In a single-pipe baseboard loop, water flows through baseboard units in series before returning to the boiler. Which option describes this arrangement?

In a single-pipe baseboard loop, water flows through baseboard units in series before returning to the boiler. Which option describes this arrangement?

• A. In parallel with other zones
• B. Through each baseboard in parallel
• C. In a loop with separate feed and return pipes per unit
• D. Through each baseboard unit in series before returning to the boiler

Answer: (D)

In a single-pipe baseboard loop, the flow path is a single continuous circuit where water moves from the boiler into the first baseboard, then through the next units in order, and finally returns to the boiler. This means the baseboard units are placed in series along one loop, sharing the same flow rather than each having its own separate supply line. As hot water travels through the loop, it releases heat to each unit and gradually cools, so the water returning to the boiler is cooler than when it started. This arrangement is best described by the statement that water passes through each baseboard unit in series before returning to the boiler. The other descriptions imply parallel feed to units or a two-pipe setup with separate feed and return per unit, which does not match a single-pipe, in-series loop.

In a single-pipe baseboard loop, the flow path is a single continuous circuit where water moves from the boiler into the first baseboard, then through the next units in order, and finally returns to the boiler. This means the baseboard units are placed in series along one loop, sharing the same flow rather than each having its own separate supply line. As hot water travels through the loop, it releases heat to each unit and gradually cools, so the water returning to the boiler is cooler than when it started.

This arrangement is best described by the statement that water passes through each baseboard unit in series before returning to the boiler. The other descriptions imply parallel feed to units or a two-pipe setup with separate feed and return per unit, which does not match a single-pipe, in-series loop.