Solid fuel heating systems & 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?

Sofia Hutson
Utilities expert
minute read
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Last Updated 29 JULY 2022

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.

Solid fuel stoves

The most common type of solid fuel stove is a wood-burning stove. They typically have a glass-fronted panel and can run on wood logs, pellets or briquettes. There are also multi-fuel stoves, which can burn both wood and smokeless coal.

Considered less messy than an open fire, wood-burning stoves are incredibly popular in the UK, instantly adding a warm and cosy feel to a room. Wood burners are usually used to heat just one room, but they can spread the heat to other areas via a connected flue or chimney.

Wood-burning stoves can also be plumbed into the central heating system and used to heat radiators and provide hot water. If you don’t have mains gas, a wood burner can be used as your main domestic heating system. If you already have a gas or electricity system, the wood burner can be linked to your conventional heating system. You could use gas or electricity to heat your home until the solid fuel stove has had a chance to warm up, then switch it off until the fire dies down.

Wood burners 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.

What are the advantages of solid fuel stoves?

  • 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.

What are the disadvantages of solid fuel stoves?

  • Higher-quality wood heats more effectively, but is also more expensive to buy – especially kiln-dried logs.
  • 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.
  • Ash needs to be cleaned out regularly and your chimney swept at least twice a year.
  • Will only heat a single room unless it’s connected to the central-heating system.

Biomass boilers

Modern biomass boilers can provide an incredibly efficient way of heating your home and water while cutting down on CO2 emissions. Thanks to modern technology, the best biomass boilers can operate at 90% efficiency, much higher than conventional boilers and electric heating systems.

Biomass energy is considered a source of renewable energy, as it comes from natural, organic materials such as wood, charcoal and even animal dung.

Domestic biomass boilers use wood logs, pellets or wood chips to deliver heating and hot water to your home. As they only produce carbon that was originally absorbed by the trees, they’re considered a carbon-neutral heating source.

Depending on whether you’ve got mains gas or not, 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.

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 wood into the boiler, but they can be cheaper than automatic models.

Biomass boilers are typically larger than a regular combi-boiler, so you need to make sure you have the space to store both the boiler and the wood. The upfront costs to buy and install biomass boilers can also be pretty high compared to other new heating systems. The good news is that you might be eligible for a £5,000 grant towards the cost of installing a biomass boiler under the government’s Boiler Upgrade Scheme.

How does the Boiler Upgrade Scheme work?

Launched in April 2022, the Boiler Upgrade Scheme has been set up to encourage more people to switch to cleaner heating systems like biomass.

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.

Find out more about BUS on GOV.UK

What are the advantages of biomass boilers?

  • Low carbon emissions
  • Fantastic energy efficiency
  • Low maintenance – produces far less ash than log fires
  • Some automatic boilers allow you to store up to a year’s worth of pellets
  • Can provide heating and hot water for the entire property.

What are the disadvantages of biomass boilers?

  • More expensive to buy and install compared to gas, oil or electric boilers
  • Bigger than a regular gas or electric boiler
  • You’ll need additional storage space for logs, pellets or chips
  • You might need planning permission
  • Unsuitable for flats and small properties in urban areas

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 boiler serviced at least once a year and your chimney swept at least twice a year by a qualified professional.

Frequently asked questions

What is the ‘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 2023.

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

As well as being the most popular heating source, gas is also one of the cheapest ways to heat your home and water. A gas boiler will heat up your home quicker than a solid fuel 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.