Sequence of operation for staged with reheat control - Verasys - LC-ZEC410-x - Field Device - ZEC410

Occupied mode:

• When the zone temperature is between the occupied heating and cooling setpoints inside of the bias, the primary air damper is at the minimum cfm and no mechanical heating runs.
• When the zone temperature rises above the cooling setpoint, the primary air damper increases the cfm and no mechanical heating runs.
• When a drop in zone temperature below the heating setpoint occurs, the supplemental heating coil is fully used before the reheat heat coil enables, and the damper opens at the minimum cfm.

Unoccupied mode:

• The primary air damper is at the minimum cfm and no mechanical heating runs when the zone temperature is between the unoccupied heating and cooling setpoints inside of the bias.
• When the zone temperature rises above the unoccupied cooling setpoint, the primary air damper increases the cfm (if available), and no mechanical heating runs.
• When the zone temperature drops below the unoccupied heating setpoint, the supplemental heating coil is fully used before the reheat heat coil enables. The damper is at the minimum cfm.

Unit enable: A network unit enable signal, controls the mode of the box.

Fan control (Optional): A parallel fan cycles on when a request for heat occurs. The fan remains off in all other states. Series fans run continuously in occupied mode. The fan moves from unoccupied mode to cycle on mode when it receives a call for heating or cooling.

Occupancy lighting switch (Optional):

• You can add an occupancy lighting switch to the box to temporarily set the VAV box to Standby mode when the occupancy is not detected. The zone switches back to occupied when the box detects occupancy.
• Standby mode uses standby temperature setpoints that are slightly higher or lower than the occupied cooling or heating setpoints, respectively. The VAV box also uses unoccupied flow setpoints in addition to the low temperatures.

Demand control ventilation (Optional):

• You can proportionally reset the minimum damper flows based on an air quality setpoint (CO₂) when the zone (CO₂) sensors wire to the boxes to detect the air quality in the zone.
• The reset of the damper minimum flows do not exceed the maximum value that you set. The CO₂ sensor with the highest value determines the reset when more than one CO₂ sensors are wired.

Figure 1. ZEC410-2 controller - VAV with incremental reheat control wiring example

Figure 2. ZEC410-2 controller wiring diagram