What type of valve is commonly used to control hot water?

The ball valve is commonly used to control hot water due to its design and functionality. It features a spherical disc, or "ball," that opens and closes the flow of water with a simple quarter-turn motion. This allows for quick and efficient on-off control, making it ideal for applications where immediate flow adjustment is necessary, such as in hot water systems.

Ball valves also provide a tight seal when closed, which prevents leaks and ensures that water doesn't flow unintentionally. Their durability and ability to handle high temperatures and pressures make them a preferred choice in plumbing systems handling hot water.

In contrast, check valves are primarily designed to prevent backflow and don't have flow control capabilities; gate valves are used mainly for isolation and are not as effective for quick flow regulation; and pressure relief valves are specifically engineered to release excess pressure, not to control water flow. This is why the ball valve stands out as the appropriate choice for managing hot water systems.