Which fluid is commonly used in hydronic systems?

Water is the most commonly used fluid in hydronic systems due to its unique properties that make it highly effective for heat transfer. It has a high specific heat capacity, meaning it can absorb and carry a significant amount of heat with relatively small temperature changes. This efficiency allows for the effective regulation of temperatures in heating systems.

Additionally, water is abundant, non-toxic, and environmentally friendly, making it a practical choice for both residential and commercial hydronic applications. Its low cost compared to other fluids further supports its widespread use. While other fluids, such as glycol, may be used in specific applications—like freeze protection in colder climates—water remains the primary fluid due to its overall advantages.