Horizontal pipes in a hydronic steam system should always slope towards the _________.

• A. Condenser
• B. Expansion Tank
• C. Radiator
• D. Boiler

Answer: (D)

When steam cools and condenses in the piping, the resulting condensate needs to return to the boiler. Horizontal sections are pitched toward the boiler so this condensate can flow back by gravity. This ensures a steady return flow, prevents pools and air pockets, and reduces the risk of water hammer, keeping the system efficient and properly pressurized. The slope is typically a light one—the idea is just enough to let condensate move back to the boiler while steam keeps moving to the radiators. If the pipe were pitched away from the boiler, condensate would tend to collect in the line, causing poor circulation and operational problems.