What advantage does a 4-pipe hydronic heating/cooling heating system have over a 2-pipe hydronic heating/cooling system?

Correct Answer: Option B — A 4-pipe hydronic heating/cooling system allows simultaneous heating and cooling of different zones, whereas a 2-pipe hydronic heating/cooling system does not.

Four-pipe hydronic systems dedicate separate supply and return lines for both chilled water and hot water loops. This complete separation enables distinct terminal units to provide simultaneous heating and cooling to different vessel zones regardless of overarching seasonal modes.