Boilers and heating

Building regulations

If a heating system or hot water system is to be replaced then an application may not be required, and, if it is required, it may not be necessary to apply in advance of carrying out the work. 

If emergency works are necessary (because for instance a hot water cylinder springs a leak) there is no bar on carrying out repairs straightaway but the repair works must comply with the requirements and after the event it is necessary to apply for retrospective approval and a completion certificate

If a new system is to be installed then the installer should proceed as if the work is being carried out in a new building.

Guidance on what is reasonable provision for compliance with the energy efficiency requirements is given in the Department for Communities and Local Government (DCLG) publication Domestic Building Services Compliance Guide (PDF).

If an existing system has been altered or replaced then the person who last worked on the system is responsible for the safe running of that system and should issue a certificate to show that the necessary checks have been carried out.

Replacing Boilers

The new standards apply only if you decide to change your existing hot-water central-heating boiler or if you decide to change to one of these boilers from another form of heating system.

Work to install a new boiler (or a cooker that also supplies central heating - Aga, Raeburn etc) needs Building Regulations approval because of the safety issues and the need for energy efficiency. This is generally achieved by employing an installer who is registered under an approved scheme.

  • Gas Boiler – An installer should be Gas Safe Registered from 1 April 2009
  • Oil fired Boiler – An installer should be registered with one of the relevant Competent Person Schemes
  • Solid fuel fired boiler – An installer should be registered with one of the relevant Competent Person Schemes

They must follow the guidelines set out in Approved Document J, which shows what is necessary for air supplies, hearths, flue linings and chimney labelling where the flue outlet can be positioned.  See diagrams 3.4 & 3.5 for gas appliances and diagram 4.2 for oil appliances.

Each boiler must have a minimum efficiency of 86% for gas and 85% for oil.  The replacement of a gas boiler will probably have to be a condensing boiler unless there is sufficient reason why one cannot be installed.  An assessment is carried out by a registered installer on the type of boiler you will be required to have. The assessment is described in the Department for Communities and Local Government publication:

For more advice on this see Gas and oil central heating boilers: Advice to householders (PDF 110Kb) information leaflet produced by the Department for Communities and Local Government (then ODPM). 

Condensing Boilers - A condensing boiler with a SEDBUK rating of A or B should be installed unless an assessment carried out by a Gas Safe Register installer from 1 April 2009 suggests that it is not viable to install one, then less efficient boilers with SEDBUK Ratings of C or D can be installed providing they have meet the minimum efficiency as stated above. 

View an explanation of SEDBUK and a list of all boilers on the UK market with their SEDBUK Ratings.

If an oil fired heating system is to have a new storage tank then there are guidelines set out in Approved Document J which should be followed for fire safety reasons and to limit risks of oil pollution.

Following the guidance in Approved Document J may mean that replacement oil storage tanks cannot be sited where the old tank was. It is possible for local authorities to set aside the guidance in the Approved Document on tank location however, where they consider that this is unreasonable in all the circumstances.  However they will consider the vulnerability of the fuel tank to a fire in the building or from beyond the boundary and the oil pollution risks in each case individually on its own merits before doing so.

In some cases householders may decide to engage a firm that is not a member of one of the approved Competent Person schemes. In this case the installer will not be able to self-certify that their work is compliant, and the firm or the householder will need to give notice to your local authority of the intention to carry out the boiler work in advance, and pay a notification fee.  The local authority building control department may choose to check the works have been carried out to the necessary standards and may employ a registered installer to do this.

When works have been completed the installer should then produce for you a commissioning certificate such as a Benchmark certificate and notify the local authority building control department either directly, or, if a member of a  Competent Person Scheme, via the scheme operator.  In due course the local authority should supply you with a building regulations completion certificate that indicates compliance.

Guidance on installing boiler and other combustion appliances, and the building provisions that are necessary to safely accommodate them (air supplies, hearths, fireplaces, flues and chimneys) can be found in Approved Document J.