What type of valve is required for a combination potable water-heating and space-heating system that exceeds 140°F?

In a combination potable water-heating and space-heating system that operates at temperatures exceeding 140°F, a temperature-actuated mixing valve is essential for ensuring safety and comfort. This type of valve is specifically designed to mix hot water with cold water to reach a safe and usable temperature for distribution.

The primary function of the temperature-actuated mixing valve is to prevent scalding and to control the temperature of the water entering fixtures, thus protecting users from high temperatures. When the system exceeds 140°F, the mixing valve helps mix in cooler water, creating a safer output temperature. This is critical in systems where hot water could be dangerous, particularly in residential settings with children or the elderly.

Additionally, the use of a temperature-actuated mixing valve contributes to system efficiency and longevity by preventing excessive temperature fluctuations that could lead to wear and tear on components. Overall, this type of valve aligns perfectly with the requirements for safety and operational efficiency in higher-temperature heating systems.