Biomass heating systems
Biomass heating systems, also called wood heating systems, burn organic materials – typically wood logs, pellets or chips – in a wood-burning stove or boiler to provide heat and hot water.
Stoves are generally used as standalone room heaters for one room. But stoves can incorporate or be connected to a boiler. This will harness the stove’s energy to provide heat and hot water to the rest of the house.
Below, we talk you through how biomass heating systems work, plus the pros and cons of getting a full wood heating system.
If you're thinking of getting a stove, it's worth taking a look at our guides:
- , which includes insider tips from owners
- - our comprehensive guide to what could affect the cost of getting a stove. It includes our handy stove-costs tool - this will help you get an idea of whether a stove could save you money on your heating bills.
We've also asked stove owners to rate their stove, enabling us to review 12 well-known stove brands, including , , , and . Visit our to find out which came top with an outstanding customer score of 94%.
How do biomass boilers work?
Stoves can be connected to a regular boiler, such as a gas boiler, or a biomass boiler. Biomass boilers, like stoves, burn wood to generate heat. They can be used along with a stove, or on their own, and are particularly good for homes not connected to mains gas.
You can also get a 'wet' stove, where an integral biomass boiler is built into the firebox. This should make the most of the heat. In some cases, you can get these retrofitted to the stove using a 'clip'.
There are also pellet boiler stoves, another form of stove and boiler in one, and flue boilers, which fit onto the flue connection between the stove and the chimney.
We wouldn't recommend adding a 'back boiler' to an old open fire as these are a lot less efficient and more polluting than modern stoves.
A thermal tank (also known as a buffer tank or accumulator) will help regulate the fluctuating use of the different energy sources - eg sun for solar panels in the summer and logs for a wood-burning stove in the winter.
Are wood-burning stoves and boilers environmentally friendly?
Biomass materials are considered to be a low carbon source of energy because, despite producing carbon dioxide when burnt, they only release roughly the same amount they absorb while growing.
However, it depends on where you're buying it from and how it's processed. Local biomass materials are even better in terms of carbon because less is produced when transporting it over shorter distances. Those from far-flung places will have a larger carbon footprint.
The carbon output will also be higher if it's been manufactured in any way - for example, if wood is dried out on a kiln or made into briquettes.
Although the manufacturing of these types of wood will create carbon, they're the most efficient to burn in terms of heat output and producing less smoke.
To get the best of both worlds, ideally you would collect wet wood and dry it yourself at home over a long period of time. This will take space and patience as you'll need to ensure the wood has less than 20% moisture content before you burn it.
It's also worth keeping in mind that stoves can produce pollutants. According to the Department for Environment, Food and Rural Affairs (Defra), the burning of wood in homes – alongside house coal and other solid fuels – is believed to be the largest contributor of harmful particulate-matter emissions.
Further studies have shown that these estimates are likely to include other types of domestic burning, such as open fires, bonfires and pizza ovens. In addition, 'dirtier' fuels, including wet logs and house coal, have much more of an impact than others.
Many other forms of heating and even day-to-day tasks, such as cooking, cause some pollution. But if the wrong fuels are used, the stove is inefficient or used incorrectly, the stove will still produce pollutants.
Pros of biomass heating
- As mentioned above, assuming you source your biomass materials sustainably, they are a low carbon fuel so should reduce your carbon footprint.
- Stoves are far more efficient than open fires This will particularly be the case in 2022 when new legislation comes into force meaning that stoves must meet higher efficiency levels than they currently do, as well as new emission limits.
- Using biomass will reduce your dependence on traditional fuels, such as gas and electricity. These are more subject to global demand, and in the future their prices are likely to be higher and more volatile.
- If you have a room thermostat in the room where a stove is installed, then your central heating will turn off sooner as the stove heats the room. So it will save you money overall.
- The Renewable Heat Incentive was launched in spring 2014 and it will pay you to produce heat from a wood heating system. Wood-burning stoves on their own don't count under the scheme, but biomass boilers, solar thermal panels, and ground source and air source heat pumps all do.
You can find out more in our guide to the .
Cons of biomass heating
Costs for installing a whole biomass system, a stove and a boiler could be more than £15,000.
- The initial cost of a wood heating system can be high - between £2,000 and £3,000 for a simple log stove and installation, and £5,000 to £11,500 for a wood pellet boiler and installation. We have spoken to industry experts and installers to find out what can affect the costs - take a look at our guide to to find out more about how much you may need to spend.
- Unlike other renewable energy technologies, with biomass you still need to buy the fuel. Fuel costs depend on the type of fuel, the distance you are from your supplier, the time of year you buy and whether you can buy in large quantities. The type of fuel you use can also impact on whether you might be able to save money - visit our page on to find out what's best.
- While biomass heating is suitable for any type of building, you need to have space to store the fuel and to access the system for loading. There are also building regulation considerations that affect where a stove can be placed, what needs to be done to the chimney and how much room it needs surrounding it, which can all impact on the cost of installation.
A reputable installer should be able to help you make a decision on what type of biomass heating system would best suit your home.
Take a look at our guide to to find out what's really involved. It also includes a video of a typical stove installation as well as a handy downloadable checklist for members to help walk you through the whole buying process.
Making your home energy efficient
As well as looking at the options for wood heating, it’s worth thinking first about other ways you can make your home more efficient. This will mean you need a lower wattage stove - which will use less fuel. Some of these include:
- and could save you up to £320 a year
- - if you have old windows, getting them replaced with double-glazed ones will cut your energy bills.