Best Hydrogen Blend-Ready Boilers: UK Costs, Reviews & Warranties

At the Paris Convention on Climate Change in 2015, the world’s largest industrial nations agreed to deal with the climate emergency by agreeing to keep the global temperature rise below two degrees.

As a result, our reliance on using carbon fuels like natural gas to heat our homes is going to eventually come to an end.

100% hydrogen fuel is the carbon-free alternative that is set to replace our current gas boilers one day, but did you know that many gas boilers are already hydrogen blend ready?

That's right, some boilers are already designed to accept hydrogen and are simply referred to as 'hydrogen-blend ready' boilers (that can accept 20% hydrogen), these are currently available from boiler manufacturers like Worcester Bosch and Viessmann. 

Note: to clarify 100% hydrogen-ready boilers (able to accept 100% hydrogen are not yet available, but we discuss the current research and prototypes below). 

Quick jargon buster: 

• Hydrogen blend or mix-ready boiler - able to accept up to 20% hydrogen gas. 

• Hydrogen-ready boiler - able to accept 100% hydrogen gas (not yet available). 

Why are gas boilers being banned? 

Gas boilers in current housing stock are not going to be banned, the proposed legislation by the UK government only includes new builds, which are set to be banned from installing gas boilers from 2025 onwards.

The transition to all homes in the country using hydrogen as their primary fuel source is likely going to take decades. So, if you buy a new gas boiler today, you are likely to get its entire lifespan e.g. over 10 years without facing any issues. 

However, it's likely that hydrogen gas is going to be fed into our homes via the gas network at some point, but this is going to be a gradual and phased process. In our hydrogen boilers article, we explain the likely scenario in full, but the transition will include three stages: 

• Phase 1
  New generation of hydrogen-ready boilers. 
  
  

• Phase 2
  New hydrogen gas blend will be rolled out using the existing gas network.
  
  

• Phase 3
  All homes will be using 100% hydrogen gas boilers. 

We are currently at the start of phase 1 where we are beginning to see a new generation of hydrogen-ready boilers emerge from the leading boiler manufacturers.

Of course, the eventual goal is to have every household in the country using a 100% hydrogen boiler, that is able to accept pure hydrogen gas. However, the reality is that it probably won't happen for several decades. 

When will we transition to hydrogen? 

Currently, nobody knows the exact timelines to when homes will be fed with hydrogen gas, but as mentioned above this will likely begin this decade.

Often referred to as phase 1, this will likely be a blend of gases, composed of 20% hydrogen and 80% natural gas. 

The good news is that most modern boilers are designed to be hydrogen blend ready, including the latest models from both Worcester Bosch and Viessmann. 

What does 'Hydrogen Ready' blend mean? 

The current gas network is already designed to accept a combination of gases, including up to 23% hydrogen in the mix. 

Almost all gas appliances are able to accept a mixture of both hydrogen and natural gas, including gas boilers. 

That means that when the government starts to increase the percentage of ‘green gases’ in the UK gas grid, homeowners can be confident their new gas boiler will be able to operate without any issues for its entire lifespan, or without the need for an upgrade. 

What does 'Hydrogen Ready' boiler mean? 

A hydrogen-ready boiler is a boiler that is designed to accept natural gas or 100% pure hydrogen gas. Hydrogen ready boilers are an essential ingredient in the transition from natural gas (which is mostly composed of methane), to green, carbon-free hydrogen. 

Hydrogen boilers look almost identical to the current gas boiler and are also installed in pretty much the same way.

Like gas boilers, they would be connected to the gas mains and hydrogen or natural gas is fed to them from there. 

Are Hydrogen Boilers available now? 

As of early 2022, it’s not yet possible to purchase a 100% hydrogen-ready boiler, nor would it make much sense, since there is not yet any reliable supply of hydrogen gas, nor is the current infrastructure able to accept pure hydrogen gas. 

20% Hydrogen Ready Boilers 

As with most gas appliances in the UK, they are already able to accept up to 23% hydrogen gas, including gas boilers, therefore, the hydrogen boilers currently available are referred to as 20% hydrogen boilers, or hydrogen-blend ready boilers. 

Most of the best combi boilers are now 20% hydrogen ready, including some of Viessman's latest models. 

100% Hydrogen Ready Boilers 

As mentioned, 100% hydrogen ready boilers are those designed to be able to accept either natural gas, a mixture, or 100% pure hydrogen. Currently, these are not available commercially, but major boiler manufacturers have been developing prototypes for several years. 

In addition, there are many other areas that are currently being explored that are crucial for the nationwide deployment of hydrogen gas in our homes. This includes trials exploring the viability of transporting the gas via the existing gas network, along with the viability of producing hydrogen gas at the required volumes. 

Currently, there are many government-funded research projects underway, exploring these very important questions. 

Advantages of Hydrogen Boilers

Industry-leading manufacturers Viessmann and Worcester Bosch have been developing their hydrogen ready boilers and continue to update the industry on progress.

This new technology is able to utilise both natural gas and hydrogen, making them the ideal transition appliance as they can be used before and after the new fuel is supplied.

So, why is hydrogen gas so much better than natural gas (which is mostly methane)...

• Emissions contain zero carbon  Fossil fuels such as coal, oil and gas are all high-carbon fuels that emit carbon dioxide when burned. This is a leading cause of global warming. Hydrogen on the other hand, only produces water, with no carbon dioxide.

• Existing Gas infrastructure can be used 
  One of the biggest benefits of hydrogen is that it only means changing to fuel supply, so it is much easier and quicker to roll out nationwide. It also avoids the costs and learning curve of households adopting completely new heating systems.

• Hydrogen is more efficient than Gas 
  There is equal energy in 1kg of hydrogen as there is in 2.8kg of gas which means you can heat homes just as well but use less fuel in the process. 

Disadvantages of hydrogen boilers 

Unfortunately, there are some concerns about the feasibility of hydrogen heating, but this is currently being reviewed by the EAC and CCC.

• Hydrogen is not cheap to produce 
  The energy company Centrica believes that hydrogen is certainly part of the mix, but believes the technology is at least 10 years away from producing it cleanly and costs are unknown. 
  
  Currently, there are two leading methods of hydrogen production: electrolysis and Steam Methane Reforming (SMR).
  
  Electrolysis works by splitting water molecules into two separate hydrogen molecules with the use of a high voltage current. When the electricity used is generated using renewable energy, this is the most eco-friendly method of producing hydrogen.
  
  The second leading method is Steam Methane Reforming which is the method of reacting steam with methane. A by-product of producing hydrogen this way is a carbon by-product. Although it isn’t all negative, the carbon produced can be captured before it’s released into the atmosphere.
  
  Right now, both hydrogen production methods are expensive and so are not viable for the mass market where megatons of hydrogen will be required to provide nationwide supply.

• Hydrogen is flammable 
  Gas is flammable, but hydrogen is arguably even more flammable due to its energy storage, however, it also doesn’t have a smell, so detectors are an essential part of their use to ensure safety is maintained.

• Storage isn’t Easy 
  Hydrogen isn’t as heavy as natural gas and so it is much more difficult to store and transport. In order to achieve adequate conditions, it needs to be turned into a liquid and stored at a low temperature.

• Hydrogen may require major changes to the gas infrastructure 

Many of the hydrogen research projects underway are going to be investigating key concerns and looking for ways to address them to help improve the feasibility of a nationwide rollout using the existing infrastructure. 

This may include some major changes to the current gas infrastructure. For example, electronics must be explosion-proof, since hydrogen essentially burns "like an explosion".

Additionally, under certain conditions, hydrogen can cause embrittlement to pipework, meaning servicing may need to be carried out more often than with natural gas. 

Hydrogen Ready Boilers FAQ

Here are some of the most common questions we receive about hydrogen-ready boilers: 

Can I buy a Hydrogen-Ready Boiler? 

100% hydrogen ready boilers i.e. boilers able to accept pure hydrogen gas are not yet available and are still in development and testing. 

However, hydrogen blend ready gas boilers are available, these are able to accept a blend of both hydrogen gas (up to 23%) and natural gas. That means that when the UK's gas infrastructure starts to add hydrogen into the mix, these boilers will be prepared for the transition and you won't need to replace your gas boiler. 

How do Hydrogen-Ready Boilers Work? 

In many ways, hydrogen-ready boilers work in a similar way to traditional gas boilers, but there are some key distinctions: 

Step 1: Hydrogen is fed into the boiler from the gas supply and oxygen from the air. The amount of hydrogen gas fed into the system is controlled by the valve, which is important since it has an impact on the flame size. 

Step 2:  Both of the gases are combined and burned, this occurs in the combustion chamber and the igniter starts the burning process. Hydrogen has a much more intense burn than natural gas, so the chambers in hydrogen boilers are designed to limit the intensity. 

Step 3: The resulting hot flue gases from the burning process enter the heat exchanger, which is surrounded by cold water. The heat from the gases is then transferred via the exchanger to the cold water to heat it up, this water is then pumped through your home's pipes where it's required e.g. to the radiators or taps. 

Step 4: The only waste product of the combustion of hydrogen is water vapour and so a condensate pipe is required for the water to escape. The hot flue gases also exit via the flue, which contains zero carbon emissions. 

Looking for the best deal on a new hydrogen blend-ready boiler? 

If so, get your boiler replacement installed with Heatable, here’s why: 

• Gas Safe installation within 24 hours

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