Three pipes coming from a piece of building equipment would most likely indicate which type of equipment?

• A. Boiler heater
• B. Heat exchanger
• C. Chiller
• D. Air handling unit

Answer: (A)

Seeing three water connections on a piece of equipment points to a hydronic heating device. A boiler supplies hot water or steam into the building loop, so it typically needs a supply line, a return line for the cooled water, and a third line that provides makeup or feedwater to maintain pressure and compensate for water loss. This three-pipe setup is characteristic of a boiler in a heating system.

In contrast, a heat exchanger can have multiple connections but isn’t defined by three pipes coming from a single unit, a chiller usually involves refrigerant piping plus separate chilled and condenser water circuits (often more than three lines), and an air handling unit primarily handles air through ducts rather than relying on three water pipes.