What is used with the thermostat to provide individual zone control in a hydronic radiant floor heating?

• A. Circulator
• B. Zone valve
• C. Telestat
• D. Air damper

Answer: (C)

In a hydronic radiant floor system, you control each zone by pairing a thermostat with a valve that responds to that thermostat. A telestat is a thermostat-controlled electric valve placed in the zone line; when the thermostat calls for heat, the telestat opens to allow water into that zone, and it closes when the zone reaches set temperature. This setup lets multiple zones share a single circulator while each zone can be heated independently. A circulator moves water, but it doesn’t provide per-zone control on its own, and an air damper isn’t used in hydronic radiant floor systems. A valve that’s driven by the thermostat is the mechanism that enables the individual zone control, which is why telestat is the best fit here.