How do zoning valves work in a hydronic heating system?

Zoning valves play a crucial role in a hydronic heating system by controlling the flow of hot water to specific zones within a building. These valves are typically installed at the branches of the heating piping system, allowing for individual temperature control in different areas or zones. When a zone's thermostat calls for heat, the zoning valve opens, enabling hot water to flow into that specific zone's heating devices, such as radiators or floor heating. This targeted approach not only enhances comfort by allowing occupants to customize their heating needs but also improves energy efficiency by not heating unoccupied areas.

In contrast, the other options do not accurately describe the function of zoning valves. They do not regulate water quality, determine water temperature, or monitor system pressure. Instead, zoning valves focus specifically on controlling the distribution of hot water as per the requirements of different zones in the heating system. This functionality makes them integral to maintaining efficient and effective hydronic heating operations.