The EMM-3U Universal Electronic MiniZone Panel controls single-stage, multi-stage, conventional or heat pump heat/cool equipment and is used on two and three zone applications. Features include automatic zone changeover with 20-minute changeover timer, individual zone fan control, and LEDs to indicate System and Zone status. The EMM-3U uses virtually any Honeywell four-wire, single-stage, multi-stage, or Trol-A-Temp heat pump thermostat. Plus it uses spring-open/power-closed, spring-closed/power-open, and power-open/power-closed dampers. Includes optional ZoneMax Sensor for capacity control. Purge timer protects equipment between calls for heating and cooling. Unit interfaces with single or dual transformer equipment.