New versions of the Viega Prevista WC suites have been released to comply with the updated requirements of Regulation 4 of the Water Supply (Water Fittings) Regulations of 1999. The new cisterns have achieved certifications with the Water Regulations Advisory Scheme (WRAS) and KIWA (KUKreg4).
To resolve industry concerns about potential backflow from WC cisterns into the mains supply, WRAS and KIWA have updated their acceptance criteria for approval of filling valves. The evidence gathered by WRAS suggested that in some cases the standard backflow protections could be compromised or were not sufficient to prevent the backflow of water stored in WC cisterns into the mains supply via the filling valve.
The water regulations now require an AG air gap on the supply inlet to the cistern and an AUK 1 air gap between the WC cistern inlet and the pan. A Type AUK1 AG air gap must meet the following criteria:
1. A Type AG air gap is a non-mechanical arrangement inside a cistern that provides a visible, unobstructed and complete physical air break between the lowest level of water discharge and the critical water level (CWL).
2. The physical air break must be at least 20mm, or twice the internal diameter of the inlet pipe, whichever is greater.
3. There must also be a gap of at least 300mm from the overflow pipe to the top or spillover level of the WC pan. The overflow must be circular and of a minimum size of 19mm, providing this is capable of accommodating maximum inlet flow.
4. Lastly there must also be at least a 15mm gap between the lowest level of the WC cistern and the top or spillover level of the WC pan.
The water regulations place a legal duty on owners, occupiers and anyone who installs plumbing systems, water fittings and water-using appliances to ensure they are installed and used in accordance with the regulations. Therefore, it is important to ensure that a WC, pre-wall system or cistern has been designed and manufactured in line with the new guidance, and that it is installed correctly.
WRAS and KIWA approved Type AG inlet valves are included in all Viega Prevista WC cisterns. The range includes the Prevista Dry WC element in construction heights 1120, 980 and 820 mm alongside the Prevista Pure 3H and 3L cisterns. This allows simple compliance with the regulations regardless of the requirements of the bathroom or washroom design.
In addition, Prevista has been designed for easy installation, long-term reliability and superior flexibility. The frames and compatible flush plates can be installed and configured quickly and easily with minimal tools required. All manually installed or adjusted components are coloured yellow for easy identification. It also features a universal shower toilet connection, providing simple compatibility with this increasingly popular choice of WC.
Prevista has also been engineered to minimise post installation issues. The cistern is manufactured as a single part using a blow moulding technique. This ensures maximum leak-tightness and reliability by removing the need to join individual elements. Each cistern is also checked for leaks and its operation tested before it leaves our factory.
For more information on Viega’s Prevista range, visit www.viega.co.uk/prevista.
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