This British Standard gives recommendations on good practice for the preparation of the circulating water in open vented or sealed heating and cooling systems in individual domestic premises during initial commissioning or re-commissioning following major remedial work (e.g. boiler replacement) and the ongoing water treatment to ensure appliance and system protection and continued efficiency in operation.

NOTE 1: The term “boiler”, as used throughout this British Standard, reflects common parlance and refers to the appliance that heats the circulating water in a domestic central heating system (see 3.4). It does not actually raise steam (i.e. boil the water).

It does not apply to commercial or municipal premises or to multiple residential premises served by one common circuit, unless that common circuit can be effectively cleaned and flushed with domestic equipment. It does apply to individual heating and cooling circuits within individual dwellings in multiple residential premises.

NOTE 2: For specialized closed circuits, such as those containing solar thermal panels and ground source heat pump loops, refer to the manufacturer’s instructions. See also BS 5918 (for solar thermal) and MIS 3005 [12] (for ground source heat pumps).
NOTE 3: For larger closed heating systems such as found in commercial or municipal premises, or the primary systems on residential developments, refer to BSRIA BG 29 [13].