What distinguishes a four-pipe system from a two-pipe system in water heating systems?

In a four-pipe system, the primary distinction lies in its ability to provide both hot and chilled water simultaneously. This dual capability is achieved through the use of separate pipes for each function—one pair for hot water and another pair for chilled water. This allows for greater flexibility in heating and cooling individual spaces, as different areas can be maintained at varying temperatures based on specific needs.

In contrast, a two-pipe system is designed to carry either hot or chilled water at a time but not both simultaneously. This limits its ability to provide temperature control in different zones, as all connected units receive either heating or cooling based on what is currently flowing through the system.

By utilizing the four-pipe configuration, building managers can better manage energy consumption, improve comfort levels, and respond to varying heating and cooling demands in real-time. This is why the ability to supply both hot and chilled water is the definitive feature that sets a four-pipe system apart from its two-pipe counterpart.