@love2hvac: Replying to @jfs.mechanical great question! before we had rupture disks or pop off valves that would release the entire charge when the pressure got too high. with A2L it is a resealable automatic valve that will open to relieve some pressure and close again. this way you don't loose the whole charge and reduce the potential for a flame. #hvac #hvactechnician #hvacarmy #love2hvac #a2l