Storage-type geysers and water heaters include a pressure and temperature relief valve as a critical safety component, designed to release water automatically if internal pressure or temperature rises beyond a safe threshold, preventing a potentially dangerous buildup inside a sealed tank. This valve should be tested periodically by manually lifting its lever briefly to confirm water flows freely and then stops when released, since a valve that has become stuck from mineral deposits or infrequent use may fail to activate when genuinely needed.
A valve that drips continuously even when not manually tested often indicates it is malfunctioning or that tank pressure is running higher than normal, either of which warrants professional inspection rather than simply tolerating the drip as a minor nuisance. Thermostat calibration is closely related to this safety function, since a thermostat that has drifted and allows water to heat beyond its intended setting increases the likelihood of the pressure relief valve needing to activate more frequently than it should under normal operation.
Installing or maintaining this valve requires ensuring its discharge pipe routes safely away from areas where hot water release could cause injury or damage, a detail sometimes overlooked during installation but important for the valve to serve its safety function effectively if it ever needs to activate.