Green Central avatar

Written by

Last updated:

Hydrogen-ready boiler – Compare the best hydrogen-ready combi boilers

hydrogen ready boiler Worcester 4000 quiet mark

As the world gears towards attaining net-zero carbon emissions, heating and hot water solutions for homes will have to undergo fundamental changes to adapt to various new technologies and contribute to decarbonizing heat.

Get fixed prices online in just 20 seconds – Click here

A number of strategies are already in use, including heat interface units (HIU) for apartments and other residential buildings, heat pumps that can provide both heating and cooling, and new boilers that can run on environmentally friendly hydrogen gas.

Hot Deals Icon

What is a Hydrogen Ready Boiler & Hydrogen blend boiler?

hydrogen ready boiler

Hydrogen blend ready boilers are natural gas boilers that can operate on up to a 20% mixture of hydrogen and natural gas in the existing gas network.

Hydrogen ready boilers are not available yet but are are being developed in anticipation of the gas boiler ban.

Hydrogen-ready gas boilers can then be changed and amended in the future to run on 100% hydrogen fuel as an alternative to gas boilers.

Why should hydrogen gas be used instead of natural gas?

The energy density per mass of hydrogen gas is up to three times that of natural gas. It produces energy by combining with oxygen to form water, and it emits no carbon dioxide or methane.

hydrogen ready boiler energy efficiency

Hydrogen heating is considered the best alternative to natural gas for heating applications such as boilers because it is environmentally friendly. The existing gas network can be used to deliver hydrogen gas to homes.

In anticipation of the transition to burning hydrogen gas and green energy, most forward-thinking manufacturers have begun designing hydrogen-ready boilers, and we will sample some of their best boiler units further down, so keep reading.

What are the drawbacks of hydrogen boilers?

However, we are not yet at the point where we can fully burn hydrogen gas due to a few unique challenges to hydrogen as an energy source:

inside hydrogen ready combi boiler
  • Pure hydrogen doesn’t occur naturally in large quantities on earth and has to be extracted from fossil fuels or biomass sources. We are yet to perfect extraction techniques to get the quantities needed to sustain our demand without supplementing it with other fuels.
  • Because of the extraction handicaps, the thermal efficiency of the hydrogen we produce is rarely at 100% of its potential. It averages between 65 and 80%, which still can’t justify a complete overhaul.
  • Hydrogen is also the smallest element, so it has a high propensity to leak from our network of natural gas pipes, making it difficult to transport and store. Researchers continuously develop appropriate storage media so that hydrogen can be supplied as easily as gas. Hydrogen is highly flammable with low ignition and high combustion energy and should be handled responsibly. Hydrogen is highly flammable, with a low ignition temperature and high combustion energy, and should be handled with caution.
Hot Deals Icon

Is hydrogen fueling the future of home heating?

That being said, hydrogen is the fuel of the future, and your favourite boiler brand should be well on its way to developing hydrogen-ready boilers.

The combi boilers we’re about to look at can handle fuel with up to 20% hydrogen concentration. This is arguably the highest level of hydrogen readiness for boilers available in the market today.

Our detailed explanation of how hydrogen-ready boilers work can help you learn more. They are already reducing their carbon footprint by using efficient natural gas and LPG.

Worried about prices? See our hydrogen boiler cost guide here for more information.

Best Hydrogen Ready Boiler UK

Take a look at some of the best natural gas boilers that are currently available and hydrogen blend ready to 20%.

All of the top brands, including Worcester Bosch, Viessmann, Ideal, and others, have boilers that can run on a combination of hydrogen gas and natural gas. Examine some of the best combi boiler and system boilers available in the UK.

Compare the best hydrogen ready boilers to 20% here

Worcester Bosch Greenstar 4000 hydrogen blend ready combi

The new Worcester Bosch 4000 hydrogen-ready boiler (20% blend), which comes from a world-renowned market leader in the natural gas boiler industry, deserves a prominent place on this list. This hydrogen blend ready boiler is available in both combi and system configurations.

Boiler outputs

The Worcester 4000 combi boilers are available with a 25kW or 30kW output, providing 9 and 10.8 litres per minute of hot water at 40°C, respectively. At a fraction of the size, they are quieter and more efficient than their predecessors. The lightweight and compact units can be stored neatly in a standard kitchen cupboard and operate quietly.

Easy to install using Worcester Bosch SimpleSwitch

These Worcester Bosch 4000 hydrogen-ready boilers are available as part of the Greenstar SimpleSwitch installation models, which include the Greenstar I Junior combi, Si combi, I ErP, I System, and I System ErP. Because they are SimpleSwitch, their installation points are modular, and you can easily swap one of these models for the other.

Their mounting points, pipe centres, and distances from the flues to the valves are all the same, and the SimpleSwitch flue adaptor ensures that you can continue to use the existing flue hole through the building’s fabric.

The Worcester Bosch 4000 hydrogen-ready boiler includes a wall frame that allows all wall pipe connections to be pre-piped before hanging the boiler, and they can all use the same pressure-reducing valve (PRV) pipework. Otherwise, replacing PRV pipework is difficult and expensive, and switching to the Worcester Bosch 4000 should be a simple process.

If this is your first Greenstar or you don’t require the SimpleSwitch benefit, the piping can also be routed directly back into the wall.

Easy access to the boiler with removable panels

All key components are accessible from the front, making installation, servicing, and maintenance simple. These hydrogen-ready boilers also pioneered the eco-friendly LCD colour control display, which serves as a system monitor and is easy to use.

The Bosch EasyControl thermostat modulates the boiler and can communicate wirelessly with the EasyControl app on the Greenstar 4000 boilers. The app supports up to six distinct users.

Worcester Bosch claims that all condensing gas boilers introduced after 2000 can accept hydrogen blends of up to 20%, making them environmentally friendly. This is a giant step toward embracing carbon-free fuels. Their wide power range also reduces gas consumption, and their water-saving ‘Quick Tap’ function reduces water waste.

Hydrogen blend ready Worcester Bosch boiler warranty

Each Worcester Bosch hydrogen-ready boiler comes with a standard seven-year warranty, which can be extended to eight years if a Greenstar System filter is used.

It can be extended for an additional £150 or for free if you use a Worcester Accredited Installer (WAI) or Partner (WAP) who is a member of their Excelerate programme.

Hot Deals Icon

Viessmann Vitodens 050-W hydrogen blend ready combi boiler

The Viessmann Vitodens 050-w hydrogen-ready (20%) combi boiler can be customised to fit modern as well as older buildings, thanks to a plethora of compatible accessories.

It will suffice to replace a variety of older models. Its compact profile allows for a variety of mounting options that do not interfere with the ambience of the room, whether it is a flat or a small apartment.

Good flow rate for compact combi boilers

The Vitodens 050-w combi boiler’s direct hot water output ranges from 5.9 to 29.3kW, increasing efficiency. These natural gas boilers reduce energy consumption by combining the actions of a premium stainless-steel Inox-Radial heat exchanger and a modulating stainless-steel cylinder burner.

High-efficiency hydrogen-ready combi boiler

The Vitodens 050-w has a 97% efficiency rating, so the carbon footprint is kept to a minimum and the unit does not strain, extending service cycles. All serviceable parts are easily accessible from the front, making service and maintenance a breeze.

The Vitodens 050-w has a domestic hot water (DHW) flow rate of 12 litres per minute at 35° rise, which is adequate for the needs of a small to medium-sized house with one bathroom. An integral booster function keeps the rate constant. It includes a vertical flue system that allows you to connect up to five boilers located on different floors for easier management.

Very quiet combi boiler

The Vitodens 050-W is extremely quiet and comes with an integrated electronic boiler control unit that allows you to switch between thermostatic and weather-compensating modes. To use this feature, an external temperature sensor should be added as an accessory.

One of the most compact hydrogen blend ready combi boilers

It is a quiet unit that is also very compact and can be mounted in any room or kitchen cabinet. When necessary, you can also manually configure the controls.

Viessmann provides a three-year warranty, which is extended to seven years if the unit is installed by a Viessmann-trained installer. This means that this hydrogen-ready boiler comes with a ten-year warranty.

Hot Deals Icon

Ideal Logic hydrogen blend ready combi boiler

The Ideal Logic hydrogen-ready combi boiler (20%) has been certified for its quiet operation, which is no small feat given the competition on and off our list.

It also received the Queen’s Award for Enterprise in 2013, as well as Housekeeping Reader Recommended Status in 2013, 2017, and 2018.

Energy efficient combi boiler

It includes a weather compensation kit, which measures the outside temperature and adjusts the water flow temperature to compensate. This maintains the house temperature, improves efficiency, and allows for fuel cost savings. It also has a pre-heat function, allowing you to save energy and water.

Easy to use LCD display

An easy-to-use backlit LCD with both symbols and text allows you to set up the boiler even in low-light conditions, and you can check the current settings while it is mounted. The pressure gauge is also prominently displayed. It is Touch RF and Touch Connect compatible, which means you can control it wirelessly from the comfort of your seat.

The lightweight, compact unit will easily fit into your cupboard and will not interfere with your kitchen layout. For added peace of mind, it comes with a 7-year parts and labour warranty.

Viessmann Vitodens 100-W hydrogen blend ready boilers

Viessmann Vitodens 100-w hydrogen-ready boilers (20%) are available in 35kW, 30kW, and 26kW configurations.

The Vitodens 100-w is ideal for small to medium sized homes with one or two bathrooms, while the 26kW model is insufficient for homes with more than one bathroom. They are wall-mounted and, because they do not require a tank, can fit in tight spaces.

Stainless steel heat exchanger

The boilers have stainless steel Inox-Radial heat exchangers that are corrosion and heat-damage resistant, promoting durability and backed by a 10-year warranty. The boiler is covered by a standard 5-year warranty.

Preheat function

It has a pre-heat function and can produce instant hot water without wasting time heating up the water. This efficiency is enhanced further by its DHW water output range of 8 to 30kW, which significantly reduces energy waste.

Higher flow rates for combi boilers

The flow rate can reach 14.3 litres per minute, which keeps the showers running smoothly even when both are on at the same time.

The combination of the pressure release valve (PRV) and condensate connections, which reduces the number of pipes required, makes installation simple and quick. The horizontal flue pipe completes the picture. It comes with an easy-to-install kit for converting to LPG.

Its serviceable parts are easily accessible for maintenance and service.

Hot Deals Icon

Worcester Bosch Greenstar 2000 hydrogen blend ready combi boiler

The Worcester Bosch 2000 hydrogen-ready combi boiler models, like the Greenstar 4000 combi, can operate with up to 20% hydrogen concentration in natural gas, which is a step in the right direction toward improved energy efficiency and lower carbon emissions from homes and buildings.

2 different outputs

This hydrogen-ready natural gas boiler is available in two sizes, 25kW and 30kW, so you can select the one that best meets your heating requirements. As an entry-level model, the prices are reasonable, and you won’t have to break the bank with your first gas boiler installation.

Good warranty

These gas boilers also come with a standard 5-year warranty, which can be extended to six years if you use a Greenstar system filter. This demonstrates Worcester Bosch’s faith in the quality and durability of these units.

Wall-mounted combi boiler

The Worcester 2000 hydrogen blend ready boilers are wall-mounted and can be connected directly to your water mains.

The small size allows it to fit in wall-mounted kitchen cabinets, and because it is the quietest Worcester Bosch combi boiler currently available, it successfully delivers your heating solutions without drawing attention to itself.

They are compatible with a variety of external third-party controls as well as an even greater number of Worcester Bosch controls, which they can connect to mechanically or wirelessly. This allows for versatility and ease of use.

Energy-efficient gas combi boilers

These natural gas boilers have C6 heat exchangers that can modulate down to 4.8kW to optimise efficiency, and their warranty periods have been extended to 10 years.

The Worcester Bosch Quick Tap water-saving feature boosts their efficiency rating, even more, allowing instant access to hot water without the mandatory wastage we were previously used to as we waited for hot water to reach our showers and taps.

When you open and immediately close a tap, the heat exchanger is triggered to reach the set temperature, and you can get hot water within 30 seconds if you open the tap again. There are convenient side panels that allow access to all essential parts, allowing the boilers to be serviced and repaired without a struggle.

Hot Deals Icon

Why choose a hydrogen ready combi boiler instead of other home heating options?

Combi boilers are a popular heating solution for a variety of reasons, making them preferable to conventional, system, or heat pump heating systems.

Energy Efficiency

Their operation is efficient because they only heat the water you require when you require it. There is no energy wasted in heating water that will cool in a storage tank and need to be heated again. This is environmentally friendly and will extend the life of your boiler.

Hot Water on Demand

They also ensure that hot water is available on demand because water is heated directly from the source and takes only a few seconds to heat up. Unlike conventional and domestic boilers, you do not need to develop strict routines or set timers. This heating system eliminates the worry that the person in the shower in front of you will exhaust all of the hot water, forcing you to wait for the next run.

Good for Small Spaces

Combi boilers take up little space because, as the name implies, they perform functions that would otherwise require multiple units. You get a heater and a hot water source in one appliance, which eliminates the need for hot water storage tanks or cylinders.

Because of their compactness and small footprints, you can reap the benefits even in small apartments with limited space. They are small enough to fit under the stairs, in utility rooms, or even in kitchen cabinets.


For several reasons, hydrogen-ready combi boilers are cost-effective. We’ve already established that their operation doesn’t waste energy warming water when it’s not needed, and there’s no need for a hot water tank. These already imply energy conservation and cost savings from fuel when not in use.

A combi boiler also eliminates the need for a tank, installation costs, and supporting pipework and equipment. Replacing the parts after years makes service costs less expensive with a combi boiler. There are fewer parts to consider, and they are also less expensive and easier to install.

A new 20% hydrogen-ready boiler cost around £2,200 on average to fit.

High Hygiene Standards

Water hygiene standards are also higher in new combi boilers than in other heating systems such as heat pumps and conventional boilers, owing to the lack of a tank. There are no spaces for sludge and its associated pathogens and debris to hide.

The water is heated directly from the main supply while it is still fresh, so what comes out of your taps and showers is as clean and safe as the source.

Hot Deals Icon


Will hydrogen replace natural gas boilers?

It has been stated that by 2026, natural gas boilers installed will be required to be hydrogen ready. Although there are no full hydrogen ready or 100% hydrogen boilers on the market, some larger boiler manufacturers have begun developing hydrogen boiler prototypes.

A hydrogen-ready boiler vs a heat pump – which is best?

Hydrogen is a far more efficient fuel than natural gas. Hydrogen’s composition also contains more energy than gas. As a result, a home would require less hydrogen to heat than a gas boiler. When there is a high demand for heating, this reduces the strain on the network.

More homes can be supplied by hydrogen production than by a gas appliance and a heat pump. For all of these reasons, a hydrogen-ready boiler may be considered a better option than a heat pump.

Why is an alternative to gas heating needed?

The United Kingdom has pledged to reduce emissions to zero by 2050. For this to occur, the government must take drastic measures. Their plan and overall industrial strategy is to implement a gas boiler pan as soon as 2025. Hydrogen production as a low-carbon alternative to gas heating is a good and viable alternative.

What is the difference between green hydrogen and blue hydrogen?

When learning more about hydrogen production, it is important to distinguish between green hydrogen and blue hydrogen. Green hydrogen is created through water electrolysis, whereas blue hydrogen is created through natural gas. Green hydrogen is viewed as a valuable and sustainable energy resource by governments.

Hot Deals Icon
Green Central avatar

Written by

Read some of our superb solar panel installation reviews from Trustpilot

Recently had solar panels fitted by Green Central and I can’t speak highly enough of the team. The whole experience has been trouble free and I would recommend them to anyone thinking about having solar panels installed – 10/10!

Rob Schofield


Our installation is now complete! 8 solar panels fitted and the journey from initial consultation through to the end product has been seamless.
Hats off Green central, Credit where it’s due.
Will definitely spread the word!



Recently had six solar panels fitted on my house by Green Central and I couldn’t have asked for a better service. In particular, I have to highlight the exceptional communications through out, the over all smooth running process and completely stress free experience, all down to Green Central. I now have grid independence which is valuable beyond estimation.


Name *
Email *
Phone No. *
Post Code *
Name *
Email *
Phone No. *
Post Code *