Section 2: Gas-fired space and water heating

2.1 Scope of guidance

This section provides guidance on the specification of gas-fired space heating and hot water systems12 in dwellings to meet relevant energy efficiency requirements in the Building Regulations. The guidance applies to systems fuelled by natural gas and liquid petroleum gas (LPG) and covers:

• wet central heating systems
• range cookers with integral central heating boilers
• warm air heating systems
• fixed independent space heating devices.

2.2 Gas-fired wet central heating systems

New systems

New systems for gas-fired wet central heating in new and existing dwellings should meet the minimum standards for:

a. boiler efficiency, system circulation, hot water storage, system preparation and commissioning in Table 2

b. boiler interlock, zoning, and time and temperature control of the heating and hot water circuits in Table 3

c. pipework insulation in Table 5.

Existing systems

Components installed as replacements in existing systems should meet the same standards as for new systems, except where indicated otherwise in Table 4.
Table 4 in addition identifies good practice upgrades to the rest of the system (beyond the requirements of the Building Regulations) when making planned and emergency replacements.

****Table 2 Recommended minimum standards for efficiency, system circulation, hot water storage, system preparation and commissioning for gas-fired wet central heating    systems****

****Table 3 Recommended minimum controls for gas-fired wet central heating systems[1]****

****Table 4 Recommended minimum standards when replacing components of gas-fired wet central heating systems[1]****

****Table 5 Recommended minimum standards for insulation of pipework in gas-fired wet central****

2.3 Gas-fired range cookers with integral central heating boiler

Note: This section does not apply to appliances with fully independent boiler and cooker parts within a shared case. For these, the standards for the boiler are as set out in Section 2.2.

Where gas-fired range cookers with an integral central heating boiler (within a single appliance body) are provided as part of a new system or as a replacement component:

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

b. The SEDBUK 2009 efficiency of the integral boiler should be not less than 75%. The manufacturer’s declaration of appliance performance and SEDBUK value should include the following words:

i. Seasonal efficiency (SEDBUK) = xx %
ii. Case heat emission value = yy kW
iii. Heat transfer to water at full load = zz kW
iv. The values are used in the UK Government’s Standard Assessment Procedure (SAP) for the energy rating of dwellings. The test data from which the values have been calculated has been certified by {insert name and/or identification of Notified Body}. See: www.rangeefficiency.org.uk.

If the integral boiler is a condensing boiler, the declaration should make clear whether the efficiency has been calculated in accordance with SEDBUK 2005 or SEDBUK 2009. If it does not, then SEDBUK 2005 must be assumed.

c. The integral boiler should meet the minimum standards for system circulation, hot water storage, system preparation, commissioning, controls and insulation in Tables 2, 3 and 5 (gas-fired central heating systems).

2.4 Gas-fired warm air heating

New systems and replacement components for gas-fired warm air heating should meet the minimum standards for:

a. efficiency and installation in Table 6

b. zoning, time control and temperature control for (a) space heating without hot water and (b) space heating combined with water heating in Table 7.

****Table 6 Recommended minimum standards for efficiency and installation of gas-fired warm air heating systems****

****Table 7   Recommended minimum controls for gas-fired warm air heating   systems****

2.5 Gas-fired fixed independent space heating appliances

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

Gas-fired fixed independent appliances for primary space heating

Where gas-fired fixed independent space heating appliances in new and existing dwellings are provided as the primary heat source:

a. The appliance should be one of the types described in Table 8.

b. The efficiency of the appliance (gross calorific value) should be not less than 63% (70% net).

c. The appliance manufacturer’s declaration of appliance performance should include the following words:

The efficiency of this appliance has been measured as specified in {insert appropriate entry from Table 8} and the result after conversion to gross using the appropriate factor from Table E4 of SAP 2012 is [x]%. The test data has been certified by {insert name and/or identification of Notified Body}. The gross efficiency value may be used in the UK Government’s Standard Assessment Procedure (SAP) for energy rating of dwellings.

d. In new dwellings, 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). In existing dwellings, wherever practical, temperature controls should be upgraded to the standards required for new dwellings.

****Table 8 Acceptable types of natural gas and LPG-fired fixed independent appliance for primary****

Gas-fired fixed independent appliances for secondary space heating

Where gas-fired fixed independent space heating appliances are provided as the secondary heat source:

a. In new dwellings, the appliance efficiency (gross calorific value) should be not less than 63% (70% net).

b. In existing dwellings, the appliance efficiency (gross calorific value) should be not less than 45% (50% net).

c. The appliance manufacturer’s declaration of appliance performance should include the following words:

The efficiency of this appliance has been measured as specified in {insert appropriate entry from Table 9} and the result after conversion to gross using the appropriate factor from Table E4 of SAP 2012 is [x]%. The test data has been certified by {insert name and/or identification of Notified Body}. The efficiency value may be used in the UK Government’s Standard Assessment Procedure (SAP) for energy rating of dwellings.

****Table 9 Acceptable types of natural gas and LPG-fired fixed independent appliance for secondary space heating****

2.6 Gas-fired fixed decorative fuel-effect fires

This type of appliance is intended for decorative purposes and therefore a minimum thermal efficiency is not specified. Note that for the purposes of SAP 2012 the efficiency of decorative fuel-effect fires is classed as 20% in the space heating requirement calculation. See Table 4a of SAP 2012.

Gas-fired decorative fires in new and existing dwellings should:

a. meet the product standards in BS EN 509:2000 Decorative fuel-effect gas appliances

b. number not more than one appliance per 100 m2 of dwelling floor area.

2.7 Gas fires for secondary space heating provided as part of a combined fire and back boiler unit

Where gas fires are provided as a secondary heat source as part of a combined fire and back boiler unit in an existing system:

a. The appliance should be one of the types described in Table 10.

b. The efficiency (gross calorific value) of the appliance should be not less than the value in Table 10 for that type of appliance.

c. The appliance manufacturer’s declaration of appliance performance should include the following words:

The efficiency of this appliance has been measured as specified in {insert appropriate entry from Table 10} and the result after conversion to gross using the appropriate factor from Table E4 of SAP 2012 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 may be used in the UK Government’s Standard Assessment Procedure (SAP) for energy rating of dwellings.

****Table 10 Minimum appliance efficiencies for gas fires in a combined fire and back boiler unit****

 

  1. 2.1 Scope of guidance
    1. 2.2 Gas-fired wet central heating systems
      1. 2.3 Gas-fired range cookers with integral central heating boiler
        1. 2.4 Gas-fired warm air heating
          1. 2.5 Gas-fired fixed independent space heating appliances
            1. 2.6 Gas-fired fixed decorative fuel-effect fires
              1. 2.7 Gas fires for secondary space heating provided as part of a combined fire and back boiler unit

                2.1 Scope of guidance

                This section provides guidance on the specification of gas-fired space heating and hot water systems12 in dwellings to meet relevant energy efficiency requirements in the Building Regulations. The guidance applies to systems fuelled by natural gas and liquid petroleum gas (LPG) and covers:

                • wet central heating systems
                • range cookers with integral central heating boilers
                • warm air heating systems
                • fixed independent space heating devices.

                 

                2.2 Gas-fired wet central heating systems

                New systems

                New systems for gas-fired wet central heating in new and existing dwellings should meet the minimum standards for:

                a. boiler efficiency, system circulation, hot water storage, system preparation and commissioning in Table 2

                b. boiler interlock, zoning, and time and temperature control of the heating and hot water circuits in Table 3

                c. pipework insulation in Table 5.

                Existing systems

                Components installed as replacements in existing systems should meet the same standards as for new systems, except where indicated otherwise in Table 4.
                Table 4 in addition identifies good practice upgrades to the rest of the system (beyond the requirements of the Building Regulations) when making planned and emergency replacements.

                ****Table 2 Recommended minimum standards for efficiency, system circulation, hot water storage, system preparation and commissioning for gas-fired wet central heating    systems****

                ****Table 3 Recommended minimum controls for gas-fired wet central heating systems[1]****

                ****Table 4 Recommended minimum standards when replacing components of gas-fired wet central heating systems[1]****

                ****Table 5 Recommended minimum standards for insulation of pipework in gas-fired wet central****

                 

                2.3 Gas-fired range cookers with integral central heating boiler

                Note: This section does not apply to appliances with fully independent boiler and cooker parts within a shared case. For these, the standards for the boiler are as set out in Section 2.2.

                Where gas-fired range cookers with an integral central heating boiler (within a single appliance body) are provided as part of a new system or as a replacement component:

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

                b. The SEDBUK 2009 efficiency of the integral boiler should be not less than 75%. The manufacturer’s declaration of appliance performance and SEDBUK value should include the following words:

                i. Seasonal efficiency (SEDBUK) = xx %
                ii. Case heat emission value = yy kW
                iii. Heat transfer to water at full load = zz kW
                iv. The values are used in the UK Government’s Standard Assessment Procedure (SAP) for the energy rating of dwellings. The test data from which the values have been calculated has been certified by {insert name and/or identification of Notified Body}. See: www.rangeefficiency.org.uk.

                If the integral boiler is a condensing boiler, the declaration should make clear whether the efficiency has been calculated in accordance with SEDBUK 2005 or SEDBUK 2009. If it does not, then SEDBUK 2005 must be assumed.

                c. The integral boiler should meet the minimum standards for system circulation, hot water storage, system preparation, commissioning, controls and insulation in Tables 2, 3 and 5 (gas-fired central heating systems).

                 

                2.4 Gas-fired warm air heating

                2.4 Gas-fired warm air heating

                New systems and replacement components for gas-fired warm air heating should meet the minimum standards for:

                a. efficiency and installation in Table 6

                b. zoning, time control and temperature control for (a) space heating without hot water and (b) space heating combined with water heating in Table 7.

                ****Table 6 Recommended minimum standards for efficiency and installation of gas-fired warm air heating systems****

                ****Table 7   Recommended minimum controls for gas-fired warm air heating   systems****

                 

                2.5 Gas-fired fixed independent space heating appliances

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

                Gas-fired fixed independent appliances for primary space heating

                Where gas-fired fixed independent space heating appliances in new and existing dwellings are provided as the primary heat source:

                a. The appliance should be one of the types described in Table 8.

                b. The efficiency of the appliance (gross calorific value) should be not less than 63% (70% net).

                c. The appliance manufacturer’s declaration of appliance performance should include the following words:

                The efficiency of this appliance has been measured as specified in {insert appropriate entry from Table 8} and the result after conversion to gross using the appropriate factor from Table E4 of SAP 2012 is [x]%. The test data has been certified by {insert name and/or identification of Notified Body}. The gross efficiency value may be used in the UK Government’s Standard Assessment Procedure (SAP) for energy rating of dwellings.

                d. In new dwellings, 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). In existing dwellings, wherever practical, temperature controls should be upgraded to the standards required for new dwellings.

                ****Table 8 Acceptable types of natural gas and LPG-fired fixed independent appliance for primary****

                Gas-fired fixed independent appliances for secondary space heating

                Where gas-fired fixed independent space heating appliances are provided as the secondary heat source:

                a. In new dwellings, the appliance efficiency (gross calorific value) should be not less than 63% (70% net).

                b. In existing dwellings, the appliance efficiency (gross calorific value) should be not less than 45% (50% net).

                c. The appliance manufacturer’s declaration of appliance performance should include the following words:

                The efficiency of this appliance has been measured as specified in {insert appropriate entry from Table 9} and the result after conversion to gross using the appropriate factor from Table E4 of SAP 2012 is [x]%. The test data has been certified by {insert name and/or identification of Notified Body}. The efficiency value may be used in the UK Government’s Standard Assessment Procedure (SAP) for energy rating of dwellings.

                ****Table 9 Acceptable types of natural gas and LPG-fired fixed independent appliance for secondary space heating****

                 

                2.6 Gas-fired fixed decorative fuel-effect fires

                This type of appliance is intended for decorative purposes and therefore a minimum thermal efficiency is not specified. Note that for the purposes of SAP 2012 the efficiency of decorative fuel-effect fires is classed as 20% in the space heating requirement calculation. See Table 4a of SAP 2012.

                Gas-fired decorative fires in new and existing dwellings should:

                a. meet the product standards in BS EN 509:2000 Decorative fuel-effect gas appliances

                b. number not more than one appliance per 100 m2 of dwelling floor area.

                 

                2.7 Gas fires for secondary space heating provided as part of a combined fire and back boiler unit

                Where gas fires are provided as a secondary heat source as part of a combined fire and back boiler unit in an existing system:

                a. The appliance should be one of the types described in Table 10.

                b. The efficiency (gross calorific value) of the appliance should be not less than the value in Table 10 for that type of appliance.

                c. The appliance manufacturer’s declaration of appliance performance should include the following words:

                The efficiency of this appliance has been measured as specified in {insert appropriate entry from Table 10} and the result after conversion to gross using the appropriate factor from Table E4 of SAP 2012 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 may be used in the UK Government’s Standard Assessment Procedure (SAP) for energy rating of dwellings.

                ****Table 10 Minimum appliance efficiencies for gas fires in a combined fire and back boiler unit****