Originally Posted by Reno

A water heater would blow the F up if the water inside was steam.. The relief valve is set to trip at 150psi and if it did trip, it would probably keep on dripping since those valves set idle for so long. The popping sound is probably thermal expansion so I would add a expansion tank or change the one you have. Also a pressure guage on the water heater will tell you all you need to know. You could also need a pressure regulator

A standard heater shouldn't go above 120-140 degrees, depending on make model..


It's sounds like Bro Turtle is narrowing it down...

Reno, I'm not trying to argumentative so with all due respect I have to disagree with you on this comment. A water heater will in fact over heat if the thermostat goes bad or if an element shorts to ground. The temps that you gave are for properly working thermostats and elements. And a HW tank will not blow up if this condition exists because they are designed to relieve the pressure if this happens. We had this exact same scenario last week at my grandfathers with the exception of low volume (which can easily be explained by sediment getting kicked up and stopping up the faucet). His was spitting and sputtering pretty violently when you turned on the hot water side and it was affecting one leg worse than the others. He had a runaway thermostat that was, in fact, causing the water to overheat. We changed it out and fixed his problem.