Some people install a relief valve, most people control the pressure more carefully so one is only there as an emergency backup, if at all. As has been said, without knowing what your system pressure is, there's no way to know if the valve is opening as it was designed, or has failed.
Code requires the home's system pressure to be <=80psi. If it gets above that, you need to know why and fix it. If it is a closed system, it could simply be you need an expansion tank. If you have one, you may need to add a pressure reduction valve (PRV). And, if you don't have an expansion tank, you need one of those, too.