Plumbing Africa August 2018 - Page 89

TECHNICAL 87 SANS 10254 and under- counter water heaters The problem facing many installers is how to get hot water to isolated terminal points. This is especially so where you need to eliminate long dead legs. By Patrick Gordon The current solution is to use a small under-basin/sink geyser. The problem that faces the installer is how to install the unit in compliance with SANS 10254. Why would this be a problem? SANS 10254 requires that all pressurised hot water vessels be installed with five basic ancillaries: 1) T&P safety valve; 2) Pressure reducing valve; 3) Expansion relief valve; and 4) Two vacuum breakers. Anybody that has ever installed one of these units will know that it is virtually impossible to do so. It is however possible to install it according to SANS 10254 as an open-vent system. This means that at all times the internal pressure in the heater will be open to vent to the atmosphere. This can only be achieved by using a specially designed mixer or connection convention. a mixing control valve unit of a type shown in Figures 1 and 2. NOTE 2: The drip tray is not required for over-basin (such as a sink or bath) installations. NOTE 3: The cold water supply connection between