Where should a check valve be installed in a recirculating system?

In a recirculating system, installing a check valve on the return side of the loop next to the tank is essential for maintaining proper circulation and preventing backflow. The check valve allows water to flow in one direction—returning to the water heater—while preventing any reverse flow that could disrupt the circulation path. By positioning the check valve here, you ensure that hot water is effectively delivered to fixtures and maintains a consistent temperature without backtracking, which helps in maximizing efficiency and performance of the overall system.

The other options may not serve the same purpose effectively. For instance, placing a check valve on the supply line does not prevent backflow after the hot water has been used, and it could hinder the flow to fixtures. Similarly, installing it at the main entrance might lead to complications in the overall system pressure and flow dynamics. Finally, placing check valves on every fixture is unnecessary and could create additional points of potential failure, complicating maintenance and system performance.