Technical Booklet P Sanitary Appliances Unvented Hot Water Storage and Scalding·Page 14·2.11
Pressure control devices
Unvented hot water storage systems must be equipped with a pressure reducing valve complying with BS EN 1567 and an expansion valve complying with BS EN 1491 to control system pressure.
An unvented hot water storage system should have the following devices to control the pressure within the system –
(a) a pressure reducing valve complying with BS EN 1567; and
(b) an expansion valve complying with BS EN 1491.
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