ABSTRACT
A fan coil unit with DX cooling and electric heating may take the form of two separate pieces; one piece being the supply fan, DX coil, and mixing box, and the other piece being a downstream electric duct heater. Hot water heating and chilled water cooling can be done as two-position control or proportional control. The chapter demonstrates the added complexity of a small air handler when we include economizer control. It focuses on the integration of all system control, into one working system, for fan coil units that require proportional control for one of its two possible modes. Dual-temp or two-pipe fan coil units have only a single coil. The coil can provide heating in the wintertime, when there is hot water in the pipe connected to it, and can provide cooling in the summertime, when chilled water is pumped to it.
