Government Backed Financial Incentives to Install Renewable Energy Heating Systems

Biomass Boilers and Stoves Funded by the Domestic Renewable Heat Incentive

Biomass Boilers - Biomass Carbon Cycle

What are Biomass Boilers?


Wood-fuelled heating systems such as biomass boilers and biomass stoves are environmentally friendly.  Biomass heating systems generate clean, green renewable heat by burning wood in the form of pellets, chips or logs.

Burning wood in biomass boilers releases the same amount of carbon dioxide into the atmosphere as was absorbed while the plants or trees were growing. This makes biomass technology a carbon-neutral form of renewable energy. Biomass heating is a mature, proven technology and biomass boilers have been used successfully for many years in countries such as Austria, Finland and Denmark.

RHI Tariffs for biomass boilers are now available to encourage householders in the UK to make the switch to biomass boilers. By taking advantage of the Domestic Renewable Heat Incentive, installing a biomass boiler will not only cut your heating bills but you can also claim Domestic RHI tariff payments for seven years.

Biomass boilers provide power for your central heating and hot water whilst biomass stoves can be used to heat a single room.

According to the Carbon Trust ‘Using biomass is one of the (few) cost effective and practical ways to provide space heating (and) hot water ….. from a low carbon source’.

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Domestic Renewable Heat Incentive and Biomass Boilers

Biomass Boilers and the Domestic Renewable Heat Incentive

Biomass boilers and stoves are normally installed in ‘off mains gas’ areas in place of other heating systems which run on LPG, oil, coal or electricity.  This is because the greatest benefits in terms of cost saving and carbon emission reduction can be achieved by replacing these ‘off gas grid’ heating systems.

Biomass boilers and biomass stoves (with integrated back boilers) which heat your home using ‘wet’ central heating systems such as radiators, will attract financial assistance through the Government’s Domestic Renewable Heat Incentive (Domestic RHI).

If you install a biomass boiler and sign up for the Domestic RHI scheme you will receive tariffs payments every quarter for seven years.

Domestic Renewable Heat Incentive - Biomass Stoves
Biomass Stove

How much will the Domestic RHI scheme pay householders who install biomass boilers?

Householders who install biomass boilers and satisfy the the Domestic Renewable Heat Incentive rules will receive a tariff of 6.88 pence per kilowatt hour of renewable heat energy generated.

For the purposes of calculating the tariff payable, the amount of renewable heat generated will be based on the estimated heat demand as illustrated on your Energy Performance Certificate (EPC).

Biomass boiler RHI tariffs apply to biomass boilers which use only biomass fuel (i.e. not wooden sticks or logs) and biomass pellet stoves with integrated back boilers.

Example of RHI Tariffs by Switching to Biomass Boilers

Based on a typical three bedroom detached house using 18,000 kilowatt hours of heat energy per year, installing a Biomass Boiler, the total annual Domestic Renewable Heat Incentive tariff will be:

kWh of renewable heat x tariff = Total annual Domestic Renewable Heat Incentive payment

18,000 kWh x 6.88 pence per kWh = £1.238.40 per year

This equates to tariff receipts of £8,668.80 over seven years but remember to factor in the savings made by switching from from your expensive oil, LPG or coal heating system.

When assessing the financial impact of switching to biomass boilers you should take into account:

  • The installation cost of the biomass boiler heating system
  • The RHI tariff receipts, which increase by inflation each year
  • The savings in switching from an expensive fuel such as oil, LPG or coal

Biomass Boilers – Costs and Savings

Installing a 18 kW wood pellet fed domestic biomass boiler should cost from approximately £7,000 for a manual version or up to £12,000 for one where the wood pellets are fed to the burners automatically. This size of boiler should be sufficient for a typical three bedroom detached house.

Running costs for biomass boilers compare favourably with most of the alternatives.  Biomass wood pellets cost around 4.4 pence per kilowatt hour (kWh), natural gas 4.2p/kWh, heating oil 6.4p/kWh, LPG 8.6p/kWh, coal 3.9p/kWh and electricity (off peak economy 7) 7.1p/kWh (at December 2013 prices).

Only natural gas and coal are cheaper per kWh than using biomass fuel but taking into account the inefficiencies of non-condensing gas boilers and open coal fires, wood pellet fed biomass boilers should work out cheaper to run in the long term, than either of these fossil fuel technologies.

You should expect an 18 kW biomass boiler to use between 4 and 5 tonnes of wood pellets each year depending on personal heating requirements and current costs of wood pellets (December 2013) are around £200 per tonne, including VAT and local delivery.

Save up to £13,958 in running costs by installing a biomass boiler

The Energy Saving Trust® has calculated the potential savings achieved by installing a domestic biomass boiler to provide all of your heating and hot water requirements, when compared to alternative types of fuel for householders applying for biomass boiler grants.

It claims that the largest potential saving can be achieved by switching from LPG to a wood pellet fed biomass boiler, which over a 7 year period could amount to £13,958 (less installation costs).

The Government’s own Domestic Renewable Heat Incentive Tariff Calculator can provide you with an estimate of your tariff receipts. You can find it HERE.

Types of Biomass Boilers and Biomass Stoves

Biomass Boilers

Wood pellet fed domestic biomass boilers are available in a range of sizes depending on your heating and hot water requirements, and generally operate at 80 – 90% efficiency.  Biomass boilers work in a similar way to conventional gas boilers, except for the type of fuel they use and method of its delivery to the burners.

Wood pellets, which can be either manually or automatically fed into the boiler, are ignited by elements and the resulting hot gases from the burning procedure are passed through a heat exchanger.

From there, the heat is transferred to the water in your central heating system pipes and radiators and to provide hot water to your taps and showers.

Modern domestic biomass boilers are ideal for residential properties where mains gas is not an option; they are generally easy to install and operate and require little maintenance.

Domestic biomass boilers can normally be installed as part of an existing central heating system and will provide you with sustainable, carbon-neutral energy for your central heating and hot water.


Biomass Stoves

Biomass stoves generally operate at 60 – 80% efficiency but will only heat a single room, so are normally used in conjunction with other heating systems.

In some circumstances they can be fitted with an integrated back boiler though, to provide hot water.

Biomass stoves are an excellent alternative to an open coal or log fire – providing some of the charm without the dirt, inefficiency and carbon dioxide emission problems of coal and logs.

Domestic Renewable Heat Incentive - Biomass Boilers
Biomass Boiler
biomass stove
Biomass Stove
Biomass Boilers FAQs

Is a biomass boiler suitable for my home?

Domestic biomass boilers can be installed in most homes whether you have mains gas or not. However, the greatest savings in heating bills and carbon emissions will be made if you convert to biomass renewable technology from fuels such as heating oil, LPG, coal or electricity.

Like all types of heating systems, biomass boilers are not necessarily the right choice for everyone and you will need to consider whether you have space in your home for the biomass boiler & fuel store and whether you need to provide a new flue or chimney.

How much space do I need for a biomass boiler?

Domestic biomass boilers are generally larger than their gas or oil equivalents and are usually floor-mounted so you will require a firm, non-combustible base to stand it on.

You will also need somewhere dry to store the wood pellet fuel for your biomass boiler, which should be easily accessible for deliveries and not too far from the boiler itself for when it needs replenishing.

Do biomass boilers require a flue or chimney?

If you have an existing chimney it may need to be fitted with a double-skin, flexible stainless steel flue liner to make it safe and legal, otherwise you should to install a new flue for the waste gases.

These precautions are necessary to prevent potentially hazardous gases returning into the house and a single skin flue liner designed for use with gas fires should not be used with a solid fuel boiler or stove.

If you do not have an existing chimney, a new flue must be installed and in some instances this may be subject to planning permission or Building Regulations.  However, if the flue or flue liner is installed as part of the boiler installation by an engineer who has been approved under a scheme such as HETAS (Heating Equipment Testing and Approval Scheme) the engineer may be able to self-certify the installation and avoid the need for a Building Regulations application.

What about the supply of wood pellets for a biomass boiler?


Recipients of Domestic Renewable Heat Incentive tariff payments will have to source their fuel from a supplier registered on an approved suppliers list, known as the RHI Biomass Suppliers List.

It may also be worthwhile checking to see if you have a local supplier of wood pellets for biomass boilers as, although some companies now offer delivery anywhere in the UK, you should take into account their delivery charges.

Are there any rules about home insulation and biomass boilers?

For those considering biomass boilers, maximum benefit in the reduction of energy bills and carbon dioxide emissions will only be achieved if your home is well insulated.

In fact, in order to benefit from the Domestic RHI scheme applicants have to complete an assessment to ensure that their home complies with current loft insulation and wall insulation energy efficiency requirements.

Renewable heating systems installed in new self-build properties are exempt from the assessment as recent Building Regulations would apply to the property anyway.

Is planning permission required to install a biomass boiler?

Domestic biomass boilers do not generally require planning permission but different rules could apply if you need to install an external flue, especially if your home is built in a conservation area or is a listed building.

All new heating systems which use wood as a fuel do have to satisfy Building Regulations but your installer can guide you on this.  Naturally, there are very specific requirements for properties with thatched roofs.

Can I install a biomass boiler is a ‘Clean Air Zone’?

Domestic biomass boilers which burn wood or wood pellets can only be used in Clean Air Zones if they have an exemption certificate.

Your installer can advise which types of biomass boilers satisfy the regulations in your case.

Do biomass boilers require much maintenance

Maintaining domestic biomass boilers amounts to little more than emptying them of ash, cleaning soot deposits away and carrying out an annual service.

Ash created by biomass boilers is generally less that 1% by volume of the wood pellet fuel they use and the waste ash can be used as a garden fertiliser.

Some biomass boilers will have self-cleaning systems which clean ash away from the heat exchanger tubes and combustion grate, whilst others compress the ash to reduce the number of times the ash bin needs to be emptied.

Emptying the ash bin can easily be done by the home owner but an annual service (cost approx. £100) and cleaning soot from the chimney and flue pipe would normally be carried out by professionals.

Where can I find an installer for biomass boilers?

We have access to the largest database of installers of domestic biomass boilers and biomass stoves in the UK.

Simply complete the form on this page and we will introduce you to up to three accredited biomass boiler installation companies for you to request quotations from.

We do not charge you anything for this service and you are under no obligation to place an order with any of the installers that we introduce you to.

Types of Biomass Fuel

In its broadest sense, biomass fuel can be any biological or organic material which has originated from plant matter and heat is produced by burning it.

Most domestic biomass boilers and biomass stoves have been developed to burn wooden pellets or briquettes which have been formed from untreated wood including bark, logs, wood chips and sawdust.  Most biomass fuel is a by-product of furniture manufacture, tree surgery or from saw-mills.

Recipients of Domestic Renewable Heat Incentive tariff payments will have to source their biomass fuel from a supplier registered on an approved suppliers list, known as the RHI Biomass Suppliers List.

Biomass Boilers and Biomass Wood Pellets
Biomass Wood Pellets

Is biomass wood fuel sustainable?

The easy answer is that wood used as fuel for biomass boilers is sustainable if it was grown sustainably and the vast majority of biomass wood fuel available in the UK is from sustainable sources.  For sustainability and cost reasons it also makes sense to source wood fuel locally wherever possible.

Burning wood releases carbon dioxide, unlike most other renewable energy technologies, but it is limited to the amount of carbon dioxide which the plant or tree absorbed while it was growing.  This means that biomass fuel is carbon neutral.

Other types of biomass fuel include high energy yield crops such as wheat which have been grown specifically for large scale biomass boilers.  Some people consider there to be an ethical issue with this though, especially when these resources could be better used in food production.  Consequently, the fuel of choice for domestic biomass boilers are wooden pellets due to their greater energy density and it will continue to be so, as long as it can be derived from sustainable sources.

Biomass wood pellet specification:

The accepted standard for the quality of biomass wood pellets in the UK is DINplus, which has the following characteristics:

  • Content – 100% untreated wood with no additives
  • Size – Maximum 30 mm long and between 5 mm and 8 mm diameter.
  • Calorific value – 4.9 kilowatts per kilogram
  • Water content – Maximum of 10% by weight
  • Ashes – Maximum of 0.5% of original weight

Which Products Qualify for the Domestic Renewable Heat Incentive

Whilst the Domestic RHI is available to all households, those off mains gas will have more to gain from biomass boiler grants by reducing both their fuel bills and carbon emissions.  This is because of the relative inefficiencies (compared to mains gas) of LPG, heating oil, coal or electricity in providing cost-effective heat and hot water for your home.

Renewable energy heating systems which are eligible for the Domestic Renewable Heat Incentive scheme include:

All of these renewable energy heating systems provide just space heating and hot water, except solar thermal, which must provide hot water only, to be eligible. Renewable energy heating systems must provide heating through a ‘wet’ central heating system such as radiators to be eligible for the Domestic RHI scheme.  Current estimates are that there are approximately four million households in the UK which don’t have access to mains gas.

The Domestic Renewable Heat Incentive scheme is available to:

  • owner-occupiers
  • private landlords
  • social housing
  • third-party owners of a heating system and
  • new self-build properties

Affordable Warmth Scheme

Another Government scheme to help with heating systems in domestic households is the Affordable Warmth Scheme. This provides grants to help to replace broken heating systems and to install insulation in homes where one of the occupants receives a qualifying State Benefit, Tax Credits or other allowance.

More information about the Affordable Warmth Scheme can be found HERE.

Renewable energy – you know it makes sense

When almost every day we hear of gas and electricity energy prices rising at a rate way above general inflation, it makes sense to take control of your domestic energy consumption.

Renewable energy technologies allow you to do that and at the same time you will:

  • Save on your household energy bills
  • Make money from the renewable energy you generate
  • Protect your household budget against price rises
  • Reduce your home’s carbon emissions
  • Secure your future energy supply from sustainable sources