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Solid fuel heating systems and boilers

If you live in an area where a mains gas supply isn’t an option, a solid fuel heating system could be an alternative way to heat your home and water.

But how do solid fuel heating systems and boilers work, and are they a sustainable way to heat your home?

If you live in an area where a mains gas supply isn’t an option, a solid fuel heating system could be an alternative way to heat your home and water.

But how do solid fuel heating systems and boilers work, and are they a sustainable way to heat your home?

Written by
Sajni Shah
Utilities comparison expert
Last Updated
5 JUNE 2023
8 min read
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What is solid fuel heating?

Solid fuel heating systems burn wood, peat or coal to heat your home and provide you with hot water. They can be used as an alternative to gas, oil and electricity, especially in off-grid rural areas that don’t have a mains gas connection.

There are two main ways to use solid fuel for your hot water and heating supply:

  • Wood-burning stoves
  • Biomass boilers

How does solid fuel central heating work?

Solid fuel heating systems can be linked up to work together with your existing central heating and hot water system. When the fuel is burned, it will heat up water in a connected hot water cylinder, which is then pumped out to the radiators.

When the fire is not lit, the primary central heating system will take over and continue to run as normal.

Here’s a closer look at the main types of solid fuel heating systems:

Solid fuel stoves

The most popular type of solid fuel heating system in the UK is a wood-burning stove. These closed fire systems typically have a glass-fronted panel and can run on wood logs, pellets or briquettes.

There are also multi-fuel stove central heating systems that can burn both wood and smokeless coal.

Wood-burning stoves can be plumbed into the central heating system and used to heat radiators and provide hot water.

A wood burning heating system could also be used to heat up your water via a hot water cylinder.

Connecting a wood burner to your central heating and/or hot water system can be complex and expensive though. In most cases, you’ll also need to install a vent to prevent pressure from building up in the system – for this reason, they’re not compatible with combi-boilers.

A wood burner should only ever be linked to your central heating or hot water system by a qualified heating engineer.

Biomass boilers

Modern biomass boilers can provide an incredibly efficient way of heating your home and water while cutting down on CO2 emissions.

As they only produce carbon that was originally absorbed by the trees, they’re considered a carbon-neutral heating source.

There are two types of biomass boiler models:

  • Automatic – pellets are automatically fed into the boiler by a ‘hopper’, and the heat can be controlled automatically. These provide an easy-to-use, no-fuss solution, but they’re more expensive to buy and install.
  • Manual – you have to manually feed the fuel into the boiler, but they can be cheaper than automatic models.

A biomass boiler can provide all your heating and hot water needs, or it can be linked and used together with a conventional gas boiler or electric heating system.

However, biomass heating systems take up more space than a regular combi-boiler, and upfront costs are a lot higher.

Open fires

What’s not to love about a cosy, crackling, romantic open fire? Well for starters, they’re not that efficient. A great deal of heat escapes up the chimney and they’re pretty labour-intensive when it comes to cleaning and setting the fire daily.

Most open fires nowadays are used for aesthetic purposes, so they’re not really useful for heating more than the room they’re situated in.

Back boilers

Back boilers were popular in the 1970s and ‘80s. Fitted on to the back of an open fireplace, they would take heat from the fire to provide central heating and domestic hot water.

Back boiler heating systems can still be found in some older properties. But they are an outdated and inefficient way to heat your home.

Since 2005, it’s been illegal to install back boilers in new properties, so you’ll find it difficult to get your old back boiler repaired if anything goes wrong.

If you still own an open fire back boiler, you should consider replacing it with a modern, more energy-efficient heating system.   

What are the advantages of solid fuel heating systems?

If you don’t have a mains gas connection, you may have little or no choice in how you heat your home and hot water. That said, solid fuel heating systems can offer several benefits:

  • Create a warm, toasty and inviting atmosphere – there’s nothing more homely than a real fire on a cold night.
  • Can provide an effective alternative heating system for rural homes that don’t have a mains gas supply.
  • A comforting and reliable heating source during a power cut.
  • Wood is pretty much carbon neutral and can be considered ‘renewable’ fuel if it comes from a responsibly sourced working forest (meaning when a tree is cut down, another one is planted in its place).
  • Low running costs if you have your own woodland and an abundant supply of seasoned wood.
  • Recycled wood briquettes are cleaner, heat more efficiently and are easier to store than traditional logs.
  • Biomass boilers offer an energy-efficient, carbon-neutral, low maintenance way to provide heating and hot water for your entire property.

What are the disadvantages of solid fuel heating systems?

If you want quick-and-easy, no-hassle heating and hot water at the turn of a switch, a solid fuel heating system may not be the ideal choice:

  • You’ll need a constant supply of wood and enough space to store it.
  • If you have your own wood supply, you must make sure logs are seasoned and dried to remove as much moisture as possible before using them – some logs can take one to three years to season from fresh.
  • Open and closed fires need to be cleaned out regularly and your chimney swept at least twice a year.
  • Higher-quality wood heats more effectively but is also more expensive to buy – especially kiln-dried logs.
  • Will only heat a single room unless it’s connected to the central-heating system.
  • Upfront costs for biomass boilers are on the high side. Their bulky size means they’re unsuitable for small properties in urban areas, and in some cases, may require planning permission.

How does the Boiler Upgrade Scheme work?

Launched in April 2022, the Boiler Upgrade Scheme (BUS) has been set up to encourage more people to switch to cleaner heating systems like biomass boilers or heat pumps.

To be eligible for a £5,000 biomass grant, you’ll need:

  • To be the owner of a property not connected to the gas grid in a rural area of England or Wales
  • To be replacing a traditional fossil fuel heating system (gas, oil or electric)
  • To own a property with an installation capacity up to 45kWth (this covers most homes)
  • A valid energy performance certificate (EPC), with no outstanding recommendations for loft or cavity wall insulation.

To benefit from the scheme, you’ll need to find an MCS-certified installer in your area who is able to carry out the work and can advise you whether your home is suitable. It’s worth getting quotes from more than one installer to make sure you’re getting good value for money.

Once you’ve found an installer you’re happy with, they will apply for the grant on your behalf, with the £5,000 saving taken off your bill.

Scotland and Northern Ireland have similar schemes.

Find out more about BUS on GOV.UK

Top tip

Make sure you fit a carbon monoxide alarm in the same room as your solid fuel burner. Carbon monoxide is an invisible, odourless and deadly gas that is produced by blocked chimneys or flues. It’s recommended that you have your solid fuel boiler serviced at least once a year and your chimney swept at least twice a year by a qualified professional

Frequently asked questions

Is solid fuel heating expensive?

The upfront costs of solid fuel heating systems can be on the high side. For example, the average cost for a biomass boiler is £16,000. 

A wood-burning stove will cost around £900-£1,500. But you also need to consider installation costs and whether structural changes are needed, such as a new chimney flue and additional vents. These could end up costing you more than the wood burner itself.

However, once your solid fuel heating system is up and running, it could be a good long-term investment.

If you don’t have your own supply of wood, haggle with suppliers to get a good deal. Buying in bulk and out of season could also reduce the overall price you’ll pay for your solid fuel.

What is ‘wet wood’?

Wet wood is unseasoned or ‘green’ wood that contains a large percentage of moisture. When burned, it releases damaging pollutants and far more smoke than dry, seasoned wood. Wet wood also produces more tar and soot, which can damage flues and chimneys.

As part of the Clean Air Strategy, the government has now introduced regulations to stop the sale of wet wood in a bid to cut air pollution.

According to the Department for Environment, Food & Rural Affairs (DEFRA), burning dry wood will give you more heat, produce less soot and can reduce emissions by up to 50% compared to wet wood.

Under the new rules, the government also aims to phase out the sale of traditional house coal by in 2023.

How do solid-fuel heating systems compare to gas central heating?

Gas is one of the cheapest and most popular ways to heat UK homes and water. A gas boiler will heat up your home more quickly than a solid-fuel central heating system, and the room temperature is easier to control.

As mains gas is piped straight into your home, you don’t have to worry about storage space for wood or coal. With solid fuel you risk no heating at all if your fuel supply is running short.

But as a fossil fuel, gas is not renewable, and it produces more CO2 emissions than biomass energy.

While biomass boilers are the most expensive type of boiler to buy new, the savings in fuel consumption and reduced emissions may make them a better long-term investment.

Can I switch from solid fuel heating to gas?

Yes, as long as you have access to mains gas.

If you’re off-grid, laying pipes to connect gas to your home could be difficult and expensive, if not impossible. If that’s the case, you may need to consider electrical, LPG or oil-fired central heating instead.

What other types of renewable heating systems are there?

If you’re looking for renewable alternatives to a biomass boiler, you might want to consider:

These low-carbon alternatives to fossil and solid fuels produce energy from two of the most sustainable sources on the planet - air and sunshine. You may also be able to get help to pay for them under the Boiler Upgrade Scheme.

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Sajni Shah - Consumer expert on utilities and money

Sajni is passionate about building products, allowing Compare the Market to help you make great financial decisions. She keeps track of the latest trends and evolving markets to find new ways to help you save money.

Learn more about Sajni