In a hydronic system, horizontal pipes should be sloped toward the ______.

In a hydronic system, horizontal pipes should be sloped toward the ______.

• A. Boiler
• B. Air Handling Unit
• C. Return Line
• D. Expansion Tank

Answer: (A)

In a hydronic system, you want to minimize air pockets and keep the flow reliable in every horizontal run. Sloping horizontal pipes toward the boiler uses gravity to guide any air and small amounts of water back to the heating unit where circulation continues. This helps purge points and prevents long sections from developing standing water or air locks, which can disrupt circulation and heat delivery. The other components listed aren’t the end points for drainage of a horizontal run—an air handling unit is a separate device, the expansion tank accommodates volume changes, and while the return line carries water back to the boiler, directing slope toward the boiler specifically supports returning any trapped air or water to the boiler for proper circulation and purging.

In a hydronic system, you want to minimize air pockets and keep the flow reliable in every horizontal run. Sloping horizontal pipes toward the boiler uses gravity to guide any air and small amounts of water back to the heating unit where circulation continues. This helps purge points and prevents long sections from developing standing water or air locks, which can disrupt circulation and heat delivery. The other components listed aren’t the end points for drainage of a horizontal run—an air handling unit is a separate device, the expansion tank accommodates volume changes, and while the return line carries water back to the boiler, directing slope toward the boiler specifically supports returning any trapped air or water to the boiler for proper circulation and purging.