If steam or excessively hot water shoots out of faucets, or you hear boilding sounds inside the hot water heater, the appliance may not be shutting off at its set temperature. The job of the temperature- pressure (TP) relief valve is to release excessive pressure from steam buildup, but this valve may have been improperly installed, or it may be faulty. Either way, this condition can be dangerous, both because hot water and steam can scald people and because enough pressure could build up to rupture the water heater.