Which component in a residential water heater is responsible for limiting the maximum temperature?

The component responsible for limiting the maximum temperature in a residential water heater is the high limit aquastat. This device functions as a safety mechanism that monitors the temperature of the water within the tank. If the water temperature exceeds a preset limit, the high limit aquastat will disconnect power to the heating elements or the burner, effectively preventing overheating. This is crucial for safety, as excessive temperatures can pose risks such as scalding or even damage to the water heater itself.

While the thermostat regulates the desired temperature and maintains it during normal operation, it does not specifically act as a safety cutoff for maximum temperatures. The temperature and pressure relief valve plays a different role, primarily designed to release excess pressure or temperature from the system to prevent hazardous conditions, but it does not actively control temperature limits. The heating element is responsible for actually heating the water but does not have a function in limiting temperature. Therefore, the high limit aquastat is the key component that ensures the safe operation of residential water heaters by limiting maximum temperature.