On a one-pipe hydronic system, which device allows a single pipe to act as both supply and return main?

On a one-pipe hydronic system, which device allows a single pipe to act as both supply and return main?

• A. Check valve
• B. Air vent
• C. Diverter Tee
• D. Gate valve

Answer: (C)

In a one-pipe hydronic system, the same pipe must carry both the supply to radiators and the return flow back toward the boiler. A diverter tee is designed for this, providing an internal pathway that directs hot supply into the radiator while allowing the cooler return water to continue back along the same pipe toward the boiler. It effectively creates two flow paths within one pipe, enabling it to act as both the supply and the return main. A check valve only blocks flow in one direction and doesn’t create the dual-path arrangement needed for a single pipe to handle both roles. An air vent only removes air, and a gate valve is just a shut-off valve.

In a one-pipe hydronic system, the same pipe must carry both the supply to radiators and the return flow back toward the boiler. A diverter tee is designed for this, providing an internal pathway that directs hot supply into the radiator while allowing the cooler return water to continue back along the same pipe toward the boiler. It effectively creates two flow paths within one pipe, enabling it to act as both the supply and the return main.

A check valve only blocks flow in one direction and doesn’t create the dual-path arrangement needed for a single pipe to handle both roles. An air vent only removes air, and a gate valve is just a shut-off valve.