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Worcester Bosch vs Vaillant - A Boiler Comparison

No to gas boilers

Time and time again, the battle for the title of ‘Top Boiler Brand’ comes down to two contenders: Worcester Bosch or Vaillant. Both brands consistently come out on top in both customer satisfaction and engineer recommendation surveys.

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When it comes to choosing between them it can be a very close call, so we’ve compared a Combi boiler manufactured by each brand to find a winner – Worcester Bosch Greenstar vs Vaillant EcoTec.

Who are Worcester Bosch and Vaillant?

Worcester Bosch began life as an independent business in Worcester, England, in 1962 before joining the international Bosch Group in 1992. They currently hold the Royal Warrant to supply heating products to the Royal Family. According to consumer and engineer research conducted by Which? the brand has been recognised as the ‘Best Buy’ boiler brand for six years running with an overall rating of 92%.

Vaillant is a German, family-run company that has been operating for over 140 years. While they boast German design and engineering, their boilers are actually manufactured in the UK which means replacement parts are easy to come by. The brand comes a close second to Worcester Bosch in consumer and engineer reviews with an overall rating of 83%. Vaillant are the only brand to have been awarded the Quiet Mark accreditation by the International Eco-Award Scheme to manufacturers of the quietest products.

Worcester Bosch Greenstar vs Vaillant EcoTec

When looking to compare Worcester Bosch and Vaillant, it makes sense to pick a comparable boiler from each manufacturer – the below table compares a wall-mounted, 25kW gas Combi boiler from each brand. Both are recommended for flats or small houses with one bathroom and up to 10 radiators.

As with all Combi boilers, they do not require a storage cylinder or tank as they heat water on demand. For that reason they are not suitable for homes with multiple bathrooms and a high demand for hot water.

Boiler Make / Model Worcester Bosch Greenstar 25i Vaillant EcoTec Plus 825
Other outputs available (kW) 30, 34, 38, 42 32, 35, 38
ErP Rating (efficiency) A (93%) A (89.4%)
Size (HxWxD) 71x40x33cm 72x44x34cm
Hot water flow rate (litres per min) 10.2 9.4
LPG compatible model available Yes Yes
Standard warranty 5 years (extendable up to 10 years if installation meets certain conditions*) 5 years (extendable up to 10 years at an additional cost)
Noise Level Output (dB) 50 46
*Boiler needs to be installed by an accredited installer, fitted with Worcester Bosch official filter and controls
and serviced annually by a Gas Safe registered engineer.

Compare more powerful boilers in these ranges in Worcester Bosch 30i vs Vaillant ecoTEC Plus 832.



When it comes to down to price there’s not a lot in it, but Vaillant do come in a little more expensive than Worcester Bosch. The typical price of a Greenstar 25i by Worcester Bosch falls between £750 – £875 while a comparable Vaillant EcoTec Plus 825 costs approximately £1000 – £1050.

Prices will vary depending on which supplier you choose. Boiler Guide can provide up to 3 different boiler quotes, tailored for you, so you can be sure you’re getting the best deal.

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Repairs and Warranties

As you’d expect for brands with such high customer and engineer recommendations, we struggled to find any ‘common’ faults associated with either brand; engineers that had come across faults reported them as easy to repair. Both brands include at least a five year warranty as standard, have dedicated engineers in the UK for call-outs and both have parts readily available in the UK.

However, while both manufacturers offer warranties of up to 10 years, it is worth noting that Vaillant’s is only available at an additional charge. In contrast, an extended Worcester Bosch guarantee is included with no extra charge providing the installation is carried out by an accredited installer who uses approved parts and the boiler continues to be serviced annually.

Find Out More About Vaillant Boilers


Worcester Bosch have a slightly wider range of boilers and sizes than Vaillant including the Greenstar Compact which will fit into most kitchen cupboards. If space is an issue in your home this may be something worth considering.


Both Worcester Bosch and Vaillant offer traditional, mechanical controls with 24 hour programming as well as digital controls that enable up to 7 day programming. In addition, there are also options to introduce wireless controls (aka smart thermostats) that can be operated via tablets or smartphones and, in some cases, sensors will automatically adjust to compensate for the weather.

The Verdict

So what’s the verdict? The two brands are so closely matched it is genuinely hard to declare a ‘winner’ in this particular battle. However, there are a handful of areas where the Worcester Bosch has the edge:

  • Typically, Worcester Bosch have a lower price tag (this can vary with the installation costs of different engineers)
  • Worcester Bosch offer an extended warranty at no extra charge if you use an accredited installer
  • They have a wider range of boilers, including compact models that will fit into a kitchen cupboard
  • Worcester Bosch have been the ‘Best Buy’ winners with an overall rating of 92% for the last 6 years


Find Out More About Worcester Bosch Boilers

Each installer will have their own experiences of each brand from past installations so it’s important to get multiple quotes. It’s worth asking the installer if they receive any incentive to install a certain brand; if the answer is yes, keep in mind that you may not be getting impartial advice. On the other hand, if an installer is specially trained to install a brand it could mean that you receive an extended manufacturer warranty.

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Excellent 4.7 out of 5

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