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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.

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.

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    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 scheme3.

    • 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 Schemes4
    • Solid fuel fired boiler – An installer should be registered with one of the relevant Competent Person Schemes5.

    They must follow the guidelines set out in Approved Document J6, 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 Ministry of Housing, Communities and Local Government publication:

    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 Ratings8.

    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 J9 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 J10.


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    The Planning Portal is delivered by PortalPlanQuest Limited which is a joint venture between TerraQuest Solutions Limited and the Department for Levelling Up, Housing & Communities. All content © 2022 Planning Portal.