General Contractor Practice Exam

A pressure relief valve on a water heater responds to which factors?

1. Only pressure changes

2. Temperature or pressure

3. Temperature changes only

4. Flow rate adjustments

The correct answer is: Temperature or pressure

The pressure relief valve on a water heater is designed to ensure safety by responding to both temperature and pressure changes within the system. This valve plays a crucial role in preventing excessive pressure buildup, which could lead to an explosion or significant damage to the water heater. When the water within the heater is heated, the temperature rises, which can increase the pressure of the steam and water inside. If the temperature exceeds safe levels, the pressure relief valve activates to release excess pressure, thereby protecting the system. Additionally, if the system detects rising pressure due to various factors, such as thermal expansion, the valve will also open to release water, thereby preventing dangerous scenarios. While focusing solely on pressure changes would seem relevant, it would ignore the critical role temperature plays in pressure regulation within the water heater. Consequently, the option that encompasses both pressure and temperature changes illustrates a comprehensive understanding of the functionality and purpose of the pressure relief valve.