Solid Fuel Heating Systems & Boilers Explained

Solid fuel heating systems are great for those living in the UK’s more remote areas or if you are looking for a measure of self-sufficiency. Whilst there are heating systems available that are better for the environment, many modern solid fuel central heating systems such as wood pellet boilers, can do a stellar job of balancing a renewable solution and a budget-friendly option.

*** Update: The UK Government will ban the solid fuels; Coal and Wet Wood for use in domestic home heating systems by 2023 to improve air quality.

We’ll run through the various options for a modern solid fuel central heating solution, the fuels available, we’ll touch on the existing regulations, and some greener alternatives.

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What Is a Solid Fuel Heating System?

A solid fuel heating system relies on burning solid fuel such as wood or coal to generate energy for the heating and hot water. This kind of system can serve as a good replacement for gas and oil. You can also use it in place of electricity if you are aiming for a more budget friendly option.

Solid fuel heating systems come in a range of types, burning a number of different fuels. Let’s run through the main categories so you get a better idea of what’s out there.

Types of Fuel

There are mainly four different kinds of materials you can use as solid fuel. These are:

  • Wood pellets ( used in biomass pellet boilers )
  • Wood ( think wood burning stoves )
  • Coal ( not recommended )
  • Smokeless fuel

Each of these options have their own unique advantages and drawbacks but when dealing with solid fuel, you are always going to have to deal with the messy nature of ash and occasional cleaning.

Wood Pellets

Wood pellets are essentially small pieces of wood that include wood shavings, sawdust, wood chips and more. These pellets are ideal for devices like biomass boilers that can automatically combust these pellets by collecting them from their storage tanks. Wood pellet heating systems usually have an semi automatic feature that keeps feeding in more wood pellets as needed. This makes it convenient to use and manage.


Wood can include anything from logs, chips and the afore mentioned pellets. The convenient thing about using wood as a solid fuel is that it can be pretty cheap to buy and there are providers covering the majority of the UK, you may even have a source on your land or property.

However, cheap wet wood with a high moisture content will be a poor source of heat in the winter and some people may not have the space needed to store wood for use throughout the winter.


Coal is another convenient solution for solid fuel. It has a much more efficient source of heat when compared to wood, leading to a better generation and maintenance of heat levels in your home. But it’s not without it’s drawbacks.

Coal is also more expensive than wood and it does lead to more toxic emissions that will pollute the environment. If you are planning on using a coal based solid fuel central heating system, be sure to check that your local authority hasn’t declared itself as a Smoke Control Zone.


Smokeless Fuel

Smokeless fuels are perhaps the most ideal kind of solid fuel. Smokeless fuels such as anthracite have an even higher level of energy output than coal. It burns hotter and longer than coal making it pretty convenient.

Remember to not only consider the cost, but also the energy efficiency. Whilst coal and smokeless fuel may seem like an easy choice, if your aim is to reduce your carbon footprint, wood is by far the best choice.

Common Types of Solid Fuel Heating and Boilers

The most common types of solid fuel heating systems are:

  • Open fires
  • Closed fires
  • Back boilers
  • Biomass boilers

Open Fires

Open fires have a romantic place in most of our hearts. Who doesn’t love to stare into an open fires flames hear the peaceful cracking of wood? An open fire provides a great center piece to most rooms but they are not particularly efficient with a lot of the heat escaping up the chimney. You also have the added headache of cleaning and setting the fire daily.

The heat is regulated via control of air flow. This usually takes the form of a grate that can be manually adjusted.

Due to the nature of open fires, the solid fuel used and temperature achieved by the fire, you will have to deal with soot and chimney cleaning on a yearly basis.

Closed Fires

Closed fires take the form of Stanley or Aga cookers or more commonly, the sitting room stove. The fire happens inside the firebox and you have much better control over airflow and adjusting how quickly your solid fuel burns. Closed fires are also much more energy efficient with little or no loss of heat up the chimney.

Closed fires offer many of the same drawbacks as open fires, meaning you’ll have to clean and set the fire daily or as needed. There are some more systems out there that have an automatic feed system, but these are found at the higher price range.

Back Boilers

Back boilers, or BBUs, were popular in the 70s and 80s in the UK. It was a system where the boiler was fitted to the back of an open fireplace. Whilst back boilers were a great step in the right direction at the time, their were very inefficient(between 55% and 70% efficient) and it’s been against building regulations to install one in a new property since 2005.

Biomass Boilers

Biomass boilers, as the name suggests, burn biomass such as wood pellets or logs and provide both space and water heating. They work in much the same way as modern condenser boilers with a very efficient use of the generated heat. Just like other wood burning options, biomass boilers are seen as a green alternative to fossil fuels. The carbon dioxide that is released into the atmosphere during combustion was the same CO2 used when the tree to grew.

You can either manually or automatically feed these biomass boilers with solid fuel depending on the kind of model. They also have reasonably low operating costs, making them a cost-effective solution as well.

Biomass boilers tend to be quite large and are not suitable for many urban homes. Not only will you need a good amount of space to house the boiler itself, you’ll also need space to store the biomass throughout the winter.


Heating Controls

Solid fuel heating systems are a lot simpler than oil, gas or electric heating systems due to their nature and many of the more traditional types of stove and open fire don’t really offer the level of control and programming that many have come to expect from their heating system.

If you opt for one of the more modern biomass boilers though, you can hook it up to thermostatic radiator valves (TRVs) that allow you to restrict the heat flow to a particular radiator and zone of your house.

Are there any other things you need to know about effective heating? Keep reading to find out!

Solid Fuel Heating Tips

Take a look at some tips that you can make use of to make your solid fuel heating system work better.

  • Sweep the chimney
  • De-ash or service your appliance often
  • Opt for quality fuel

#1 Sweep the Chimney

Solid fuel heating systems can be a messy business. For open and closed fires, you will need regularly have the chimney swept to prevent any danger of fires and for an efficient fire. The (relatively) low temperatures don’t allow the heating system to burn up soot and noxious gases during the process of combustion, leaving all this residue on the inside of the chimney. It may seem ‘quaint’ to younger generations, but a clean chimney is essential for a good and efficient solid fuel fire.

The more modern biomass boilers don’t have the same issues as they burn much hotter than traditional fires and the same condensing process as in a modern gas boiler happens.

#2 De-ash or Service Your Appliance Often

To maintain the efficiency of your solid fuel heating system, you must make it a point to remove the ash from your appliance or fire every time you use it. A clean fire or appliance means a more efficient heating.

Don’t forget that modern biomass boiler will also need a yearly service in order to get rid of all the minor issues that may have built up.

#3 Opt for Quality Fuel

It is extremely important to opt for and buy high-quality fuel instead of simply going for a cheaper option. The fuel you use will determine the amount of heat it produces and transfers. When buying wood based solid fuel, make sure that it is sufficiently dry. Any water in the wood will impede the process of combustion making it much more inefficient .

Now that you know all about solid fuel heating systems, their types, usage and more, let us now try to figure out how effective and efficient they will be in the longer run.

The Future of Solid Fuel in the UK

Solid fuel heating systems can cost you anywhere between £500 and £5,000 on top of the cost of installation. And if you are opting for a solid fuel system, you are more than likely in a remote area, meaning that installation might cost you more.

While coal might seem more effective, it is also more expensive when compared to wood. This is where you also need to consider the future and long-term costs of these fuels and future government regulations.

Since coal is being slowly phased out by the UK government to reduce carbon emissions, wood and biomass pellets seem like a better option.

Installing a biomass system can also provide you with regular payments from the government through the Renewable Heat Incentive (RHI) as long as you are eligible for it. Thus, when it comes to wood and biomass boilers, you can rely on their future effectiveness.

There are, however, more efficient alternatives that you can consider.

Greener Heating Alternatives

While solid fuel heating systems can be green solution (compared to gas boilers), there are even greener alternatives that you can opt for. These are:

  • Condensing combi boilers
  • Heat pumps
  • Hydrogen boilers
  • Solar thermal heating

Condensing Combi Boilers

Condensing boilers come with heat water on demand and use a very efficient heating process that greatly reduces the amount of harmful gasses released into the atmosphere. They come in a variety of sizes and can be powered by LPG and oil for those homes that fall outside the Gas network.

It should be noted that gas boilers, though very efficient rely on fossil fuels and the UK government has made it clear that new homes should be kitted out with greener solutions such as heat pumps.

Heat Pumps

Heat pumps are electrical heating systems that transfer heat from a cooler to a warmer space. They make use of compressors and refrigerants to extract, warm and transfer this heat from one place to another.

Since they only have to pump heat, they use less electricity, making this an energy-efficient and cost-friendly solution. When combined with solar panels, the cost of electricity can be further reduced significantly.

Hydrogen Boilers

Hydrogen boilers make use of hydrogen instead of natural gas or oil to produce heat. This makes it a renewable and energy-efficient alternative. They are also low-carbon heating solutions to reduce the carbon footprint. They also have the added benefit of being retrofitted into your existing infrastructure.

Things look good for hydrogen in the UK but, these hydrogen boilers are not yet widely available on the UK market. They are still being tested and developed.

Solar Thermal Heating

Solar thermal panels work similarly to solar panels. Here, however, instead of converting the sun’s energy to electricity, they convert it to heat and use that to provide home heating and hot water.

Since this is a renewable source of heat, it is a highly energy-efficient option that reduces your carbon footprint to a great extent while also helping you save money on bills.

You can also combine this with other low-carbon heating systems to help you save even more energy and money.

Last Updated on July 17, 2021

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Last Updated on July 17, 2021

Frequently Asked Questions

What does solid fuel heating mean?

Solid fuel heating systems burn fossil fuels such as coal and wood. The heat is often transferred to a hot water cylinder and pumped around to the radiators thereby heating the home. Solid fuel heating systems are not as efficient as other modern methods of heating such as heat pumps or gas boilers.

Is solid fuel heating expensive?

Solid fuel heating is relatively inexpensive. The exact costs depend on the source of fuel and the government levies applied. If you have a source of wood and a process for drying or seasoning the wood, it can be almost free.

What are the drawbacks of using solid fuel?

There are a number of disadvantages to using solid fuel. These include; solid fuel is often dirty and requires space for storage. You will also need to regularly clean your fire or appliance of ash and soot. Solid fuel heating systems take time to get going and often need more attention to manage.


Author: Indra Gupta

Indra is an in-house writer with a love of Newcastle United and all things sustainable.

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