Which of the following is a sign of a faulty mixing valve?

A faulty mixing valve is designed to blend hot and cold water to deliver water at a safe and consistent temperature. When the mixing valve malfunctions, it often fails to regulate the temperature effectively, leading to fluctuating hot water temperatures. This means that users may experience sudden changes in water temperature, such as bursts of hot water followed by cooler water, which can be uncomfortable and potentially dangerous.

In contrast, consistent water temperature indicates that the mixing valve is functioning properly, maintaining an even blend of hot and cold water. Increased water pressure, while it can indicate other plumbing issues, is not a primary sign of a faulty mixing valve. Similarly, no water flow points to a different kind of issue altogether, such as blockages or closed valves, rather than a problem with temperature regulation specific to a mixing valve.