VG and VGF are pressure relieved 2-way normally open (NO) valves, designed to be combined with: -AVT thermostatic actuators; STM safety temperature monitors and STL safety temperature limiters. In combination with AVT thermostatic actuators, valves can be used primarily: for domestic hot water (DHW) production (Hot water tanks, Storage charge systems and Instantaneous domestic hot water production) and in mixing loops and room heating systems as well.