3. Oil-fired wet central heating systems

Section 3 - Oil-fired space heating and hot water systems

This section provides guidance on the specification of oil-fired space heating and hot water systems in dwellings to meet the 2019 Building Regulations energy efficiency requirements.

All oil appliances must be installed by a suitably qualified person and the installation should be carried out in accordance with the manufacturer’s instructions and comply with all other relevant parts of the Building Regulations.

3.1 - Scope of guidance

The guidance in this section applies to systems fuelled by oil. The following types of oil-fired heating systems are addressed:

• Wet central heating systems.

• Range cookers with integral central heating boilers.

• Vaporising appliances providing secondary heating or hot water.

• Fixed independent space heating devices.

Where appropriate, it may be necessary to refer to the sections in this guide covering community heating, underfloor heating, heat pumps, solar water heating and micro-CHP.

3.2 Oil-fired wet central heating systems

This section provides guidance on the specification of oil-fired wet central heating systems for dwellings that, if followed, will satisfy the energy efficiency requirements of the 2008 Building Regulations.

Terminology and applicability of guidance to different scenarios in new and existing dwellings

The guidance in this section applies to the following situations:

1. The specification of central heating systems in new dwellings – this situation is referred to in this section as a new system.

2. The specification of central heating systems in existing dwellings where previously space heating was not provided by central heating – this situation is also referred to in this section as a new system.

3. The specification of a replacement central heating system and/or component in existing dwellings where central heating is already installed – this situation is referred to in this section as a replacement system.

In situations (a) and (b) above the guidance for compliance of new systems (in new and existing dwellings) with Part L is the same.

In situation (c) above, that is for replacement systems in existing dwellings, in most cases the guidance for compliance with Part L is as for new systems, unless otherwise stated in the relevant section.

In order to comply with the requirements of Part L, oil-fired central heating systems which are provided as new systems or replacement systems in dwellings should meet all of the following conditions:

1. The boiler should have a minimum efficiency (as defined by its HARP value) as given in Table 9 (row a),

AND

1. The minimum provisions for system circulation as given in Table 9 (row b),

AND

1. The minimum provisions for hot water storage and labelling of storage vessels as given in Table 9 (row c).

AND

1. The minimum provisions for system preparation and water treatment as given in Table 1 (row d).

AND

1. The system should be commissioned in accordance with the minimum provisions given in Table 9 (row e).

AND

1. The minimum provisions for boiler interlock, zoning and time control and temperature control of the heating and hot water service circuits as described in Table 10. An acceptable alternative to these is any boiler management system that delivers the specified zoning, timing and temperature and boiler interlock control provisions. When oil boilers are installed as part of a replacement system, the minimum level of system controls should be provided, as described in Table 10, unless they are already installed and fully operational. If an individual component of the control system is being replaced in an existing system, for example a room thermostat, it is not necessary to upgrade the system to meet the minimum requirements.

AND

1. Pipework should be insulated as described in Table 11.

Table 9

Tables 9A, B, C & D

Table 10

Table 10

3.3 - Oil-fired range cookers with integral central heating boilers

Oil-fired range cookers with integral central heating boilers for space heating and hot water in dwellings.

Note the guidance applies only to twin burner cooker boilers, which should not be confused with the type of range cooker described as a single burner ‘dry heat’ range cooker. The latter is intended to provide only a cooking function, is not included in DEAP 2008 calculations, and does not come within the scope of the 2008 Building Regulations energy efficiency requirements.

In order to comply with the 2008 Building Regulations energy efficiency requirements, oil-fired range cookers with an integral central heating
boiler which are provided in new or existing dwellings should meet all of the following conditions:

1. The appliance should have two independently controlled burners (one for the cooking function and one for the boiler).

AND

1. The boiler should have a Seasonal Efficiency (HARP) value in excess of 75%. The manufacturer’s declaration of appliance performance and HARP value should include the following words:

• “Seasonal efficiency (HARP) = xx%

• Case heat emission value = yy kW

• Heat transfer to water at full load = zz kW

• The efficiency values are used in the Dwelling Energy Assessment Procedure (DEAP) for the energy rating of dwellings. The test data from which they have been calculated has been certified by {insert name and/or identification of Notified body}”.

AND

1. The minimum provisions for oil-fired central heating systems with respect to the integral central heating boilers as given in Table 9 (rows b to e).

AND

1. The minimum provisions for boiler interlock, zoning and time control and temperature control of the heating and hot water circuits with respect to the integral central heating boilers as given in Table 10 for oil-fired central heating systems. An acceptable alternative to these is any boiler management system that delivers the specified zoning, timing and temperature provisions. When oil boilers are installed as a replacement for existing boilers, the minimum level of system controls should be provided, as described in Table 10 unless they are already installed and fully operational. If an individual component of the control system is being replaced in an existing system, for example a room thermostat, it is not necessary to upgrade the system to meet the minimum requirements.

AND

1. Pipework should be insulated as described in Table 11.

3.4 - Continually burning oil-fired vaporising appliances providing secondary heating or hot water

This section provides guidance on the specification of oil-fired vaporising appliances providing heating or hot water for dwellings that, if followed, will satisfy the 2008 Building Regulations energy efficiency requirements.

The guidance does not apply to appliances which have been converted from another fuel (for example from solid fuel to oil).

In order to comply with the 2008 Building Regulations energy efficiency requirements, oil-fired vaporising appliances in new and existing dwellings should have the minimum provision of controls as given in

Table 11a:

Table 11a (11b for file purposes)

3.5 - Oil-fired fixed independent space heating appliances

This section provides guidance on the specification of oil-fired fixed independent space heating appliances for dwellings.

Fixed independent space heating appliances may be installed as a means of primary or secondary space heating.

Oil-fired fixed independent appliances for primary heating

Oil-fired fixed independent space heating appliances in new dwellings which are provided as the primary heat source should meet the following conditions:

1. The efficiency of the appliance (gross calorific value) should be no less than 60%. The appliance manufacturer’s declaration of appliance performance shall include the following words:

“The net efficiency of this appliance has been measured and the result is [x]%. The test data from which it has been calculated has been certified by {insert name and/or identification of Notified Body}. The efficiency value when converted to gross by use of the appropriate conversion factor from Table D2.2 in DEAP 2008 may be used.”

AND

1. Each appliance should be capable, either independently or in conjunction with room thermostats or other suitable temperature sensing devices, of controlling the temperatures independently in areas that have different heating needs (e.g. separate sleeping and living areas).

Oil-fired fixed independent appliances for secondary heating

In order to comply with the 2008 Building Regulations energy efficiency requirements, oil-fired fixed independent space heating appliances in new dwellings which are provided as the secondary heat source should have a minimum efficiency (gross calorific value) of not less than 60%.

Supplementary Information

Further guidance on oil-fired heating systems is available in the following publications:

Energy Efficiency Best Practice in Housing publications see http://www.oftec.org:

• CE29 Domestic heating by oil: boiler systems;

• CE51 Central heating system specifications (CHeSS);

• CE54 Whole house boiler sizing method for houses and flats;

• OFTEC Technical Books 2, 3, 4 and 5 (see http://www.oftec.org);

• BS 5410.