Four pipes and two tanks coming from a piece of building equipment would most likely indicate which equipment?

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

Answer: (B)

When you identify equipment by what’s connected to it, the number and type of pipes and any attached vessels tell you a lot. A chiller typically has two separate fluid circuits: a chilled-water loop that cools the building and a condenser-water loop that rejects heat. Each loop needs an inlet and an outlet, which adds up to four main pipes coming from the unit. The two tanks seen with the system often serve as expansion or receiver tanks tied to those loops, which is a common arrangement in chilled-water systems. That combination—four pipes for two distinct water circuits plus two tanks for each loop’s volume/pressure management—is the telltale sign of a chiller.

Boilers mainly show fuel supply, combustion air, exhaust, and a single water circuit, not two separate loops with associated tanks. Air handling units are focused on moving air and connect to ducts rather than large water pipelines with storage tanks. Heat exchangers exist inside systems and may have piping, but they don’t typically present two distinct circulating loops with two tanks as a recognizable external feature.