Gas Fitter Practice Test 2026 – The All-in-One Guide to Mastering Your Certification!

The recommended water temperature setting from a mixing valve for domestic water in combined heating systems falls within the range of 49°C to 54°C (120°F to 130°F). This temperature is optimal for several reasons.

First, this range provides a safe and comfortable level for domestic hot water, minimizing the risk of scalding while ensuring effective sanitation. At temperatures lower than this range, there might be a heightened risk of bacterial growth, particularly from microorganisms such as Legionella, which thrive in lukewarm water.

Second, setting the temperature in this range strikes a balance between energy efficiency and sufficient heating performance. Water that is too hot can lead to wasted energy, while water that is too cool may not effectively meet household needs.

Setting temperatures above this recommended range, such as options discussing 60°C to 66°C (140°F to 150°F) or higher, can increase the risk of burns and scalding, particularly for vulnerable populations, such as children and elderly individuals.

By adhering to the recommended temperature setting, combined heating systems can effectively provide safe and efficient domestic hot water service.