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Which is the Best 30kW Combi Boiler?

Adam Cherry
By: Adam Cherry
Updated: 15th September 2021

Best 30kW Combi Boilers

You know you need a 30kW combi boiler but now you need to find one.

To do that, you'll need to know whether that 30kW output rating (which is a measure of the boiler's power) is for central heating or hot water. As combi boilers have a separate output rating for each one. And these ratings are rarely the same.

Here you’ll find a list of the best combi boilers with a 30kW output for central heating (CH) and the best for domestic hot water (DHW) – jump to the list you need:

Best 30kW combi boilers (DHW)
Best 30kW combi boilers (CH)

What is a 30kW combi boiler?

All types of boiler heat the home on demand but only a combi provides instant hot water.

That's because they don't store water in a cylinder – like system boilers and regular boilers. Instead, they heat water from the mains each time you turn on a hot tap

For this reason, combi boilers have a central heating output rating as well as a domestic hot water output rating. Both will need to match the needs of your home.

Is a 30kW combi boiler right for my home?

A combi boiler with a DHW output of 30 kW is great for homes with a bathroom and ensuite. Meanwhile, a CH output of 30kW suits homes with around 15 radiators.

Not sure if a 30kw combi is right for your home? Then contact a Gas Safe registered engineer to find out.

Best 30kW combi boiler: Domestic hot water

If you're looking for a combi boiler with a domestic hot water output of 30kW, you should consider one of these:

  • Ariston Clas One
  • Baxi 830
  • Ideal Logic Max
  • Vaillant ecoTEC Pro
  • Viessmann 200-W
  • Worcester Greenstar 8000 Style
Best 30kW combi boilers CH output DHW output Seasonal space heating efficiency Warranty
Ariston Alteas One Net 28 kW 30 kW 90.3% 12 years
Baxi 830 21.1 kW 30 kW 93% 10 years
Ideal Logic Max C30 24.2 kW 30.3 kW 94% 10 years
Vaillant ecoTEC Pro 25.7 kW 30 kW Up to 94% 2 years
Viessmann 200-W 25.4 kW 30.5 94% Up to 10 years
Worcester Greenstar 8000 Style 30 kW 30.2 kW 94% Up to 12 years

Ariston Alteas One Net

Ariston Clas One Net
The Ariston Alteas One Net is a highly efficient condensing combi boiler with a sleek black-coloured glass front, which gives it a very modern look and feel. The warranty period of 12 years is the most extensive you'll find on a combi boiler and if you use the heating controls provided with your Ariston boiler, it will achieve an ErP A+ rating.

Benefits of the Alteas One Net

  • Quiet operation levels that are similar to a fridge freezer
  • Easy-to-use LCD display gives greater control
  • Fitted with an XtraTech stainless steel heat exchanger which boasts 142% wider waterways to increase its effectiveness and greatly reduce the risk of a blockage
  • The 'COMFORT' function ensures that the heat exchanger remains pre-heated to deliver instant hot water when you need it
  • Weighs only 35.3kg making it lightweight and simple to install
  • Additional space within the boiler makes installation, servicing and any repairs simple for engineers

The Alteas One Net range includes another combi boiler with an output rating of 35 kW.

Baxi 830

Baxi 830
The Baxi 830 is part of the Baxi 800 range of boilers, which are compact, lightweight and fitted with brass hydraulics. It's potentially the most affordable of the best 30kW combi boilers but is still a high-quality heating system that's covered by a lengthy 10 year warranty.

Features of the Baxi 830

  • Fitted with an ADEY Micro2 magnetic system filter which protects the boiler and entire heating system
  • Able to fit within a standard kitchen cupboard
  • Low lift weight (29.2kg) makes for an easier installation
  • Flue options of up to 20 metres for a flexible installation
  • Control the boiler wherever you are using a smartphone or tablet

This range from Baxi also includes the 825 (25kW) and 836 (36kW) models.

Ideal Logic Max C30

Ideal Logic Max C30
Ideal are one of the most reputable boiler brands around and their Logic Max C30 is a highly efficient and effective home heating system. Their confidence in this unit is shown proven by an extensive 10 year warranty which can be extended to 12 years when installed by an Ideal Max accredited installer.

Features of the Ideal Logic Max

  • Easy to use thanks to a large backlit LCD digital display
  • Compact in size which means it can be hidden away in a standard cupboard
  • Fully-compatible with Ideal controls
  • Boiler frost protection to prevent the water in the boiler from freezing should the temperature drop below 5°C

If a heating engineer recommends a lower or higher output for the heating and hot water demands of your home, the Logic Max range also offers outputs of 24kW and 35kW.

Vaillant ecoTEC Pro

Vaillant ecoTEC Pro
Vaillant are a manufacturer well known for delivering efficient heating systems and their ecoTEC Pro 30 boasts efficiency of up to 94%. Compared with other combi boilers, the 2 year warranty period of the ecoTEC Pro is relatively short but it can be extended to 7 years when the installation is registered through Vaillant Advance.

Features of the Vaillant ecoTEC Pro

  • A premium stainless steel heat exchanger increases efficiency
  • Compact dimensions of 720 x 440 x 338mm (HxWxD) will save space
  • Awarded Quiet Mark accreditation thanks to low noise levels during operation
  • Delivers hot water at a rate of 12.3 litres per minute
  • The 'aquaCOMFORT' feature increases the speed of hot water delivery
  • Fitted with a low NOx burner and fan that are fully modulating to increase efficiency
  • Take control of the heating wherever you are using the vSMART app

Other outputs in the Vaillant ecoTEC Pro combi range include 24kW and 28kW models.

Viessmann 200-W

Viessmann 200-W
With the ability to achieve efficiency ratings of up to 98%, the Viessmann 200-W is one of the most efficient combi boilers available on the market.

Viessmann 200-W features

  • Quiet during operation
  • Modulation range of 1:17 for increased efficiency
  • Fitted with a stainless steel Inox-Radial heat exchanger to increase efficiency
  • Control from your smartphone or tablet using the ViCare app
  • Option to extend the warranty period to 10 years

Output ratings of 26kW and 35kW are also available in this range of Viessmann boilers.

Worcester Greenstar 8000 Style

Worcester Bosch Greenstar 8000 Style
Not many boilers are available in different colours but Greenstar 8000 Style boilers give you the choice of white or black. So you can make sure it suits your home.

Features of the Greenstar 8000 Style

  • Take your pick of a black or white unit
  • A modulation ratio of 1:10 means the boiler can greatly reduce the amount of energy it uses to help lower your bills
  • Lightweight to make installation easier, help to lower installation costs
  • Full-colour digital display with clear text
  • The standard 5 year guarantee can be extended to 12 years

Best 30kW combi boilers: Central heating

These combi boilers are a great option for a home with around 15 radiators.

Best 30kW combi boilers (CH) CH output DHW output Seasonal space heating efficiency Max warranty
Alpha E-TEC 29.7 kW 32 kW 93% 7 years
Baxi Duo-tec 30.3 kW 33 kW 93% 7 years
Vaillant ecoTEC Plus 838 30.1 kW 38.7 kW 94% 10 years
Worcester Bosch Greenstar 8000 Style 30 kW 30.2 kW 94% 12 years

Only the Worcester Bosch Greenstar 8000 Style features in both lists of the best 30kW combi boilers.

Alpha E-TEC

Alpha E-Tec
The Alpha E-Tec is the smallest combi boiler ever made by Alpha so it can be hidden away in a cupboard.

Features of the Alpha E-TEC

  • Increased efficiency thanks to a stainless steel heat exchanger
  • Delivers 14.1 litres of hot water to a tap in a minute
  • You'll be well covered by a warranty of 7 years

Baxi Duo-tec

Baxi Duo-Tec
Baxi are well-known for making efficient and reliable heating systems and the Duo-tec combi is no different.

Features of the Baxi Duo-tec

  • A strong flow rate of 13.5 litres per minute
  • Greater choice of where to fit the boiler thanks to a range of flue lengths
  • Lengthy warranty of up to 7 years
  • Designed for easy installation so the installer won't need to be in your home for long

Vaillant ecoTEC Plus 838

Vaillant ecoTEC Plus 838
The Vaillant ecoTEC Plus 838 has the highest DHW output of all the boilers in this article (38.7 kW). So it can comfortably meet the hot water needs of a home with 2 bathrooms.

Features of the ecoTEC Plus 838

  • A very powerful DHW output of 38.7 kW
  • Delivers a flow rate of 20 litres per minute
  • Low energy usage thanks to a modulation range of 1:6
  • Quiet Mark approved to show that it's near-silent as it heats the home
  • The warranty can be extended from the standard 5 years to 10 years

Worcester Bosch Greenstar 8000 Style

Worcester Bosch Greenstar 8000 Style
The Worcester Greenstar 8000 Style is the only combi boiler to offer a 30kW output for both central heating and domestic hot water. Making it the ideal choice for homes with 2 bathrooms and around 15 radiators.

Features of the Greenstar 8000 Style

  • Take control of the heating and hot water with the Bosch EasyControl app
  • Pressure will remain strong thanks to the intelligent filling system
  • Energy consumption is kept to a minimum thanks to a modulation ratio of 1:10
  • You can extended the warranty to 12 years

30kW combi boiler costs

The best 30kW combi boilers will potentially cost around £960 to £1,565.

This is before addingthe installation which will typically be priced at between £500 – £1,000. But completely depends on the ease of installation and rates charged by the installer. Which is why comparing quotes is always a good idea.

Best 30kW Combi Boilers (DHW) Potential Cost
Ariston Alteas One Net £1,300
Baxi 830 £955
Ideal Logic Max C30 £1,026
Vaillant ecoTEC Pro 30 £1,211
Viessmann 200-W £1,550
Worcester Bosch Greenstar 8000 Style £1,200
Best 30kW Combi Boilers (CH) Potential Cost
Alpha E-TEC £745
Baxi Duo-tec £898
Vaillant ecoTEC Plus 838 £1,408
Worcester Bosch Greenstar 8000 Style £1,200

Best 30kW combi boilers for off-grid homes

All of the best 30kW combi boilers we've highlighted above are fueled by natural gas which can't be installed into off-grid properties. Homes in this situation will need either an LPG or oil boiler, fuels that can be stored onsite.

Fortunately, the majority of the best 30kW combi boilers are LPG compatible. Find out which in the table below.

Best 30kW Combi Boilers (DHW) LPG Compatible?
Ariston Alteas One Net Yes
Baxi 830 No
Ideal Logic Max C30 Yes
Vaillant ecoTEC Pro No
Viessmann 200-W Yes
Worcester Bosch Greenstar 8000 Style Yes
Best 30kW Combi Boilers (CH) LPG Compatible?
Alpha E-TEC Yes
Baxi Duo-tec No
Intergas Combi Compact Eco RF Yes
Vaillant ecoTEC Plus 838 No
Worcester Bosch Greenstar 8000 Style Yes

The alternative to LPG is oil. There aren't any oil combi boilers with an output rating of 30kW but Warmflow and Worcester Bosch have models that could still be suitable.

Oil Combi Boilers Output Rating Efficiency Warranty Potential Cost
Warmflow Utility UC120HEE 33 kW 89.1% 5 years £1,990
Worcester Bosch Greenstar Heatslave II 32 kW 91% 2 years £2,350

Free combi boiler installation quotes

If you're looking for a new combi boiler, we can connect you with Gas Safe registered engineers based in your area who are fully-qualified to carry out the installation. Simply pass through our online form and you'll get free quotes from up to 3 heating engineers based in your area.

Adam Cherry

About the author

Adam Cherry

Adam is our resident home heating expert. His experience and advice has helped millions of customers improve the efficiency of their homes and save money.

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