Building valves - Combined temperature and pressure relief valves - Tests and requirements

This document specifies dimensions, materials and performance requirements, including test methods, for combined temperature and pressure relief valves, of nominal sizes from DN 15 to DN 40, having working pressures1) from 0,3 MPa (3 bar) to 1,0 MPa (10 bar).Combined temperature and pressure relief valves control and limit the temperature and pressure of the water contained in a hot water heater to the valves rating pressure and a temperature not exceeding 100 °C and will prevent water to steam formation when other temperature controls fail.Combined temperature and pressure relief valves are classified having a maximum opening temperature range from 90 °C to 95 °C for class A and 75 °C to 80 °C for class B.They are not intended to act as an expansion valve and do not control cold water flow.Alone it does not constitute the control functions for a water heater.A combined temperature and pressure relief valve is an independently mechanically operating device, therefore operating without an external energy source.NOTE The use of the device specified in this document does not override the need to use controls (e.g. thermostats and cut-outs) which act directly on the power sources of water heaters (for more information, see Annex B).