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Last edited 01 Apr 2021
Hot water safety
- The central heating system which supplies hot water to radiators located around a building.
- Domestic hot water supplied to taps and sometimes to appliances.
 Hot water safety under Section G3 of Approved Document G
Section G3 of Approved Document G defines ‘domestic hot water’ as water that has been heated for cooking, food preparation, personal washing or cleaning purposes. Under Approved Document G, the “suitable installation for the provision of heated wholesome water or heated softened wholesome water” is required.
Section G3 provides specific guidance regarding hot water safety for sanitaryware (including washbasins, sinks, baths, showers and bidets) and other water storage systems (including cisterns or other water supply vessels). Under Section G3, systems should incorporate precautions to:
- Prevent the temperature of the water stored in the vessel at any time exceeding 100C.
- Ensure that any discharge from safety devices is safely conveyed to where it is visible but will not cause a danger to persons in or about the building.
Furthermore, the hot water supply to any fixed bath must be so designed and installed as to incorporate measures to ensure that the temperature of the water that can be delivered to that bath does not exceed 48C.
- Vented hot water storage systems
- Unvented hot water storage systems – all systems
- Unvented hot water storage systems – systems up to 500 litres capacity and 45kW power input
- Unvented hot water storage systems – systems over 500 litres capacity or over 45kW power input
Solar water heating
Prevention of scalding
 Further guidance
- BS EN 806-5:2012 Specifications for installations inside buildings conveying water for human consumption. Operation and maintenance.
- BS 8558:2015 Guide to the design, installation, testing and maintenance of services supplying water for domestic use within buildings and their curtilages.
- BS EN 12897:2006 Water supply.
 Related articles on Designing Buildings Wiki
- BSI, BS EN 806-5:2012 Specifications for installations inside buildings conveying water for human consumption. Operation and maintenance.
- BSI, BS 8558:2015 Guide to the design, installation, testing and maintenance of services supplying water for domestic use within buildings and their curtilages.
- BSI, BS EN 12897:2006 Water supply.
- Gov.uk, Approved Document G.
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