Hi all,

Does a standard temperature-pressure-relief valve have a "kick-off" rating? I.e. the tag on the TPR on my furnace says "50 PSI" meaning that the "kick-on" is 50 PSI - if the pressure exceeds 50 PSI, the valve will activate. So my question is, will the valve shut off as soon is it's below 50 PSI, or is there a "kick-off" value as well (for example, if the kick-off is, say, 35 PSI, then even though the system can normally stay at 45 PSI without activating the TPR valve, once the pressure goes above 50, the TPR valve will not close until it has dropped all the way down to 35 PSI)?

I ask this because I "tested" the TPR valve by pulling the lever on it a little bit, (havng raised the pressure since the last time I tested it) and instead of closing as soon as I let go, it continued to shoot out water for several seconds afterward. Did this happen because of the "kick-off" theory mentioned above, or should I just assume that a piece of debris had goten loged in the opening for a few seconds or something, preventing it from closing right away?