

Here at HomeSage, we love to help you choose the best boiler for your property needs and budget.

That’s why we have developed our own 100% unique boiler scoring system to make sure you are as informed as possible for your new boiler purchase.

Our system takes a variety of features and factors into consideration in order to give you as much knowledge as possible.

Our ranking system takes the following into consideration:

  • the type of fuel the boiler uses (as gas is the cheapest option in the UK, each gas boiler gets a maximum score for this automatically),
  • the length of the guarantee included,
  • the energy efficiency rating, and
  • genuine customer reviews and the average company rating from Trustpilot.com

Warranties for gas boilers are usually much longer than other boilers too which is reflected in the scores. 

Best gas combi boilers for a small home

Combi boilers are the most energy efficient boilers so your annual heating bill will always be lower.

They are also great if you are short on space as many can be hidden under the stairs or in a cupboard and you don’t need a loft for extra storage tanks. 

There are currently 77 gas combi boilers suitable for small homes on the market in the UK at time of writing and the average cost is £1,035.

Baxi Platinum 24kw Boiler (92.69%)

Make and ModelBaxi Platinum 24 Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating89.00%
Band RatingB
LPG Compatible?No
Parts and Labour Warranty in months120
Heat Exchange Warranty in months120
Output kW24
MountingWall Mounted
Flow Rate in litres per second9.8
Price from£870
Price to£910
ERP HeatA
ERP WaterA
TOTAL92.69%

Coming in first is the extremely popular Baxi Platinum 24 boiler which benefits from a huge 10-year warranty as standard for peace of mind.

The dimensions of this boiler are 780mm x 450mm x 345mm so it is slightly larger than others available but houses top quality brass components and is built in the UK factory. 

The platinum range from Baxi all have energy efficiency ratings of ‘A’ and high water flow rates – regardless of the output.

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Baxi EcoBlue Advance 24kw Boiler (92.51%)

Make and ModelBaxi EcoBlue Advance 24 Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating89.10%
Band RatingB
LPG Compatible?No
Parts and Labour Warranty in months120
Heat Exchange Warranty in months120
Output kW24
MountingWall Mounted
Flow Rate in litres per second9.8
Price from£945
Price to£980
ERP HeatA
ERP WaterA
TOTAL92.51%

The Baxi EcoBlue Advance 24kw is a boiler perfect for a smaller property that needs a reliable and long-lasting boiler. 

It comes complete with a standard 10-year warranty providing you follow the terms and conditions.

The measurements of this boiler are 763mm x 450mm x 345mm and it features a traditional white casing which is durable and scratch resistant. 

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Worcester Bosch 2000 25kw Boiler

worcester bosch 2000 boiler
Credit: Worcester Bosch
Make and ModelWorcester Bosch 2000 25 Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating93.00%
Band RatingA
LPG Compatible?No
Parts and Labour Warranty in months60
Heat Exchange Warranty in months60
Output kW25
MountingWall Mounted
Flow Rate in litres per second9
Price from£760
Price to£795
ERP HeatA
ERP WaterA
TOTAL91.89%

This is an affordably priced mid-output boiler from Worcester Bosch which has an excellent grade ‘A’ energy efficiency rating. 

This boiler measures in at 724mm x 400mm x 300mm and it has been developed to be ultra-quiet so you won’t be disturbed by any bangs or knocks. 

You can get a guarantee of 6-years with this boiler if you choose to install it with any Greenstar System Filter

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Worcester Bosch Greenstar 25i Boiler (91.41%)

greenstar cdi boiler
Make and ModelWorcester Bosch Greenstar 25i Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating94.00%
Band RatingA
LPG Compatible?Yes
Parts and Labour Warranty in months60
Heat Exchange Warranty in months60
Output kW25
MountingWall Mounted
Flow Rate in litres per second9
Price from£955
Price to£995
ERP HeatA
ERP WaterA
TOTAL91.41%

The Greenstar range from Worcester Bosch are their most popular boilers due to their simple controls and user-friendly settings.

This model measures 710mm x 400mm x 330mm and it features an easy-use display panel concealed by a flip-down cover. 

With an efficiency rating of 94%, you can be secure in the knowledge your energy bill will be as low as possible as there is very little wasted energy with this boiler. 

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Worcester Bosch Greenstar 25Si Compact Boiler (91.16%)

Make and ModelWorcester Bosch Greenstar 25Si Compact Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating94.00%
Band RatingA
LPG Compatible?Yes
Parts and Labour Warranty in months60
Heat Exchange Warranty in months60
Output kW25
MountingWall Mounted
Flow Rate in litres per second8.9
Price from£1,055
Price to£1,095
ERP HeatA
ERP WaterA
TOTAL91.16%

This is a boiler with the same benefits as the previous Greenstar model yet constructed in a compact form. 

The measurements of this model are 690mm x 390mm x 280mm so can easily be installed in behind a standard kitchen unit for those short on space.

It features a high energy efficiency rating and comes complete with a 10-year warranty providing it is installed by an accredited Worcester Bosch engineer. 

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Best gas combi boilers for a medium-sized property

Combi boilers with outputs between 28kW and 34kW work well in medium-sized homes and they will cost less to run annually than a traditional or system boiler. 

There are currently 80 gas combi boilers in this category and the average price is £993.

Baxi Platinum 28kw Boiler (92.36%)

Make and ModelBaxi Platinum 28kw Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating89.00%
Band RatingB
LPG Compatible?No
Parts and Labour Warranty in months120
Heat Exchange Warranty in months120
Output kW28
MountingWall Mounted
Flow Rate in litres per second11.5
Price from£1,005
Price to£1,045
ERP HeatA
ERP WaterA
TOTAL92.36%

This boiler is just slightly shy of the grade ‘A’ SEDBUK rating with 89% efficiency but it features a 10-year warranty and it is built using high quality brass components for durability and longevity. 

The dimensions of the Baxi Platinum 28kw are 780mm x 450mm x 345mm.

It boasts EasyFill technology which tops up the central heating pressure automatically meaning less chance of needing an engineer. 

As with all the Baxi Platinum boilers, it comes in a smart, white design and features a chrome trim. 

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Baxi EcoBlue Advance 28kw Boiler (92.18%)

Make and ModelBaxi EcoBlue Advance 28kw Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating89.10%
Band RatingB
LPG Compatible?No
Parts and Labour Warranty in months120
Heat Exchange Warranty in months120
Output kW28
MountingWall Mounted
Flow Rate in litres per second11.5
Price from£1,080
Price to£1,125
ERP HeatA
ERP WaterA
TOTAL92.18%

The Baxi EcoBlue Advance 28kw boiler is an Energy Savings Trust Endorsed product and it meets the minimum energy saving requirements for Boiler Plus compliance and has a SEDBUK rating of ‘B’.

The dimensions of this boiler are 763mm x 450mm x 345mm and it has a 10-year warranty as standard.

This boiler is focused on being a reliable and energy efficient boiler suitable for a medium sized home. 

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Baxi Platinum 33kw Boiler (92.18%)

Make and ModelBaxi Platinum 33kw Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating88.90%
Band RatingB
LPG Compatible?No
Parts and Labour Warranty in months120
Heat Exchange Warranty in months120
Output kW33
MountingWall Mounted
Flow Rate in litres per second13.5
Price from£1,080
Price to£1,120
ERP HeatA
ERP WaterA
TOTAL92.18%

A Baxi Platinum boiler with a higher output, this model measures in at 780mm x 450mm x 345mm and is a wall-mounted unit. 

It features a minimal design with a concealed user panel and is complete with a chrome trim that adds to the modern finish. 

It has an energy efficiency rating of just over 88% and it is a favourite in the UK due to its ease of installation and maintenance

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Baxi EcoBlue Advance 33kw Boiler (91.94%)

Make and ModelBaxi EcoBlue Advance 33kw Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating89.10%
Band RatingB
LPG Compatible?No
Parts and Labour Warranty in months120
Heat Exchange Warranty in months120
Output kW33
MountingWall Mounted
Flow Rate in litres per second13.5
Price from£1,175
Price to£1,225
ERP HeatA
ERP WaterA
TOTAL91.94%

Much like the smaller EcoBlue model previously reviewed, the Baxi EcoBlue Advance 33kw boiler is a reliable unit with a 10-year warranty

The dimensions are 763mm x 450mm x 345mm and the internal components are housed in a classic white shell with a concealed user panel. 

This boiler is made in the UK Baxi factory and features front access to all parts which makes maintenance and servicing stress-free and quick

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Worcester Bosch 2000 30kw Boiler (91.62%)

worcester bosch 2000 boiler
Make and ModelWorcester Bosch 2000 30kw Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating93.00%
Band RatingA
LPG Compatible?No
Parts and Labour Warranty in months60
Heat Exchange Warranty in months60
Output kW30
MountingWall Mounted
Flow Rate in litres per second10.8
Price from£870
Price to£910
ERP HeatA
ERP WaterA
TOTAL91.62%

A competitively priced boiler for a medium sized home, the Worcester Bosch 2000 30kw boiler is a modern looking system with a chic circular digital display panel.

It measures 724mm x 400mm x 300mm, it has been designed to be extra quiet and it is easy access and quick to install. 

This boiler comes with a 6-year guarantee providing it is installed by a Worcester Bosch accredited engineer alongside any Greenstar Filter System. 

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Best gas combi boilers for larger homes

Using a combi boiler can work well to save you money in a larger home providing you install a boiler with an output of 35kW or higher

There are currently 49 gas combi boilers on the market that are suitable for larger properties and the average price is £1,370. 

Baxi 636 Boiler (92.43%)

Make and ModelBaxi 636 Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating89.00%
Band RatingA
LPG Compatible?Yes
Parts and Labour Warranty in months84
Heat Exchange Warranty in months84
Output kW36
MountingWall Mounted
Flow Rate in litres per second15
Price from£975
Price to£1,015
ERP HeatA
ERP WaterA
TOTAL92.43%

This is a powerful boiler that can easily be linked to your smart device for the ultimate in home-heating control on the go using the USense app.

It has an exceptionally light lift-weight of 29.5kg for easy installation, and benefits from the EasyFill Baxi technology to keep your central heating water pressure held at optimum level

It measures 700mm x 390mm x 285mm and features an LED control panel alongside two easy-use control knobs. 

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Baxi EcoBlue Advance 40kw Boiler (91.80%)

Make and ModelBaxi EcoBlue Advance 40kw Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating89.10%
Band RatingB
LPG Compatible?No
Parts and Labour Warranty in months120
Heat Exchange Warranty in months120
Output kW40
MountingWall Mounted
Flow Rate in litres per second16.4
Price from£1,235
Price to£1,285
ERP HeatA
ERP WaterA
TOTAL91.80%

The largest output model for the Baxi EcoBlue Advance range is the 40kW model which also boasts an impressive 16.4 flow rate to keep up with hot water demand.

This boiler comes with an impressive free 10-year warranty and easy to use controls. 

It measures 763mm x 450mm x 345mm and can be combined with the Baxi Time and Temperature control system to be Boiler Plus compliant. 

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Baxi Platinum 40kw Boiler (91.50%)

Make and ModelBaxi Platinum 40kw Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating88.90%
Band RatingB
LPG Compatible?No
Parts and Labour Warranty in months120
Heat Exchange Warranty in months120
Output kW40
MountingWall Mounted
Flow Rate in litres per second16.4
Price from£1,355
Price to£1,415
ERP HeatA
ERP WaterA
TOTAL91.50%

The highest level of output available in the Baxi Platinum range is the 40kW model which has dimensions of 780mm x 450mm x 345mm. 

As with the lower output models, it can be used in conjunction with the Time and Temperature control system from Baxi which would result in this boiler being Boiler Plus compliant. 

It comes complete with a free 10-year warranty as standard and it’s compatible with the uSense smart control app so you can program your favourite heat settings easily wherever you are. 

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Worcester Bosch Greenstar 8000 Life 35kw Boiler (90.59%)

Make and ModelWorcester Bosch Greenstar 8000 Life 35kw Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating94.00%
Band RatingA
LPG Compatible?Yes
Parts and Labour Warranty in months60
Heat Exchange Warranty in months60
Output kW35
MountingWall Mounted
Flow Rate in litres per second14.3
Price from£1,290
Price to£1,340
ERP HeatA
ERP WaterA
TOTAL90.59%

The latest range from Worcester Bosch is built upon the award winning Greenstar CDi classic range but boasts a brand new, modern design. 

This model measures 824.95mm x 440mm x 364.6mm and it is available in a gloss white finish with a unique port-hole style digital control panel. 

This range includes Worcester Bosch’s most powerful domestic boiler (50kW) and this 30kW model has the same great features including smart control technology and a 12-year guarantee as standard

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Worcester Bosch Greenstar 36CDi Compact Boiler (90.45%)

Make and ModelWorcester Bosch Greenstar 36CDi Compact Boiler
TypeCombi
PowerGas
LocationInternal
Condensing?Condensing
Efficiency Rating94.00%
Band RatingA
LPG Compatible?Yes
Parts and Labour Warranty in months60
Heat Exchange Warranty in months60
Output kW36
MountingWall Mounted
Flow Rate in litres per second12.9
Price from£1,345
Price to£1,395
ERP HeatA
ERP WaterA
TOTAL90.45%

This compact boiler measures 690mm x 390mm x 280mm but certainly does not lack in power or water flow rate.

It features user-friendly controls, frost protection and it has a low energy pump which will further reduce your heating costs

The Worcester Bosch Greenstar 36CDi Compact comes with a 10-year guarantee providing it is installed by a Worcester Bosch accredited engineer and serviced annually. 

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The top 10 system and regular boilers for larger homes

As you can see, the results for the top 10 regular and system boilers are dominated by models from Worcester Bosch

This is due to their generous warranty schemes, affordable price points, impressive customer reviews, and high efficiency ratings

MakeModel NameTypeEfficiency RatingParts and Labour WarrantyOutput kWPrice fromTOTAL
Worcester Bosch Greenstar 12Ri BoilerRegular92.00%6012£80091.79%
Worcester Bosch Greenstar 15Ri BoilerRegular92.00%6015£82591.72%
Worcester Bosch Greenstar 9i BoilerSystem93.00%609.2£88091.59%
Worcester Bosch Greenstar 18Ri BoilerRegular92.00%6018£88091.59%
Worcester Bosch Greenstar 12i BoilerSystem94.00%6012.2£89091.57%
Worcester Bosch Greenstar 24Ri BoilerRegular92.00%6024£93591.45%
Worcester Bosch Greenstar 15i BoilerSystem94.00%6015.3£95091.42%
Worcester Bosch Greenstar 21Ri BoilerRegular92.00%6021£97591.36%
Worcester Bosch Greenstar 18i BoilerSystem94.00%6018.4£1,00591.29%
Worcester Bosch Greenstar 21i BoilerSystem94.00%6021.6£1,01591.26%
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How much do gas combi boilers cost to install and how long does it take?

The cost to install a gas combi boiler can vary dramatically according to who installs it and how much work your property needs in order for it to function.

Depending on if you are moving the location of your boiler or if this is the first time you are using a combi boiler, you may have to pay anything up to or beyond £3,000 for installation. 

It also depends on who installs your boiler – for example, using an independent trader as opposed to a national provider may increase or decrease your bill. 

It can take anything from 1 to 3 days to install a gas combi boiler depending on how much preparation work is needed. 

We always recommend speaking to a Gas Safe engineer to find out an approximate quote for your property. 

How much will an A-rated boiler save you every year?

Here, we have compiled a table to show you roughly how much you could save by investing in a new ‘A’ rated boiler. 

We have adapted these statistics from figures released by the Energy Saving Trust. 

Your current boilerIts energy efficiencyFlatMid-terrace propertyDetached bungalowDetached two-story homeSemi-detached two story home
GUp to 70%£95£165£150£295£190
F70%-74%£65£115£100£205£135
E74%-78%£55£95£85£170£110
D78% to 82%£55£85£75£150£100

Although the cost of purchasing and installing a new boiler is a considerable outgoing, it’s worth noting that a new boiler will most likely pay for itself through the reduction in your gas bills over the following couple of years. 

Save up to 54% on your new gas boiler cost

You could save up to 54% of the cost of the supply and the installation of your new gas boiler by leaving your details with us on our form. 

We will contact three or four local, trusted, and Gas Safe-regulated engineers with your details who will get in touch with you directly for a free quote and any relevant advice. 

Our service is completely free for you and it is no obligation – there is no pressure to accept any of the offers from our partner installers if you decide not to go ahead so there really is nothing to lose.

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Andy

Andy is one of the HomeSage founders and an occasional content contributor. His love for boilers is only just outweighed by his love for football.