Which of the following is not used as an anti-scald device?

The water heater thermostat is not classified as an anti-scald device. Its primary function is to regulate the temperature of the water in the water heater, ensuring that it does not exceed a set point for efficiency and safety reasons. While a well-regulated water heater can help maintain a safe supply temperature, the thermostat itself does not actively prevent scalding in the plumbing system.

In contrast, devices such as pressure balance valves and thermostatic mixing valves are specifically designed to prevent scalding by responding to fluctuations in temperature or pressure in the system, thus maintaining a consistent and safe output temperature. Temperature control valves also serve a similar purpose by adjusting the hot and cold water mixes to prevent excessively hot water from reaching the fixtures.