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Ariston vs Vaillant: Boiler Comparison & Reviews

Rob Wells
By: Rob Wells
Updated: 19th September 2023

Ariston Alteas One Net vs Vaillant ecoTEC Plus

Vaillant have been a leading UK boiler manufacturer for a number of years, setting industry standards with their innovative technology. Ariston, on the other hand, have built a good reputation in the heating industry and with the release of the ONE Series may well be worth considering alongside the premium Vaillant boilers.

To see if Ariston have bridged the gap to Vaillant, we've put them head-to-head to help you choose the right manufacturer when the time comes to replace your existing boiler.

Which will come out on top, Ariston or Vaillant?

Ariston One Series vs Vaillant ecoTEC Plus

We've put ranges from each manufacturer head-to-head to show what each brand has to offer: the Ariston ONE Series, Ariston's most advanced boilers to date and the Vaillant ecoTEC Plus, a range of boilers that deliver efficiency and performance.

Ariston vs Vaillant combi boilers

The One Series is Ariston's leading range of condensing wall-mounted boilers gas-fired combi and system boilers. Thanks to the high levels of efficiency these units can achieve, they've been endorsed by the Energy Saving Trust which should give you the confidence that an Ariston One Series boiler will help to keep your energy bills down.

The Vaillant ecoTEC Plus range of boilers have proven popular with homeowners as they're available in a wide range of outputs and can help to reduce energy bills. They're also highly rated amongst installers thanks to their ease of use and quality of the components.

Boiler CH output DHW output Efficiency
Alteas ONE Net 30 28 kW 30 kW 94%
Alteas ONE Net 35 31 kW 35 kW 94%
ecoTEC Plus 825 20.4 kW 25.4 94%
ecoTEC Plus 832 25.7 kW 31.8 kW 94%
ecoTEC Plus 835 32.2 kW 35 kW 94%
ecoTEC Plus 838 30.1 kW 38.7 kW 94%

CH = Central Heating. DHW = Domestic Hot Water.

Ariston vs Vaillant system boilers

Boiler CH output Efficiency
Clas System ONE 18 18 kW 90%
Clas System ONE 24 22 kW 90%
Clas System ONE 30 28 kW 90%
ecoTEC Plus 612 12.2 kW 92%
ecoTEC Plus 615 15.4 kW 93%
ecoTEC Plus 618 18.5 kW 94%
ecoTEC Plus 624 24.4 kW 94%
ecoTEC Plus 630 30.4 kW 94%
ecoTEC Plus 637 37.6 kW 94%

CH = Central Heating.

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Ariston ONE Series vs Vaillant ecoTEC


When compared with many other manufacturers, Vaillant often come out on top in terms of efficiency thanks, in part, to having a heat exchanger made from stainless steel. However, in Ariston ONE Series boilers have one too.

If used with the Cube RF heating controls (provided with the boiler) the Alteas ONE Net can achieve an ErP efficiency rating of A+. Plus, by using the Ariston Net app on your smart device, you will have the ability to control your heating from wherever you are and you'll also receive recommendations and advice to keep your energy bills down.


One Series and ecoTEC Plus boilers are made up of some key components that build on previous offerings by each manufacturer.

Features of Ariston One Series boilers:

  • Compared to previous Ariston boilers, the waterways are 142% wider which allows for increased amounts of water to pass through the system at a faster rate and greatly reduce the risk of a blockage.
  • The stainless steel XtraTech heat exchanger transfers heat at a better rate than previous models for increased efficiency.
  • If you're tired of the conventional white casing of most boilers, the Alteas ONE Net is fronted by an Ultrasafe black glass panel to give it a sleek modern design.
  • LPG conversion kits available for off-grid properties
  • Endorsed by the Energy Saving Trust

Features of Vaillant ecoTEC boilers:

  • Stainless steel heat exchanger for increased efficiency and extended lifetime
  • Precision heating helps to keep your energy bills down
  • Combi boilers are able to deliver hot water to taps and showers within 5 seconds
  • The ecoTEC Plus Combination Store unit is unlike other combi boilers as it can store up to 20 litres of hot water in the actoSTOR.
  • LPG models also available
  • Awarded a Quiet Mark accreditation thanks to being ultra-quiet during operation
  • Endorsed by the Energy Saving Trust


With Ariston introducing some of the lengthiest warranty periods available on the market, they're now in a much better position to compete with the likes of Vaillant than they might have been a few years ago.

As standard, Ariston boilers come with a 2 year warranty but warranty periods of 8-12 years are available depending on the model


As Ariston aren't often considered a leading boiler manufacturer, falling short of the standards set by the likes of Vaillant, Ideal, Worcester Bosch and Baxi, you might expect them to be competitive on price. However, with their ONE Series this isn't really the case, with price tags not too dissimilar to the Vaillant ecoTEC units.

Having said this, the high efficiency, extensive warranties and premium components available with Ariston boilers could mean they're making a case for being one of the leading manufacturers.

Based on the reviews from installers, Vaillant have built a reputation for manufacturing reliable systems that won't let you down making them a worthwhile investment.


On top of the price of the unit itself, you will also need to consider the installation costs which will vary based on a number of reasons:

  • Time of year
  • Where you live (installers in London tend to be more expensive)
  • Rates charged by the installer or company
  • Type of boiler being installed
  • How simple the boiler is to install

We're going to focus on this last point as manufacturers are continuously working to make the installation of their boilers more straightforward.

Ariston ONE Series boilers are lightweight and have simple-to-fit connections. Plus, if you already have an Ariston boiler installed in your home, the ONE series units connect up in all the same places, making the installation a much simpler process.

Once the unit has been installed, when it comes to servicing or any repairs, frontal access as well as generous spacing between components makes the whole process much simpler.

Vaillant ecoTEC Plus combi boilers have been voted the easiest combi boiler to install by installers in the 2019 UK Domestic Gas Boiler Survey. This comes mainly down to the compact dimensions and low lift weight but the addition of a filling loop – which refills the central heating system with water – helps to make things simpler too.

To help you find the most competitive price for installation, we highly recommend comparing quotes from multiple engineers. And at Boiler Guide, we've made finding quotes simpler than ever.

Simply take a few moments to click through our online form and you'll soon get free quotes from up to 3 boiler installers based near you. Compare the quotes based on price, knowledge and customer service then you choose to hire the best installer for you. Or not, there's no-obligation whatsoever.

Winning boiler manufacturer: Ariston or Vaillant?

So, is an Ariston boiler worth considering over a Vaillant unit?

There's no denying that the Alteas ONE Net with its black glass front has made a mark on the industry and not only in terms of aesthetics. The Ariston ONE Series includes a range of highly-efficient units covered by extensive warranties that are pretty straightforward to install too.

Vaillant have been a trusted range for a number of years, leading the way in terms of innovation and their ecoTEC Plus range includes some of the best boilers on the market. Their boilers have been tried and tested and if your decision ultimately comes down to price, a Vaillant ecoTEC Plus boiler could be the cheaper choice.

While we might have crowned Vaillant the winner, they'll need to keep on their toes because Ariston are an ambitious brand manufacturing some very desirable boilers.

Rob Wells

About the author

Rob Wells

Rob is another of our resident home heating experts. He manages our external partnerships, making sure you get the most up to date information.

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