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Which is the Best Combi Boiler? Pros, Cons and Costs

Best Combi Boiler
 

Looking for the best combi boiler? You want a combi boiler which is reliable, effective, has a long warranty and is cheap to run. We are here to help by not only highlighting the 5 best combi boilers, but also answering that all important question: how much does a combi boiler cost?

Year after year, these boiler manufacturers are well reviewed by both homeowners and installers thanks to providing the most reliable, energy efficient and high performance range of combi boilers available today.

What is a combi boiler?

Combi boilers are the most commonly installed type of boiler in the UK for a number of reasons. While system and regular boilers require a hot water storage cylinder, a combi boiler is an all-in-one unit which will produce hot water for central heating and your taps. This saves a great deal of space in your home and often means it can be tucked away in a kitchen cupboard. With no water tank or cylinder needed it also results in a simpler and faster installation.

A combi boiler takes its water supply directly from the mains which usually results in a stronger pressure. A combi boiler gives you the luxury of hot water on demand so there's no need to worry about running out and having to wait for the tank to refill. CCombi boilers work by heating water directly from the mains, so you don't need a hot water storage cylinder or cold water tank.

5 best combi boilers

Choosing the best boiler replacement can be a confusing process at first, but with the right professional advice you needn't worry. While some larger or older homes may require a system or regular boiler because of a higher hot water demand or incompatible pipework/radiators, most homeowners will install a combi boiler with a power output sized between 24 – 40 kW.

But which are the best combi boilers on the market? We've put together this article to point you in the right direction.

Year after year, these boiler manufacturers are well reviewed by both homeowners and installers thanks to providing the most reliable, energy efficient and high performance range of combi boilers available today.

  1. Vaillant ecoTEC plus Combi
  2. Worcester Bosch Greenstar i Combi
  3. Baxi 800 Platinum+ Combi
  4. Viessmann B2KB Vitodens 200W
  5. Ideal Vogue Max Combi

Vaillant ecoTEC plus Combi

Vaillant ecoTEC Plus Combi Boiler

The ecoTEC Plus is Vaillant's 'flagship' model and widely recommended by professional heating engineers. It is available in outputs of 25, 32, 35 or the largest 38 kW which is a great choice for larger homes with a high demand for hot water.

This boiler includes a 5 year warranty as standard with 7 or 10 years available when installed by a Vaillant accredited installer.

The ecoTEC Plus is also one of the more stylish models on the market with back lit digital display, contoured case and stainless-steel heat exchanger. The boiler has been awarded the Quiet Mark accreditation because of how quiet the boiler is when it is in operation.

Key Vaillant ecoTEC Plus features:

  • Rapid hot water delivery in just 5 seconds
  • Wide modulation range of up to 1:6 results improves energy efficiency
  • Flame lift detection system enables quieter combustion
  • Stylish contoured case design
  • Two-stage frost protection built in
  • Quiet Mark accreditation
  • Designed for quick installation
  • Compatible with aroTHERM air to water heat pump hybrid system
  • LPG convertible
  • Available with a range of controls including wired, wireless and smart (vSmart by Vaillant)

The ecoTEC plus includes smart technology enabling it to drop to just 16% of its power when you don't need much heating, so you can save money and reduce emissions.

Worcester Bosch Greenstar i Combi

Worcester Bosch Greenstar i Combi Boiler
According to Worcester Bosch, this is their most popular combi boiler. It has been awarded a Which? Best Buy Award for 7 years running and regularly tops both homeowner and installer polls for reliability and performance. In addition, the brand currently holds the Royal Warrant to supply heating to the Royal Family.

Worcester Bosch Greenstar i features & benefits:

  • Simple boiler controls with clear information display
  • Zero risk of condensate pipe freezing in severe weather (resilient to freezing up to -15C)
  • Wide choice of controls including mechanical, digital and smart (Wave by Worcester Bosch)
  • Compact design for kitchen cupboard installation
  • Low energy pump reduces electrical usage
  • LPG convertible
  • Which? Best Buy Award for 7 years running
  • Achieves an A+ ErP package efficiency rating for heating when installed with a Wave smart internet connected control
  • Fills a standard kitchen sink in 45 seconds

The Greenstar i is ideally suited to small and medium sized homes looking for a low maintenance, low cost and reliable combi boiler.

Baxi 800 Platinum Combi

Baxi 800 Platinum
Baxi have been building a great reputation amongst boiler installers and offer homeowners having been manufacturing since 1866. Baxi offers an extensive range of gas boilers that are innovative, efficient and durable.

The Baxi 800 Platinum range is available in outputs of 24, 28, 33 and 40 kW. The boiler delivers an impressive flow rate with the 40 kW delivering up to 16.4 litres of hot water per minute which is perfect for homes with more than one bathroom.

Other key features and benefits include:

  • A rated for energy efficiency
  • Can be controlled using your smartphone or tablet
  • Optional built-in mechanical 24 hour timer
  • A low lift weight and compact size makes for a simple installation
  • Front access means easy maintenance and servicing saving you time and money
  • The Adey Micro2 Magnetic System filter offers long lasting protection
  • Available with an extensive 10 year warranty
  • Built-in frost thermostat.

The Baxi 800 Platinum 40 kW is ideal for larger homes with more than one bathroom.

Viessmann B2KB Vitodens 200W

Viessmann B2KB Vitodens 200W

The Viessmann 200W is available in several outputs between 1.9 – 35 kW. Other key features and benefits include:

  • A rated for efficiency with up to 98% of fuel used by the unit can be turned into heat
  • Very quiet in operation
  • The stainless steel Inox-Radial heat exchanger increases efficiency and reliability
  • Long life thanks to the MatriX-Plus burner with stainless steel MatriX surface
  • 7-inch colour touchscreen
  • You can control your boiler by connecting it to the WiFi and controlling it from your smartphone or tablet using the ViCare app
  • Includes a 3 year warranty as standard which extends to 5 year warranty if installed by a Viessmann accredited installer with the option to extend to 10 years
  • Compact wall-mounted boiler
  • Low fan speed results in quiet operation

The digital Viessmann 200W is A rated for efficiency – up to 98% of fuel used by the unit can be turned into heat – saving the homeowner money and keeping emissions to a minimum.

Ideal Vogue Max Combi

Ideal Vogue Max

Ideal has been designing high quality boilers in the UK for over 100 years and is well known in the industry for producing great boilers at more affordable prices than other manufacturers. Ideal offers real value for money when compared to some other brands and is a popular choice for many homeowners and installers.

The Vogue Max Combi boiler is a relatively recent addition to the manufacturer's range and is regarded as their premium boiler. It is available in outputs of 26, 32 or 40 kW. This boiler includes a 10 year standard warranty straight out of the box, but this is increased to 12 years when the boiler is installed by an Ideal "Max" accredited installer.

  • 10 or 12 year warranty
  • Easy to read pressure gauge
  • Compatible with range of Ideal controls
  • Full text support for fault modes
  • Premium product using best components available
  • Compact unit with low lift weight enables quick installation
  • Service timer with telephone number display / service display to remind you when the annual service is due
  • Features a stylish composite design with damped opening control cover and large rotary control dials
  • Simple customer user interface; 3.5in full colour large backlit LCD display with plain text and graphics.

In addition to a high quality boiler with a 12 year warranty, Ideal offers real value for money when compared to some other brands.

Boiler-Comparison-Tool
Boiler-Comparison-Tool

How much does a combi boiler cost?

When it comes to combi boiler prices, the first thing to realise is that you will get different prices depending on the installer you choose to supply and fit the boiler. Having said that, there is a difference between brands in terms of price as some are more costly than others.

We can't provide quotes or guarantees about how much a boiler is likely to cost you, but we can give you some estimates based on research.

Of the combi boilers we have looked at in this article, the Viessmann Vitodens is generally the most expensive on the market, while the Ideal Vogue Max is the least expensive.

Combi Boiler Model Typical Price (excluding installation)
Vaillant ecoTEC plus Combi £1,100 – £1,500
Worcester Bosch Greenstar i Combi £900 – £1,200
Baxi 800 Platinum+ Combi £1,200 – £1,500
Viessmann B2KB Vitodens 200W £1,400 – £1,700
Ideal Vogue Max Combi £800 – £1,100

Combi boiler installation costs

Once you've found the right combi boiler for your home, you'll need to hire a Gas Safe registered engineer to carry out the installation, which will add to the upfront cost of the unit itself.

The simplest, and likely to be the cheapest, combi installation is a like-for-like replacement, in other words, replacing an old combi boiler with a new one in the exact same location. Typically, this type of installation will cost somewhere between £500 and £700.

A more complex combi installation, which could involve replacing a different type of boiler (regular or system) or having the combi installed in a new location, would end up costing you more. In some of the most extreme cases, the total cost of having a new boiler installed could reach £2,500.

Combi Boiler Model Typical Price (excluding installation) Approximate cost of boiler fully installed
Vaillant ecoTEC plus Combi £1,100 – £1,500 £1,600 – £2,200
Worcester Bosch Greenstar i Combi £900 – £1,200 £1,400 – £1,900
Baxi 800 Platinum+ Combi £1,200 – £1,500 £1,700 – £2,200
Viessmann B2KB Vitodens 200W £1,400 – £1,700 £1,100 – £1,500
Ideal Vogue Max Combi £800 – £1,100 £1,300 – £1,800

Boiler-calculator
Boiler-calculator

Best oil combi boilers

While most homes in the UK use gas combi boilers, there are some homes which are not connected to the gas grid. For these homes, oil combi boilers or LPG (liquid petroleum gas) combi boilers may be the best option. With oil and LPG boilers, you need to keep fuel on your property in a safe storage container and have your fuel delivered on a regular basis.

Of the gas combi boilers we have included in this article, the following are compatible with LPG:

  • Worcester Bosch Greenstar i
  • Viessmann B2KB Vitodens 200W
  • Vaillant ecoTEC plus Combi
  • Ideal Vogue Max Combi

If you are looking for an oil fired combi boiler, here are 3 of the best oil combi boilers on the market as well as average costs.

Combi Boiler Model Available Outputs (kW) Approximate cost of boiler (excluding installation)
Worcester Bosch Greenstar Heatslave II 18, 25, 32 £2,000 – £2,400
Grant Vortex Blue Internal 15-21, 21-26, 26-36 £1,500 – £2,500
Warmflow Kabin-Pak Combi 21, 26, 33 £1,900 – £2,200

Which size combi boiler do you need?

Combi boilers are available in a range of outputs to suit homes of most sizes from 1 bedroom flats to 4 bedroom houses and it's vital that you get a combi boiler with the right output installed for your home. A combi that's too small won't be able to meet your heating and hot water requirements, while a combi that's too powerful will end up increasing your energy bills.

However, if you have plans to expand your home, e.g. you're adding a conservatory, converting a loft space and/or adding more inhabitants, you may want to get a bigger boiler to ensure it meets your long term needs.

Generally speaking, the more bedrooms and bathrooms you have, the higher the output of your boiler needs to be. A professional installer will be able to recommend the best combi boiler for your home but to help you narrow down your search, we've put together some guidelines based on industry recommendations:

Bedrooms Bathrooms Radiators Recommended Output
1 – 2 1 Up to 10 24 – 27kW
2 – 3 2-3 Up to 15 28 – 34kW
4+ 3+ Up to 20 35 – 42kW

For larger properties with multiple bathrooms, lots of inhabitants or a particularly high need for hot water, a combi boiler may not be suitable. This is because a combi boiler takes its water supply directly from the mains and heats on demand when a tap or shower is turned on. If multiple outlets require hot water at the same time, the combi boiler may struggle to maintain a consistent supply. For this reason a professional heating engineer may recommend a system or regular boiler rather than a combi as these systems include a hot water cylinder that stores a higher volume of hot water.

To help in your search for the best combi boiler for your home, you can compare combi boilers with different outputs in these guides:

1-2 bedroom house

Combi boilers are ideal for small homes with 1-2 bedrooms and one bathroom. Typically, the best size combi boiler for these homes is between 20-27 kW. If you have two bathrooms, e.g. a family bathroom and an ensuite, you may need a slightly more powerful combi boiler. Here are the best combi boilers in that size range:

  • Vaillant ecoTEC plus 25 kW
  • Worcester Bosch Greenstar i 25 kW
  • Baxi 800 Platinum Combi 24 kW
  • Viessmann B2KB Vitodens 200W 26 kW
  • Ideal Vogue Max Combi 18 or 26 kW
  • 3-4 bedroom house

    Homes with 3-4 bedrooms and two bathrooms may need a more powerful combi boiler to cope with the higher number or radiators and greater demand for hot water. Here are the best combi boilers in that size range:

    • Vaillant ecoTEC plus 32 or 35 kW
    • Worcester Bosch Greenstar i 32 kW
    • Baxi 800 Platinum Combi 28 or 33 kW
    • Viessmann B2KB Vitodens 200W 30 or 35 kW
    • Ideal Vogue Max Combi 32 kW

    5+ bedroom house

    Generally speaking, a combi boiler is not suitable for a bedroom with lots of bedrooms and multiple bathrooms. It's likely that an engineer will recommend a system boiler which incorporates a hot water cylinder to store a higher volume of hot water. If you have an older home or weak water pressure in your area, a regular boiler may be more suitable.

    Having said that, there are some manufacturers which produce powerful combi boilers for larger homes:

  • Vaillant ecoTEC plus 38 kW
  • Baxi 800 Platinum Combi 40 kW
  • Benefits of a combi boiler

    No matter which of the best combi boilers you choose, there are a number of general benefits to having a modern combi boiler provide your central heating and hot water.

    Combi boilers are the most commonly installed boiler type in the UK. When you turn on the heating or a tap, the combi boiler responds within seconds taking water directly from the mains supply and heating it on demand. There's no need for a tank of cold water in the attic or a large storage cylinder in an airing cupboard – the combi boiler does it all from one compact unit.

    High levels of efficiency

    All combi boilers installed in UK homes have to meet efficiency levels of at least 92%, meaning that combi boilers achieve incredibly high levels of efficiency which will not only help to lower your carbon footprint but could reduce your energy bills too.

    Can help to lower your energy bills

    Thanks to their high energy efficiency, a combi will help to save you money on your energy bills. A combi boiler with 92% efficiency, will only lose 8% of the fuel it uses, meaning that for every £1 you’re spending on your energy bills, only 8p is wasted.

    So, if you’re planning to replace your current boiler with a modern combi boiler, then you could potentially be saving £315* a year on your energy bills.

    Space saving thanks to their compact size

    There are 3 different types of boiler: combi, regular (traditional or heat-only too) and system.

    Out of these, combi boilers are the only type that don’t need any water tanks or storage cylinders. This is because everything it needs to heat your home and hot water is wrapped up into a single compact unit.

    Hot water to taps on demand

    Rather than the hot water being stored in a hot water cylinder, which can mean having to wait for hot water, like with regular and system boilers, combi boilers take water straight from the mains and heat it on demand when you turn the hot water tap. Not only does this get you quicker access to hot water but stronger water pressure too.

    Easy to install

    With everything being wrapped up into a single unit, combi boilers are the easiest type of boiler to install, especially when replacing an old combi boiler with a new one. This will help to save you time and money when it comes to the installation.

    Quiet as they heat the home

    The quietest combi boilers heat the home at a noise level similar to modest rainfall. Find the Quietest Combi Boiler.

    Find the best combi boiler installers

    While the price of installation will vary depending on the type of installation, you can really help yourself by comparing quotes from multiple combi boiler installers and that's where we can help.

    Complete our simple online form to let us know the type of work you need, which shouldn't take long at all, and we'll match your needs with fully-qualified Gas Safe engineers in your local area. You'll soon be contacted by up to 3 heating engineers who will all provide a free quote, leaving you free to compare them. That way, you can choose the quote that's best for you and make the best possible start with your combi boiler installation.


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    Adam

    About the author

    Adam

    Adam is our lead content writer who spends most of his time researching and writing articles for the Boiler Guide website. You can rely on him to keep you up to date about the future of home heating.

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