Rain Water Header Break Tank Wall Tray

£510.00 £612.00 inc. vat

In stock


Rainwater header tank supplies rainwater under gravity to appliances with an automatic mains water backup facility. The primary benefit of this header system is the continuation of water supply during electrical power failures. The rainwater model is similar to the AB18 but features a second float valve – for mains water top-up, set to open at a lower level. Typically the cistern will be full of rainwater having been pumped from a large underground storage tank. If there is insufficient rainwater or electrical failure, the cistern will automatically top-up with mains water. The AB18T should be mounted sufficiently higher than the application – e.g. 5 m = 0.5 bar. Note – minimum pressure required for washing machines. Where there is insufficient head refer to pumped systems – “Boost-A-Break” (BTAB) or “Midi-Break” (BTMIDI). Up to 12 litres of rainwater can be drawn off before the mains float valve opens. In practice, the rainwater float valve normally fills at a similar rate as the draw off preventing unnecessary mains top-up when rain water is available.


Toilets; Clothes washing machines; Hose Union Taps; Underground or surface irrigation – see HUBG datasheet; Applications deemed to be Category 5 by water company

Product Specification
  • Cistern Size 18 Litres
  • Inlet Size 15 mm
  • Outlet Size 22 mm
  • Powered No
Specification Clause

Where indicated on the drawing a Rainwater Header Break Tank with automatic mains water backup and Fluid Category 5 type AB air gap complying with EN13077: 2008 shall be installed – model AB18T – as manufactured by Arrow Valves Ltd – Tel 01442 823123 www.arrowvalves.co.uk. The assembly shall have an 18 litre nominal capacity cistern with a stainless steel mesh screened weir slot. The cistern shall be located in a stainless steel drip tray with integral bracket for wall mounting. The rainwater inlet shall have a 15 mm “Torbeck” compact float operated valve. The mains water inlet shall have a second “Torbeck” float valve operated at a lower level by a linear linkage assembly. The cistern shall be suitably elevated to provide adequate static pressure. The cistern outlet shall be 22 mm push-fit and 22 mm overflow should be connected to the drip tray.

Data Sheets


ab18datasheet-3.pdf (0.99 MB)