G3 – Hot Water Supply and Systems: What are the controls on the hot water supply and hot water systems?
With regard to supply, the provision requires that heated wholesome water (or softened wholesome water) is provided to any washbasin or bidet provided in or adjacent to a room containing a sanitary convenience, to any washbasin, bidet, bath or shower in a bathroom and to any sink provided in any area where food is prepared. In relation to hot water systems, the provision extends the scope of the previous safety regime to all types of system (not just unvented ones). This includes new guidance in the Approved Document to ensure that all parts of the system are capable of resisting the effects of temperature and pressure. In particular, this introduces guidance to ensure cold water cisterns supplying and receiving water from hot water cisterns are properly supported, following tragedies resulting from just such failures.
In addition, it also introduces a provision that all new homes (including those created by a change of use) have the temperature of the hot water supplied to a bath limited to no more 7 than 48°C. It’s likely that this will normally be complied with by the fitting of a thermostatic mixing valve (TMV).