Water Supply Industry Interpretations and Advice

  • Area of Interest : Backflow prevention
  • Topic : Water heaters
  • Title : Filling and topping up heating system primary circuits.
  • Clause Reference : Schedule 2 paragraph 15 : G15.3 & G24.2
  • Reference Number : B22
  • Decision Date : June 2002 (Revised May 2004 & March 2014)

Water suppliers take account of government guidance in their enforcement of the Water Supply (Water Fittings) Regulations, Byelaws in Scotland, but recognise that guidance cannot cover all circumstances.

The categorisation of non-domestic primary circuits or heating systems is given in guidance as fluid category 4. Water suppliers do however adopt a risk based approach to enforcement and where a risk assessment indicates that the risk associated with a primary circuit or heating system is lower than a fluid category 4 risk they will accept alternative approaches.

Factors taken into consideration when risk assessing non-domestic primary circuits or heating systems include, but are not restricted to:-

  • The type and use of chemical inhibitors; and
  • The size and type of system i.e. whether it is a vented (open to atmosphere a vented system would be deemed to be of a higher risk) or unvented (sealed) system

    (Also see B54 'Disconnection of temporary filling loops')