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 4.7 stars

1,265 reviews

 4.7 stars

1,265 reviews

Vaillant or Glow-worm: Boiler Comparison & Reviews

Vaillant vs Glow-worm

Vaillant and Glow-worm are both part of the Vaillant Group, Europe's second largest heating manufacturer, but when it comes to choosing the right manufacturer for you, their boiler ranges offer different advantages.

While Vaillant are one of the leading manufacturers thanks to delivering highly efficient units, Glow-worm boilers tend to be much more affordable with no compromise on reliability.

So, Vaillant or Glow-worm? We've put them head-to-head to give you the confidence that you're investing in the right boiler manufacturer for you.

Who are Vaillant and Glow-worm?

Vaillant are a well-known name when it comes to central heating boilers and have built a great reputation. They were the pioneering innovators behind the combi boiler and they continue to lead the way with their ecoTEC Pro range.

Glow-worm have been the go-to manufacturer of affordable boilers that are reliable and easy to install. Since being founded in 1934, they've grown into one of the leading UK manufacturers and are well reviewed by heating engineers.

What makes this head-to-head interesting is that both Vaillant and Glow-worm are part of the Vaillant Group.

Vaillant boiler reviews

Vaillant UK are often found on lists of the best boiler manufacturers and are reviewed positively by homeowners as well as heating engineers.

What often separates Vaillant boilers from their competitors is that they're fitted with a stainless steel heat exchanger. This is compared to other manufacturers commonly using aluminium, which doesn't offer as many benefits as stainless steel:

  • Extended boiler lifetime
  • More efficient
  • Less prone to faults

In addition to the stainless steel heat exchanger, Vaillant units have a Quiet Mark accreditation which means that you won't be disturbed as it works to heat your home.

Glow-worm boiler reviews

With the Energy range of boilers, Glow-worm are looking to propel themselves up into the list of best boiler manufacturers and they're certainly making a great case. In terms of reliability and efficiency, you won't find much better than Glow-worm when it comes to budget-friendly units and the Ultimate range comes with a Grundfos pump – an industry leading central heating pump.

Vaillant & Glow-worm boiler ranges

Vaillant and Glow-worm manufacture gas-fired combi, regular and system boilers so no matter the heating needs of your home, these brands are likely to have a perfect solution.

Combi boilers

A combi boiler is ideal for smaller homes with 1-2 bathrooms and a fairly moderate demand for heating and hot water. Vaillant and Glow-worm have a number of units to choose from but their leading ranges are the ecoTEC Pro and Energy.

Boiler Range Output Ratings (kW) Efficiency Rating Warranty
Vaillant Combi Boilers
ecoTEC Exclusive with Green iQ 35 & 43 94% 5 Years
ecoTEC Plus 25, 32, 35 & 38 89.3% 5 Years
ecoTEC Pro 24, 28 & 30 93% – 94% 5 Years
ecoFIT Pure 25, 30 & 36 89% – 89.4% 2 Years
Glow-worm Combi Boiler Ranges
Energy 25, 30 & 35 89.2% 7 Years
Energy 35 Store 35 89.4% 7 Years
Ultimate3 30 & 35 89.6% – 89.7% 5 Years
Betacom4 24 & 30 89.2% 5 Years
Easicom3 24 & 28 89.6% 3 Years
Essential 24 & 28 89.3% 3 Years

Regular boilers

Regular, or heat-only boilers, are the best heating system for larger homes and are often found in older properties. They can meet higher demand for heating and hot water as the water is stored in a cylinder but that means, unlike combi boilers, they can't provide hot water on demand.

Vaillant offer the widest choice of output ratings but there isn't much to separate all of the boilers in terms of efficiency and the Glow-worm Energy range comes with the longest warranty.

Boiler Range Output Ratings (kW) Efficiency Rating Warranty
Vaillant Regular Boilers
ecoTEC Plus 12, 15, 18, 24, 30 & 35 89.2% – 89.3% 5 Years
ecoFIT Pure 12, 15, 18, 24, 30 & 35 87.9% – 89.8% 2 Years
Glow-worm Regular Boiler Ranges
Energy 12, 15, 18 & 25 89.3% 7 Years
Ultimate3 25 89.6% 5 Years
Easicom3 25 89.6% 5 Years

System boilers

System boilers sit somewhere between combi and regular boilers in terms of how they operate and when it comes to Vaillant or Glow-worm, we think the Vaillant ecoTEC Plus system boiler is the best option thanks to the stainless steel heat exchanger, various outputs and high efficiency rating.

Boiler Range Output Ratings (kW) Efficiency Rating Warranty
Vaillant System Boilers
ecoTEC Exclusive with Green iQ 27 89.6% 5 Years
ecoTEC Plus 12, 15, 18, 25 & 30 94% 5 Years
ecoFIT Pure 12, 15, 18, 25 & 30 94% 2 Years
ecoTEC Plus 48 & 64 kW 48 & 64 94% 5 Years
Glow-worm System Boiler Ranges
Energy 12, 15, 18, 25 & 30 89.3% 7 Years
Ultimate3 25 89.7% 5 Years
Easicom3 25 89.7% 3 Years

Our Boiler Comparison Tool will allow you to compare all boilers manufactured by Vaillant and Glow-worm – as well as all leading boiler manufacturers. Once you've found the right boiler for your home, complete our simple online form and you'll get free installation quotes from heating engineers in your local area.

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Vaillant vs Glow-worm


On the whole, Vaillant boilers come out on top as the most efficient.

Their ecoTEC Pro combi boilers, ecoFIT Pure regular boilers, and ecoTEC Plus system boilers are all more efficient than the ranges made available by Glow-worm – although there isn't much between the system boilers in terms of the efficiency rating.

When comparing Vaillant and Glow-worm boilers it's important to look out for units with a stainless steel heat exchanger. A heat exchanger made from stainless steel, rather than the more common aluminium, offers increased efficiency, longer lifetime and is much less prone to any faults.


Price is the deciding factor in many decisions and when it comes to a new boiler it can make one more appealing than another. Between these manufacturers, Vaillant have the most premium boilers which inevitable come at a higher price but both brands do have more budget-friendly options available.

Vaillant Potential Cost Glow-worm Potential Cost
Combi £875 – £1,600 £550 – £1,580
Regular £790 – £1,500 £713 – £870
System £590 – £1,500 £725 – £860


Vaillant boilers are covered by a standard warranty of 2-5 years, which can be extended to 7-10 years when installed by a Vaillant Advance Installer. Meanwhile, Glow-worm have a standard 2-7 year warranty available depending on the model being installed. The longest longest warranty of the two is from Glow-worm who have a massive 15 years available when installed by a Glow-worm Club Energy installer.

Both warranties cover parts and labour and only cover a fault that is the result of an issue during the manufacturing process. Should it be found that the issue has been caused by contaminated water, you could end up being charged for the heating engineer's visit.

Which brand takes the crown?

The Vaillant Group is well-known for delivering customers with highly-efficient and reliable home heating systems. Vaillant and Glow-worm sit under the Vaillant Group umbrella and both deliver on the promises of their parent company.

If your decision ultimately comes down to finding a boiler that meets a fairly tight budget then Glow-worm is the manufacturer for you. They have several units that won't see you having to break the bank and they often come with a lengthy warranty.

Despite that, we're going to have to award victory to Vaillant. After all, they are a leading boiler manufacturer for a reason. Their boilers are highly efficient, which will help to keep your energy bills to a minimum, they're fitted with state of the art stainless steel heat exchanger and you'll be covered by a comprehensive warranty period.

Whether you plan to have a Vaillant or Glow-worm boiler installed, using Boiler Guide you can get free quotes for the installation from Gas Safe Registered engineers based near you. After taking a few moments to let us know about the work you need doing by going through our online form, you'll be contacted by up to 3 heating engineers who will each provide their quote.

Comparing multiple quotes is the best way to increase your chances of finding the most competitive price for a gas boiler installation.

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Boiler Guide Team

About the author

Boiler Guide Team

Boiler Guide has been home to a host of heating experts who have helped millions of UK homeowners searching for advice and guidance. If you’ve got heating questions, we’ll have the answers.

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