Conservation of fuel and power: Approved Document L, Volume 2 — Buildings other than dwellings

L1(b), L2 O N L I N E V E R S I O N Boiler controls 6.7 Boiler systems with an output of more than 100kW should have both of the following. a. Optimum start/stop control with either: i. night setback ii. frost protection outside occupied periods. b. Either: i. two-stage high/low firing facility in boiler ii. multiple boilers with sequence control to provide efficient part-load performance. 6.8 Gas-fired boilers and multi-stage oil-fired boilers with an output of more than 500kW should have fully modulating burner controls. Biomass boilers 6.9 The efficiency of biomass boilers at their nominal load and tested to BS EN 12809 should be no lower than the following. a. For independent gravity-fed boilers of ‹20.5kW output: 65%. b. For independent automatic pellet/woodchip boilers: 75%. Gas and oil-fired warm air heaters 6.10 In addition to meeting the general requirements for heating systems in Section 5, warm air systems in new and existing buildings should meet the heat generator seasonal efficiency in Table 6.3. Table 6.3 M inimum heat generator seasonal efficiency for gas and oil-fired warm air heaters Warm air heater type Heat generator seasonal efficiency Product standard (net calorific value/thermal efficiency) Gas-fired forced convection to 91% BS EN 621 for unfanned appliances assist transportation of combustion BS EN 1020 for fanned appliances air and/or combustion products Direct gas-fired forced convection(1) n/a BS EN 525 Oil-fired forced convection 91% BS EN 13842 NOTE: 1. For direct gas-fired forced convection air heaters, 100% of the net heat input is delivered to the space. Specific ventilation requirements as defined in BS EN 525 should be met. Gas and oil-fired radiant heaters 6.11 In addition to meeting the general requirements for heating systems in Section 5, radiant heaters in new and existing buildings should meet the heat generator seasonal efficiency in Table 6.4. 6.12 For flued appliances, thermal efficiency should be measured to either of the following test standards, as applicable: a. BS EN 1020 42 Approved Document L Volume 2, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N