+60 Visual Maps That Make Unvented Hot Water (G3) Finally Click

The discharge from the temperature relief valve and the expansion relief valve of an unvented hot water storage system is to be conveyed by way of a pipe of suitable material, of a size not less than that of the valve outlet, to a tundish incorporating a visible air break, which tundish should be installed in a vertical position, in the same space as the storage vessel, and located within a specified distance of the point of discharge, having due regard to the requirement that any discharge be readily visible to the occupants.

From the tundish, the discharge pipe should incorporate a vertical section of a minimum length before any bend or elbow, and thereafter be laid to a continuous fall, with the resistance to flow of the pipework, including the number of elbows and bends, being taken into account when determining the size of pipe, the maximum permitted length for any given size being reduced accordingly for each such fitting, as set out in the relevant table.

The point of termination should be selected so as to avoid any danger to persons in the vicinity of the discharge, with consideration given to the possibility of the discharge being of very hot water or steam, to the provision of suitable guards where persons may come into contact with the discharge, and to the avoidance of termination above windows, entrances or other areas used by the public, all of which should be confirmed prior to commissioning and recorded accordingly.