Gas Boilers

Ethical shopping guide to gas condensing boilers, from Ethical Consumer

Ethical shopping guide to gas condensing boilers, from Ethical Consumer

This is a product guide from Ethical Consumer, the UK's leading alternative consumer organisation. Since 1989 we've been researching and recording the social and environmental records of companies, and making the results available to you in a simple format.

We're sorry but the score table for this report has been removed because it is out of date.

The report includes:

  • Ethical and environmental ratings for 25 gas condensing boilers
  • Best Buy recommendations
  • which are the most energy efficient boilers
  • Company profiles


Best Buys

as of July/August 2011
As our ratings are constantly updated, it is possible that company ratings on the scorecard may have changed since this report was written.


The Best Buys are Energy Saving Trust models from: Ravenheat, Alpha, Dimplex, Ideal, Johnson and Starley, Sime.
Find their EST models at

Of these Ravenheat and Sime have the highest SEDBUK rating.

Grant, Vaillant, Potterton and Glow-worm head up the Which? list of Best Buys.

Published: July/August 2011 



Reaching boiling point


With a few exceptions all new and replacement boilers in the UK must, by law, be high efficiency condensing boilers. These can reduce CO2 emissions by up to 30% and heating bills by a further 40% compared to old-style boilers.

Condensing boilers are the most efficient available as they convert over 90% of the fuel they use into useful heat, compared to around 60% for an old-style boiler.

You can buy high efficiency condensing boilers in different types.

These are:
•    Combination boilers, which heat up hot water on demand
•    System boilers, where a separate hot water cylinder is required
•    Heat-only boilers
The companies on the scoretable produce a range of the above.





Energy ratings


All condensing boilers have a Seasonal Efficiency of Domestic Boilers in the UK (SEDBUK) rating label. This SEDBUK rating provides a basis for fair comparison of different boiler models by grading boilers according to their efficiency. SEDBUK rates boilers from A to G. We recommend that you only buy an A rated machine which will have an energy rating of around 90%.
Keston, Fonderie Sime, Gledhill, Ravenheat, Worcester, Fontecal all have models of this standard.
You can see a full list of boilers along with their ratings on the SEDBUK website.

The following diagram shows the bands and their corresponding energy efficiencies.


Diagram shows bands and their energy efficiencies


A number of brands have models that are recommended by the Energy Saving Trust (EST). The EST says that only the most energy efficient products carry the Energy Saving Trust Recommended logo. The aim is to help consumers save on energy bills and reduce emissions. The Energy Saving Trust tests products every year against strict criteria. The criteria is set by an independent panel and reviewed annually. Theirs is a particularly useful logo in this market as there is no statutory EU Energy Label scheme for boilers.




Company profiles


Most companies did not have a supply chain or an environmental policy, and of the few that did, none scored best in these categories.

The Worcester brand, owned by Bosch, is bottom of the table after picking up marks in a number of categories. These include: Climate Change for supplying the automotive industry and People for supplying the military. It’s also been criticised for being a member of the World Business Council for Sustainable Development, an international corporate lobby group which has been criticised for exerting undue corporate influence on policy-makers.

Above them on the table is Veissmann, which, along with marks for having operations in Oppressive Regimes and subsidiaries in tax havens, also picks up marks in the Climate Change category for running an airfield and a fleet of private jets.



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