Originally posted by MMILLER:
What is a good reason for this valve to be leaking, other than over pressure/overtemp?
Defective Valve would be a great reason or one not properly calibrated as to temperature and or pressure.
A lot of folks will never let any helper give advice unless the helper is going out for coffee for the real mechanics and may then suggest a good coffee shop Other then that their advice is normally useless like tits on a bull.
You see even though a normal T&P is rated for 210 degrees and 150 PSI. We sometimes use a lower rated valve as why run this heater to Max capacity?
A residential heater has only an operating control and NO safety devices other then the T&P unlike a commercial heater or a boiler.
What you could do is read the valve tag on your T&P and possibly test it by use of the test lever as described in your owners manual.
Not all plumbers will allow a helper into the home as these folks would just install a T&P with total disregard to firing rate they only know to replace in kind with no rhyme or reason WHY.
Just because a gauge says 45# or 125 degrees doesn’t mean it is accurate.
As a “certified” plumber-boiler – pressure vessel inspector we are also required to check the calibration of gauges and if necessary re calibrate the gauge or replace it.
When in doubt call a local licensed Master plumber and DEMAND to see their license before you even allow them in your home to do testing/inspection of your equipment.