Boilers

Finding an ethical and eco-friendly boiler

Boilers may not be glamorous, but they are political. Behind each is a story about infrastructure, energy justice, and the kind of future we’re building.

We take a look at the current state of play of boilers – including Westminster’s decision to delay the 2035 phase-out of gas boilers in England and Wales, and how Scotland may be following the same path for existing homes. We also spotlight a so-called “zero-emission” option, Tepeo, and lay out what support is available to make heating more affordable and less polluting.

If you’re in a position to move away from boilers altogether, a heat pump is still the most climate-friendly option. But for some, the cost or complexity puts that out of reach. That’s why we’re continuing to cover boilers: both gas and electric.

We are not covering biomass or hydrogen boiler brands because it is generally agreed that these fuels should not be used for home heating where other more efficient, lower cost and lower carbon alternatives, like heat pumps, already exist.

Are there any environmentally-friendly boilers?

Only one brand in this guide received our 'best buy' rating, with lots of brands clumping around the average zone for scores. In a market that isn't hugely high scoring, the finer details like price and warranties may help you differentiate between brands. We cover both topics in this guide.

Which boiler brands are in the guide?

We have rating 18 brands of boilers, from the big names such as Alpha, Baxi, Glow Worm, Ideal, Vaillant, Viessmann and Worcester Bosch, to small independent UK firms such as the Electric Heating Company and Tepeo. 

We have included gas and electric boilers.

How energy efficiency are boilers?

If you're comparing boilers, you might look to the ErP (Energy-related Product) label for guidance. 

This EU-derived system, still used in the UK, rates heating products from A+++ to G. Most modern condensing gas boilers earn an A rating, while non-condensing boilers (largely phased out since 2007) tend to fall to around G, operating at under 70% efficiency.

But the label doesn’t tell the full story.

Your A-rated gas boiler may never actually perform at 90%+ efficiency in real life. It depends heavily on how the system is installed, maintained, and set up. Many gas boilers in UK homes are oversized and run too hot to reach their “condensing mode” – the state in which they operate most efficiently. This means they waste more gas than they should.

Getting a trained heating engineer to lower the flow temperature or adjust the boiler’s minimum output can help. You can also tweak settings yourself to boost performance (see further down). 

Electric vs gas boilers

Electric boilers are technically 100% efficient at the point of use – they turn all the electricity they consume into heat. But despite this, they often receive lower ErP ratings than gas boilers.

Why? Because the energy rating label takes into account upstream energy production: how the electricity was generated and delivered.

The UK grid is still partly powered by fossil fuels, mainly gas (around 38% as of early 2025) so electricity is seen as “less efficient” from source to socket. But that picture is rapidly changing. Over 50% of UK electricity now comes from renewables, with offshore wind capacity booming and solar adoption on the rise.

The National Grid aims to operate a zero-carbon electricity system by 2035, and peak renewable output has already hit records in 2024 and 2025.

Despite this progress, the price of electricity – which is still significantly higher than gas per kWh, and means electric boilers are more expensive to run – continues to skew perceptions. Current energy rating labelling reflects both carbon intensity and cost, not just system performance.

Campaigners and independent energy experts argue this creates a false equivalence. A gas boiler may look more efficient on paper, but when you factor in real-world carbon emissions and the rapidly greening grid, many electric systems are already cleaner and will only get greener. Some are calling for the ErP system to be revised or replaced entirely to reflect the urgency of the climate crisis.

In short, don’t take the label at face value. A well-installed, right-sized boiler used smartly can outperform its rating. If you’re considering switching from gas to electric, it's worth looking beyond the ErP score and weighing up what the label doesn’t show: carbon emissions over time, real-life performance, and your energy source.

Which boiler brands are switching to electric and renewable energy?

There was a noticeable division in our Climate rating between electric-only and transition-focused companies versus larger gas-reliant companies, with electric boiler brands generally scoring more points.

Electric-only companies including Advance Appliances, the Electric Heating Company, Elnur, and Tepeo highlighted that it was possible to run their products using renewables rather than fossil fuels.

Viessmann, which produces electric and gas boilers, scored well for the detail in its climate targets, scope reporting, and discussion of wider issues such as reduction of its waste. It’s also investing €1bn to increase the production of products that can be run on renewable energy.

By contrast, Immergas (Alpha) and BDR Thermea (Baxi Heating) were criticised in a 2022 report by the European Environmental Bureau and Cool Products that audited and ranked companies according to European climate objectives.

They were classed as lagging behind, defined in the report as companies that “sell stand-alone boilers or water heaters; have no plans to stop doing so before it is required by law; and do not support a 2030 (or earlier) ban on sales of such products.”

Bosch, Vaillant, and Viessmann did not respond to that audit.

Ban on gas boilers scrapped

In late 2024, the UK Labour Government confirmed it would scrap its target to phase out the installation of new gas boilers by 2035. The original plan – part of the broader push to reach net zero – had aimed to end the sale of gas boilers for most homes within a decade, encouraging a switch to cleaner technologies like heat pumps.

Now that commitment has been dropped entirely. Instead, the government says it will “go with the grain of consumer choice,” meaning that buying new fossil-fuel boilers will remain available for the foreseeable future. This follows the earlier rollback in 2023, which pushed back the phase-out of gas boilers in off-grid homes from 2026 to 2035.

The latest U-turn drew sharp criticism from climate groups and independent advisors. The Climate Change Committee warned that delaying boiler regulation undermines the UK’s legally binding climate targets and risks pushing up long-term energy bills by locking households into fossil fuel dependency.

According to analysis by E3G, continuing gas boiler installations into the 2040s could add over £10bn in avoidable costs over the coming decades, compared to a faster shift to electrified heating.

Critics also point out the inconsistency: the government still claims to be committed to heat pump adoption yet refuses to send clear market signals to phase out the gas alternative. This confuses consumers, slows investment, and weakens industry momentum.

More encouragingly, the Future Homes Standard, which will come into force in 2026, will at least end the installation of gas or oil boilers in new-build homes.

Scotland's heating plans

Scotland sets its own building regulations and is taking a slightly firmer approach.

Under the New Build Heat Standard in force since April 2024, all new homes in Scotland must use zero direct emissions heating systems (such as heat pumps or electric boilers). This effectively bans gas boilers in new-builds.

For existing homes, Scotland had proposed a ban on replacing fossil fuel boilers from 2030. However, that timeline has also slipped. The Scottish Government is now expected to revise its plans following public consultation and industry pressure.

While both governments claim to support pragmatic transitions, the delays leave the UK trailing behind countries like the Netherlands and Germany, which have introduced much clearer fossil fuel phase-outs and incentives for clean heat.

Price and warranty comparisons

As many of the brands in this guide score similar points in our ethical ratings, the deciding factor of what to buy may be on cost and their warranties. 

We compare boiler prices and warranty length and conditions. 

How much do gas and electric boilers cost?

According to Checkatrade, the average cost of a new boiler plus installation is around £3,000.

The price of a new boiler depends a lot on what size and how large a space you’re heating. Cheaper brands with boilers starting from under £700 include Advance Appliances, Alpha, Glow-worm, Heatrae Sadia, Ideal, Potterton, and Worcester Bosch.

The brands with the most expensive boilers over £3,000 include EHC, Heatrae Sadia, Thermaflow, and Tepeo.

Boiler warranties

All brands require registration of the product, usually through their website, within a restricted time frame in order for the warranty to be valid. If not registered, then the standard warranty is limited to 12 months, which is the legally required minimum. Always read the terms and conditions of each brand for the fine print of what is covered.

Most brands offer a range of warranties depending on the model, or offer the possibility to buy extended warranties. 

The shortest warranties come from Advance Appliances, EHC, Heatrae Sadia, Thermaflow, and Viessmann. 

Brands with options for 10-year warranties/ guarantees or longer include Alpha, Baxi, Ideal, Intergas, Tepeo, Vaillant, and Worcester Bosch.

Table info

All prices listed in our table are excluding installation and running costs and show a range according to different models. Limited offer discounts were not included. The table shows the prices found on company websites in June 2025 for their domestic ranges. For the companies that did not list prices for their products on their website, an internet search was conducted of the first 20 results and may not represent the whole range of boiler models.

Many boiler companies link trusted suppliers or in-house installers on their websites, where the final price will include the product plus installation.

[E] or [G] after the brand name indicates if it sells electric or gas boilers, or both.

*Provides a guarantee and not a warranty.

Mould, cold homes and heating inequality

The UK is facing a growing mould crisis. In recent years, reports of damp and mould in rented homes have surged – particularly in low-income areas, where poor insulation and high energy costs make heating a struggle.

A 2024 survey by Citizens Advice found that one in five renters were living with damp or mould, with disproportionate impacts on Black and Asian households. Respiratory conditions linked to mould – such as asthma – are rising, and tragically, cases like that of Awaab Ishak, the two-year-old who died in 2020 due to prolonged exposure to mould in his home, show how dangerous this issue can be. Shockingly, the proportion of private renters with children who are living in damp homes has almost doubled since the pandemic.

How do boilers link to damp homes?

Heating is a key factor in preventing mould, especially in cold, wet months. But rising energy prices have made it harder for many to keep their homes warm enough, for long enough.

Gas boilers are typically cheaper to run than electric systems, but many low-income homes also have old, inefficient boilers – or no central heating at all. See the section on grants and financial support available in the UK.

Even when a boiler is present, high running costs can force households to ration heat, particularly if they’re on a prepayment meter. That means that walls stay cold, condensation builds up, and mould spreads. In social housing or rentals, tenants often have no control over the type of boiler they have or when it’s replaced.

A new standard, due to come into effect in October 2025, for social housing in England and Wales will require landlords to investigate and repair dangerous levels of damp and mould within fixed timeframes. Dubbed Awaab’s Law, it’s a long overdue shift in accountability and has been shaped by tireless campaigning from housing activists and journalists like Vicky Spratt. Recently announced, the Decent Homes Standard is due to come into effect in 2035 and will require all rented properties to be free from damp and mould.

The transition to low-carbon heating needs to address this head-on. It’s not just about technology, it’s about justice. Any path away from gas must ensure that vulnerable households aren’t left colder, sicker, or paying even more. Warm, dry, habitable homes are a human right – not a luxury.

Are zero emission boilers the future of home heating?

Tepeo markets its flagship product as a “Zero Emission Boiler” (ZEB) – a plug-and-play replacement for gas boilers that runs entirely on electricity. It draws electricity from the grid when it’s cheapest and greenest (usually overnight), and stores that energy as heat. This stored heat is then released throughout the day to warm your home, mimicking the behaviour of a traditional boiler by integrating with your existing hot water tank and radiators.

What does “zero-emission” actually mean?

The name “Zero Emission Boiler” is clever marketing – but perhaps not entirely accurate. The unit itself doesn’t produce emissions during use (like all electric heating systems), but it depends on how green the grid is when it charges. If it’s powered overnight by wind or surplus renewables, emissions can be close to zero. But if that electricity comes from gas-fired power stations, emissions are still involved – just upstream. The unit itself is also made from a number of materials, including mined minerals in its electrics, which has an impact.

Tepeo argues that by intelligently timing when the boiler draws power, it can minimise those emissions. The system uses smart controls and links to grid data, aiming to charge only when the grid is low carbon.

Advantages of ZEBs:

• Compatible with existing systems – no need to replace your radiators or pipework.
• Efficient – it is considered 100% efficient compared to conventional gas boilers. This doesn’t quite compare to the 300-400% efficiency that you can get from a heat pump, but it’s not bad.
• No on-site emissions – and potentially zero-carbon if charged from renewable energy.
• Smart grid integration – helps balance national electricity demand.
• Time-of-use savings – stores heat when electricity is cheaper (if you're on the right tariff).

Disadvantages of the ZEB:

• Doesn’t cool – unlike heat pumps, which can offer cooling as well as heating.
• Government grants mostly unavailable – as the technology is still relatively new, and like most direct electric boilers, it is generally not included in existing schemes.
• Is not truly zero-emission – but relatively low emissions if powered exclusively by renewables.
• Still relatively expensive (£6k) – especially compared to gas boilers, even factoring in time-of-use savings.
• Very high electricity demand – requires a dedicated connection and may not suit all homes

Our view on zero emission boilers

Tepeo’s ZEB is an innovative solution that could suit households unable to afford the upfront costs of a heat pump – particularly in well-insulated homes with existing wet heating systems. It’s also a step toward a smarter, more flexible grid.

But calling it “zero-emission” is a stretch unless (and until) the grid becomes entirely generated by renewables, and doesn’t take into account its manufacture as a physical product. As with all new tech, it should be assessed critically – and in context of wider home efficiency improvements. 

Climate rating

As pressure continues to grow on companies to show a commitment to reduce their climate impacts, the companies in this guide came out with pretty average scores in this category overall.

Many of the companies acknowledged that the main source of their carbon emissions were in the use of their products, for example Viessmann said that 98% of their emissions came from product use, while it was 99% for the Remeha Group (Baxi, etc). This puts into perspective where the main impacts are in the sector.

When, in 2022, the European Environmental Bureau asked the question, “Would your company/group support a legal ban in Europe on the sale of new domestic boilers and water heaters that run on fossil fuels?” 82% of 49 companies selling those products said “Yes”.

Conflict minerals in boilers

Although at first the link between mining for minerals and boilers doesn’t appear obvious, minerals including tin, tantalum, tungsten, and gold (also known as 3TG) as well as others like cobalt are often used in the electrical components for boilers and other heating systems.

The term “conflict minerals”’ refers to the fact that many of the minerals come from mines linked to conflict and human rights abuses, in regions such as the Democratic Republic of Congo. As well as the human cost, there are grave environmental costs to such extraction.

Only three companies in this guide had a conflict minerals policy and received any points in this category: Bosch, Vaillant (Glow-Worm and Vaillant), and Viessmann. Vaillant and Bosch scored best for at least having some kind of policy, but this meant only 30 out of 100 for this category rating.

Vaillant’s policy had a commitment to conflict-free sourcing and expanded its policy to mica and cobalt, and included its policy in supplier contracts. Bosch also included its policy in supplier contracts, and identified 15 high-risk raw materials it was monitoring.

In correspondence with Ethical Consumer, one of the companies stated that it did not publish a conflict minerals policy because: “The majority of our spend is with large, multinational businesses who will have to address the requirements of the Dodd Frank Act [a US regulation requiring companies selling there to check their supply chains for conflict minerals].” Despite this, we could not find evidence that the majority of companies had policies in their supplier code of conduct for protections around this issue.

For more on conflict minerals in household goods see our separate article. 

Workers rights for home appliances

Bosch made headlines in 2021 and 2022 for its treatment of workers, with protests linked to factory closures and strikes over pay.

No companies in this guide scored highly for workers' rights, but Baxi Heating (Stichting Aandelen Remeha) and Tepeo were in the upper end of the pile:

Baxi’s code of conduct applied beyond its first tier of suppliers and it expressed a preference for long-term supplier relationships.

Tepeo got most of its points for designing and manufacturing the overwhelming majority of its products in-house at its facility.

While the smallest companies – Advance Appliances, Electric Heating Company, and Thermaflow – lost points in our Workers rating due to minimal websites lacking information (a common issue among smaller companies).

Some of the largest companies with more resources and reporting also scored poorly. Intergas, Groupe Atlantic (Ideal, Keston), and Viessmann scored particularly badly with barely any robust policies in place. 

Tax and boiler companies

The two largest companies by revenue in the guide, Bosch and Carrier Global (Viessmann), received zero points for owning high-risk company types registered in countries considered by Ethical Consumer to be tax havens.

Groupe Atlantic (Ideal, Keston) was found to only have one high risk company in its portfolio, an investment banking company in Switzerland.
 

Service your boiler

According to a Which? survey, around three in ten boilers that are serviced annually needed a repair in their first six years. This doubled to around six in ten boilers if the boiler was only serviced every two to five years.

They also found that paying for repairs only when needed was cheaper than paying through a boiler cover scheme. You might already have cover for boiler breakdown if you have home insurance, so check that too.

For servicing, Which? recommends a list of trusted traders, who are all Gas Safe-registered engineers, and it should cost about £80-£110, as of 2024. 

Change your boiler setting to save energy and money

In October 2022, the Money Saving Boiler Challenge was launched by Nesta, a UK charity that promotes innovation. They want at least one million households to change their combi boiler settings this winter to save energy.

It turns out that many boilers are installed to have a ‘flow temperature’ of 70-80°C but could be turned down to 60°C or even lower, using less gas and thereby saving emissions and money.

This is nothing to do with your thermostat and doesn’t mean your radiators won’t get as hot. It’ll just take a little longer than before, and the boiler will be able to condense more efficiently, recovering more heat as it’s designed to do. If your flow temperature was on 80 degrees to start with this could knock over £100 off your household’s annual energy bill and save you 170 kg of carbon emissions (which is about 1% of your total carbon footprint). And it only takes a few minutes to make the change.

Nesta also explains more ways that don’t cost anything to save gas at home, including lowering the settings on radiators, turning down the hot water temperature, and reducing the cylinder temperature safely if you don’t have a combi boiler – boilers with a hot water tank need to be kept over 60°C to avoid Legionnaires disease.

Alternative to gas boilers

Hydrogen boilers are a diversion

In September 2022, the campaign organisation Global Witness released a report criticising several gas boiler companies for their misleading messaging around hydrogen boilers:

"Gas boiler companies are greenwashing their products with hydrogen- or hydrogen-blend ready labels, making them appear climate friendly."

Brands making hydrogen claims often say that the only by-product of burning hydrogen gas is water, and that hydrogen heating is 'emission-free'. However, when it is burned in air, rather than pure oxygen, it produces dangerous nitrogen oxides which exacerbate respiratory problems.

It’s true that burning hydrogen does not produce carbon emissions, but unfortunately, 96% of Europe’s hydrogen is currently produced by burning fossil fuels. There are also concerns about hydrogen leaks, as it reacts with other gases in the atmosphere, giving it a warming potential 33 times greater than carbon dioxide over a twenty-year period.

Hydrogen can also be more costly. 

A review of 32 hydrogen studies, published in the peer-reviewed journal Joule, concluded that “hydrogen use for domestic heating is less economic, less efficient, more resource intensive” than several low- and no-carbon alternatives, and “associated with larger environmental impacts.”

A range of international and national bodies say that hydrogen fuel should be reserved for sectors where more efficient and cheaper technologies do not exist, i.e., not for home heating. 

The Global Witness report concludes that:

"Boiler manufacturers appear to be cynically and misleadingly marketing hydrogen-ready boilers, taking advantage of customers’ desire to take climate action, to allow themselves to continue to sell fossil gas boilers and avoid changes to their business models."

What about biomass boilers?

Like hydrogen, the limited supply of biomass is generally agreed to be best used for other sectors where better low-carbon alternatives don’t already exist.

A separate guest article explores the environmental impacts of burning wood and other plant matter for heating.

Additional research for the guide by Louisa Gould.