The pressure and temperature relief valves (PTR) available from the Australian Valve Group are designed to relieve the increase in pressure caused by water expansion during the normal heating cycle.
The function of the valves is to relieve the increase in pressure by releasing drips of hot water to the drain line. Should the electrical temperature cut-out device cease to operate correctly, the water will overheat and this will cause the temperature probe to open the Pressure and Temperature Relief valves and discharge hot water to the drain line.
Some local governments make it mandatory to install an ECV valve in the cold water line in order to relieve cold water, not hot water, during the heating cycle, saving energy and increasing the life of the PTR valves.
PTR and ECV valves are safety valves and should be replaced every 4 years.