Conservation of fuel and power: Approved Document L, Volume 1 — Dwellings

O N L I N E V E R S I O N L1(a) External pipework for district heat networks 4.27 Pipework for district heat networks should be insulated to meet either of the following. a. The standards in BS EN 253 for pre-insulated pipes. b. An equivalent performance for conventionally insulated pipes. 4.28 Where pipework is above ground, the performance of the pipe insulation should be at least as high as the insulating performance of pipework in the buried part of the system. Heated water storage for space or domestic hot water 4.29 Vessels that store heated water for a heating or domestic hot water system should have standing losses that do not exceed the heat loss given in Table 4.5 for that system type. Table 4.5 Maximum daily heat loss for a hot water cylinder(1) Nominal volume (litres) Heat loss (kWh/24h) Nominal volume (litres) Heat loss (kWh/24h) 50 1.03 400 2.59 100 1.49 500 2.80 150 1.88 600 2.98 200 2.06 700 3.14 250 2.22 800 3.29 300 2.36 900 3.44 350 2.48 1000 3.57 NOTE: 1. For sizes of cylinder not listed, the heat loss from the cylinder should not exceed (16.66 + 8.33 � V0.4)/(1000 ÷ 24), where V is the volume in litres. 4.30 Hot water storage vessels should comply with all of the following. a. Copper hot water storage combination units should comply with BS 3198. b. Vented cylinders should comply with the heat loss and heat exchanger requirements of BS 1566-1 or BS EN 12897 as appropriate. c. Unvented hot water storage system products should comply with BS EN 12897. 4.31 Primary storage systems should meet the insulation requirements of the Hot Water Association’s Performance Specification for Thermal Stores. Heat interface units 4.32 Vessels that store heated water for a heating or domestic hot water system should have standing losses that do not exceed the heat loss given in Table 4.5 for that system type. 32 Approved Document L Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N